bluuebunny/crossref_metadata_2025 huggingface dataset:
Subjective need for implant dentistry in a Swedish population aged 45–69 years
Authors: Palmqvist Sigvard , Söderfeldt Björn , Arnbjerg Dorte
Published: March 2003

The present paper is part of a comprehensive study of dental conditions and attitudes in a Swedish county population aged 45–69 years. A questionnaire was mailed to 3000 randomly‐sampled individuals. The response rate was 79.4% Part of the questionnaire contained questions about subjective need for implant treatment. The subjects were informed of the clinical procedures as well as of the fees for implant treatment in the Swedish insurance system. The subjects wearing removable dentures were asked if. instead of their removable denture(s), they wanted dental implants if such treatment was possible. Of those wearing removable partial dentures, 23% answered “yes”. The corresponding figure for subjects totally edentulous in one jaw was 17%; for subjects totally edentulous in both jaws 8%percnt;. The individuals who had reported missing teeth not replaced were asked if they wanted their missing teeth replaced by dental implants if such treatment were possible. The % answering “yes” was 21%. The subjects with all teeth remaining were hypothetically asked what kind of treatment they wanted if they would lose 1 or 2 of their teeth. The answer “dental implant” was given by 51%. Thus, subjective need for dental implants tended to decrease with poorer dental conditions. The major reason for not wanting dental implants was satisfaction with present dental conditions. Cost for treatment had some importance. while environmental and psychological factors showed only very limited influence.
Supraplan®, a novel implant system based on the principle of guided bone generation. A preliminary study in the rabbit.
Authors: Schmid J. , Hämmerle C. H. F. , Stich H. , Lang N. P.
Published: March 2003

Supraplant®, the skull in 6 rabbits. The results demonstrate that an implant which is placed on top of bone can be osseointegrated by the guided generation of new bone using membrane barriers.
Plasminogen activator in human gingival tissue adjacent to dental implants
Authors: Schmid B. , Spicher I. , Schmid J. , Lang N. P.
Published: March 2003

The installment of endosseous dental implants has become an accepted treatment procedure, and the long‐term clinical results appear excellent. The composition of the soft tissue environment, however, is different from that around natural teeth. One characteristic of original junctional epithelium is its association with plasminogen activator (PA) activity. In 11 patients with a total of 30 IT1 hollow‐screw titanium dental implants, 16 biopsies were taken. Histologic cryostat sections were assayed for the presence of PA in the junctional epithelium. The results demonstrated that junctional epithelium around titanium implants yields PA activity in a manner very similar to that of natural teeth. The ability to produce this enzyme activity is not related to the developmental origin of the junctional cells, but to their position and function at the base of the gingival sulcus.
Putative periodontal and teeth in pathogens on titanium implants and teeth in experimental gingivitis and periodontitis in beagle dogs
Authors: Leonhardt Å. , Berglundh T. , Ericsson I. , Dahlen G.
Published: March 2003

The microflora around titanium implants and teeth in 4 beagle dogs was analyzed in order to follow the longitudinal development from healthy conditions to experimental gingivitis and periodontitis. A 2‐month plaque control program was performed to establish healthy conditions on titanium implants and control teeth (baseline, day 0). Subgingival bacterial samples and radiographs were obtained. The plaque control was ceased and all measurements were repeated on day 21 (gingivitis). A new period of plaque control was initiated to re‐establish healthy conditions (day 49). A cotton ligature was placed subgingivally around the implants and the control teeth to induce tissue breakdown. The ligatures were removed on day 91. The study was completed with registrations on day 121 (periodontitis). No significant microbiological difference was found between titanium implants and teeth in healthy conditions and in gingivitis and periodontitis. The mean total viable count increased 10 times on implants as well as on teeth. Streptococci were dominating at baseline: 40.2% on implants and 60.6% on teeth and decreased in gingivitis to 11.7% and 5.4%. When periodontitis had developed, the proportion of streptococci was < 1%. At baseline few Porphyromonas gingivalis and Prevotella intermedia were detected. They increased at gingivitis to 37.4% and 21.0%; when periodontitis developed, they comprised about 25.0%. Microbial colonization and establishment on titanium implants with healthy gingiva, experimental gingivitis and periodontitis follow the same pattern as on teeth.
Mechanical resistance of cemented post and core buildups for ITI‐Bonefit implants
Authors: Wiskott H. W. A. , Belser U. C.
Published: March 2003

In order to improve the prosthetic versatility of the ITI‐Bonefit implant system, a clinical technique was tested whereby a custom made post and core buildup was cemented into implants. Specially designed threaded and serrated posts were machined in precious metal. After the posts were seated into the threaded channel of the implants, cores were built using autopolymerizing resin. Those were then cast and cemented into the implants. For the remainder of the procedure, the buildups were treated like natural abutments using conventional prosthodontic techniques. Mechanical tests were performed to assess the clinical viability of these buildups. The ultimate tensile strength of annealed posts lies in the 700–800 N range. By comparison, the pull‐out resistance of posts cemented into natural roots ranged between 108 and 177 N, and the maximum pull‐out resistance of manufactured abutments is about 1040 N. When the resistance against lateral forces was tested, the cemented build‐ups ranged between 981 and 1128 N. whereas natural teeth fractured between 206 and 903 N depending on the diameter of the root. Manufactured abutments failed at stress levels of about 1020 N. Considering these favorable results, we conclude that the technique described above can be applied clinically for further investigation. Additionally, we suggest some modifications in implant design that would enhance the versatility of the system.
Laser Doppler flowmetry of blood perfusion in mucoperiosteal flaps covering membranes in bone augmentation and implant procedures. A pilot study in dogs.
Authors: Zanetta‐barbosa D. , Klinge B. , Svensson H.
Published: March 2003

