Implant-based factor as possible risk for peri-implantitis.

Peri-implantitis is currently a topic of major interest in implantology. Considered one of the main reasons of late implant failure, there is an emerged concern whether implant characteristics could trigger inflammatory lesion and loss of supporting bone. The purpose of this narrative review is to provide an evidence based overview on the influence of implant-based factors in the occurrence of peri-implantitis. A literature review was conducted addressing the following topics: implant surface topography; implant location; occlusal overload; time in function; prosthesis-associated factors (rehabilitation extension, excess of cement and implant-abutment connection); and metal particle release. Although existing data suggests that some implant-based factors may increase the risk of peri-implantitis, the evidence is still limited to consider them a true risk factor for peri-implantitis. In conclusion, further evidences are required to a better understanding of the influence of implant-based factors in the occurrence of peri-implantitis. Large population-based studies including concomitant analyses of implant- and patient-based factors are required to provide strong evidence of a possible association with peri-implantitis in a higher probability. The identification of these factors is essential for the establishment of strategies to prevent peri-implantitis.

Related papers:

title: Long-term evaluation of submerged and nonsubmerged ITI solid-screw titanium implants: a 10-year life table analysis of 468 implants.
abstract: Submerged and nonsubmerged ITI solid-screw titanium implants were followed retrospectively from 1989 to 1993 and prospectively from 1994 on to analyze long-term prognosis in partially and fully edentulous patients.



A total of 468 implants were consecutively inserted in 191 patients from 1989 to 1998. Two hundred twenty-eight successfully integrated fixed-restoration implants and 238 with removable restorations were restored following a healing period of 4 to 6 months (9 months in sinus floor elevation sites). From 1994 on all implants inserted were documented annually up to 9 years. During examination the clinical status of the implants was analyzed and evaluated according to predefined criteria of success and this allowed the calculation of 10-year cumulative survival and success rates for 468 implants.



Two implants (0.43%) did not successfully integrate during the healing period, and 8 implants (1.7%) were classified as failures during follow-up (1 late failure under load, 7 with a progressive bone loss from 1 to 3 threads). Including 68 implants in subjects who dropped out (with a dropout rate of 14.4%), the 10-year cumulative survival and success rates were 99.2% and 96.4%, respectively.



Over the course of this long-term study, osseointegrated implants, once used as a last possible solution, became nearly standard in cases of single-tooth implants because of the high rate of long-term success. Life table analysis not only determines whether an implant is functioning, it also makes a statement about its clinical status according to strict success criteria.



The study demonstrated that ITI solid-screw titanium implants achieved success rates above 95% in a clinical center for an observation period of up to 10 years.

title: Nine- to fourteen-year follow-up of implant treatment. Part I: implant loss and associations to various factors.
abstract: The aim of the present study was to evaluate the long-term result of implant therapy, using implant loss as outcome variable.



Two hundred and ninty-four patients had received implant therapy (Brånemark System) during the years of 1988-1992 in Kristianstad County, Sweden. The patients were recalled to the speciality clinic 1 and 5 years after placement of the suprastructure. Between 2000 and 2002, 9-14 years after implant placements, the patients were again called in for a complete clinical and radiographic examination.



Two hundred and eighteen patients treated with 1057 implants were examined. Twenty-two patients had lost 46 implants and 12 implants were considered "sleeping implants". The overall survival rate was 95.7%. Implant loss appeared in a cluster in a few patients and early failures were most common. Eight patients lost more than one fixture. A significant relationship was observed between implant loss and periodontal bone loss of the remaining teeth at implant placement. Maxillary, as opposed to mandibulary implants, showed more implant loss if many implants were placed in the jaw. A significant relationship between smoking habits and implant loss was not found.



A history of periodontitis seems to be related to implant loss.

title: 10-Year Survival and Success Rates of 511 Titanium Implants with a Sandblasted and Acid-Etched Surface: A Retrospective Study in 303 Partially Edentulous Patients
abstract: This retrospective study assessed the 10-year outcomes of titanium implants with a sandblasted and acid-etched (SLA) surface in a large cohort of partially edentulous patients. 
 
 Records of patients treated with SLA implants between May 1997 and January 2001 were screened. Eligible patients were contacted and invited to undergo a clinical and radiologic examination. Each implant was classified according to strict success criteria. 
 
 Three hundred three patients with 511 SLA implants were available for the examination. The mean age of the patients at implant surgery was 48 years. Over the 10-year period, no implant fracture was noted, whereas six implants (1.2%) were lost. Two implants (0.4%) showed signs of suppuration at the 10-year examination, whereas seven implants had a history of peri-implantitis (1.4%) during the 10-year period, but presented with healthy peri-implant soft tissues at examination. The remaining 496 implants fulfilled the success criteria. The mean Plaque Index was 0.65 (±0.64), the mean Sulcus Bleeding Index 1.32 (±0.57), the mean Probing Depth 3.27 mm (±1.06), and the mean distance from the implant shoulder to the mucosal margin value −0.42 mm (±1.27). The radiologic mean distance from the implant shoulder to the first bone-to-implant contact was 3.32 mm (±0.73). 
 
 The present retrospective analysis resulted in a 10-year implant survival rate of 98.8% and a success rate of 97.0%. In addition, the prevalence of peri-implantitis in this large cohort of orally healthy patients was low with 1.8% during the 10-year period.

title: Implant dentistry: Long-term implant prognosis in patients with and without a history of chronic periodontitis: a 10-year prospective cohort study of the ITI dental implant system
abstract: Implant survival was lower in patients with implants replacing teeth lost on account of periodontitis.

title: In recognition of an implant pioneer: Professor Dr. André Schroeder.
abstract: An international pioneer of endosseous dental implant investigation and an esteemed dental educator from Berne, Switzerland, Professor André Schroeder was recently recognized by the Academy of Osseointegration with Honorary Fellowship in the Academy. In bestowing its highest honor on Professor Schroeder, the Academy paid tribute to one of the unsung giants in the field. His long and productive career in research and clinical science is only now receiving the worldwide acclaim it so richly deserves.

title: Long‐Term Effect of Surface Roughness and Patients' Factors on Crestal Bone Loss at Dental Implants. A Systematic Review and Meta‐Analysis
abstract: Publications from 2011 to 2015 were selected to evaluate effect of implant surface roughness on long-term bone loss as surrogate for peri-implantitis risk. 87 out of 2,566 papers reported the mean bone loss after at least 5 years of function. Estimation of the proportion of implants with bone loss above 1, 2, and 3 mm as well as analysis the effect of implant surface roughness, smoking, and history of periodontitis was performed. By means of the provided statistical information of bone loss (mean and standard deviation) the prevalence of implants with bone loss ranging from 1 to 3 mm was estimated. The bone loss was used as a surrogate parameter for "peri-implantitis" given the fact that "peri-implantitis" prevalence was not reported in most studies or when reported, the diagnostic criteria were unclear or of dubious quality. The outcome of this review suggests that peri-implant bone loss around minimally rough implant systems was statistically significant less in comparison to the moderately rough and rough implant systems. No statistically significant difference was observed between moderately rough and rough implant systems. The studies that compared implants with comparable design and different surface roughness, showed less average peri-implant bone loss around the less rough surfaces in the meta-analysis. However, due to the heterogeneity of the papers and the multifactorial cause for bone loss, the impact of surface roughness alone seems rather limited and of minimal clinical importance. Irrespective of surface topography or implant brand, the average weighted implant survival rate was 97.3% after 5 years or more of loading. If considering 3 mm bone loss after at least 5 years to represent the presence of "peri-implantitis," less than 5% of the implants were affected. The meta-analysis indicated that periodontal history and smoking habits yielded more bone loss.

title: Implant surface roughness and patient factors on long‐term peri‐implant bone loss
abstract: Dental implant placement is a common treatment procedure in current dental practice. High implant survival rates as well as limited peri-implant bone loss has been achieved over the past decades due to continuous modifications of implant design and surface topography. Since the turn of the millennium, implant surface modifications have focused on stronger and faster bone healing. This has not only yielded higher implant survival rates but also allowed modifications in surgical as well as prosthetic treatment protocols such as immediate implant placement and immediate loading. Stable crestal bone levels have been considered a key factor in implant success because it is paramount for long-term survival, aesthetics as well as peri-implant health. Especially during the past decade, clinicians and researchers have paid much attention to peri-implant health and more specifically to the incidence of bone loss. This could furthermore increase the risk for peri-implantitis, the latter often diagnosed as ongoing bone loss and pocket formation beyond the normal biological range in the presence of purulence or bleeding on probing. Information on the effect of surface topography on bone loss or peri-implantitis, a disease process that is to be evaluated in the long-term, is also scarce. Therefore, the current narrative review discusses whether long-term peri-implant bone loss beyond physiological bone adaptation is affected by the surface roughness of dental implants. Based on comparative studies, evaluating implants with comparable design but different surface roughness, it can be concluded that average peri-implant bone loss around the moderately rough and minimally rough surfaces is less than around rough surfaces. However, due to the multifactorial cause for bone loss the clinical impact of surface roughness alone on bone loss and peri-implantitis risk seems rather limited and of minimal clinical importance. Furthermore, there is growing evidence that certain patient factors, such as a history of periodontal disease and smoking, lead to more peri-implant bone loss.

title: Ultrastructural characterization of the implant/bone interface of immediately loaded dental implants.
abstract: Primary stability and an optimized load transfer are assumed to account for an undisturbed osseointegration process of implants. Immediate loaded newly designed titanium dental implants inserted in the mandible of minipigs were used for the characterization of the interfacial area between the implant surface and the surrounding bone tissue during the early healing phase. Histological and electron microscopical studies were performed from implant containing bone specimens. Two different load regimens were applied to investigate the load related tissue reaction. Histological and electron microscopical analysis revealed a direct bone apposition on the implant surfaces, as well as the attachment of cells and matrix proteins in the early loading phase. A striking finding of the ultrastructural immunocytochemical investigations was the synthesis and deposition of bone related proteins (osteonectin, fibronectin, fibronectin receptor) by osteoblasts from day one of bone/biomaterial interaction. Calcium-phosphate needle-like crystallites were newly synthesized in a time-related manner directly at the titanium surface. No difference in the ultrastructural appearance of the interface was found between the two loading groups. Our experimental data suggest that loading of specially designed implants can be performed immediately after insertion without disturbing the biological osseointegration process.

title: Cell and matrix reactions at titanium implants in surgically prepared rat tibiae.
abstract: The tissue response of rat tibiae to the surgical placement of commercially pure titanium implants was examined at 2, 6, 10, and 28 days. The transcortical placement of 1.5-mm x 2-mm implants resulted in the apposition of threaded implant surfaces within cortical and cancellous regions of the tibia. In all regions, evidence of bone formation was obtained through pre-embedding fracture of the implant from the bone tissue interface. Scanning electron microscopy examination of early responses revealed a fibrin clot and rapid formation of a loosely organized collagenous matrix. Many extravasated blood cells contacted the implant surface. At day 6, a more organized matrix containing many blood vessels opposed the implant surfaces, and few extravasated blood cells remained in contact with the implant surface. By day 10, the surgical wound was filled with woven bone that approximated the contours of the threaded implant. Later, few cells were attached to the retrieved implants. The consolidation of the forming matrix was clearly evident at 28 days. The tissue interface was an amorphous matrix that revealed the surface characteristics of the machined implant. Light microscopic analysis of ground sections indicated that, from day 6 onward, cells morphologically consistent with the osteoblastic phenotype were predominant within the gap between the surgical margin and implant surface. Osteoblastic cells had achieved the formation of an osteoid seam upon which bone formation progressed. The matrix that had formed represented woven bone containing many osteocytes. At day 6, evidence of remodeling was observed at sites distant from the surgical site, and by day 28 osteoclastic activity was observed at trabecular sites adjacent to the implant surface. The rat tibia model provides evidence of rapid formation of bone at implant surfaces.

title: Mediation of osteogenic differentiation of human mesenchymal stem cells on titanium surfaces by a Wnt-integrin feedback loop.
abstract: Peri-implant bone formation depends on the ability of mesenchymal cells to colonize the implant surface and differentiate into osteoblasts. Human mesenchymal stem cells (HMSCs) undergo osteoblastic differentiation on microstructured titanium (Ti) surfaces in the absence of exogenous factors, but the mechanisms are unknown. Wnt proteins are associated with an osteoblast phenotype, but how Wnt signaling regulates HMSC differentiation on microstructured Ti surfaces is not known. HMSCs were cultured on tissue culture polystyrene or Ti (PT [Sa = 0.33 μm, θ = 96°], SLA [Sa = 2.5 μm, θ = 132°], modSLA [hydrophilic-SLA]). Expression of calcium-dependent Wnt ligand WNT5A increased and canonical Wnt pathway ligands decreased on microstructured Ti in a time-dependent manner. Treatment of HMSCs with canonical ligand Wnt3a preserved the mesenchymal phenotype on smooth surfaces. Treatment with Wnt5a increased osteoblastic differentiation. Expression of integrins ITGA1, ITGA2, and ITGAV increased over time and correlated with increased WNT5A expression. Treatment of HMSCs with Wnt5a, but not Wnt3a, increased integrin expression. Regulation of integrin expression due to surface roughness and energy was ablated in WNT5A-knockdown HMSCs. This indicates that surface properties regulate stem cell fate and induce osteoblast differentiation via the Wnt calcium-dependent pathway. Wnt5a enhances osteogenesis through a positive feedback with integrins and local factor regulation, particularly though BMP signaling.

title: Survival/Success of Dental Implants with Acid-Etched Surfaces: A Retrospective Evaluation After 8 to 10 Years.
abstract: The aim of this study was to conduct a retrospective evaluation of the survival and success rates of dental implants with acid-etched surfaces after 8-10 years of function. Forty-four patients who received 183 implants 8-10 years ago were evaluated. Clinical examinations were performed around the implants and natural teeth. The following parameters were measured: visible plaque index (VPI), marginal bleeding index (MBI), probing depth (PD), bleeding on probing (BOP) and clinical attachment level (CAL). To considerer an implant as a success case, the following criteria were considered: absence of peri-implant infection and suppuration, absence of implant mobility, absence of persistent pain and dysesthesia and absence of radiolucency around the implant. Overall, 178 implants were categorized as surviving (97.3%), 155 were categorized as successful (84.7%), 5 implants (2.7%) were lost (1 in the maxilla and 4 in the mandible), and 3 implants were not under functional load (2.0 %). 20 implants were diagnosed with peri-implantitis. Thus, the survival rate was 97% and the success rate was 85%. In conclusion, implants with acid-etched surfaces showed high survival and success rates after a period of 8 to 10 years of function.

title: Long-term retrospective follow-up of turned and moderately rough implants in the edentulous jaw.
abstract: To compare the long-term clinical outcome of turned vs. moderately rough implants.



Patients treated with implants in the edentulous mandible and/or maxilla were invited for a clinical examination. After prosthesis removal, the pocket depth was measured and the bleeding scored. Also, a new radiograph was taken for bone loss evaluation. Patients were also requested to rate their satisfaction with the treatment.



One hundred and ninety-seven implants in 33 patients were evaluated. After a mean follow-up of 172 months (SD 42, range 120-252), the mean loss was 1.61 mm (SD 1.35, range 0.00-8.25). Bone loss was higher in the maxilla compared to the mandible (P < 0.001), and at implants, that was restored on implant level (P = 0.003). Multivariate analyses demonstrated a significant effect of implant surface roughness and time of loading on bone loss. Smoking, on the other hand, did not affect the outcome. Mean pocket probing depth was 3.64 mm (SD 0.96, range 1.25-7.25). A total of 4.1% of the implants demonstrated signs of peri-implantitis. The overall patient satisfaction rate was 98.5%.



Implant treatment in the edentulous jaw has a predictable long-term outcome with limited complications.

title: A retrospective comparison of oxidized and turned implants with respect to implant survival, marginal bone level and peri-implant soft tissue conditions after at least 5 years in function.
abstract: Long-term clinical follow-up studies comparing different implant surfaces with regard to survival and marginal conditions are rare.



The objective of this study was to compare the clinical performance of turned and oxidized implants after more than 5 years of loading.



