bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of nestin and other intermediate filament expression distinguish between gastrointestinal stromal tumors, leiomyomas and schwannomas*
Authors: Sarlomo‐Rikala Maarit , Tsujimura Tohru , Lendahl Urban , Miettinen Markku
Published: March 2003

The KIT‐positive specific gastrointestinal stromal tumors (GISTs), leiomyomas, and schwannomas are the three most common types of primary mesenchymal tumors of the gastrointestinal (GI) tract. The intermediate filaments are abundant cytoskeletal proteins commonly used as cell differentiation markers in diagnostic immunohistochemistry. Their patterns have not been fully characterized in GI mesenchymal tumors, and could offer differential diagnostically useful parameters. Very recently, nestin, a class VI intermediate filament expressed in neuroectodermal stem cells and skeletal muscle progenitor cells, has been shown in GISTs and suggested as a marker for these tumors. In this study we immunohistochemically examined the expression of nestin and other intermediate filament proteins, including desmin, keratins (Ks), glial fibrillary acidic protein (GFAP), neurofilament, and vimentin in GISTs of different sites, esophageal leiomyomas and GI schwannomas. Nestin was nearly consistently present in GISTs of different locations whether spindle cell or epithelioid, and benign or malignant. It was also detected in 23 of 24 (96%) GI schwannomas, whereas leiomyomas were uniformly negative. Vimentin was present in both GISTs and schwannomas, whereas it was typically absent in leiomyomas (25% positive, usually focally). Desmin was present in all leiomyomas, whereas only 3% of GISTs (4 of 140) were positive, and all schwannomas were negative. K18 was detected in a minority of GISTs, leiomyomas, and schwannomas. Malignant GISTs were more commonly keratin positive than the benign ones; there was 18% K18 positivity in malignant gastric and small intestinal GISTs, but 9% K18 positivity in benign gastric and small intestinal GISTs. Moreover, K8, albeit to a lesser degree, was detected in a minority of GISTs, but K7, K14, K19 and K20 were not detected. GFAP was present in the majority of schwannomas, whereas all GISTs were negative; some leiomyomas had weak cytoplasmic positivity. These results document distinctive patterns of intermediate filament proteins in GI mesenchymal tumors. Nestin is confirmed to be consistently expressed in GISTs but it is also present in most GI schwannomas; GFAP is helpful when separating GISTs and schwannomas, since only the latter are positive. The potential presence of K8 and K18 in GISTs should not lead to the misdiagnosis of carcinoma on biopsy.
Candida glabrata, an emerging fungal pathogen, exhibits superior relative cell surface hydrophobicity and adhesion to denture acrylic surfaces compared with Candida albicans
Authors: Luo G. , Samaranayake L. P.
Published: March 2003

Oral candidosis is a common opportunistic infection in debilitated individuals and Candida glabrata is the second most frequently isolated species from this condition, after Candida albicans. Candidal adherence to various biological or non‐biological surfaces is considered a prerequisite for colonization, and pathogenesis of candidal infections, and their relative cell surface hydrophobicity (CSH) is likely to be a possible contributory force involved in this process. Whereas a large body of data on the latter features of C. albicans is available, there is surprisingly little information on C. glabrata. As a comprehensive database on the relative adhesion and CSH of Candida spp. is instructive and useful, we investigated in vitro the latter attributes of 34 oral isolates of C. glabrata and 15 isolates of C. albicans. There were remarkable intraspecies differences in both the CSH and the adhesive ability of C. glabrata strains (p<0.001). Compared with C. albicans, C. glabrata demonstrated a four‐fold greater CSH value (30.63±11.20% vs 7.23±3.56%, p<0.0001) and a two‐fold greater tendency to adhere to denture acrylic surfaces (75.18±39.96 vs 30.36±9.21, p<0.0001). A significant positive correlation between CSH and adhesion was also noted for both C. glabrata (r=0.674, p<0.0001) and C. albicans (r=0.636, p<0.05). When the effect of different incubation conditions on the relative CSH and adherence of C. glabrata was examined, CSH and the adherence to acrylic surfaces of four of six C. glabrata isolates were significantly affected by a reduction of the culture temperature (from 37 °C to 25 °C). A positive relationship also emerged when the temperature‐induced variations in the adherence values were correlated with their relative CSH. These data provide hitherto unavailable archival information on important pathogenic attributes of the two most common oral Candida species that may help explain their predominance in this milieu.
Modes of participation of macrophages in the formation of membranocystic lesions
Authors: NAKAMURA TOSHITSUGU , FUJIWARA MASAYUKI
Published: March 2003

We investigated the modes of participation of macrophages in the formation of non‐specific (i.e., unrelated to membranous lipodystrophy) membranocystic lesions (MCLs). Surgical specimens of atherosclerosis and chronic panniculitis containing MCLs as well as experimentally formed MCLs were examined, using paraffin sections, by Sudan black B (SBB) stain and by immunostaining for CD68, Bax protein and advanced glycation end products (AGEs). In the atherosclerotic lesions, MCLs were formed by a gradual fusion of SBB‐positive multivesicular structures in the macrophages, associated with the cell breakdown. MCLs in the panniculitis were formed in the macrophages, as in atherosclerosis, or derived from degenerative fat cells, often with attachment of macrophages. CD68 was demonstrated in some MCLs or around them, and Bax was also present in some MCLs as well as some macrophages in both lesions. On the other hand, macrophages were not involved in the experimental MCLs. AGEs were widely detected in some MCLs, macrophages and degenerative background in all specimens. These results suggest that MCLs share AGEs as common components with various types of fat degeneration, and are formed physicochemically in the event that macrophages cannot dispose of the degenerative fat sufficiently due to their relative functional impairment and/or the physical circumstances.
Fixed reconstructions in partially edentulous patients using two‐part ITI implants (Bonefit®) as abutments. Treatment planning, indications and prosthetic aspects.
Authors: Brägger U. , Hämmerle C. , Weber H.‐P.
Published: March 2003