In guided tissue regeneration (GTR) procedures, flap recession or sloughing may occur as an unwanted sequel to the placement of a membrane. This study was designed to assess the applicability of laser Doppler flowmetry (LDF) in the evaluation of blood perfusion in the mucoperiosteal flap covering the membrane. Five Labrador dogs were initially used inthe study, but one animal was later excluded due to post‐operative problems. Maxillary premolar teeth were extracted and full thickness mucoperiosteal flaps were raised. Following removal of the buccal bone plate, 4 titanium implants were placed on each side. An experimental biodegradable polylactic‐acid membrane was placed over the fixtures on one side to allow for GTR. The mucoperiosteal flap was repositioned and secured with sutures. The contralateral side served as control with no membrane. Blood perfusion was measured in the flaps before surgery, immediately after suturing and at 24, 48 and 72 h postoperatively. A laser Doppler flowmeter was used to assess the blood perfusion. In 3 animals the membrane was exposed within 2 weeks post‐operatively, and in these 3 animals the LDF values were lower on the membrane side than on the control side. The mean LDF value was lower on the membrane side for each of the 4 periods studied. The tindings suggest that LDF can be a valuable method to study blood perfusion of oral mucosal flaps and that there may be a relationship between a reduced relative LDF value and subsequent exposure of the membrane to the oral environment.
New periodontal ligament formation on a synthetic hydroxyapatite surface
Authors: Takata T. , Katauchi K. , Akagawa Y. , Nikai H.
Published: March 2003

The aim of this study was to investigate whether a new connective tissue attachment can occur on a surface of hydroxyapatite (HA) when peri‐odontal ligament (PDL)‐derived cells with the ability to form new connective tissue attachment are allowed to populate the surface of HA. Six maxillary canines from 3 cats were used for this experiment. Under anesthesia, fenestration of the buccal alveolar bone was performed over the canine root and a cavity was prepared on the root surface. A synthetic HA block was inlaid and cemented into the root cavity. A Teflon membrane was then placed to cover the access opening of the alveolar bone to guide PDL‐derived cell proliferation into the surface of the HA block. Finally, the gingival tissue flap was replaced and sutured. Six months after the operation, histologic evaluation was done by serial sections. In 4 of the 6 canines, PDL‐derived cells successfully populated the HA surfaces and a layer of cementum‐like tissue was formed on the HA blocks. A PDL‐like connective tissue layer was seen between the cementum‐like layer covering the exposed HA surface and the newly formed alveolar bone sealing the bone fenestration. Collagen fibers in the PDL‐like tissue inserted their ends into the newly formed bone and the cementum‐like tissue. The present findings demonstrated that PDL‐derived cells can 1 form a new connective tissue attachment on HA.
Radiological evaluation of marginal bone loss at tooth surfaces facing single Brånemark implants
Authors: Esposito M. , Ekestubbe A. , Gröndahl K.
Published: March 2003

A radiologic evaluation of marginal bone loss around single implants ad modum Brånemark and their adjacent teeth was performed: 58 adults with 71 fixtures were followed up to 3 years after crown installation. The following factors were considered: age, cause of tooth loss, vertical relation between fixture and teeth, distance between adjacent teeth, distance between fixture and natural tooth, jaw region. Specified distance were measured as well as marginal bone levels around fixtures and tooth surfaces in magnified standardized intraoral radiographs. The results show a loss of marginal bone support at tooth surfaces adjacent to inserted implants during the interval between preoperative examination and crown installation that exceeds the loss during subsequent years. The largest bone loss was observed when implants were placed next to lateral upper incisors. A strong correlation was found between bone loss at adjacent teeth and the horizontal distance fixture‐tooth. With decreasing distance the bone loss increased, especially in the upper incisor region. At present it seems difficult to predict which individual or individual condition may have a higher risk for bone loss, due to large intra‐ and 1 interindividual variation.
Digital image processing. I. Evaluation of gray level correction methods in vitro.
Authors: Fourmousis I. , Brägger U. , Bürgin W. , Tonetti M. , Lang N. P.
Published: March 2003