One hundred three patients (43 men, 60 women; mean age 67.4 years, range 32-90) previously treated with 287 implants (Nobel Biocare AB, Gothenburg, Sweden), 133 with turned surface (MKIII, Nobel Biocare AB) and 154 with an oxidized surface (MKIII, TiUnite, Nobel Biocare AB) were examined after at least 5 years of loading (mean 82 months, range 60-93 months). The implants had been used for support of single crowns (33 patients/36 implants), partial bridges (39 patients/103 implants), or full bridges (31 patients/148 implants) following an early loading protocol (14 patients /54 implants), a one-stage protocol (32 patients/59 implants) or a two-stage protocol (57 patients/174 implants). Clinical examinations of bleeding on probing (BoP) and pocket depth (PD) were performed. Intraoral radiographs were used for assessments of marginal bone levels (MBLs).



Seven turned implants and one oxidized implant failed, giving overall cumulative survival rates of 94.7 and 99.4%, respectively. There were no differences for BoP scores (0.5 ± 0.7 vs 0.4 ± 0.6) and PD measurements (1.7 ± 0.8 mm vs 1.8 ± 1.0 mm) parameters when comparing turned and oxidized implants, respectively. The mean MBL was 1.8 ± 0.8 mm and 2.0 ± 0.9 mm for turned and oxidized implants, respectively, after more than 5 years in function (NS). Frequency distribution of MBL loss showed no statistically significant differences between the two surfaces. A total of four implants (1.4%) (three oxidized and one turned) showed a PD > 3 mm, MBL > 4 mm, and BoP. However, none of these were associated with suppuration on examination.



The present study does not state any differences in implant failure, MBL, presence of bleeding or PD around implants when comparing turned and oxidized titanium implants after at least 5 years of function.

title: Implant survival and marginal bone loss at turned and oxidized implants in periodontitis-susceptible smokers and never-smokers: a retrospective, clinical, radiographic case-control study.
abstract: Little is known about the long-term outcome of oxidized surface oral implants, especially in periodontitis-susceptible smokers. The aim of this study is to determine implant survival and marginal bone loss at turned and oxidized implants in smokers and never-smokers with periodontitis.



Forty smokers and 40 never-smokers with experience of advanced periodontal disease, treated with implants 5 years previously, are included in this study. Groups were matched for sex, oral hygiene, and implant distribution, and patients were subgrouped by implant surface type (turned or oxidized).



The overall implant survival rate was 96.9% in never-smokers and 89.6% in smokers. Compared with oxidized implants, turned implants failed more frequently in smokers. In smokers, mean (standard error of the mean) marginal bone loss at 5 years was 1.54 (0.21) mm at turned and 1.16 (0.24) mm at oxidized implants. In never-smokers, significantly greater bone loss was found at oxidized implants, 1.26 (0.15) mm, than at turned implants, 0.84 (0.14) mm. Oxidized implants demonstrated similar bone loss for both groups. Turned implants lost significantly more bone in smokers. Compared with never-smokers, the smokers' likelihood ratio for implant failure was 4.68, 6.40 for turned and 0.00 for oxidized implants.



The results of the study underscore the need for prevention and cessation of smoking. Turned implants failed more frequently and lost more marginal bone in smokers. In contrast, oxidized implants showed similar failure rates and bone loss in smokers and never-smokers. Turned implants displayed less bone loss than oxidized implants in never-smokers. Oxidized surface implants are more suitable for patients susceptible to periodontitis who smoke.

title: The association between selected risk indicators and severity of peri-implantitis using mixed model analyses.
abstract: The aim of the study was to assess possible risk indicators for peri-implantitis at different levels of severity using multi-level analyses.



One hundred and nine subjects attended the examination, 69 females and 40 males. Mean time of implants in function was 8.4 years (standard deviation 4.6) (subject level). The participants were examined clinically and radiographically. Information regarding general health and habits was gathered, with special emphasis on smoking, oral hygiene and susceptibility to periodontitis. The relation between possible risk indicators and the following features were assessed: • Detectable peri-implantitis: detectable radiographic bone loss (>0.4 mm) and inflammation • Overt peri-implantitis: radiographic peri-implant bone loss 2.0 mm and bleeding on probing /suppuration at pocket probing depth 4 mm.



Multi-level statistical analyses identified location in the maxilla as risk indicator for detectable peri-implantitis. Regarding overt peri-implantitis, gender (male) and history of periodontitis were identified as risk indicators.



Individuals with a history of periodontitis were prone to peri-implantitis, peri-implant bone loss ≥ 2.0 mm and overt in the present study. No association was found between smoking and peri-implant disease in the present study population.

title: Cross-sectional study on the prevalence and risk indicators of peri-implant diseases.
abstract: To evaluate the prevalence of peri-implant diseases in a university patient sample and to analyse possible risk variables associated with their occurrence.



One hundred and eighty-six patients with 597 implants were examined clinically and radiographically. The mean period of function was 5.5 years (range 1 to 16.5 years). A subgroup analysis was performed for implants with a minimum function time of 5 years. Outcome measures were implant failures, prevalence and risk indicators of peri-implant diseases. In order to identify statistically significant risk indicators of peri-implant mucositis and peri-implantitis multi-level logistic regression models were constructed.



The prevalence of peri-implantitis and peri-implant mucositis on patient levels were 12.9% (13.3% for ≥ 5 years) and 64.5% (64.4% for ≥ 5 years), respectively. Multi-level analysis showed that a high plaque score (OR = 1.365; 95% CI: 1.18 to 1.57, P < 0.001) was a risk indicator for periimplant mucositis, while augmentation of the hard or soft tissue at implant sites had a protective effect (OR = 0.878 95% CI: 0.79 to 0.97, P = 0.01). It was also shown that the odds ratio for having peri-implant mucositis increased with the increase of plaque score in a dose-dependent manner. With respect to peri-implantitis, loss of the last tooth due to periodontitis (OR = 1.063; 95% CI: 1.00 to 1.12, P = 0.03) and location of the implants in the maxilla (OR = 1.052, 95% CI: 1.00 to 1.09, P = 0.02) were identified as statistically significant risk indicators.



Within the limitations of this study, the history of periodontal disease was the most significant risk indicator for peri-implantitis and the level of oral hygiene was significantly associated with peri-implant mucositis.

title: Extent and location of bone loss at dental implants in patients with peri-implantitis.
abstract: Peri-implantitis is an infectious disease, which leads to loss of supporting bone around dental implants. To evaluate the extent and location of bone loss, 43 patients with peri-implantitis were examined. The bone loss was clinically measured at the time of dental surgery. Data revealed that 25% of subjects had bone loss associated with all their implants although the majority of the subjects had fewer than 50% of their implants affected by bone loss. A total number of 264 implants were examined and 131 of those had peri-implantitis associated bone loss. The pattern of bone loss at implants varied between and within subjects and location in the jaws. The highest proportion of implants with peri-implantitis was found in the upper jaw and within this group, at implants located in the incisor area of the upper jaw; the lowest was the canine area of the lower jaw. The highest proportion of implants that lost ≥ 2/3 of their bone support was found in the incisor area of the maxilla. We concluded that in the presence of peri-implant inflammation, bone quantity and characteristics may influence the progression of peri-implantitis bone loss at dental implants. We hypothesize that the ability of the bone to withstand occlusal forces will be altered as consequence of the loss of bone at the neck of the implants. To achieve an understanding of the local degradation of bone due to peri-implantitis, we need to analyze the microstructure of the bone as well the cellular biology of the peri-implant inflammation.

title: Prevalence of peri-implant inflammatory disease in patients with a history of periodontal disease who receive supportive periodontal therapy.
abstract: To describe the status of implants in periodontally compromised patients who regularly receive supportive periodontal therapy (SPT) and to determine the factors associated to peri-implant inflammatory disease in those patients.



Clinical and radiographic data of implants in periodontal patients who, after being treated and included in a SPT programme, wore implant prostheses for at least 6 months were recorded. The implants were classified according to the criteria of the 6th European Workshop on Periodontology in health, mucositis and peri-implantitis. Logistic regression analysis was performed to analyse the individual and adjusted effects of each study variable on mucositis or peri-implantitis, using SUDAAN to account for clustering (multiple implants within the patient).



A total of 786 implants were placed in 239 patients. At patient level, 60.3%, 24.7% and 15.1% were classified as healthy, mucositis and peri-implantitis patients, respectively. At implant level, the respective percentages were 77.4%, 12.8% and 9.8%. For mucositis, at implant level, the adjusted ORs indicate a significant association with plaque index (P = 0.050), type of periodontitis (P = 0.030) and location (P = 0.045). For peri-implantitis, the adjusted ORs indicate a significant association with plaque index (P < 0.001) and location (P = 0.002).



The prevalence of peri-implant inflammatory disease in periodontal patients who regularly undergo SPT is clinically significant. The factors associated with peri-implant inflammatory disease were plaque index and implant location, and mucositis was also affected by the type of periodontitis the patient had.

title: Peri-implantitis and late implant failures in postmenopausal women: a cross-sectional study.
abstract: Systemic bone loss is a major cause of fractures in postmenopausal women and may also affect the jawbone; however, its consequences on the success of dental implants remain poorly understood.



In this cross-sectional study, the relation between self-reported osteoporosis and the success rate of dental implants in an adult female population was evaluated. The primary outcome parameters were the occurrence of peri-implantitis and late implant failures. Women with unknown bone status were excluded from the study. The potential confounders age, recipient site, smoking, periodontal disease and time of loading were recorded.



Data from 203 women with a mean age of 63 ± 9 years and 967 dental implants were investigated. The patients were classified according to their medical history into one of three groups: osteoporosis (47 women), osteopenia (16 women) and healthy controls (140 women). Patients with unknown bone status (n=26) were excluded. The multi-level statistical analysis showed no association between peri-implantitis [odds ratio (OR) 2.1; p=0.6] or implant failure [hazards ratio (HR) 2.5; p=0.2] and systemic bone loss.



No relation was found between osteoporosis and peri-implantitis in an adult female population.

title: The influence of implant location and position characteristics on peri-implant pathology..
abstract: Peri-implant pathology is a multifactorial disease, incorporating biological and biomechanical components in its pathogenesis; however; few studies address the possible risk factors. This study investigated the effect of implant location and position characteristics on the occurrence of Peri-implant pathology. A total of 1350 patients with dental implants were included 270 patients with peri-implant pathology and 1080 healthy controls. Results demonstrated that in the absence of bacterial plaque and smoking, the variable proximity of the implant to other implants or teeth revealed a significant difference between groups with a protective effect, but not in the presence of bacterial plaque and smoking.

title: Effect of prosthetic restoration on implant survival and success
abstract: The objective of this work was to evaluate the effect of prosthetic restoration on the survival of implants and on the incidence of implant-related complications.



From a prospectively documented clinical study, 1569 implants placed in 630 patients (mean age 59.56 years) were evaluated. Selection criteria were a conventional loading protocol, prosthetic restoration with at least one follow-up, and a minimum observation period of 9 months. Implants that failed before prosthetic restoration were excluded. The sample included 1345 tissue-level implants and 104 bone-level implants (Straumann), and 120 Replace implants (Nobel Biocare). The observation period ranged between 9 months and 11 years after prosthetic restoration (mean 4.0 years; SD 2.5). The implants were restored with single crowns (n = 557), fixed dental prostheses (n = 594), or removable dental prostheses (RDP) (n = 418). In the RDP group, 356 implants were restored with telescoping crowns, 22 with bar units 24 with bar joints, and 16 with locator attachments. The incidence of implant-related complications and failures was analyzed by use of Kaplan-Meier survival curves. Cox regression analysis was used to identify possible risk factors.



Twenty-seven failures (1.8%; loosened or removed implants) were observed after prosthetic restoration; the incidence of failure was 3% for implants placed in males and 1% for implants placed in females. Other factors had no effect on the incidence of failure. Peri-implantitis (n = 29) and marginal bone loss >2 mm without acute inflammation (n = 6) also resulted in a 4% incidence of severe implant-related complications (62 of 1569; success 96%). Cox regression analysis revealed combined tooth-implant-supported restorations as a significant risk-reducing factor for severe implant-related complications (hazard ratio, HR = 0.34; P = 0.04). There was, furthermore, a tendency toward a greater incidence of complications for implants restored with RDPs than for single crowns (P = 0.08). Other factors, for example location (anterior/posterior, maxilla/mandible), age, sex, or implant placement combined with bone augmentation, had no significant effect on the incidence of implant-related complications (P values ranging between 0.16 and 0.94).



The type of support has a small but significant effect on implant prognosis. For detailed analysis of the effects of loading by different types of prosthetic restoration, larger sample sizes are required.

title: Prevalence of Peri-implant Diseases: Analyses of Associated Factors.
abstract: AIM. Identify the relationship between specific factors (age, sex, smoking, time of prosthesis in function, implant location, and width of peri-implant keratinized mucosa) and peri-implant diseases in patients from the Center of Research and Continuing Education in Implant Dentistry (CEPID) at the Federal University of Santa Catarina (UFSC), Brazil.



A cross-sectional study was conducted in 193 patients that had received 725 external-hexed cylindrical implants supporting functional prosthesis for at least 1 year (range from 1-9 years). Clinical examination included probing depths, bleeding on probing and/or suppuration. Radiographic exam was conducted to measure peri-implant bone levels.



There was no statistically significance in the association between prevalence of peri-implant diseases and age, sex, time with prostheses in function and implant location variables independently. There was a statistically significant association between the independent variables of smoking and the width of keratinized peri-implant mucosa less than 2mm, and the presence of peri-implant diseases. When all the categories were evaluated together in relation with the peri-implant diseases, the prostheses in function for 5 years and more had association with presence of both, peri-implant mucositis an peri-implantitis. Peri-implantitis prevalence was higher for males with the prostheses in use for 5 years or more. Peri-implant mucositis was more associated with the participants over 57 years of age, with systemic disease and with the prostheses in function for more than 5 years.



Smoking habits and the width of peri-implant keratinized mucosa as independent variables were associated with the prevalence of peri-implant diseases.

title: Periodontal status of tooth adjacent to implant with peri-implantitis.
abstract: To evaluate the relationship between peri-implantitis and the periodontal health of the adjacent tooth, the periodontal status of the teeth adjacent and contralateral to the implants with and without peri-implantitis.



Fifty-three subjects with existing dental implants and chronic periodontitis were examined in this cross-sectional study. Seventy implants were categorized into peri-implantitis (n = 42) and healthy/mucositis (n = 28) groups. The periodontal and peri-implant status, including probing depth (PD), clinical attachment level (CAL), and gingival recession (GR) were measured at 6 sites around the implants and the teeth adjacent and contralateral to those implants. In total 560 sites of the 70 teeth/implant sets, the association between the periodontal status at the near and away sites of the teeth (according to implant) and the implant status (without/with peri-implantitis) was examined.



A significantly different mean PD (5.01 ± 1.69, 4.42 ± 1.8, 3.55 ± 0.88, and 3.71 ± 1.07 mm, p < 0.001) and CAL (6.02 ± 2.36, 4.89 ± 2.04, 4.35 ± 1.11, and 4.35 ± 1.5 mm, p < 0.001) were noted at the near sites of the teeth adjacent to the implants with peri-implantitis when compared with the away sites of adjacent and contralateral teeth and the near sites of contralateral teeth. With generalized estimating equation (GEE), the presence of peri-implantitis (β  = 1.041 mm, confidence interval = 0.646-1.435, and p < 0.001; β  = 0.857 mm, confidence interval = 0.279-1.434, and p < 0.004) and tooth location (β  = 0.65 mm, confidence interval = 0.4-0.9, and p < 0.001; β  = 0.682 mm, confidence interval = 0.34-1.024, and p < 0.001) were significantly associated with the values of the PD and CAL of the teeth. Moreover, the factor of examining sites (i.e. near and away sites of the tooth) was significantly associated with CAL (β = 0.304 mm, confidence interval = 0.019-0.588, and p = 0.036) and GR (β = 0.136 mm, confidence interval = 0.02-0.252, and p = 0.022).



The existence of peri-implantitis, the tooth location, and the examining site are significantly associated with the periodontal measurements of the remaining teeth.



Peri-implant health is related to the periodontal health of the natural teeth close to the dental implant.

title: Site‐level risk predictors of peri‐implantitis: A retrospective analysis
abstract: The goal of the present investigation was to identify site-level factors that might allow prognostication of individual implants in partially dentate patients with multiple non-splinted restorations.