The aims of this study were a) to assess in an in vitro model the amount of density changes measured in digitally subtracted images due to electronic noise and image alignment error, and b) to test the accuracy of different gray level correction procedures in the reduction of densitometric image mismatches. A section of a pig mandible in which a hollow cylinder ITI Bonefit® implant had been placed was used to obtain pairs of standardized radiographs. Series of radiographs were obtained with different exposure times (0.34, 0.39, 0.44, 0.51, 0.58 s). The radiographs were captured through a video camera, digitized and stored in a personal computer. The same radiographic image was recorded and subtracted from itself 10 times to study the error of the method due to electronic transformations of the images and image alignment. The noise due to the analog‐to‐digital transformation of the radiographic images was calculated to be +2 gray levels i.e., 2% of the scale of gray levels. This kind of error was reduced up to 40% by capturing the images more than once and averaging the values per pixel. The manual superimposition of the images to be subtracted caused an increase of the error to ±3 gray levels (2.7%). Seven methods of gray level correction based either on a linear least squares approximation or on the cumulative density function (CDF) were tested. The group based on the CDF algorithm gave significantly better results than any other method. Pixels yielding differences smaller or equal ±7 gray levels (5.5% of the scale of gray levels) should be excluded from further calculations in order to eliminate (false‐positive) errors due to the normalizing algorithms. Furthermore, the CDF method on an arbitrarily chosen area of the image or on the wedge seems to give to subtraction images the ability of revealing real subtle changes in tissue density (fewer false‐negative errors). The use of reference structures did not futher improve the ability of the normalization methods to correct gray level mismatches between radiographic pairs.
Qualitative study of collagenous and noncollagenous glycoproteins of the human healthy keratinized mucosa surrounding implants
Authors: Chavrier C. , Couble M. L. , Hartmann D. J.
Published: March 2003

The purpose of this study was to analyse the distribution of interstitial collagenous and noncollagenous glycoproteins of keratinized mucosa surrounding successful endosseous implants. Biopsies were incubated with highly purified antibodies against types I. III. IV collagen. laminin and fibronectin and routinely observed by immunofluorescence staining. Whereas no significative difference in the distribution of collagenous components was observed in comparison with healthy human gingiva, the collagen fibers of the connective tissue attachment ran parallel to the long axis of the implant. In 50% of the biopsies the gingival connective tissue underlying the junctional epithelium was rich in inflammatory cells and poor in collagenous components. However, the increased staining of type III collagen and the intense presence of fibronectin in this area reflect the very important remodeling ability of the local keratinized mucosa.
Histological evidence of osseointegration 4 years after implantation. A case report.
Authors: Grätz K. W. , Zimmermann A. P. , Sailer H. F.
Published: March 2003

Histological examinations of clinically successful dental implants are very rare in the literature. This article presents a clinical case where an ITI hollow‐cylinder titanium implant type F (red mark, 16 mm) had to be removed simultaneously with the resection of a squamous cell carcinoma of the lower jaw. The duration of functional loading of the implant was 49 months. The fixture was situated at the margin of the tissue to be resected during tumor surgery and could therefore be prepared as a histological specimen independent of the tumorous tissue. In the sections obtained. close contact of alveolar bone to the implant surface was clearly visible. Together with the clinical success of the implant, criteria of osseointegration seems to have been matched. This observation represents the longest histological survery of a clinically successful fixture of this implant system.
Histological characteristics of peri‐implant mucosa around Brånemark and single‐crystal sapphire implants
Authors: Arvidson K. , Fartash B. , Hilliges M. , Köndell P. Å.
Published: March 2003

Soft tissues surrounding Brånemark titanium implants and single crystal sapphire implants were studied by conventional light‐ and transmission electron microscopy and by immunohistochemical markers for cytokeratin, protein S‐100, Factor VIII and KP1. Histological sections of biopsies obtained from clinically healthy peri‐implant mucosa were separated into a keratinized outer implant epithelium and an inner, non‐keratinized epithelium, both immunoreactive towards cytokeratin. The inner implant epithelium terminated in a junctional epithelium, apically only a few cell layers thiih. The cells adjacent to the implant showed a condensed cytoplasm, resembling hemidesmosomes. In the underlying connective tissue, rich in fibroblasts and factor VIII immunoreactive blood vessels, the bundles of collagen ran in different directions. S‐100 immunoreactive nerve structures were more frequently found beneath the outer than the inner implant epithelium. Inflammatory cell infiltrates, some KP1 positive, were observed in the apical parts of the inner implant epithelium. S‐100 positive Langerhans' cells were present mainly within the the outer implant epithelium. For the two implant systems, the techniques disclosed no qualitative structural differences in the adjacent soft tissues.
The biocompatibility (cell culture and histologic study) of hydroxy‐apatite‐coated implants created by ion beam dynamic mixing
Authors: Yoshinari Masao , Klinge Björn> , Dérand Tore
Published: March 2003

Titanium implants were coated with hydroxyapatite by using a method of ion beam dynamic mixing. Coated and noncoated plates of titanium were placed in a growth medium with fibroblast cells. Implant screws, coated and noncoated, were inserted in rabbit bones and the animals were euthanized after 7, 27 and 122 days, respectively. The results from the cell culture test showed no visible difference between the specimens. Histologic examination of implant specimens indicated more new bone activity against coated screws at 27 days, and that was more pronounced at 127 days. Although the amount of new bone formation was not significantly different, certain signs of favourable new bone formation could be seen in contact with coated implants compared to the noncoated controls.
Influence of initial implant mobility on the integration of titanium implants. An experimental study in rabbits.
Authors: Ivanoff C.‐J. , Sennerby L. , Lekholm U.
Published: March 2003