We analysed clinical and radiographic characteristics of 222 non-splinted single implants in function for at least 5 years in 86 partially dentate individuals at the time of functional loading and at follow-up, with the outcome variable being peri-implantitis. Principal component analysis identified factors contributing to greatest variability and linear discriminant analysis coupled with Random Forest Classifier used to identify risk predictors.



After controlling for patient-level factors, the following characteristics were associated with significantly increased risk for peri-implantitis: Periodontal disease on adjoining teeth at the time of restoration (Odds Ratio (OR): 8.0), implant placement at a depth of 6 mm or more in relation to the CEJ of adjacent tooth (OR: 8.5), asymmetric prosthesis (OR: 4.3), history of tooth loss due to periodontitis (OR: 2.4) and a mean baseline plaque index of 1.6 or more (OR: 7.9).



Our findings suggest that a system that incorporates both subject level and implant-level factors is required to effectively prognosticate the success of individual implants.

title: Histological evaluation of peri-implant bone at implants subjected to occlusal overload or plaque accumulation.
abstract: Breakdown of bone around oral implants following occlusal overload or plaque accumulation was evaluated in monkeys. 5 screw-type implants of pure titanium (Astra Tech) were inserted in the mandible of 4 monkeys (Macaca Fascicularis). 6 months after insertion of the implants a fixed partial prosthesis was mounted on the 2 implants in 1 of the lateral segments. The prosthesis was in supra-occlusal contact with an antagonizing splint and caused a lateral directed excessive occlusal load (overload). Implants retaining the prosthesis were brushed 1 x week and subgingival cleaning was performed 1 x month. The remaining implants were never cleaned and, additionally, a cotton cord was placed around the abutments of these implants to promote plaque accumulation. 6 out of 8 implants with occlusal overload became loose. 2 of these were lost, whereas the remaining 4 were retained in the jaws. After 18 months of occlusal load or plaque accumulation, the monkeys were sacrificed. Tissue blocks with the implants were infiltrated and embedded in acrylic resin. Approximately 50 microns thick sections of the implants and surrounding tissues were made. All implants with plaque accumulation were osseointegrated, but exhibited an average histologic marginal bone loss of 2.4 mm (range: 0.8-4.0 mm). Of the 6 implants with occlusal overload available for histologic analysis, 2 implants in 1 monkey had lost osseointegration completely and 2 other implants were osseointegrated in the apical part only, whereas the remaining 2 were still osseointegrated but exhibited a bone loss of 1.8-1.9 mm.

title: Observation of the bone surrounding an overloaded implant in a novel rat model.
abstract: Although the recent success rates of dental implants are quite high, it is still true that loading during the bone healing period may be more likely to discourage osseointegration and that occlusal overloading might result in implant failure, even after osseointegration is established. The purposes of this study were to establish an appropriate experimental animal model and to histologically assess degenerative changes in established osseointegration under early and excessive occlusal loading.



Forty rats were divided into control and experimental groups. The maxillary first and second molars on both sides were extracted, and machined-surface titanium implants were placed. In the experimental group, 2 or 4 weeks after implant placement, abutments that were designed to overload the implants were attached. Control group implants did not receive abutments and remained in situ 2 or 4 weeks. Sections were prepared and observed histologically.



Attrition of occluding opposite teeth and shiny spots on the abutments indicated that this model was useful for histologic investigation of the remodeling and bone changes around implants. Specimens showed remarkable bone loss and deterioration of osseointegration when overloading began at 2 weeks. Overloading applied after 4 weeks of healing induced active bone resorption in remote areas of the implants after 15 days of occlusion, while bone resorption at the interface was limited.



The authors successfully established an implant occlusion model using rats. This model revealed degenerative changes in osseointegration and/or in the bone around implants upon excessive occlusal loading. These results emphasize the risks associated with immediate loading and overloading. This is the first study to reveal the possibility of bone loss around overloaded implants in the absence of infection using a small animal model.

title: The influence of controlled occlusal overload on peri-implant tissue. Part 3: A histologic study in monkeys.
abstract: The influence of experimental occlusal overload on peri-implantitis in monkeys (Macaca fascicularis) has been examined to explain the pathology of the disease that develops in the tissue around osseointegrated implants. In the first article of this series, it was reported that bone resorption was not observed around implants when occlusal trauma was produced by a super-structure that was in supraocclusal contact with an excess occlusal height of approximately 100 microns, provided there was no inflammation in the peri-implant tissue. In the second part of the study, experimental inflammation was created in the peri-implant tissue, and occlusal overload was produced by a superstructure with an excess occlusal height of 100 microns. Notable bone resorption was observed around the implant with the passage of time. These results suggested that, in addition to the control of inflammation in peri-implant tissue, traumatic occlusion may play a role in bone breakdown around the implant. In the present study, while the peri-implant tissue was kept in an inflammation-free state, bone level changes around the implants were investigated when various levels of traumatic force were exerted. The supraoccluding prostheses were defined as excessively high by 100 microns, 180 microns, and 250 microns, respectively. The heights were determined with an image analysis device, and the bone responses around the implants induced by the traumatic forces were investigated. The results showed that bone resorption around implants tended to increase with 180 microns or more excessive height of the superstructure. This suggests that the threshold of excessive height of the superstructures at which peri-implant tissue breakdown may start is approximately 180 microns. It is also suggested that there is a possibility of bone resorption around the implants caused by excess occlusal trauma, even when there is no inflammation in peri-implant tissue.

title: Histological features of peri-implant bone subjected to overload.
abstract: The aim of this review has been to investigate the histological findings of bone structure surrounding implants subjected to excessive load.



Clinical and pre-clinical histological studies that observed overloaded intraoral implants were included.



All included studies (n=15) were conducted on animals. Most of them failed to find pathological alteration in the microstructure of bone surrounding overloaded implants. Overload and infection alone may induce bone loss, but related lesions have different and peculiar features.



The different histological features observed around implants subjected to overload or to ligature-induced peri-implantitis may indicate a specific pathogenetic mechanism for overload or infection-induced loss of osseointegration. The clinical significance of these findings should be confirmed in human studies.

title: Does excessive occlusal load affect osseointegration? An experimental study in the dog.
abstract: The purpose of this study was to evaluate the effect of excessive occlusal load following placement of titanium implants in the presence of healthy peri-implant mucosal tissues.



Mandibular bilateral recipient sites in six Labrador dogs were established by extracting premolars and molars. After 3 months, two TPS (titanium plasma sprayed) implants and two SLA (sandblasted, large grit, acid etched) implants were placed on each side of the mandible in each dog. Three implants were lost in the initial healing phase, leaving 45 implants for evaluation. Following 6 months of healing, gold crowns were placed on implants on the test side of the mandible. The crowns were in supra-occlusal contact with the opposing teeth in order to create excessive occlusal load. Implants on the control side were not loaded. Plaque control was performed throughout the experimental period. Clinical measurements and standardised radiographs were obtained at baseline and 1, 3 and 8 months after loading. At 8 months, the dogs were killed and histologic analyses were performed.



At 8 months, all implants were osseointegrated. The mean probing depth was 2.5+/-0.3 and 2.6+/-0.3 mm at unloaded and loaded implants, respectively. Radiographically, the mean distance from the implant shoulder to the marginal bone level was 3.6+/-0.4 mm in the control group and 3.7+/-0.2 mm in the test group. Control and test groups were compared using paired non-parametric analyses. There were no statistically significant changes for any of the parameters from baseline to 8 months in the loaded and unloaded implants. Histologic evaluation showed a mean mineralised bone-to-implant contact of 73% in the control implants and 74% in the test implants, with no statistically significant difference between test and control implants.



In the presence of peri-implant mucosal health, a period of 8 months of excessive occlusal load on titanium implants did not result in loss of osseointegration or marginal bone loss when compared with non-loaded implants.

title: Impact of implant overloading on the peri-implant bone in inflamed and non-inflamed peri-implant mucosa.
abstract: To assess the impact of overloading on peri-implant bone level and the bone-to-implant contact (BIC) in the presence of healthy or inflamed peri-implant tissues.



Four screw-shaped machined implants were placed bilaterally in the mandible of four beagle dogs and left submerged for 3 months. Prosthetic abutments were connected either in supra-occlusal contact with the opposite teeth (overloaded) or in infra-occlusal position (unloaded). In each dog, cotton floss ligatures were placed unilaterally around abutments to promote plaque accumulation; the contralateral side was brushed three times a week. There were four experimental sites, two implants in each: loaded uninflamed (LU), loaded inflamed (LI), unloaded uninflamed (UU), and unloaded inflamed (UI). Clinical and radiographic parameters were recorded at baseline and every 3 months throughout the observation period. At 12 months, the dogs were sacrificed and histomorphometric analysis was performed.



Implants with ligature-induced peri-implantitis presented high inflammatory indices throughout the observation period. Clinical parameters did not change from baseline for both LU and UU. Loading significantly increased the percentage of BIC (BIC%) (P<0.05) and slightly increased crestal bone resorption, but not apical to the implant neck. Both LI and UI groups showed significant peri-implant bone loss (P<0.01), mostly horizontal on the buccal aspect and angular on the lingual aspect, which exposed implant threads. Loading significantly (P<0.05) increased implant thread exposure due to buccal and lingual vertical bone resorption.



In the presence of uninflamed peri-implant mucosa, overloading of implants in the dog model increased BIC% and slightly reduced marginal bone level. However, resorption did not progress beyond the implant neck. Overloading aggravated the plaque-induced bone resorption when peri-implant inflammation was present.

title: The effects of off-axial loading on periimplant marginal bone loss in a single implant.
abstract: A discrepancy between crown width and implant width may contribute to potential bending overload.



The purpose of this study was to evaluate the influence of the crown width-fixture width ratio on crestal bone loss around single dental implants placed in the first molar area.



Seventy-six participants (37 men and 39 women; age range, 25-83 years; mean age [standard deviation], 56.3 ±10.6 years) were selected from individuals who were treated with single tooth implants between May 2004 and December 2009 at the Department of Periodontology, Gangnam Severance Dental Hospital. The marginal bone-level change and gingival parameters (modified plaque index and modified sulcus bleeding index) of the periimplant soft tissue were assessed 1 year after functional loading. The perpendicular distances from the vertical axis of each fixture to the most distal aspect of the crown and most mesial aspect of the crown were measured in the periapical radiographic view.



No statistically significant relationship was found between crown width-fixture width ratio and the 1-year bone-level change (Pearson correlation, P=.06; Spearman rank test, P=.14). No statistically significant differences in marginal bone-level change were found between axial and nonaxial loading implants (2 independent samples t test; P=.19). The bone-level change for the surface adjacent and distant to the cantilever was not statistically significant (paired t test; P=.10).



From this study, it may be concluded that off-axial loading that results from a high crown width-fixture width ratio does not increase the risk for periimplant marginal bone loss after 1-year functional loading.

title: Occlusal overload and bone/implant loss.
abstract: The aim of this search was to assess the biological consequences that overload might have on already osseointegrated oral implants through a systematic screening of the scientific literature.



Detailed searches through PUBMED, OVID, EMBASE and LILACS databases were made. Articles published up to December 2011 and those reported on the clinical, radiographic and/or histological outcome of oral implants subjected to so-called overload were considered eligible for inclusion. Identified studies were assessed by one non-blinded reviewer according to well-defined inclusion and exclusion criteria. When doubt arose, the co-authors were counselled until final agreement was obtained. The PICO questions formulated was:"what is the effect of overload vs. no overload on bone/implant loss in clinically stable implants?"



The database searches as well as additional hand searching, resulted in 726 potentially relevant titles. Eventually, 16 clinical and 25 animal studies were considered relevant to the topic. After inclusion/exclusion criteria assessment, all clinical studies and all but three animal studies and one systematic review were considered at high risk of bias and excluded. The included animal studies did not reveal an association between overload and peri-implant bone loss in the absence of peri-implant inflammation, whereas in its presence, overload seemed to aggravate the peri-implant tissue breakdown.



The effect of implant overload on bone/implant loss in clinically well-integrated implants is poorly reported and provides little unbiased evidence to support a cause-and-effect relationship. The PICO question remained unanswered. At the animal level, "overload", mimicked by supra-occlusal contacts acting in an uninflamed peri-implant environment, did not negatively affect osseointegration and even was anabolic. In contrast, supra-occlusal contacts in the presence of inflammation significantly increased the plaque-induced bone resorption.

title: Effects of occlusal overload on peri-implant tissue health: a systematic review of animal-model studies.
abstract: This study systematically evaluates the effect of occlusal overload (OV) on peri-implant tissue health in animal studies.



MEDLINE, EMBASE, and LILACS databases were searched for articles published up to and including January 2010. Studies that reported outcomes of non-splinted titanium dental implants submitted to OV were eligible for inclusion. Probing depth (PD), clinical attachment level (CAL), radiographic and histologic distances from the implant base to the most coronal point of bone-to-implant contact (RDIB and DIB, respectively), and bone density (BD) were the main outcomes of interest.



Two controlled trials were included in this review and both were considered at a high risk of bias. The marked heterogeneity between studies did not allow data to be combined for meta-analyses. Two studies reported no association between OV and peri-implant tissue breakdown in the absence of dental plaque, with PD and CAL varying from 2 to 3 mm at the end of the experiments. In the presence of plaque accumulation, OV played a key role in peri-implant tissue breakdown (PD change: 5.3 mm; DIB: 6.0 mm). Trends suggested that OV may increase BD.



Data on OV on stable implants are limited and conflicting. OV may lead to bone loss in the presence of dental plaque and to an increase in BD in areas where plaque control is performed.

title: Bone resorption around fixtures in edentulous patients treated with mandibular fixed tissue-integrated prostheses.
abstract: Bone loss around osseointegrated titanium fixtures supporting mandibular fixed prostheses has been measured by means of stereoscopic intraoral radiography. Forty-six patients treated with the osseointegration implant method according to Brånemark have been followed for an observation period of up to 6 years. The bone loss was small, approximately 0.5 mm during the first postsurgical year and thereafter 0.06 to 0.08 mm annually. Poor oral hygiene and clenching of teeth significantly influenced bone loss. More bone was lost around the medial fixtures than around the more posterior ones.

title: A prospective 15-year follow-up study of mandibular fixed prostheses supported by osseointegrated implants. Clinical results and marginal bone loss.
abstract: In this prospective study 47 edentulous patients were treated with mandibular fixed prostheses supported by osseointegrated Brånemark implants and followed for 12 to 15 years. Three (1%) of the 273 inserted implants were lost, two before and one six years after placement of the fixed prosthesis. The cumulative success rate (CSR) of the implants was 98.9% both after 10 and 15 years. None of the fixed prostheses was lost and at the last follow-up, all patients had stable fixed prostheses in function (CSR 100%). The marginal bone loss around the implants was small, on average 0.5 mm during the first post surgical year and thereafter about 0.05 mm annually. More bone was lost around the anterior implants than around the most posterior ones. Smoking and poor oral hygiene had significant influence on bone loss, while occlusal loading factors such as maximal bite force, tooth clenching and length of cantilevers were of minor importance. It is concluded that the long-term results of the mandibular implant treatment were extremely successful, regarding both the fixed prostheses and implant stability. Bone resorption around the implants, albeit limited, was influenced by several factors, smoking and oral hygiene appeared to be most important.

title: Histopathologic observations on late oral implant failures.
abstract: Despite good success rates of osseointegrated oral implants, failures do occur. To minimize losses, failure mechanisms should be elucidated.



This study sought to describe the morphology of tissues surrounding late failed Brånemark implants in relation to their clinical and radiographic findings to acquire a better understanding of the etiologic factors.



Ten failed implants and their surrounding tissues were consecutively retrieved from nine patients after prosthesis placement (late losses). On radiographs, a radiolucent line was visible around nine clinically mobile implants. Tightening of the abutment screw evoked pain at seven mobile implants. Clinically, no other visual inflammatory sign or symptom was manifest. A fistula originated from one stable implant, surrounded on radiographs by a diffuse bone rarefaction. Retrieved implants were electrochemically dissolved. Intact tissue-implant thin (1 micron) and ultrathin (70-80 nm) sections were analyzed with light and transmission electron microscopy.