In the present study, the influence of initial instability on the healing of titanium implants was studied in 9 lop‐eared rabbits. Titanium implants (Brånemark System®) were inserted in the tibiae, a location with cortical bone only. in such a way that they were either stable (control), rotation‐mobile, or totally mobile. Implants were also inserted in the distal femoral condyles, representing an implantation bed with mainly cancellous bone, so they either showed no initial mobility (control) or were rotation‐mobile. After 12 weeks of healing, the implants were retrieved, together with surrounding bone, fixed, dehydrated, and embedded in plastic resin. About 10 μm thick ground sections were prepared for light microscopic morphometry. The mineralized bone to titanium contact, and the amount of bone occupying the threads, were calculated, whereafter the outcome of the different locations were compared. All retrieved implants were clinically stable at the end of the experiment. For the tibia sites, a statistically significant less bone to titanium contact, and a less amount of bone in the threads, were found for the totally mobile implants, as compared tothe corresponding initially stable controls. Moreover, a statistically significant higher amount of bone was found in the threads of the rotation‐mobile implants inserted in the femoral condyle as compared to their initially stable controls. The study indicated that initial rotation‐mobility, independent if it occurs in cortical or trabecular bone, does not necessarily lead to an inferior integration of unloaded implants. However, initial total implant mobility within the cortical layer results in a statistically significant less amount of lb one around the implants, as compared to stable controls.
Progressive peri‐implantitis. Incidence and prediction of peri‐implant attachment loss.
Authors: Jepsen S. , Rühling A. , Jepsen K. , Ohlenbusch B. , Albers H.‐K.
Published: March 2003

The aim of this prospective study was to characterize an implant patient population exhibiting clinical signs of peri‐implantitis and to determine subsequently the incidence of progressive attachment loss. The predictive values of diagnostic parameters were evaluated. 25 patients with 54 endosseous implants that had been loaded for 41±15 months were included in the study. Clinical parameters included the assessment of plaque, bleeding on probing, probing depth, attachment levels, and Periotest® values. Probing measurements were performed in duplicate by means of a controlled force electronic probe (Periprobem). Peri‐implant crevicular fluid samples were collected and assayed for neutral proteolytic enzyme (NPE) activity (Periocheck®). Analysis of duplicate baseline probing data revealed a high degree of reproducibility (mean difference: 0.1±0.3mm). A minimum threshold of 1.0mm (>3×S.D.) loss of probing attachment was chosen to classify a site as positive for breakdown. Alternatively, the tolerance method was employed to identify sites with progressive attachment loss. After 6 months, irrespective of the analytical method, 6 percent of all sites (in 19% of the implants) and 28% of the patients had experienced further per attachment loss. There were significant differences (p<0.05) in mean plaque (73% vs. 45%) and NPE (36% vs. 12%) scores between patients with progressive peri‐implantitis and those with stable peri‐implant conditions. Both bleeding on probing and the NPE‐test were characterized by high negative predictive values, and thus negative scores can serve as indicators for stable peri‐implant conditions. For monitoring peri‐implant health during recall visits, attachment level recordings with a controlled force electronic probe in conjunction with enzymatic diagnostic tests of the host response can be recommended.
Resonance frequency measurements of implant stability in viva. A cross‐sectional and longitudinal study of resonance frequency measurements on implants in the edentulous and partially dentate maxilla.
Authors: Meredith N. , Books K. , Fribergs B. , Jemt T. , Sennerby L.
Published: March 2003

The aim of this investigation was to evaluate the use of resonance frequency measurements in the clinical measurement of implant stability. Resonance frequency measurements are undertaken by measuring the response of a small transducer attached to an implant fixture or abutment. Two groups of patients were selected for study. Group A comprised 9 patients who had a total of 56 implants placed. Resonance frequency measurements were made at fixture installation and repeated 8 months later at abutment connection. The resonance frequency of the implant/transducer system increased for 50 out of the 56 implants from a mean value of 7473 Hz ± 127 Hz (P<0.05) to a mean of 7915 Hz ± 112 Hz (P<0.05). Two implants had failed to integrate and the resonance frequency of these had fallen. Group B comprised 9 patients who had been provided with fixed prostheses and had a total of 52 implants placed. They were examined 5 years after fixture placement and the prostheses removed. All implants were judged clinically to be osseointegrated. The level of the marginal bone around each implant was calculated by measuring the number of exposed threads on intraoral periapical radiographs and added to the length of each abutment to give a value termed the effective implant length (EIL). Measurements indicated a correlation (R=0.78, P<0.01) between EIL and resonance frequency. The results support the hypothesis that the resonance frequency of an implant/transducer system is related to the height of the implant not surrounded by bone and the stability of the implant/tissue interface as determined by the absence of clinical mobility.
Blood supply to the maxillary sinus relevant to sinus floor elevation procedures
Authors: Solar Peter , Geyerhofer Ursula , Traxler Hannes , Windisch Alfred , Ulm Christian , Watzek Georg
Published: March 2003