Peri-implant marginal tissues displayed moderate inflammatory infiltrates located adjacent to and beneath the junctional epithelium. One patient affected by oral lichen planus displayed an intense lymphocyte/plasma cell-dominated immune reaction. Deep peri-implant tissues surrounding mobile implants consisted of a dense, fibrous tissue capsule with minimal inflammation. Epithelial downgrowth was observed around four implants. Small areas of nonmineralized bone in contact with the implant were noticed in the apical portion of two implants. One implant was almost entirely colonized by bacterial plaque with the exception of its apical portion, where bone-implant contact was observed. The stable implant was characterized by bone-implant contact.



Altogether clinical, radiographic, and histologic findings indicated that two major etiologic factors might have been implicated in the failure process of the investigated implants: excessive occlusal load in relation to the bone-supporting capacity and, in two cases, infection.

title: Stress and Inflammation as a Detrimental Combination for Peri-implant Bone Loss
abstract: The causes of peri-implant bone loss continue to be controversial. To determine the impact of biomechanical stress and inflammation, we investigated a total of 80 interforaminal implants in situ for more than 10 years. Two stress groups, with 14 patients each, were established: a low-stress situation with single-standing implants, and an increased-stress situation with splinted implants. To categorize inflammation, we introduced a Composite Inflammation Score using 4 inflammatory parameters. Peri-implant bone loss was calculated from digital panoramic radiographs. To differentiate between the effects of stress and inflammation, we compared bone loss in both stress groups at equivalent levels of inflammation. With greater Composite Inflammation Score values, a clear discrepancy between single-standing and splinted implants was evident (p = 0.117/0.000, regression analysis; p = 0.135/0.000, analysis of variance; p = 0.002, t tests). While stress and inflammation alone may not necessarily be detrimental factors, the presence of stress heightens peri-implant bone loss significantly as inflammation increases.

title: Distinguishing predictive profiles for patient-based risk assessment and diagnostics of plaque induced, surgically and prosthetically triggered peri-implantitis.
abstract: To investigate whether specific predictive profiles for patient-based risk assessment/diagnostics can be applied in different subtypes of peri-implantitis.



This study included patients with at least two implants (one or more presenting signs of peri-implantitis). Anamnestic, clinical, and implant-related parameters were collected and scored into a single database. Dental implant was chosen as the unit of analysis, and a complete screening protocol was established. The implants affected by peri-implantitis were then clustered into three subtypes in relation to the identified triggering factor: purely plaque-induced or prosthetically or surgically triggered peri-implantitis. Statistical analyses were performed to compare the characteristics and risk factors between peri-implantitis and healthy implants, as well as to compare clinical parameters and distribution of risk factors between plaque, prosthetically and surgically triggered peri-implantitis. The predictive profiles for subtypes of peri-implantitis were estimated using data mining tools including regression methods and C4.5 decision trees.



A total of 926 patients previously treated with 2812 dental implants were screened for eligibility. Fifty-six patients (6.04%) with 332 implants (4.44%) met the study criteria. Data from 125 peri-implantitis and 207 healthy implants were therefore analyzed and included in the statistical analysis. Within peri-implantitis group, 51 were classified as surgically triggered (40.8%), 38 as prosthetically triggered (30.4%), and 36 as plaque-induced (28.8%) peri-implantitis. For peri-implantitis, 51 were associated with surgical risk factor (40.8%), 38 with prosthetic risk factor (30.4%), 36 with purely plaque-induced risk factor (28.8%). The variables identified as predictors of peri-implantitis were female sex (OR = 1.60), malpositioning (OR = 48.2), overloading (OR = 18.70), and bone reconstruction (OR = 2.35). The predictive model showed 82.35% of accuracy and identified distinguishing predictive profiles for plaque, prosthetically and surgically triggered peri-implantitis. The model was in accordance with the results of risk analysis being the external validation for model accuracy.



It can be concluded that plaque induced and prosthetically and surgically triggered peri-implantitis are different entities associated with distinguishing predictive profiles; hence, the appropriate causal treatment approach remains necessary. The advanced data mining model developed in this study seems to be a promising tool for diagnostics of peri-implantitis subtypes.

title: Occurrence of peri‐implant diseases and risk indicators at the patient and implant levels: A multilevel cross‐sectional study
abstract: High prevalence rates of peri-implant diseases have been reported; however, the lack of standardization of definition criteria has lead to variations in the observed estimates. In addition, scarce data are available concerning patient and implant related factors associated to peri-implantitis. The aim of this study was to determine the prevalence of peri-implant diseases and their risk indicators at the patient and implant levels.



One hundred forty-seven patients with 490 dental implants were included. Dental implants were clinically and radiographically evaluated to determine their peri-implant conditions. Patient-related conditions and implant and prosthetic-related factors were recorded. Multivariable Poisson regression was fitted and prevalence ratios (PR) were reported.



85.3% of implants (95%CI 80.2 to 90.4) had mucositis and 9.2% (95%CI 4.7 to 13.7) had peri-implantitis. 80.9% (95%CI 73.8 to 86.8), and 19.1% (95%CI 12.6 to 25.5) of patients had mucositis and peri-implantitis. At the patient level, it was observed an increased probability of peri-implantitis in individuals with pocket depths ≥6 mm (PR = 2.47) and with ≥4 implants (PR = 1.96). Smoking increased the probability of peri-implantitis by three times (PR = 3.49). The final multilevel Poisson regression model at the implant level indicated that platform switching reduced the probability of peri-implantitis (PR = 0.18) and implants in function for ≥5 years increased this probability (PR = 2.11). The final model including patient and implant level indicators demonstrated that higher time of function (PR = 2.76) and smoking (PR = 6.59) were associated with peri-implantitis.



Peri-implant diseases are highly prevalent in the studied sample, and factors associated with the occurrence of peri-implantitis were presence of pockets ≥6 mm, smoking, time of function, and type of platform.

title: Peri-implant diseases may be associated with increased time loading and generalized periodontal bone loss: preliminary results.
abstract: The aim of this study was to evaluate the prevalence of peri-implant diseases around Branemark system implants in Brazilians and the possible relationship with periodontal bone loss, systemic condition, and demographic profile. A total of 113 individuals were enrolled in this study, and they received 347 implants. The implants were clinically and radiographically examined and diagnosed as healthy implants, mucositis, or peri-implantitis. The demographic and systemic profiles of the individuals were assessed via questionnaires, and the time of loading was obtained from files. The presence of periodontal bone loss in partially edentulous patients was determined by standardized radiographic evaluation. With regard to implants, the prevalence was 60.5% (n = 210), 32% (n = 111), and 7.5% (n = 26) for healthy tissues, mucositis, and peri-implantitis, respectively. No correlation was found between peri-implant tissue conditions and socioeconomic status, body mass index, smoking status, gender, age, diabetes mellitus, osteopenia, and osteoporosis. Statistically significant positive correlations were found in implants with mucositis and peri-implantitis in relation to time of loading and with peri-implantitis in relation to periodontal bone loss in the 4 quadrants (P < .05). Presence of peri-implant diseases may be associated with the increasing time of loading and generalized periodontal bone loss.

title: Prevalence and risk factors for peri-implant disease in Belgian adults.
abstract: This study aimed to evaluate in a Belgian population the frequence of mucositis and peri-implantitis in patients with implants of at least 5 years of function. Another outcome was to access implants/patients characteristics as possible risk indicators for peri-implantitis.



One hundred and three patients (38 males/65 females) with a total of 266 implants were examined. Implants had been inserted in university hospitals as well as in private clinics and the mean time of implants in function was 8.5 years (±3.2). The average patients' age within the population was 62 years (±13.4). General health informations were recorded as well as habits regarding smoking, maintenance visits and oral hygiene. Full mouth clinical parameters (PlI, BoP, PPD) were assessed and radiographs taken to determine the periodontal status and implants diagnosis.



Prevalences of mucositis and peri-implantitis at the patient's level were respectively 31% and 37%. They were 38% and 23% at the implant's level. Subjects older than 65 years (OR = 1.39) and those with active periodontitis (OR = 1.98) were prone to peri-implantitis. The association was stronger for hepatitis (OR = 2.92) and totally edentulous patients (OR = 5.56). Finally, at the implant's level, a significant correlation was found in the multi-level analyses between rough surfaces, overdentures and peri-implantitis.



After 8.5 years an important proportion (±60%) of implants presented biological complications. Furthermore, a positive correlation was showed between age, periodontitis, absence of teeth, rough surfaces and peri-implantitis. Consequently, patients with such characteristics should be informed before implant placement and frequently re-called after for maintenance visits.

title: Prevalences of peri-implantitis and peri-implant mucositis: systematic review and meta-analysis.
abstract: Due to the inconsistent definitions, reporting methods and study characteristics, prevalences of peri-implant diseases significantly varied in studies. This study aimed to systematically analyze implant-based and subject-based prevalences of peri-implant diseases and assess clinical variables potentially affecting the prevalence.



Electronic search of studies was conducted using MEDLINE (PubMed), EMBASE and Web of Science. Publication screening, data extraction, and quality assessment were performed.



Clinical studies having an at least average three-year follow-up period were selected. The numbers of subjects and implants in the studies had to be equal to or more than thirty.



Forty seven studies were selected and prevalences of peri-implant diseases were analyzed. Since heterogeneity existed in each outcome (I2=94.7, 95.7, 95.3, and 99.3 for implant-based and subject-based peri-implantitis and peri-implant mucositis, respectively), the random-effects model based on the DerSimonian and Laird method, which incorporate an estimate of heterogeneity in the weighting, was applied to obtain the pooled prevalence. Weighted mean implant-based and subject-based peri-implantitis prevalences were 9.25% (95% Confidence Interval (CI): [7.57, 10.93]) and 19.83% (CI [15.38, 24.27) respectively. Weighted mean implant-based and subject-based peri-implant mucositis prevalences were 29.48% (CI: [22.65, 36.32]) and 46.83% (CI: [38.30, 55.36]) respectively. Functional time and implant to subject ratio were associated with subject-based peri-implantitis prevalence, but not peri-implant mucositis prevalences.



Peri-implant diseases were prevalent and prevalence of peri-implantitis increased over time. Prevalences of peri-implantitis and peri-implant mucositis might not be highly associated since the prevalences were influenced by distinct variables. The results should be carefully interpreted because of data heterogeneity.



Peri-implant diseases affect a significant number of dental implants and patients. It is important to understand the difficulties in diagnosis of these diseases and risk factors which may be modified to reduce the potential for disease occurrence or progression.

title: Prevalence and risk variables for peri-implant disease in Brazilian subjects.
abstract: The aim of this study was to verify the prevalence of peri-implant disease and analyse possible risk variables associated with peri-implant mucositis and peri-implantitis. The study group consisted of 212 partially edentulous subjects rehabilitated with osseointegrated implants.



The implants placed were examined clinically and radiographically to assess the peri-implant status. The degree of association between peri-implant disease and various independent variables was investigated using a multinomial regression analysis.



The prevalence of peri-implant mucositis and peri-implantitis were 64.6% and 8.9%, respectively. In univariate modelling, healthy peri-implant subjects presented lower plaque scores, less periodontal bleeding on probing, and less time elapsed since placement of supra-structures. In multivariate analyses, the risk variables associated with increased odds for having peri-implant disease included: gender, plaque scores, and periodontal bleeding on probing. Presence of periodontitis and diabetes were statistically associated with increased risk of peri-implantitis. The only two factors, which did not contribute to the presence of the disease, were the time elapsed since placement of supra-structures and the frequency of visits for maintenance care.



Our data suggest that subjects with periodontitis, diabetes, and poor oral hygiene were more prone to develop peri-implantitis.

title: Incidence of peri-implantitis and oral quality of life in patients rehabilitated with implants with different neck designs: A 10-year retrospective study.
abstract: To evaluate peri-implant bone loss, the presence of peri-implantitis, aesthetic satisfaction, and quality of life in patients with implant-based prosthetic restorations using implants with or without smooth necks, placed in different bone positions.



400 patients received 1,244 implants: 515 with smooth neck monitored over an average of 6.44 ± 2.55 years and 729 without smooth neck monitored over 5.61 ± 2.52 years. Radiographic bone loss, presence of periimplantitis, implant loss, quality of life (OHIP-14), and patient satisfaction with prosthetic esthetics were evaluated, comparing groups.



120 implants developed peri-implantitis, 15 with a 2.5 mm smooth neck and 105 without smooth neck. Patients without smooth-necked implants showed a worse quality of life with statistically significant difference (p < 0.001). Patient satisfaction with prostheses was higher among the group without smooth neck.



Implants with smooth polished necks would appear to suffer less bone loss and peri-implantitis, and lead to better patient quality of life. However, implants without smooth necks placed crestally led to higher patient satisfaction with aesthetics.

title: Mucositis, peri-implantitis, implant success, and survival of implants in patients with treated generalized aggressive periodontitis: 3- to 16-year results of a prospective long-term cohort study.
abstract: The aim of this prospective study is to evaluate the prevalence of mucositis, peri-implantitis, implant success, and survival in partially edentulous patients treated for generalized aggressive periodontitis (GAgP) and in periodontally healthy individuals.



Thirty-five patients treated for GAgP and 18 periodontally healthy patients orally rehabilitated with osseointegrated implants participated in the study. They were first examined 2 to 4 weeks before extraction of the non-retainable teeth (baseline) and 3 weeks after insertion of the final abutments. Additional examinations were performed during a 3-month recall schedule over a 5- to 16-year period (mean, 8.25 years). At every session, clinical parameters were recorded. At 1, 3, 5, 10, and 15 years after insertion of the superstructure, a microbiological and radiographic examination was performed.



The results show implant survival rates of 100% in periodontally healthy individuals versus 96% in GAgP patients. The implant success rate was 33% in GAgP patients and 50% in periodontally healthy individuals. In GAgP patients, mucositis was present in 56% and peri-implantitis in 26% of the implants. In periodontally healthy individuals, 40% of the implants showed mucositis and 10% peri-implantitis. GAgP patients had a five times greater risk of implant failure, a three times greater risk of mucositis, and a 14 times greater risk of peri-implantitis.



These results suggest that patients with treated GAgP are more susceptible to mucositis and peri-implantitis, with lower implant survival and success rates.

title: Cement-associated peri-implantitis: a retrospective clinical observational study of fixed implant-supported restorations using a methacrylate cement.
abstract: Cement-retained fixed implant-supported restorations involve the risk of excess cement, which can associate peri-implantitis. In connection with routine therapy using a methacrylate cement (Premier Implant Cement, Premier(®) Dental Products Company, Plymouth Meeting, PA, USA) to retain fixed implant-supported restorations, complications, that is, inflammations, were developed in some cases. After removing the suprastructure and the abutment, residual excessive cement was found. For this reason, all implant-supported restorations that had been fixed with this type of methacrylate cement were reevaluated and retreated.



In a retrospective clinical observational study including 71 patients with 126 implants, the findings made during retreatment were documented. In all cases, the suprastructure and the abutment were removed. For recementation, Temp Bond ( USA) was used. If an inflammation had developed, a follow-up appointment was scheduled 3-4 weeks later.



In 59.5% of the implants, cement residues were identified. Bleeding on probing was diagnosed at 80% of the implants with excess cement and suppuration at 21.3% of the implants. After removal of the excess cement and recementation with Temp Bond, a 76.9% reduction in bleeding on probing was found at follow-up. Suppuration was not found around any of the implants at follow-up.



Excess cement left in the implant-mucosal interface caused bleeding on probing in most cases and suppuration in some. The removal of excess cement after cementation should be given high priority. In this retrospective observational study, an unusually high number of implants with excess cement after cementation was found with the methacrylate cement applied in the study.

title: Peri-Implantitis Associated with Type of Cement: A Retrospective Analysis of Different Types of Cement and Their Clinical Correlation to the Peri-Implant Tissue.
abstract: The cementation of fixed implant-supported dental restorations involves the risk of leaving excess cement in the mouth which can promote biofilm formation in the peri-implant sulcus. As a result, an inflammation may develop.



The aim of the present study was to investigate the clinical effect of two different luting cements on the peri-implant tissue.



Within the scope of a retrospective clinical follow-up study, the prosthetic structures of 22 patients with 45 implants were revised. In all cases, a methacrylate cement (Premier Implant Cement [PIC], Premier® Dental Products Company, Plymouth Meeting, PA, USA) had been used for cementation. In 16 additional patients with 28 implants, the suprastructures were retained with a zinc oxide-eugenol cement (Temp Bond [TB], . These patients were evaluated in the course of routine treatment.