The maxillary blood supply is essential for preserving the vitality of the affected maxillary region, integration of the grafting material, and wound healing such as following sinus floor elevation. Although it is well established that edentulous maxillae demonstrate a decreasing vascularity as bone resorption progresses, the vascular conditions relevant to sinus floor elevation procedures have not been investigated yet. This study deals with maxillary arteries relevant to sinus floor elevation surgery and examines the vascularization of the lateral maxilla after tooth loss. The vessels of the lateral maxilla of 18 maxillary specimens (10 male, 8 female, mean age 67 years) were prepared anatomically and the local main arteries, the number of macroscopically discernible branches and anastomoses, their calibers, and the distance between the caudal main branches and the alveolar ridge recorded. The lateral maxilla is supplied by branches of the posterior superior alveolar artery (PSAA) and the infraorbital artery (IOA) that form an anastomosis in the bony lateral antral wall, which also supplies the Schneiderian membrane. This intraosseous anastomosis was found in all of the specimens. Eight of 18 also showed an extraosseous anastomosis between PSAA and IOA, vestibular to the antral wall, giving off an average of 3 branches cranially and 5 branches caudally. The two anastomoses form a double arterial arcade to supply the lateral antral wall and, partly, the alveolar process. The PSAA had a mean caliber of 1.6 mm and exhibited an average of 2 endosseous and 1 extraosseous branches. The IOA had a mean diameter of 1.6 mm and showed an average of 1 endosseous and 3 extraosseous branches. The mean distance between the intraosseous anastomosis and the alveolar ridge was 19 mm in 2 defined measuring sites. Its mean length was 44.6 mm. The epiperiosteal vestibular anastomosis was situated further cranially, at a mean distance of 23 to 26 mm from the alveolar ridge and had a mean length of 46 mm. The rather large caliber of the vessels supplying the lateral antral wall seems to be crucial to the fact that the periosteal blood supply is maintained even in severe maxillary atrophy and after complete disappearance of the centro‐medullary vessels.
Oblique lateral cephalometric radiographs of the mandible in implantology: usefulness and accuracy of the technique in height measurements of mandibular bone in vivo
Authors: Verhoeven Jan Willem , Cune Marco Stephan
Published: March 2003

Various radiographic techniques are used for longitudinal studies of changes in the height of the mandible with implants. Advantages and disadvantages of panoramic radiographs, lateral cephalometric radiographs, periapical films and modern CT‐ and MRI‐techniques are briefly discussed. In this study, the usefulness of a conventional radiographic technique for measuring the height of the mandible, i.e. oblique lateral cephalometric radiography (OLCR) is evaluated in vivo. In 16 patients with permucosal implants in the anterior mandible OLCRs were repeated the same day. The mean total error for the radiographic procedure and analysis was 0.38 mm. The intra‐observer error for the determination of the mandibular height by means of the image analysis procedure was 0.16 mm (analysis error). In 12 other patients pairs of radiographs of the same area of the mandible were made using both a “standard” horizontal X‐ray beam direction and an individually determined “optimal” horizontal X‐ray beam direction; the maximum difference between these two angulations was plus or minus 7.5 degrees. The effect of this different angulation on the height measurements is comparable to the above‐mentioned total error of the measurement procedure (positioning error). An accurate positioning of the patient seems important for reliable measurements. The described radiographic (OLCR) and analysis (IBAS) technique can be used relatively simply for clinical studies. The described methods appear to be useful for measuring the mandibular height in longitudinal studies in patients with or without implants.
Implant placement in the maxillary tuberosity: the Summers' technique performed with modified osteotomes
Authors: Nocini Pier Francesco , Albanese Massimo , Fior Andrea , De Santis Daniele
Published: March 2003

The maxillary tuberosity region is becoming increasingly involved in preprosthetic surgery as part of a comprehensive implant treatment planning. The lower success rates in osteointegrated implant placements seen in the posterior regions of the upper maxilla as compared to the anterior regions of the jaws, most often come from bone quality types and the presence of the maxillary sinus. In order to overcome these limitations and obtain a successful result in such a demanding area, several authors suggest that long implants (15.0 to 20.0 mm long) should be placed in the maxillary tuberosity region as an alternative to sinus floor elevation. The challenges frequently associated with the surgical placement of “maxillary tuberosity implants” (MTI), can be reduced through a “Ridge Expansion Osteotomy” (REO) procedure as described by Summers (1994). This indeed improves the recipient bed bone quality and causes no bone overheating. In order to improve this technique performed for MTI, in co‐operation with Ing. Albanese G, authors have developed different prototypes of modified osteotomes. A case report using these new instruments is presented. Clinical and radiographic evaluations are obtained.
Onlay grafts in combination with endosseous implants in severe mandibular atrophy: one year results of a prospective, quantitative radiological study
Authors: Verhoeven Jan Willem , Ruijter Jan , Cune Marco Stephan , Terlou Maarten , Zoon Marjolein
Published: March 2003