In both populations, the retention time of the suprastructures was similar (TB 3.77 years, PIC 4.07 years). In the PIC cases, 62% of all implants had excess cement. In the TB cases, excess cement was not detectable on any of the implants. Bleeding on probing was significantly more frequent on implants cemented with PIC (100% with and 94% without excess cement) than on implants cemented with TB (46%). Pocket suppuration was observed on 89% of the PIC-cemented implants with excess cement (PIC without excess cement 24%), whereas implants with TB were not affected by it at all. The peri-implant bone loss was significantly greater in the PIC patients (with excess cement 1.37 mm, without excess cement 0.41 mm) than it was in the TB patients (0.07 mm).



The frequency of undetected excess cement depends essentially on the type of cement used. Cements that tend to leave more undetected excess have a higher prevalence for peri-implant inflammation and cause a more severe peri-implant bone loss.

title: Cement‐associated peri‐implant mucositis. A 1‐year follow‐up after excess cement removal on the peri‐implant tissue of dental implants
abstract: Methacrylate-based cements seem to promote peri-implant tissue inflammation even in the absence of excess cement.



The present study deals with the question of whether the removal of methacrylate cement from the peri-implant sulcus will lead to peri-implant tissues free of inflammation on a 1-year follow-up basis.



Implant supported suprastructures that had been in the mouth for at least 3.5 years either cemented with methacrylate (premier implant cement [PIC]) or zinc eugenol (temp bond [TB]) cement were compared. All superstructures in 33 patients with a total of 61 implants (35 with PIC and 26 with TB) were removed and excess cement, bleeding on probing (BOP), suppurationen and probing depth were documented. Excess cement found was removed, and in all cases the suprastructure was recemented with TB. Patients were followed up after 4 weeks (F1) and 1 year (F2).



Excess cement was found around 60% of the implants with PIC. No excess cement was found around implants with TB. At the time of revision therapy, BOP was found around 100% of the implants with PIC and excess cement (PIC+), 93% around implants with PIC but no excess cement (PIC-), and around 42% of the TB-cemented implants (Chi-squared P < .01). Suppuration was observed in 86% of the PIC+ implants, in 14% of the PIC- implants and in 0% of the TB implants (Chi-squared P < .01). At the time of both F1 and F2, the inflammation parameters, that is BOP and suppuration, on implant level were significantly reduced in the PIC+ cases (McNemar's test P < .01). For PIC-, BOP was significantly reduced at both points in time (P < .05). For TB no differences were found. Probing depth at F2 had significantly decreased in all groups (t test P < .05).



The removal of excess cement and recementation with TB had an anti-inflammatory effect on the peri-implant tissues after 1 year.

title: The positive relationship between excess cement and peri-implant disease: a prospective clinical endoscopic study.
abstract: Cement-retained restorations are commonly used on dental implants. Residual excess cement after placement of fixed partial dentures has been associated with clinical and radiographic signs of peri-implant disease. The purpose of this study was to explore the relationship between excess dental cement and peri-implant disease using the dental endoscope.



Thirty-nine consecutive patients with implants exhibiting clinical and/or radiographic signs of peri-implant disease were studied. Patients were enrolled in the study during a 5-year period in a private periodontal practice. Twelve of these patients had similar implants without signs of inflammation; these implants served as controls. There were 20 controls and 42 test implants. All were evaluated using a dental endoscope initially, and all but one implant was evaluated at a 30-day follow-up. Results from both groups were assessed by two trained operators and recorded.



None of the controls and all 42 of the test implants had clinical signs of peri-implant disease at initial treatment. Excess cement was found in none of the controls and 34 of the test sites. Thirty days after cement removal, 25 of 33 test sites from which the cement was removed had no clinical or endoscopic signs of inflammation.



Excess dental cement was associated with signs of peri-implant disease in the majority (81%) of the cases. Clinical and endoscopic signs of peri-implant disease were absent in 74% of the test implants after the removal of excess cement.

title: The influence of the cementation margin position on the amount of undetected cement. A prospective clinical study.
abstract: To evaluate the amount of undetected cement after cementation and cleaning of implant-supported restorations.



Fifty three patients were treated with 53 single implant-supported metal-ceramic restorations. The subgingival location of the margin of each implant was measured with a periodontal probe mesially, distally, buccaly, and lingually(,) resulting in 212 measurements. The data were divided into four groups: equally with tissue level (14 samples), 1 mm subgingivally (56), 2 mm (74), and 3 mm (68) below tissues contour. Metal-ceramic restorations were fabricated with occlusal openings and cemented on standard abutments with resin-reinforced glass-ionomer. After cleaning, a radiograph was taken to assess if all cement had been removed. Then the abutment/crown unit was unscrewed for evaluation. All quadrants of the specimens and peri-implant tissues were photographed and analyzed with Adobe Photoshop. Two proportions were calculated: (1) the relation between the cement remnants area and the total area of the abutment/restoration and (2) the relation between the cement remnants and the total area of implant soft tissue contour. Significance set to 0.05.



Excess on the crown groups: 1 (0.002 ± 0.001); 2 (0.024 ± 0.005); 3 (0.036 ± 0.004); 4 (0.055 ± 0.007). Undetected excess increased when the margin was located deeper subgingivally (P = 0.000), significant difference was found among all groups (P ≤ 0.05). Remnants in the soft tissue groups: 1 (0.014 ± 0.006); 2 (0.052 ± 0.011); 3 (0.057 ± 0.009); 4 (0.071 ± 0.012). The increase of the remnants was statistically reliable (P = 0.0045), significant difference was found between group 1 and 2 (P ≤ 0.05). Radiographic evaluation showed that cement remnants mesially were visible in four cases of 53 or 7.5%, and in six cases of 53 distally (11.3%).



The deeper the position of the margin, the greater amount of undetected cement was discovered. Dental radiographs should not be considered as a reliable method for cement excess evaluation.

title: Excess cement and the risk of peri‐implant disease – a systematic review
abstract: The aim of this systematic review was to assess the role of excess cement as risk indicator for peri-implant diseases.



A systematic literature search with the keywords peri-implant disease, peri-implant mucositis, peri-implantitis, excess cement, cemented, and screw-retained restorations was performed for articles published by June 2016 using MEDLINE and EMBASE electronic databases, complemented by hand searching.



The included 26 publications referring to 21 study groups were published between 1999 and 2016 and comprised 945 subjects with 1010 cemented implant restorations in 10 prospective and eight retrospective studies and eight case reports/series with pronounced heterogeneity of the study designs. Prevalence of peri-implant diseases varied between 1.9% and 75% of the implants with cemented restorations, with proportions of 33-100% associated with excess cement. In publications including early follow-ups and regular recall intervals, peri-implant disease was mostly detected at an early stage. Cofactors, such as type of abutment (standardized or individualized) and cementum medium used, did not have a significant influence, while higher prevalence of peri-implant diseases was found with immediate loading or cementation subsequent to reentry, and with cemented vs. screw-retained restorations.



Excess cement was identified as a possible risk indicator for peri-implant diseases and was more frequently observed with soft tissue healing periods shorter than 4 weeks. To reduce the risk of peri-implant disease associated with excess cement, a crown margin at the level of the mucosal margin providing sufficient access is recommendable, and soft tissue maturation and early follow-ups after restoration placement should be assured.

title: Prevalence and predictive factors for peri-implant disease and implant failure: a cross-sectional analysis.
abstract: Long-term studies worldwide indicate that peri-implant inflammation is a frequent finding and that the prevalence of peri-implantitis correlates with loading time. Implant loss, although less frequent, has serious oral health and economic consequences. An understanding of predictive factors for peri-implant disease and implant loss would help providers and patients make informed decisions.



A cross-sectional study was performed on 96 patients with 225 implants that were placed between 1998 and 2003. Implant placement data were collected from patient records, and patients presented for a clinical and radiographic follow-up examination. Implant status and periodontal status were determined, the data were analyzed to determine the prevalence of peri-implant disease or implant loss, and a predictive model was tested.



The mean follow-up time for the patients was 10.9 years. The implant survival rate was 91.6%. Peri-implant mucositis was found in 33% of the implants and 48% of the patients, and peri-implantitis occurred in 16% of the implants and 26% of the patients. Individuals with peri-implantitis were twice as likely to report a problem with an implant as individuals with healthy implants. Peri-implantitis is associated with younger ages and diabetes at the time of placement and with periodontal status at the time of follow-up. Implant loss is associated with diabetes, immediate placement, and larger-diameter implants.



One in four patients and one in six implants have peri-implantitis after 11 years. The data suggest that periodontal and diabetes status of the patient may be useful for predicting implant outcomes.

title: Investigation of the Association Between Cement Retention and Prevalent Peri-Implant Diseases: A Cross-Sectional Study.
abstract: The aim of this study is to examine the association between retention type (cement-retained versus screw-retained restorations) and prevalence of peri-implant diseases in a German university-treated population.



Data were analyzed from individuals that underwent clinical and radiographic peri-implant examinations as part of a university-based cross-sectional study from September 2011 to October 2012.



Data from 139 individuals (mean age: 57.59 years) having 394 implants were analyzed: 192 implants supporting single crowns and 202 fixed partial dentures. Overall, 11.9% of the participants had peri-implantitis, whereas 68.9% had peri-implant mucositis. Crude odds ratios (95% confidence intervals) for peri-implantitis and peri-implant mucositis for cement- versus screw-retained restorations were 1.43 (0.45, 4.60) and 0.89 (0.53, 1.48), respectively. Results remained non-significant in multivariable models adjusting for type of restoration and smoking (all P values >0.50). There was also no effect of splinting restorations on disease prevalence in adjusted analyses (P values >0.32).



In this university-treated sample, there is no association between the type of prosthesis retention and peri-implant diseases. Current findings show that, when appropriate selection and removal of cement is performed, cement retention is not a risk indicator for peri-implant diseases.

title: Comparison of Clinical, Radiographic, and Immunologic Inflammatory Parameters Around Dental Implants with Cement-Retained and Screw-Retained Restorations: A 5-Year Prospective Cohort Study in Men.
abstract: To compare bleeding on probing (BoP), probing depth (PD; ≥ 4 mm), radiographic (peri-implant crestal bone loss [CBL]), and immunologic inflammatory (interleukin-1beta [IL-1β] and matrix metalloproteinase-9 [MMP-9]) parameters around dental implants with cement-retained (CR) and screw-retained (SR) implant-supported crowns.



Based on the mode of retention of the restoration, 51 patients were divided into two groups: Group 1, consisting of 26 single implants restored with CR crowns, and Group 2, consisting of 25 single implants restored with SR crowns. Peri-implant BoP, PD, and CBL were scored, and levels of IL-1β and MMP-9 in the peri-implant crevicular fluid (PICF) in both groups were measured in duplicate using enzyme-linked immunosorbent assay. Full-mouth mechanical debridement was performed biannually in both groups. Statistical analysis was performed using Kruskal-Wallis test with the significance level set at P < .05.



The mean CBL among implants in groups 1 and 2 was 1.7 ± 0.5 mm and 1.7 ± 0.4 mm, respectively. There was no statistically significant difference in mean BoP, PD, and CBL among implants in both groups (P > .05). There was no statistically significant difference between groups 1 and 2 in the PICF levels of IL-1β (7.3 ± 0.5 and 7.2 ± 0.5, respectively) and MMP-9 (165 ± 9.4 and 182 ± 10.6, respectively) (P > .05).



The mode of retention of implant-supported crowns does not appear to affect their clinical correlations with BoP, PD, CBL, and levels of IL-1β and MMP-9 in the PICF when zinc oxide eugenol cement is used.

title: The influence of margin location on the amount of undetected cement excess after delivery of cement-retained implant restorations.
abstract: The aim of this study was to evaluate the amount of the residual cement excess after cementation and cleaning of implant-supported restorations with various positions of the margins.



Twenty-five casts with embedded implant analogs and flexible soft-tissue imitation were used in the study. Individual abutments with different position of the margin - from 1 mm supragingivally to 3 mm below the gingival level - were modelled and divided equally into five groups. The same amount of polished metal crowns was luted to prosthetic abutments, excess cement was cleaned and the restorations were removed for evaluation of the undetected cement remnants. All quadrants of each specimen were photographed for calculation of the ratio between the cement remnants area and the total specimen area using Adobe Photoshop. Afterwards, cement remnants were cleared from each specimen and weighed with analytical balances.



The measurements in all the groups consisted of (1) the relation between the cement remnants area and the total area of the specimen; and (2) cement excess weight in grams after cleaning: group 1 (0.0111 ± 0.021; 0.0003 ± 0.0001 g); group 2 (0.0165 ± 0.019; 0.0008 ± 0.0003 g); group 3 (0.0572 ± 0.028; 0.0013 ± 0.0005 g); group 4 (0.1158 ± 0.054; 0.0051 ± 0.0013 g); and group 5 (0.1171 ± 0.059; 0.0063 ± 0.0021 g). Results showed significant increase of undetected cement quantity, as the restoration margins were located deeper subgingivally, using weighting (P=0) and calculation of proportion (P=0). There was a significant correlation between evaluation techniques (r=0.889; P=0).



The amount of residual cement after cleaning increased as the restoration margins were located more subgingivally.

title: In vitro effects of dental cements on hard and soft tissues associated with dental implants
abstract: Dental cements for cement‐retained restorations are often chosen based on clinician preference for the product's material properties, mixing process, delivery mechanism, or viscosity. The composition of dental cement may play a significant role in the proliferation or inhibition of different bacterial strains associated with peri‐implant disease, and the effect of dental cements on host cellular proliferation may provide further insight into appropriate cement material selection.  The purpose of this in vitro study was to investigate the cellular host response of bone cells (osteoblasts) and soft tissue cells (gingival fibroblasts) to dental cements.  Zinc oxide (eugenol and noneugenol), zinc phosphate, and acrylic resin cements were molded into pellets and directly applied to confluent preosteoblast (cell line MC3T3 E1) or gingival fibroblast cell cultures (cell line HGF) to determine cellular viability after exposure. Controls were defined as confluent cell cultures with no cement exposure. Direct contact cell culture testing was conducted following International Organization for Standardization 10993 methods, and all experiments were performed in triplicate. To compare either the MC3T3 E1 cell line, or the HGF cell line alone, a 1‐way ANOVA test with multiple comparisons was used (&agr;=.05). To compare the MC3T3 E1 cell line results and the HGF cell line results, a 2‐way ANOVA test with multiple comparisons was used (&agr;=.05).  The results of this study illustrated that while both bone and soft tissue cell lines were vulnerable to the dental cement test materials, the soft tissue cell line (human gingival fibroblasts) was more susceptible to reduced cellular viability after exposure. The HGF cell line was much more sensitive to cement exposure. Here, the acrylic resin, zinc oxide (eugenol), and zinc phosphate cements significantly reduced cellular viability after exposure with respect to HGF cells only.  Within the limitation of this in vitro cellular study, the results indicated that cell response to various implant cements varied significantly, with osteoblast proliferation much less affected than gingival fibroblast cells. Furthermore, the zinc oxide noneugenol dental cement appeared to affect the cell lines significantly less than the other test cements.

title: Evaluation of the solubility of dental cements in artificial saliva of different pH values.
abstract: The aim of this study was to determine the solubility of dental cements in artificial saliva of different pH values. A total of 180 specimens--20 specimens (20 mm diameter x 1.5 mm thickness) for each dental cement-were prepared. After the specimens were weighed, they were set in the media with different pH values. After 24 hours, 72 hours, seven days, and 28 days, the specimens were taken out, dried in a desiccator, and re-weighed. Percentage of solubility at each time period was calculated as 100 per cent times weight loss divided by the initial weight of the specimen. Analysis of variance and LSD multiple comparison test were applied. It was found that cement type, storage time, and medium pH exerted statistically significant (p<0.001) effects on solubility. Among the tested cement types, zinc phosphate cement (Adhesor Carbofine) presented the highest solubility. In terms of medium pH, the cements seemed to be most stable in the medium with pH 7.