In taking an overall view of the radiographs made of patients that underwent simultaneous onlay‐grafting and implant placement in the anterior mandible, changes are seen in the grafts. The impression arose that a number of stages could be distinguished in this process of remodelling of the graft. The purpose of the present study was to objectivate the existence of those stages in the first year after bone‐grafting by densitometric and height measurements of the onlay grafts using standardized extraoral radiographs (OLCR) and densitometric analysis in a group of 8 patients. OLCRs were taken at regular intervals in the first year after surgery. The measurements were performed in three fixed fields, both ventrally and dorsally of each implant. Generally the densitometric measurement fields were located at the (upper) cortex, the upper spongiosa and the lower spongiosa of the onlay graft. The OLCRs were also used for measurements of the height of the complete graft and of the thickness of the cortex of the graft, using a gauged caliper. The results indicate the following remodelling of the structure of the onlay grafts: 1) decrease in the thickness and the radiographic density of the (upper) cortex of the onlay graft predominantly in the first 6‐month period; 2) no significant changes in the radiographic density of the upper spongeous part of the graft; 3) a decrease of approximately 25% in the overall height of the graft, particularly during the first 6‐month period; 4) an increase in the radiographic density of the lower part of the spongeous bone in the second 6‐month period. It is concluded that the remodelling of the graft has a predictable pattern in time: the first half year being dominated by bone resorption, mainly confined to the cortex of the graft, whereas the second half year is characterized by an increase in bone density in the (remaining) cortex as well as the lower spongeous parts of the graft.
Mechanical complications of dental implants
Authors: Schwarz Melvyn S.
Published: March 2003

Adverse occlusal forces can result in mechanical complications of implant components. While unacceptably high incidences of mechanical failures have been reported for the two‐stage external hex screw‐type implant systems, the standard‐diameter ITI® solid‐screw implant does not seem to be vulnerable to these problems. The 8° Morse taper has eliminated abutment screw loosening and fracture. The incidence of prosthetic screw loosening has been minimized by the 45° bevel on the implant shoulder and by the 1.5 mm vertical abutment walls. The design of the standard‐diameter solid‐screw ITI implant and the material used in its fabrication (cold worked type IV cp titanium) have eliminated fixture fracture. However, because there have been some reported instances of fractures involving reduced‐diameter and hollow implants, these designs should be used with caution.
A computer‐assisted measurement technique to assess bone proximal to oral implants on intraoral radiographs
Authors: Wyatt Chris C. L. , Bryant S. Ross , Avivi‐Arber Limor , Chaytor Douglas V. , Zarb George A.
Published: March 2003

Abstract: A computer‐assisted measurement technique for measuring bone levels proximal (mesial and distal) to oral implants imaged on standardized intraoral radiographs offers promise for accuracy and reliability. There were no differences between bone measurements made directly from bone proximal to implants placed in a dry mandible and those resulting from the computer‐assisted measurement technique. In addition, there were no differences between measurements made of bone proximal to oral implants in vivo using the microscope and the computer techniques. The computer technique had a low intra‐ and inter‐operator variability, and operators found fewer “unreadable” sites compared to the microscope technique. The computer‐assisted measurement of bone levels proximal to oral implants on standardized intraoral radiographs offers accuracy and reliability.
Removal of HA and TPS implant coatings and fibroblast attachment on exposed surfaces
Authors: Rühling Andreas , Hellweg Arne , Plagmann Hans‐Christian , Kocher Thomas
Published: March 2003

Abstract: The removal of implant coatings may be necessary if rough implant surfaces are exposed subgingivally due to progressive peri‐implant bone loss or if they are also supragingivally exposed because of progressive gingival recession, thus facilitating plaque formation and impairing tooth cleaning done at home. The aim of this experimental study was to develop diamond‐coated files and rubberized polishers for machine‐driven instrumentation of implant cylinders, and present an instrumentation concept for the complete removal of rough titanium plasma spray (TPS) and hydroxylapatite (HA) layers and polishing exposed titanium surfaces. The surface structure and its possible contamination by the instrumentation process was investigated using laser profilometry, scanning electron microscopy, and x‐ray fluorescence analysis. The effect of impurities on the growth of human fibroblasts was tested in cell culture. The results show that TPS and HA implant coatings can be removed with the modified implant files. After polishing the exposed titanium surfaces, roughness depths of Rz=4.6 μm (TPS) and Rz=5.7 μm (HA) and, for implant cylinders, 3.4 μm were found. During the instrumentation of implant surfaces, contamination with the material of the instrument must be expected. It was shown that, in principle, growth of human gingival fibroblasts on the instrumented surfaces is possible. The cells were intimately associated with one another and, compared to culture controls, demonstrated good adhesion with strict orientation to the microstructure of the scoring left by instrumentation. The biological consequences and mechanisms of cell adhesion on instrumented surfaces require further investigation.
Retrospective analysis of the influence of abutment structure design on the success of implant unit
Authors: Bambini Fabrizio , Muzio Lorenzo Lo , Procaccini Maurizio
Published: March 2003