title: The Impact of Residual Subgingival Cement on Biological Complications Around Dental Implants: A Systematic Review
abstract: To perform a systematic review on the impact of residual subgingival cement on peri-implant diseases and crestal bone loss.  MEDLINE, SCOPUS, ISI Web of Knowledge and Cochrane Central Register of Controlled Trials (CENTRAL) databases were used to identify articles published without time limits.  A total of 6 articles were selected for a total of 389 patients (687 implants). The studies were heterogeneous and had a moderate-to-high risk of bias, but met the inclusion criteria. Four of 6 studies were published by the same research group and assessed similar populations over time. A positive relationship between residual cement and peri-implant inflammation was observed. Data on peri-implant probing depths and crestal bone loss were reported in 1 study.  Residual subgingival cement seems to be strongly associated with peri-implant mucositis which is a risk factor for increased probing depths crestal bone loss and peri-implantitis. Zinc oxide eugenol cements should be preferred to resin cements especially in patients with a history of periodontitis.

title: A new implant design for crestal bone preservation: initial observations and case report.
abstract: Following the exposure and restoration of two-piece dental implants, some change in the vertical level of the peri-implant crestal bone height has been reported. This change in crestal bone height has not, however, negatively impacted long-term implant success. This article describes how the concept of platform switching is incorporated into a new implant design as a means of reducing or eliminating the occurrence of crestal bone loss. Preliminary observations from clinicians utilizing this new implant design are herein presented.

title: Platform switching: a new concept in implant dentistry for controlling postrestorative crestal bone levels.
abstract: Histologic and radiographic observations suggest that a biologic dimension of hard and soft tissues exists around dental implants and extends apically from the implant-abutment interface. Radiographic evidence of the development of the biologic dimension can be demonstrated by the vertical repositioning of crestal bone and the subsequent soft tissue attachment to the implant that occurs when an implant is uncovered and exposed to the oral environment and matching-diameter restorative components are attached. Historically, two-piece dental implant systems have been restored with prosthetic components that locate the interface between the implant and the attached component element at the outer edge of the implant platform. In 1991, Implant Innovations introduced wide-diameter implants with matching wide-diameter platforms. When introduced, however, matching-diameter prosthetic components were not available, and many of the early 5.0- and 6.0-mm-wide implants received "standard"-diameter (4.1-mm) healing abutments and were restored with "standard"-diameter (4.1-mm) prosthetic components. Long-term radiographic follow-up of these "platform-switched" restored wide-diameter dental implants has demonstrated a smaller than expected vertical change in the crestal bone height around these implants than is typically observed around implants restored conventionally with prosthetic components of matching diameters. This radiographic observation suggests that the resulting postrestorative biologic process resulting in the loss of crestal bone height is altered when the outer edge of the implant-abutment interface is horizontally repositioned inwardly and away from the outer edge of the implant platform. This article introduces the concept of platform switching and provides a foundation for future development of the biologic understanding of the observed radiographic findings and clinical rationale for this technique.

title: Platform-switched restorations on wide-diameter implants: a 5-year clinical prospective study.
abstract: The purpose of the present investigation was to clinically assess and compare crestal bone changes, over a 5-year period, around external-hexagon wide-diameter implants restored with either matching wide-diameter prosthetic components or with platform-switched prosthetic components.



During the years 2000 to 2002 all patients who received a single 5-mm-diameter implant with an external hexagon in a private office setting were included in this study. All implants were placed in the posterior areas of the jaws. Maxillary left molars (group A1) and mandibular right molars (group A2) were restored with matching wide-diameter prosthetic components; maxillary right molars (group B1) and mandibular left molars (group B2) were restored with platform-switched prosthetic components. Marginal bone resorption was measured via intraoral radiographs each year after abutment and crown insertion. Statistical analyses were used to determine whether there was a significant difference in marginal bone levels with respect to the width of prosthetic components used.



In all, 182 single 5-mm-diameter implants were placed in 144 patients and all implants survived. Eighty-five implants were restored with matching wide-diameter prosthetic components (group A), and 97 implants were restored with platform-switched prosthetic components (group B). A significant difference in marginal bone levels was found between group A and group B implants after 1 year. The mean marginal bone resorption was 0.9 mm (SD 0.3 mm) for group A implants and 0.6 mm (SD 0.2 mm) for group B implants. Marginal bone resorption observed at the second, third, fourth, and fifth years after abutment and crown insertion did not show any significant change.



Statistically significant differences in marginal bone loss were observed between study groups. The 85 implants restored with matching wide-diameter prosthetic components showed more bone loss than the 97 implants restored with platform-switched prosthetic components.

title: Effect of platform switching on crestal bone levels around implants in the posterior mandible: 3 years results from a multicentre randomized clinical trial
abstract: Evaluation of differences in the clinical performance and crestal bone levels between implants restored with single crowns with platform‐matched or platform‐switched abutments after 3 years.  The study enrolled adult patients missing two or more adjacent teeth in the posterior mandible with natural teeth mesial to the implant site. Randomization followed open‐flap implant insertion and the corresponding matching or switching healing abutments placed at surgery. Conventional loading was made with cemented crowns. Clinical follow‐up took place annually after loading up to 3 years. Bone level changes were measured in standardized radiographs as the variation in crestal bone from one evaluation to the next.  Sixty‐three patients with a total of 135 implants (66 platform matching, 69 platform switching) were analysed. From surgery to 36 months, mean bone loss was 0.28 ± 0.56 mm for the platform‐switching group and 0.68 ± 0.64 mm for the platform‐matching group. A statistically significant difference was found between groups (p = 0.002) with an estimate of 0.39 mm (0.15–0.64, 95% CI) in favour of platform switching.  After 3 years, platform‐switching restorations showed a significant effect in the preservation of marginal bone levels compared to platform‐matching restorations.

title: Radiographic evaluation of conical tapered platform‐switched implants in the posterior mandible: 1‐year results of a two‐center prospective study
abstract: Long‐term success of dental implants depends on healthy peri‐implant soft tissues and adequate bone levels. This prospective study aims to assess bone level changes around implants with internal conical connection and platform‐switching abutments in the posterior mandible.  Adult patients missing at least two teeth in the posterior mandible and with a natural tooth mesial to the implant site received two or three adjacent internal conical connection implants. After a minimum transmucosal healing period of 8 weeks, single crown restorations were cemented over platform‐switching abutments. Changes in marginal bone levels were measured in standardized periapical radiographs from surgery and loading (baseline) to 12 months post‐loading.  Twenty‐four patients received 52 implants. Bone remodeling took place between surgery and loading (−0.53 ± 0.40 mm). From loading to 12 months, there was a mean bone gain of 0.12 ± 0.42 mm which occurred mainly in the first 6 months after prosthesis delivery (0.11 ± 0.36 mm) and stabilized afterward. A total of 71.7% of all implants presented bone preservation or gain. No implant was lost at 1 year and the success rate was 100%. Patient inquiry revealed high satisfaction.  Internal conical connection implants with platform‐switching abutments presented high success rate and enhancement or preservation of marginal bone levels after 1 year of loading.

title: Platform switch versus platform match in the posterior mandible – 1-year results of a multicentre randomized clinical trial
abstract: The purpose of this ongoing randomized study was to assess differences in bone level changes and success rates using implants supporting single crowns in the posterior mandible either with platform matched or platform switched abutments.  Patients aged 18 and above, missing at least two teeth in the posterior mandible and with a natural tooth mesial to the most proximal implant site were enrolled. Randomization followed implant placement. Definitive restorations were placed after a minimum transgingival healing period of 8 weeks. Changes in crestal bone level from surgery and loading (baseline) to 12-month post-loading were radiographically measured. Implant survival and success were determined.  Sixty-eight patients received 74 implants in the platform switching group and 72 in the other one. The difference of mean marginal bone level change from surgery to 12 months was significant between groups (p < 0.004). Radiographical mean bone gain or no bone loss from loading was noted for 67.1% of the platform switching and 49.2% of the platform matching implants. Implant success rates were 97.3% and 100%, respectively.  Within the same implant system the platform switching concept showed a positive effect on marginal bone levels when compared with restorations with platform matching.

title: Peri-implant Inflammation Defined by the Implant-Abutment Interface
abstract: An implant-abutment interface at the alveolar bone crest is associated with sustained peri-implant inflammation; however, whether magnitude of inflammation is proportionally dependent upon interface position remains unknown. This study compared the distribution and density of inflammatory cells surrounding implants with a supracrestal, crestal, or subcrestal implant-abutment interface. All implants developed a similar pattern of peri-implant inflammation: neutrophilic polymorphonuclear leukocytes (neutrophils) maximally accumulated at or immediately coronal to the interface. However, peri-implant neutrophil accrual increased progressively as the implant-abutment interface depth increased, i.e., subcrestal interfaces promoted a significantly greater maximum density of neutrophils than did supracrestal interfaces (10,512 ± 691 vs. 2398 ± 1077 neutrophils/mm2). Moreover, inflammatory cell accumulation below the original bone crest was significantly correlated with bone loss. Thus, the implant-abutment interface dictates the intensity and location of peri-implant inflammatory cell accumulation, a potential contributing component in the extent of implant-associated alveolar bone loss.

title: Bone response to loaded implants with non-matching implant-abutment diameters in the canine mandible.
abstract: One way to evaluate various implant restorations is to measure the amount of bone change that occurs at the crestal bone. The objective of this study was to histologically evaluate the alveolar bone change around a bone-level, non-matching implant-abutment diameter configuration that incorporated a horizontal offset and a Morse taper internal connection.



The study design included extraction of all mandibular premolars and first molars in five canines. After 3 months, 12 dental implants were placed at three levels in each dog: even with the alveolar crest, 1 mm above the alveolar crest, and 1 mm below the alveolar crest. The implants were submerged on one side of the mandible. On the other side, healing abutments were exposed to the oral cavity (non-submerged). Gold crowns were attached 2 months after implant placement. The dogs were sacrificed 6 months postloading, and specimens were processed for histologic and histometric analyses.



Evaluation of the specimens indicated that the marginal bone remained near the top of the implants under submerged and non-submerged conditions. The amount of bone change for submerged implants placed even with, 1 mm below, and 1 mm above the alveolar crest was -0.34, -1.29, and 0.04 mm, respectively (negative values indicate bone loss). For non-submerged implants, the respective values were -0.38, -1.13, and 0.19 mm. For submerged and non-submerged implants, there were significant differences in the amount of bone change among the three groups (P <0.05). The percentage of bone-to-implant contact for submerged implants was 73.3%, 71.8%, and 71.5%. For non-submerged implants, the respective numbers were 73.2%, 74.5%, and 76%. No significant differences occurred with regard to the percentage of bone contact.



Minimal histologic bone loss occurred when dental implants with non-matching implant-abutment diameters were placed at the bone crest and were loaded for 6 months in the canine. The bone loss was significantly less (five- to six-fold) than that reported for bone-level implants with matching implant-abutment diameters (butt-joint connections).

title: Platform switching and marginal bone-level alterations: the results of a randomized-controlled trial.
abstract: This randomized-controlled trial aimed to evaluate marginal bone level alterations at implants restored according to the platform-switching concept, using different implant/abutment mismatching.



Eighty implants were divided according to the platform diameter in four groups: 3.8 mm (control), 4.3 mm (test group(1)), 4.8 mm (test group(2)) and 5.5 mm (test group(3)), and randomly placed in the posterior maxilla of 31 patients. After 3 months, implants were connected to a 3.8-mm-diameter abutment and final restorations were performed. Radiographic bone height was measured by two independent examiners at the time of implant placement (baseline), and after 9, 15, 21 and 33 months.



After 21 months, all 80 implants were clinically osseointegrated in the 31 patients treated. A total of 69 implants were available for analysis, as 11 implants had to be excluded from the study due to early unintentional cover screw exposure. Radiographic evaluation showed a mean bone loss of 0.99 mm (SD = 0.42 mm) for test group(1), 0.82 mm (SD = 0.36 mm) for test group(2) and 0.56 mm (SD = 0.31 mm) for test group(3). These values were statistically significantly lower (P<0.005) compared with control (1.49 mm, SD = 0.54 mm). After 33 months, five patients were lost to follow-up. Evaluation of the remaining 60 implants showed no difference compared with 21 months data except for test group(2) (0.87 mm) and test group(3) (0.64 mm). There was an inverse correlation between the extent of mismatching and the amount of bone loss.



This study suggested that marginal bone level alterations could be related to the extent of implant/abutment mismatching. Marginal bone levels were better maintained at implants restored according to the platform-switching concept.

title: Biomechanical analysis on platform switching: is there any biomechanical rationale?
abstract: The purpose of this study was to examine the biomechanical advantages of platform switching using three-dimensional (3D) finite element models.



3D finite element models simulating an external hex implant (4 x 15 mm) and the surrounding bone were constructed. One model was the simulation of a 4 mm diameter abutment connection and the other was the simulation of a narrower 3.25 mm diameter abutment connection, assuming a platform-switching configuration.



The stress level in the cervical bone area at the implant was greatly reduced when the narrow diameter abutment was connected compared with the regular-sized one.



Within the limitations of this study, it was suggested that the platform switching configuration has the biomechanical advantage of shifting the stress concentration area away from the cervical bone-implant interface. It also has the disadvantage of increasing stress in the abutment or abutment screw.

title: Prevalence of peri-implant disease on platform switching implants: a cross-sectional pilot study.
abstract: The objective of this study was to assess the prevalence of mucositis and peri-implantitis associated with the use of two types of implants-conventional versus platform switching after one year of loading. A longitudinal study of 64 implants in 25 patients was performed. Clinical variables, such as clinical pocket depth and bleeding upon probing, plaque, mobility, gingival recession, clinical attachment loss, and radiographic bone loss, were analyzed. The case definition for peri-implantitis was established as pockets of ≥ 5 mm with bleeding and bone loss ≥ 2 mm. One year after implant loading, the prevalence of mucositis and peri-implantitis with conventional implants (CIs) was 81.2% and 15.6%, respectively. For platform switching implants (PSIs) the prevalence was 90% and 6.6%, respectively. These differences were not statistically significant (p = 0.5375). However, there was a trend towards a lower prevalence of peri-implantitis with platform switching Implants.

title: Histologic, biochemical, and ion analysis of tissue and fluids retrieved during total hip arthroplasty.
abstract: Large amounts of metal and polyethylene debris and high ion readings are found in capsule and fibrous membranes of both loose titanium and cobalt-chromium stems. Prostaglandin E2, interleukin-1, and collagenase levels are elevated when compared to control values with collagenase having the highest and most consistent elevations. Synovial fluid and blood ion readings were elevated in loose cemented and cementless stems made from both materials. Blood ion readings were not elevated in fixed stems. Fixed stems had much less particulate debris in soft tissues. The data showed that failure of most metal hip stems was initially due to a mechanical cause, with high debris and ion counts occurring secondarily in capsule and fibrous membranes. Particulate debris and high ion readings are primarily a focal problem contained by the periprosthetic fibrous connective-tissue encapsulation within the femoral canal and joint capsules. No systemic problems were manifest in any of the patients examined and followed in this study.

title: Detachment of titanium and fluorohydroxyapatite particles in unloaded endosseous implants.
abstract: The shape, surface composition and morphology of orthopaedic and endosseous dental titanium implants are key factors to achieve post-surgical and long-term mechanical stability and enhance implant osteointegration. In this study a comparison was made between 12 titanium screws, plasma-spray-coated with titanium powders (TPS), and 12 screws with an additional coating of fluorohydroxyapatite (FHA-Ti). Screws were implanted in the femoral and tibial diaphyses of two mongrel sheep and removed with peri-implant tissues 12 weeks after surgery. The vibrational spectroscopic, ultrastructural and morphological analyses showed good osteointegration for both types of implants in host cortical bone. The portion of the FHA-Ti implants in contact with the medullary canal showed a wider area of newly formed peri-implant bone than that of the TPS implants. Morphological and EDAX analyses demonstrated the presence of small titanium debris in the bone medullary spaces near the TPS surface, presumably due to the friction between the host bone and the implant during insertion. Few traces of titanium were detected around FHA-Ti implants, even if smaller FHA debris were present. The present findings suggest that the FHA coating may act as a barrier against the detachment of titanium debris stored in the medullary spaces near the implant surface.