Abstract: A comparative study of 96 Spline and Threadloc implants is presented. The authors examined the possibility of the failure of the retaining screws of two different antirotational systems (the Threadloc system with hexagonal polyhedral extension and the Spline system), and the possible incorrect link between the abutment and the transfer. After an observation period of 36 months starting from the day of prosthesis insertion, three single Threadloc fixtures (20%) and five pairs of joint Threadloc fixtures (5.7%) presented problems and a partial prosthetic screw loosening. For the Spline series fixtures, no screw loosening was encountered. Regarding the safety of the link between abutment and implant, the best results were obtained from the Spline system, which did not hinder the dentist in positioning the link with the abutment. This is the result of the different geometries of the two antirotational mechanisms which are present on the two fixtures. It is believed that the precise contact between the abutment and the fixture avoids the triggering of a phlogistic process, which can develop into periimplantitis. Therefore, when hex systems are used, an x‐ray, which verifies this correct situation, is always recommended during the follow‐up.
Augmentation of the mandible with GTR and onlay cortical bone grafting
Authors: Donos Nikolaos , Kostopoulos Lambros , Karring Thorkild
Published: March 2003

Abstract: The aim of the present study was to evaluate the effect of augmenting the mandible with onlay mandibular bone grafts that were covered with e‐PTFE membranes according to the principle of guided tissue regeneration (GTR). The experiment was carried out in 30 rats. The inferior border of the mandible and parts of the mandibular body were exposed on both sides. On one side, an autogenous bone graft that was harvested from the angle of the mandible was placed on the inferior border of the mandible and was fixed with a titanium microimplant. Subsequently, the graft was covered with an e‐PTFE membrane. The contralateral side, serving as control, was treated the same way except for the placement of the membrane. Groups of six animals were sacrificed 15, 30, 60, 120 and 180 days following surgery, and specimens that were prepared from the experimental and control sites were analyzed histologically. The bone graft underneath the membrane initially presented superficial resorption but, subsequently, the space that was created by the membrane gradually became filled with bone. After 180 days, the area underneath the membrane was completely filled with bone and it was impossible to distinguish between the bone graft and the newly formed bone. Generally, the bone grafts at the control sides were characterized by a gradual resorption during the entire experimental period. At 180 days after transplantation, only a few grafts at the control sites had retained their height, and there was frequently a lack of continuity between the bone graft and the underlying mandibular bone. It can be concluded that onlay mandibular bone grafts combined with GTR may improve the predictability of mandibular augmentation, in comparison to bone grafting alone.
Dynamics of bone marrow pressure with tapping of titanium and hydroxyapatite implants in rabbits
Authors: Tomotake Yoritoki , Ichikawa Tetsuo , Kanitani Hideo , Nakao Masahide , Kitaoka Naoki
Published: March 2003

Abstract: The purpose of the present study was to evaluate the difference in stress transfer between titanium (Ti) and hydroxyapatite (HA) by the measurement of bone marrow pressure using a catheter pressure transducer. Ti and HA implants were inserted in the tibiae of rabbits. A hole of 1 mm in diameter was drilled in the bone and a fine catheter pressure transducer was placed in the bone marrow through a tube. The top of the abutment was vertically tapped with an impulse hammer, and the acceleration signal from the hammer and pressure signal from the catheter pressure transducer were examined. The time of contact (impulse duration) recorded in the impulse with Ti and HA was 166±17 μsec and 164±17 μsec, respectively. Maximum bone marrow pressure (BMP) with Ti and HA was 54.2±32.6 and 47.5±10.0 mmHg, respectively. Variation of the BMP with Ti was significantly larger than that with HA (P<0.05). A negative correlation coefficient between impulse duration and BMP was found. The results of the present study suggest that the stress transfer is different between Ti and HA implants using dynamics of the bone marrow pressure.
Peri‐implant bone tissue strains in cases of dehiscence: a finite element study
Authors: Van Oosterwyck Hans , Duyck Joke , Vander Sloten Jos , Van der Perre Georges , Naert Ignace
Published: March 2003

Abstract: When patients with a narrow alveolar bone ridge are treated with oral implants, a dehiscence can occur. The lack of bony support at the buccal or lingual side of the implant may present an unfavourable situation from a biomechanical point of view. The hypothesis as to whether the presence of dehiscence leads to an increased risk of marginal bone overload was tested by means of the finite element method. Three different situations for a cylindrical oral implant, which was placed in a mandible, were modelled: i) no dehiscence, ii) a dehiscence at the buccal side and iii) dehiscences at the buccal and lingual sides. It was found that the presence of buccal and/or lingual dehiscences led to a marked increase in marginal bone strains at the mesial and distal sides of the implant, thus increasing the risk of bone tissue overload at these locations. Marginal bone strains at the buccal and/or lingual sides, however, did not increase.
Osteocalcin, deoxypyridinoline and interleukin‐1β in peri‐implant crevicular fluid of patients with peri‐implantitis
Authors: Murata Masashi , Tatsumi Jun‐ichi , Kato Yumi , Suda Satoru , Nunokawa Yasuko , Kobayashi Yukinao , Takeda Hiroyuki , Araki Hisao , Shin Kitetsu , Okuda Kazuhiro , Miyata Takashi , Yoshie Hiromasa
Published: March 2003

Abstract:The aim of the present study was to analyze the levels of osteocalcin, deoxypyridinoline (Dpd) and interleukin‐1β as markers of bone metabolism in peri‐implant crevicular fluid (PICF) from peri‐implantitis patients. PICF was sampled from a total of 34 endosseous titanium implants from 16 patients; nine females (mean age 52.8, range 40–62 years) and seven males (mean age 56.0, range 36–66 years). The implants had been in place for a period of 9–112 months (mean; 35.8 months) since the loading. These sites were categorized as six peri‐implantitis, eight peri‐implant mucositis and 20 healthy implant. PICF volume from peri‐implantitis sites was significantly higher than mucositis and healthy implant sites (P < 0.01). Osteocalcin levels in PICF from mucositis sites were significantly higher than healthy implants (P < 0.05), whereas peri‐implantitis sites were not significantly different from either mucositis or healthy implant sites. Dpd could not be detected in any of the samples examined. IL‐1β levels in PICF from peri‐implantitis sites were significantly higher than levels from peri‐implant mucositis (P < 0.05) and healthy implant sites (P < 0.01). In conclusion, osteocalcin in PICF may reflect increased local bone turnover around implants. Further, IL‐1β should be a useful marker for peri‐implant inflammation.
Analysis of a device for assessment of abutment and prosthesis screw loosening in oral implants
Authors: Hanses Gunnel , Smedberg Jan‐Ivan , Nilner Krister
Published: March 2003

Abstract: Screw loosening is an irritating problem in implant dentistry. Loosened abutment screws and prosthesis screws are often found at yearly examinations. Loosened screws may cause costly complications, such as screw fractures and fracture of the framework, and methods to prevent them would be welcome. The purpose of this study is firstly to describe a mechanical protractor device designed to fit the electrical Torque Controller (Nobel Biocare®, DEA 020, Gothenburg, Sweden) and measure the number of degrees necessary to retighten the abutment screw or the prosthesis screw to reach the target torque value. A second purpose is to analyse the precision and validity of the device. The results of the study indicate that the degree of preset loosening of abutment and prosthesis screws can be well reflected in the number of degrees necessary for retightening. It was also shown that it is possible to retighten the abutment and prosthesis screws with a precision of 1.7° and 1.3°, respectively. The study shows that the device has good precision and validity. By using this device, we hope to be able to evaluate various parameters for screw stability, such as the type of implant system, the number of fixtures, the type of abutments, the type of bridge material and the need for retightening of the abutment and prosthesis screws.
Long‐term evaluation of osseointegrated dental implants in the treatment of partly edentulous patients
Authors: Hultin Margareta , Gustafsson Anders , Karolinska Björn Klinge
Published: March 2003

Aim:

The aim of this study was to evaluate the clinical, radiographic and microbiological status of implants after 10 years of functional load in patients treated for partial edentulism.

Method: 15 patients, each successfully treated with 2–6 implants ad modum Brånemark placed in free‐standing fixed prostheses, were included in the study.

Results: Clinical evaluation revealed similar degrees of inflammation around teeth and implants. The probing pocket depth (PPD) was significantly greater around implants than around teeth. The mean marginal bone loss during 10 years of functional load was comparable to that found at the time of the 5‐year follow‐up. 74% of the implants remained free of marginal bone loss exceeding 1 mm. Marginal bone loss exceeding 2 mm, was found at only 5 sites. No marked differences in bacteria were present between teeth and implants. T. denticola, S. intermedia and P. micros were the commonest organisms detected around teeth and implants. The periodontal pathogens A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus, and T. denticola, were found at implants with a marginal bone loss of more than 2 mm.

Conclusion: Our study shows that the long‐term results with implants in partially dentate patients are similar to those seen in edentulous patients and that no significant change occurred after 5‐year follow‐up over an additional period of 5 years.
Subgingival polishing with a teflon‐coated sonic scaler insert in comparison to conventional instruments as assessed on extracted teeth
Authors: Kocher Th. , Langenbeck M. , Rühling A. , Plagmann H.‐C.
Published: March 2003

Background: Recent studies have shown that endotoxins are located on the periodontally diseased root cementum and not within it. These studies led to the suggestion that the root surface could be treated less aggressively during periodontal therapy. Thus, we designed a teflon‐tubed sonic scaler insert for subgingival polishing. It was our objective to assess to which extent this new instrument is capable of removing bacterial deposits in deep pockets in comparison with conventional scaling instruments.

Method: We compared the extent to which plaque and calculus could be removed with a curette, a conventional sonic and ultrasonic scaler insert, a Per‐io‐tor insert, and a teflon‐tubed sonic scaler insert. 84 teeth requiring extraction had been treated with one of these instruments. After extraction, the teeth were stained with Malachite green, and the following areas were assessed: area lacking plaque and calculus, calculus, and area only covered with plaque. For statistical comparison, nonparametric analyses were carried out.

Results: Curettes and conventional ultrasonic and sonic‐scaler inserts had more area lacking plaque and calculus (97.5%, 92.2%, 92.1%) than did the Per‐io‐tor (80.1%) or the teflon‐coated sonic scaler insert (84.4%). A similar effectivity sequence was observed for residual soft deposits (curette: 1.9%, ultrasonic scaler: 6.1%, sonic scaler: 5.4%, teflon‐coated sonic scaler: 5.1% and Per‐io‐tor: 9.5%).

Conclusions: The Per‐io‐tor and the teflon‐coated sonic scaler insert seem to be suitable for the removal of soft deposits on the root surface, but not for the removal of calculus.