title: Dissemination of Wear Particles to the Liver, Spleen, and Abdominal Lymph Nodes of Patients with Hip or Knee Replacement*
abstract: The importance of particles generated by wear and corrosion of joint replacement prostheses has been understood primarily in the context of the local effects of particle-induced periprosthetic osteolysis and aseptic loosening. We studied dissemination of wear particles in patients with total hip and knee replacement to determine the prevalence of and the histopathological response to prosthetic wear debris in the liver, spleen, and abdominal para-aortic lymph nodes.  Postmortem specimens from twenty-nine patients and biopsy specimens from two living patients with a failed replacement were analyzed. Specimens of tissue obtained from the cadavera of fifteen patients who had not had a joint replacement served as controls. The concentration of particles and the associated tissue response were characterized with the use of light microscopy of stained histological sections. Metallic particles were identified by electron microprobe analysis. Polyethylene particles were studied with the use of oil-red-O stain and polarized light microscopy. The composition of polyethylene particles was confirmed in selected cases by Fourier transform infrared spectroscopy and hot-stage thermal analysis. Twenty-one of the patients studied post mortem had had a primary total joint replacement. Eleven of them had had a hip prosthesis for a mean of sixty-nine months (range, forty-three to 171 months), and ten had had a knee replacement for a mean of eighty-four months (range, thirty-one to 179 months). The other eight patients studied post mortem had had a hip replacement in which one or more components had loosened and had been revised. The mean time between the initial arthroplasty and the time of death was 174 months (range, forty-seven to 292 months), and the mean time between the last revision procedure and the time of death was seventy-one months (range, one to 130 months).  Metallic wear particles in the liver or spleen were more prevalent in patients who had had a failed hip arthroplasty (seven of eight) than in patients who had had a primary hip (two of eleven) or knee replacement (two of ten). The principal source of wear particles in the majority of these patients involved secondary nonbearing surfaces rather than wear between the two primary bearing surfaces as intended. In one living patient, dissemination of titanium alloy particles from a hip prosthesis with mechanical failure was associated with a visceral granulomatous reaction and hepatosplenomegaly, which required operative and medical treatment. Metallic wear particles were detected in the para-aortic lymph nodes in 68 percent (nineteen) of the twenty-eight patients with an implant from whom lymph nodes were available for study. In 38 percent (eleven) of all twenty-nine patients with an implant who were studied post mortem, metallic particles had been further disseminated to the liver or spleen, where they were usually found within small aggregates of macrophages occurring as infiltrates without apparent pathological importance. Polyethylene particles elicited a similar response. They were identified in the para-aortic lymph nodes of 68 percent (nineteen) of the twenty-eight patients and the liver or spleen of 14 percent (four) of the twenty-nine patients. The majority of the disseminated wear particles were less than one micrometer in size. Currently available methods lack the sensitivity and specificity necessary to detect very low concentrations of submicrometer polyethylene particles and probably underestimated the prevalence of polyethylene wear debris in the liver and spleen.  In this study, systemic distribution of metallic and polyethylene wear particles was a common finding, both in patients with a previously failed implant and in those with a primary total joint prosthesis. The prevalence of particles in the liver or spleen was greater after reconstructions with mechanical failure. In the majority of patients, the concentration of wear particles in these organs was relatively low and without apparent pathological importance. However, in one rare case, granulomas formed in the liver, spleen, and abdominal lymph nodes in response to heavy accumulation of wear debris from a hip prosthesis with mechanical failure and compromised hepatic function.  These findings underscore the necessity of minimizing the production of particulate debris by joint replacement devices and the need for the surgeon to consider expeditious revision in patients in whom large amounts of particulate debris may be generated. Serum and urine trace-metal analyses may provide early confirmation of failure and aid in the timing of a revision operation in a patient with a symptomatic or failed device.

title: Metal ion release from titanium‐based prosthetic segmental replacements of long bones in baboons: A long‐term study
abstract: Forty‐five baboons that had received titanium‐based fiber metal composite segmental bone replacements were studied along with 13 controls without implants. Thirty‐eight baboons with implants were sacrificed, and titanium, aluminum, and vanadium levels were assayed in homogenized lung, kidney, spleen, liver, adjacent muscle, and regional lymph nodes. In seven living baboons with implants, blood and urine samples were obtained for trace metal analysis as well as for biochemical and hematological profiles. In the 38 sacrificed baboons with implants, increased titanium levels were noted in the lungs, spleen, adjacent muscle (quadriceps, soleus, and triceps), and regional lymph nodes (inguinal, axillary, and popliteal) in comparison to those of six sacrificed controls without implants. In addition, vanadium was significantly elevated in the lungs of some animals, while aluminum increases were noted in adjacent muscle (quadriceps, soleus, and triceps), lung, and regional lymph nodes (inguinal, axillary, and popliteal). In the seven living baboons with implants, a sixfold increase (p < 0.0005) in the urine titanium level was noted in comparison to that of seven living controls without implants. Additionally, elevated aluminum levels were found in the serum (p < 0.0005) of the group with implants. Biochemical and hematological studies did not indicate statistically significant differences in serum electrolytes, in liver and renal function tests, or in complete blood counts between the seven living baboons with implants and their controls.

title: Foreign bodies associated with peri-implantitis human biopsies.
abstract: Peri-implantitis is an inflammatory condition that can lead to implant loss. The aim of this descriptive retrospective study is to describe the histopathologic findings in soft tissue biopsies of implants with peri-implantitis.



Thirty-six human peri-implantitis biopsies were analyzed using light microscopy (LM) and scanning electron microscopy (SEM). The composition of foreign materials found in the tissues was assessed using an energy dispersive x-ray spectrometer.



At the LM level, the inflammatory lesion of peri-implantitis was in most cases a mixture of subacute and chronic inflammation dominated by plasma cells. At the SEM level, radiopaque foreign bodies were identified in 34 of the 36 biopsies. The predominant foreign bodies found were titanium and dental cement. These foreign materials were surrounded by inflammatory cells.



At present, the exact mechanism for introduction of these materials and their role in peri-implantitis is unknown. Further research is warranted to determine their etiology and potential role in pathogenesis.

title: Metal elements in tissue with dental peri-implantitis: a pilot study.
abstract: Dental peri-implantitis is characterized by a multifactorial etiology. The role of metal elements as an etiological factor for peri-implantitis is still unclear. The aim of this study was to investigate the incidence of metal elements in bone and mucosal tissues around dental Grade 4 CP titanium implants with signs of peri-implantitis in human patients.



In this prospective pilot study, all patients were enrolled consecutively in two study centers. Bone and soft tissue samples of patients with peri-implantitis with indication for explantation were analyzed for the incidence of different elements (Ca, P, Ti, Fe) by means of synchrotron radiation X-ray fluorescence spectroscopy (SRXRF) and polarized light microscopy (PLM). The existence of macrophages and lymphocytes in the histologic specimens was analyzed.



Biopsies of 12 patients (seven bone samples, five mucosal samples) were included and analyzed. In nine of the 12 samples (75%), the SRXRF examination revealed the existence of titanium (Ti) and an associated occurrence with Iron (Fe). Metal particles were detected in peri-implant soft tissue using PLM. In samples with increased titanium concentration, lymphocytes were detected, whereas M1 macrophages were predominantly seen in samples with metal particles.



Titanium and Iron elements were found in soft and hard tissue biopsies retrieved from peri-implantitis sites. Further histologic and immunohistochemical studies need to clarify which specific immune reaction metal elements/particles induce in dental peri-implant tissue.

title: Exfoliative cytology and titanium dental implants: a pilot study.
abstract: Oral exfoliative cytology is a diagnostic method that involves the study of cells exfoliated from the oral mucosa. Ions/particles released from metallic implants can remain in the peri-implant milieu. The aim of the present study is to assess the presence of metal particles in cells exfoliated from peri-implant oral mucosa around titanium dental implants.



The study comprised 30 patients carrying titanium dental implants, who had neither a metallic prosthesis nor metal restorations in neighboring teeth. Individuals undergoing orthodontic therapy and those who had oral piercing were also excluded from the study. The study sample included patients with and without peri-implantitis. Cytologic samples of the peri-implant area were collected. Samples of the marginal gingiva on the contralateral side of the implant were taken from the same individuals to serve as control. Cytologic analysis was performed using light microscopy. Titanium concentration was determined using inductively coupled plasma-mass spectrophotometry.



Metal-like particles were observed inside and outside epithelial cells and macrophages in cytologic smears of peri-implant mucosa of both patients with and without peri-implantitis. No particles were found in the control cytologic samples. The concentration of titanium was higher in the peri-implantitis group compared with the group without peri-implantitis; no traces of titanium were observed in controls.



Regardless of an inflammatory response, ions/particles are released from the surface of the implant into the biologic milieu. Exfoliative cytology is a simple technique that may be used to detect metal particles in cells exfoliated from the peri-implant mucosa.

title: Titanium ions form particles that activate and execute interleukin‐1β release from lipopolysaccharide‐primed macrophages
abstract: Peri‐implantitis is a destructive inflammatory process characterized by destruction of the implant‐supporting bone. Inflammasomes are large intracellular multiprotein complexes that play a central role in innate immunity by activating the release of proinflammatory cytokines. Although inflammasome activation has previously been linked to periodontal inflammation, there is still no information on a potential association with peri‐implantitis. The aim of this study was to examine cytotoxic and proinflammatory effects, including inflammasome activation, of metals used in dental implants, in an in vitro model, as well as from clinical tissue samples.  Human macrophages were exposed to different metals [titanium (Ti), cobalt, chromium and molybdenum] in a cell‐culture assay. Cytotoxicity was determined using the neutral red uptake assay. Cytokine secretion was quantified using an ELISA, and the expression of genes of various inflammasome components was analysed using quantitative PCR. In addition, the concentrations of interleukin‐1β (IL‐1β) and Ti in mucosal tissue samples taken in the vicinity of dental implants were determined using ELISA and inductively coupled plasma mass spectrometry, respectively.  Ti ions in physiological solutions stimulated inflammasome activation in human macrophages and consequently IL‐1β release. This effect was further enhanced by macrophages that have been exposed to lipopolysaccharides. The proinflammatory activation caused by Ti ions disappeared after filtration (0.22 μm), which indicates an effect of particles. Ti ions alone did not stimulate transcription of the inflammasome components. The Ti levels of tissue samples obtained in the vicinity of Ti implants were sufficiently high (≥ 40 μm) to stimulate secretion of IL‐1β from human macrophages in vitro.  Ti ions form particles that act as secondary stimuli for a proinflammatory reaction.

title: Surgical therapy of advanced ligature-induced peri-implantitis defects: cone-beam computed tomographic and histological analysis.
abstract: To evaluate radiological bone level (RBL) (i.e. cone-beam computed tomography) and histological bone levels (HBL) as well as re-osseointegration [bone-to-implant contact (BIC)] after surgical resective (i.e. implantoplasty) and/or regenerative therapy of advanced ligature-induced peri-implantitis in dogs.



At all defect sites (n=6 dogs, n=48 implants), the intrabony component was filled with a particulate bovine-derived natural bone mineral (NBM). The supracrestal component was treated by either the application of an equine bone block (EB) or implantoplasty. In a split-mouth design, NBM and EB were soak-loaded with recombinant human bone morphogenetic protein (rhBMP)-2 or sterile saline. All sites were covered by a native collagen membrane and left to heal in a submerged position for 12 weeks.



A premature wound exposure was observed at nine defect sites. Mean RBL and HBL values were lowest in the P+rhBMP-2 group, reaching statistical significance when compared with the EB group. Mean BIC values were comparable in all groups. Within-group comparisons commonly revealed a close correlation between RBL and HBL values.



It was concluded that (i) in all groups the investigations failed to predictably obtain complete defect resolution, (ii) the surgical procedure was associated with high exposure rates, and (iii) RBL was closely correlated with HBL.

title: Fast element mapping of titanium wear around implants of different surface structures.
abstract: The effect of unintended titanium release around oral implants remains a biological concern. The current study was undertaken to evaluate a new detection system of element mapping in biological probes. A new scanning electron microscopy-energy dispersive spectroscopy detection method was used to map the features of titanium contamination in peri-implant bone around implants with different surface structures. The amount of titanium wear was highest adjacent to titanium-plasma-sprayed surfaces, followed by sandblastered large grid acid-etched and smooth surfaces. A high sensitivity of titanium detection over large areas of bone tissue was observed. A high spatial resolution of titanium wear particles (20 nm) could be reached and correlated to the ultrastructural morphological features of peri-implant tissue. Cells adjacent to titanium wear revealed no signs of morphological alterations on a nanoscale level at early periods of implant/bone interaction. The new technique may serve as a fast and effective tool to evaluate titanium release effects in biological probes.

title: Wear particles, periprosthetic osteolysis and the immune system.
abstract: The immune system modulates many key biological processes in humans. However, the exact role of the immune system in particle-associated periprosthetic osteolysis is controversial. Human tissue retrieval studies, in vivo and in vitro experiments suggest that the immune response to polymer particles is non-specific and macrophage-mediated. Lymphocytes may modulate this response. However direct lymphocyte activation by polymer particle-protein complexes seems unlikely. However, metallic byproducts may complex with serum proteins and lead to a Type IV, lymphocyte-mediated immune reaction. In predisposed individuals, this reaction may rarely lead to persistent painful joint effusions, necessitating debridement and excision of the bearing surfaces of the prosthesis. In these patients, retrieved periprosthetic tissues exhibit histological evidence of perivascular lymphocytic cuffing. These findings are worrisome, given the fact that increasing numbers of metal-on-metal joint implants are being implanted in younger more active individuals worldwide.

title: Effects of Ti ions and particles on neutrophil function and morphology.
abstract: We compared the cytotoxicity of soluble and particulate titanium (Ti), vanadium (V) and nickel (Ni) by biochemical functional analysis and by microscopic morphology with micro-area elemental analysis in vitro using human neutrophils as probes and in vivo in animals. The biochemical analyses of LDH, superoxide anion, TNF-alpha and scanning electron microscopy (SEM) showed that Ni in solution destroys the cell membrane of neutrophils, whereas Ti and V in solution stimulate neutrophils and increase the quantity of released superoxide anions. Fine Ti particles (1-3 microm), which smaller than neutrophils (about 5 microm), were phagocytized by the cells and the results were similar in vivo. These results showed that the cytotoxic effect of Ti particles is size dependent, and that they must be smaller than that of cells. The present study demonstrated that the biochemical functional tests are useful for evaluating the biocompatibility of materials.

title: Accumulation of element Ti in macrophage-like RAW264 cells cultured in medium with 1 ppm Ti and effects on cell viability, SOD production and TNF-alpha secretion.
abstract: The adverse effect of Ti on body-defense macrophage is not well understood. The aims of this study were twofold: (1) to examine the intracellular accumulation of Ti element; and (2) to measure the cell viability, superoxide dismutase (SOD) production, and TNF-alpha secretion of macrophage-like RAW264 cells cultured for two days in medium with 1 ppm Ti prepared from acidic ICP Ti standard solution. PIXE analysis showed that element Ti was accumulated up to 7.3 ppm in RAW264 cells when cultured in the medium with 1 ppm Ti. Further, RAW264 cells cultured in the medium with 1 ppm Ti exhibited cell viability of about 60%, SOD production of about 180%, and TNF-alpha secretion of about 170% relative to those of control cells cultured in the medium without Ti. It was speculated that phagocytosis of minute Ti-containing complex (mostly TiO2) by macrophage caused oxidative stress and inflammatory reaction, leading to cell proliferation arrest and increased production of SOD and TNF-alpha.

title: Release of titanium ions from an implant surface and their effect on cytokine production related to alveolar bone resorption.
abstract: Although interest in peri-implant mucositis and peri-implantitis has recently been increasing, the mechanisms driving these diseases remain unknown. Here, the effects of titanium ions on the inflammation and bone resorption around an implant were investigated. First, the accumulated amount of Ti ions released into gingival and bone tissues from an implant exposed to sodium fluoride solution was measured using inductively coupled plasma mass spectrometry. Next, the cellular responses in gingival and bone tissues to Ti ions and/or Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) were assessed using a rat model. More Ti ions were detected in the gingival tissues around an implant after treatment with sodium fluoride (pH 4.2) than in its absence, which suggests that the fluoride corroded the implant surface under salivary buffering capacity. The injection of Ti ions (9ppm) significantly increased the mRNA expression and protein accumulation of chemokine (C-C motif) ligand 2, as well as the ratio of receptor activator of nuclear factor-κB ligand to osteoprotegerin, in rat gingival tissues exposed to P. gingivalis-LPS in a synergistic manner. In addition, the enhanced localization of toll-like receptor 4, which is an LPS receptor, was observed in gingival epithelium loaded with Ti ions (9ppm). These data suggest that Ti ions may be partly responsible for the infiltration of monocytes and osteoclast differentiation by increasing the sensitivity of gingival epithelial cells to microorganisms in the oral cavity. Therefore, Ti ions may be involved in the deteriorating effects of peri-implant mucositis, which can develop into peri-implantitis accompanied by alveolar bone resorption.

title: Comparison of Cellular Uptake and Inflammatory Response via Toll-Like Receptor 4 to Lipopolysaccharide and Titanium Dioxide Nanoparticles
abstract: The innate immune response is the earliest cellular response to infectious agents and mediates the interactions between microbes and cells. Toll-like receptors (TLRs) play an important role in these interactions. We have already shown that TLRs are involved with the uptake of titanium dioxide nanoparticles (TiO2 NPs) and promote inflammatory responses. In this paper, we compared role of cellular uptake and inflammatory response via TLR 4 to lipopolysaccharide (LPS) and TiO2 NPs. In the case of LPS, LPS binds to LPS binding protein (LBP) and CD 14, and then this complex binds to TLR 4. In the case of TiO2 NPs, the necessity of LBP and CD 14 to induce the inflammatory response and for uptake by cells was investigated using over-expression, antibody blocking, and siRNA knockdown experiments. Our results suggested that for cellular uptake of TiO2 NPs, TLR 4 did not form a complex with LBP and CD 14. In the TiO2 NP-mediated inflammatory response, TLR 4 acted as the signaling receptor without protein complex of LPS, LBP and CD 14. The results suggested that character of TiO2 NPs might be similar to the complex of LPS, LBP and CD 14. These results are important for development of safer nanomaterials.

title: Trojan-Like Internalization of Anatase Titanium Dioxide Nanoparticles by Human Osteoblast Cells
abstract: Dentistry and orthopedics are undergoing a revolution in order to provide more reliable, comfortable and long-lasting implants to patients. Titanium (Ti) and titanium alloys have been used in dental implants and total hip arthroplasty due to their excellent biocompatibility. However, Ti-based implants in human body suffer surface degradation (corrosion and wear) resulting in the release of metallic ions and solid wear debris (mainly titanium dioxide) leading to peri-implant inflammatory reactions. Unfortunately, our current understanding of the biological interactions with titanium dioxide nanoparticles is still very limited. Taking this into consideration, this study focuses on the internalization of titanium dioxide nanoparticles on primary bone cells, exploring the events occurring at the nano-bio interface. For the first time, we report the selective binding of calcium (Ca), phosphorous (P) and proteins from cell culture medium to anatase nanoparticles that are extremely important for nanoparticle internalization and bone cells survival. In the intricate biological environment, anatase nanoparticles form bio-complexes (mixture of proteins and ions) which act as a kind of ‘Trojan-horse’ internalization by cells. Furthermore, anatase nanoparticles-induced modifications on cell behavior (viability and internalization) could be understand in detail. The results presented in this report can inspire new strategies for the use of titanium dioxide nanoparticles in several regeneration therapies.

title: Effects of Titanium Dioxide Nanoparticle Aggregate Size on Gene Expression
abstract: Titanium dioxide (titania) nanoparticle aggregation is an important factor in understanding cytotoxicity. However, the effect of the aggregate size of nanoparticles on cells is unclear. We prepared two sizes of titania aggregate particles and investigated their biological activity by analyzing biomarker expression based on mRNA expression analysis. The aggregate particle sizes of small and large aggregated titania were 166 nm (PDI = 0.291) and 596 nm (PDI = 0.417), respectively. These two size groups were separated by centrifugation from the same initial nanoparticle sample. We analyzed the gene expression of biomarkers focused on stress, inflammation, and cytotoxicity. Large titania aggregates show a larger effect on cell viability and gene expression when compared with the small aggregates. This suggests that particle aggregate size is related to cellular effects.

title: Effects of Particle Size on Cell Function and Morphology in Titanium and Nickel
abstract: The dependence of cytotoxicity on particles size in titanium (Ti) and nickel (Ni) was investigated by biochemical functional analysis and by microscopic observation of cellular morphology, in vitro using human neutrophils as probes and in vivo in animal implantation test. The biochemical analyses of cell survival rate, LDH, superoxide anion, cytokines of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and observation by scanning electron microscopy (SEM) showed that Ti fine particles (2 µm) stimulate neutrophils and increases the quantity of released superoxide anions, whereas Ni particles deform or disrupt the cell membrane of neutrophils. The 2 µm Ti particles, smaller than neutrophils of about 5‐10µm, were phagocytized by cells in vivo and the results were similar in vitro, which lead to the remarkable release of TNF-α. These results showed that there is the size-dependent cytotoxic effect in Ti fine particles and the effect is the most pronounced when they are smaller than cells. On the other hand, Ni particles caused the disruption of neutrophils in vitro and necrosis of tissue in vivo mainly through ions produced by their dissolution.

title: Titanium Activates the DNA Damage Response Pathway in Oral Epithelial Cells: A Pilot Study.
abstract: To evaluate the effect of titanium (Ti) particles on oral epithelial cell homeostasis and the potential of dental implants to release Ti debris upon insertion.



Dental implants with varying surface treatments were employed to determine the feasibility of particle release during implant placement as well as the impact of free Ti debris on oral epithelial cells. Ti particles derived from implant surfaces were isolated and cultured in direct contact with normal oral epithelial cells for 48 hours. Further, cells were fixed and processed for immunofluorescence assay to detect the activation of the DNA damage response (DDR) using CHK2 and BRCA1 molecular markers. Positive cells demonstrating DNA damage were quantified and statistically analyzed.



Ti particles derived from implants containing phosphate-enriched titanium oxide (PETO), fluoride-modified (FM), and grit-blasted (GB) surface treatments were able to activate CHK2 and trigger the recruitment of BRCA1 in oral epithelial cells. Also, implants with GB surfaces were able to release Ti particles upon implant placement.



The results indicate that Ti debris may be detached from the implant surface upon placement. Also, free Ti particles can trigger DDR signaling in oral epithelial cells. These findings suggest that Ti particles/debris released into a surgical wound may contribute to the disruption of epithelial homeostasis, and potentially compromise the oral epithelial barrier.

title: Biological response to prosthetic debris.
abstract: Joint arthroplasty had revolutionized the outcome of orthopaedic surgery. Extensive and collaborative work of many innovator surgeons had led to the development of durable bearing surfaces, yet no single material is considered absolutely perfect. Generation of wear debris from any part of the prosthesis is unavoidable. Implant loosening secondary to osteolysis is the most common mode of failure of arthroplasty. Osteolysis is the resultant of complex contribution of the generated wear debris and the mechanical instability of the prosthetic components. Roughly speaking, all orthopedic biomaterials may induce a universal biologic host response to generated wear débris with little specific characteristics for each material; but some debris has been shown to be more cytotoxic than others. Prosthetic wear debris induces an extensive biological cascade of adverse cellular responses, where macrophages are the main cellular type involved in this hostile inflammatory process. Macrophages cause osteolysis indirectly by releasing numerous chemotactic inflammatory mediators, and directly by resorbing bone with their membrane microstructures. The bio-reactivity of wear particles depends on two major elements: particle characteristics (size, concentration and composition) and host characteristics. While any particle type may enhance hostile cellular reaction, cytological examination demonstrated that more than 70% of the debris burden is constituted of polyethylene particles. Comprehensive understanding of the intricate process of osteolysis is of utmost importance for future development of therapeutic modalities that may delay or prevent the disease progression.

title: Titanium and zirconia particle-induced pro-inflammatory gene expression in cultured macrophages and osteolysis, inflammatory hyperalgesia and edema in vivo.
abstract: The biological reaction to wear debris is critical to the osteolysis underlying aseptic loosening of joint prosthetic implants. In an attempt to reduce aseptic loosening, ceramics have been introduced. This study was designed to evaluate, compare and correlate the expression of Toll-like receptors (TLRs), their intracellular adaptors and proinflammatory cytokines in cultured macrophages challenged with titanium or zirconia particles, as well as particle-induced osteolysis in calvaria and hyperalgesia and edema in hind paw.



TLRs and their adaptors were evaluated at the mRNA level by RT-PCR, and cytokine expression was evaluated at the mRNA and protein levels. Osteolysis and hyperalgesia and edema were evaluated in vivo, in calvaria and hind paw, respectively.



Cultured macrophages challenged with zirconia or titanium particles expressed increased mRNA for TLRs 2, 3, 4 and 9, and their adaptors MyD88, TRIF and NF-κB and cytokines TNF-α, IL-1β and IL-6, which were also increased at protein level. Quantitative differences are evident and, in general, zirconia particle-induced pro-inflammatory gene expression was lower than that induced by titanium particles. In in vivo experiments, exposition to titanium or zirconia particles induced osteolysis in calvaria and hyperalgesia and edema in hind paw; however those induced by zirconia particles were significantly lower. There is a strong and positive correlation between the expressions of mRNA for TLR4, NF-κB, TNF-α, IL-1β and IL-6.



Collectively, our data suggest that zirconia ceramic particles are less bioactive than titanium particles.

title: Surface Damage on Dental Implants with Release of Loose Particles after Insertion into Bone.
abstract: Modern dental implants present surface features of distinct dimensions that can be damaged during the insertion procedure into bone.



The aims of this study were (1) to quantify by means of roughness parameters the surface damage caused by the insertion procedure of dental implants and (2) to investigate the presence of loose particles at the interface.



Three groups of dental implants representing different surface topographies were inserted in fresh cow rib bone blocks. The surface roughness was characterized by interferometry on the same area before and after the insertion. Scanning electron microscopy (SEM)-back-scattered electron detector (BSD) analysis was used to identify loose particles at the interface.



The amplitude and hybrid roughness parameters of all three groups were lower after insertion. The surface presenting predominance of peaks (Ssk [skewness] > 0) associated to higher structures (height parameters) presented higher damage associated to more pronounced reduction of material volume. SEM-BSD images revealed loose titanium and aluminum particles at the interface mainly at the crestal cortical bone level.



Shearing forces during the insertion procedure alters the surface of dental implants. Loose metal particles can be generated at bone-implant interface especially around surfaces composed mainly by peaks and with increased height parameters.

title: How do titanium and Ti6Al4V corrode in fluoridated medium as found in the oral cavity? An in vitro study.
abstract: The purpose of this work was to evaluate the corrosion of commercially pure (CP) titanium and Ti6Al4V in vitro at different F(-) concentrations regularly found in the oral cavity by using different electrochemical tests and surface analysis techniques. electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) and potentiodynamic polarization tests were associated to advanced characterization techniques such as SEM, EDS, AFM, ICP-MS and XPS. OCP tests revealed a higher reactivity of both CP titanium and Ti6Al4V at 12,300 ppm F(-) concentration than that recorded at 227 ppm F(-). Also, a significant decrease of the corrosion resistance of both materials was noticed by EIS in fluoride solutions. Material loss caused by corrosion was noticed on titanium surfaces by SEM and AFM in the presence of high F(-) concentration. CP titanium degraded by pitting corrosion while Ti6Al4V suffered from general corrosion showing micro-cracks on surface. Furthermore, a high release of metallic ions from the test samples after immersion at high F(-) concentrations was detected by ICP-MS, that can be potentially toxic to oral tissues.

title: Mechanical and chemical analyses across dental porcelain fused to CP titanium or Ti6Al4V.
abstract: The aim of this study was to evaluate the evolution of mechanical properties and chemical variation across veneering dental porcelain fused to different titanium-based substrates. Test samples were synthesized by fusing dental feldspar-based porcelain onto commercially pure titanium grade II or Ti6Al4V alloy. Samples were cross-sectioned at angles of 10 and 90° to the interface plane. Afterwards, nanoindentation tests and Scanning Electron Microscopy (SEM) imaging coupled to an Energy Dispersive Spectroscopy (EDS) system were carried out across interfaces extending from the metal towards the porcelain area. Elemental diffusion profiles across the porcelain-to-metal interfaces were also obtained by EDS analysis. The mismatch in mechanical properties found in porcelain-to-Ti6Al4V interfaces was lower than that of porcelain-to-CP titanium. Cracking was noticed at low-thickness veneering dental porcelain regions after the nanoindentation tests of samples cross-sectioned at low angles to the interface plane. A wide reaction zone between titanium and porcelain as well as higher incidence of defects was noticed at the porcelain-to-CP titanium interfaces. This study confirmed Ti6Al4V as an improved alternative to CP-titanium as it showed to establish a better interface with the veneering dental porcelain considering the slight chemical interaction and the lower mechanical properties mismatch. The elastic modulus of porcelain-to-Ti6Al4V samples showed to be less sensitive to porcelain thickness variations.

title: Corrosion behaviour of titanium in the presence of Streptococcus mutans.
abstract: The main aim of this in vitro study was to evaluate the influence of Streptococcus mutans on the corrosion of titanium.



S. mutans biofilms were formed on commercially pure titanium (CP-Ti) square samples (10mm×10mm×1mm) using a culture medium enriched with sucrose. Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements were used to evaluate the corrosion behaviour of CP-Ti in the presence of S. mutans in Fusayama's artificial saliva. The corrosion of biofilm-free CP-Ti samples was also evaluated in artificial saliva. Biofilms biomass was measured by spectrophotometry, using crystal violet staining, after 1, 2 and 7 days.



The OCP values recorded on CP-Ti in the presence of S. mutans (-0.3±0.02V vs. SCE) was lower than those on biofilm-free CP-Ti (-0.1±0.01V vs. SCE) after 2h of immersion in artificial saliva (p<0.05). That reveals a high reactivity of titanium in presence of S. mutans. Impedance spectra revealed the formation of a compact passive film on titanium in artificial saliva or in the presence of a 2 days old S. mutans biofilm even though the corrosion resistance of CP-Ti has decreased in presence of a S. mutans biofilm.



The presence of bacterial colonies, such as S. mutans, negatively affected the corrosion resistance of the titanium.

title: Is Metal Particle Release Associated with Peri-implant Bone Destruction? An Emerging Concept
abstract: Peri-implant diseases affecting the surrounding structures of endosseous dental implants include peri-implant mucositis and peri-implantitis. The prevalence of peri-implantitis ranges between 15% and 20% after 10 y, highlighting the major challenge in clinical practice in the rehabilitation of dental implant patients. The widespread nature of peri-implant bone loss poses difficulties in the management of biological complications affecting the long-term success of osseointegrated implant reconstructions. Metal and titanium particles have been detected in peri-implant supporting tissues. However, it remains unclear what mechanisms could be responsible for the elicitation of particle and ion release and whether these released implant-associated materials have a local and/or systemic impact on the peri-implant soft and hard tissues. Metal particle release as a potential etiologic factor has been intensively studied in the field of orthopedics and is known to provoke aseptic loosening around arthroplasties and is associated with implant failures. In dental medicine, emerging information about metal/titanium particle release suggests that the potential impact of biomaterials at the abutment or bone interfaces may have an influence on the pathogenesis of peri-implant bone loss. This mini-review highlights current evidence of metal particle release around dental implants and future areas for research.

title: Can degradation products released from dental implants affect peri‐implant tissues?
abstract: This study aimed to assess the literature available on the effects, on peri-implant tissues, of degradation products released from dental implants as a consequence of therapeutic treatment for peri-implantitis and/or of wear-corrosion of titanium. A literature review of the PubMed medline database was performed up to December 31, 2016. The following search terms were used: "titanium wear and dental implant"; "titanium corrosion and dental implant"; "bio-tribocorrosion"; "peri-implantitis"; "treatment of peri-implantitis"; "titanium particles release and dental implant"; and "titanium ion release and dental implant". The keywords were applied to the database in different combinations without limits of time period or type of work. In addition, the reference lists of relevant articles were searched for further studies. Seventy-nine relevant scientific articles on the topic were retrieved. The results showed that pro-inflammatory cytokines, infiltration of inflammatory response cells and activation of the osteoclasts activity are stimulated in peri-implant tissues in the presence of metal particles and ions. Moreover, degenerative changes were reported in macrophages and neutrophils that phagocytosed titanium microparticles, and mutations occurred in human cells cultured in medium containing titanium-based nanoparticles. Debris released from the degradation of dental implants has cytotoxic and genotoxic potential for peri-implant tissues. Thus, the amount and physicochemical properties of the degradation products determine the magnitude of the detrimental effect on peri-implant tissues.