Fixed reconstructions on implant abutments may be a welcome modality in the treatmcnt of partially edentulous patients following the principle of a prophylactically oriented comprehensive care. The option to create artificial tissue integrated abutments widens the range of indications for fixed reconstructions. Risky long‐span bridges as well as the preparation of intact teeth for bridge abutments may frequently be avoided. Never should the contours of the prosthesis interfere with the patient's performance of optimal plaque control. Furthermore, supportive periodontal therapy with regular maintenance visits may be provided to optimize a long‐term prognosis of the dention as well as the tissue‐integrated artificial abutments.
The effects of preoperative resorption and jaw anatomy on implant success. A report of 303 cases.
Authors: Bass S. L. , Triplett R. G.
Published: March 2003

The purpose of this paper is to report the outcome of 1097 consecutively implanted endosteal implants (Brånemark®) into 303 jaws, between September 1983 and May 1990. All implants were placed using the prescribed technique suggested by manufacturer, and were restored either with fixed or removable prosthesis. Alveolar bone resorption (quantity) was scored from lesser to greater degree by assigning a value of l–5 to each jaw, and jaw anatomy was scored from l–l, based on decreasing cortical and cancellous bone quality. The data were separated into fixed and removable prosthesis and analyzed to determine the correlation between success and the scored resorption and jaw anatomy, as well as implant position. Assessment demonstrated a maxillary success rate of 93.4% and a mandibular success rate of 97.2% over a 36‐month period (mean). Results of correlations of success with jaw anatomy for both fixed and removable prosthesis revealed that bone quality 4 exhibited the greatest failure rate. Preoperative resorption values (1‐S) had little effect on failure, and quality appears to influence failure more than I quantity.
Experimental breakdown of peri‐implant and periodontal tissues. A study in the beagle dog
Authors: Lindhe J. , Berglundh T. , Ericsson I. , Liljenberg B. , Marinello C.
Published: March 2003

The objective of the present experiment was to study lesions in the peri‐implant and periodontal tissues resulting from ligature placement and subgingival plaque formation. The experiment was performed in 5 beagle dogs which at the start of the study were about 15 months old. They were given a diet which allowed gross plaque formation. The mandibular right premolars were extracted, 3 fixtures (a.m. Brånemark) installed and abutment connection performed. Towards the end of a 6‐month plaque control period, a clinical and radiographic examination was performed. Ligatures were placed in a subgingival position at 2 of the implants and the contralateral premolars. Plaque was allowed to accumulate. After 6 weeks, the ligatures were removed. 1 month later, the clinical and radiographical examination was repeated and samples from the subgingival microbiota obtained. Biopsies from the teeth and implant sites were harvested and processed for histometric and morphometric analyses. The results from the clinical and histological examinations revealed that:(i) clinical and radiographic signs of tissue destruction were more pronounced at implants than at teeth;(ii) the size of the soft tissue lesion was larger at implants than at teeth;(iii) the lesion at implants but 1 not at teeth extended into the bone marrow.
Bone formation over a TiAl6V4(IMZ) implant placed into an extraction socket in association with membrane therapy (Gengiflex)
Authors: Novaes Jr. A. B. , Novaes A. B.
Published: March 2003

Complete restoration of an osseous defect around a TiAl6V4(IMZ) implant is accomplished by the combined use of an implant placed in the alveolus of a fractured lower bicuspid and the principles of guided tissue regeneration. Gengiflex (Gengiflex ‐ BioFill ‐ Productos Biotecnologices, Curitiba, PR, Brazil), a new membrane, was used to cover the implant and porous hydroxyapatite was used as grafting material. The filling of the osseous defect that also covered the implant was verified clinically at re‐entry 6 months later. Histological analysis of the mineralized tissue collected during exposure of the implant confirmed bone formation.
The influence of the masticatory mucosa on the peri‐implant soft tissue condition
Authors: Wennström J. L. , Bengazi F. , Lekholm U.
Published: March 2003

The aim of this study was to evaluate the soft tissue conditions at osseointegrated oral implants in relation to the width of masticatory mucosa. Thirty‐nine patients who had received a full‐arch fixed bridge reconstruction ≥ 10 years ago or a partial reconstruction ≥ 5 years ago on a total of 171 implants ad modum Brsnemark were included in the study. The examinations involved assessments of plaque, gingivitis, bleeding on probing, probing depth, width of masticatory mucosa and marginal tissue mobility. Simple correlation analysis as well as multiple regression analysis were performed to evaluate relationships between recorded parameters. The results showed that 24% of the sites were lacking masticatory mucosa, and an additional 13% of the implants had a width of less than 2 mm. Mobility of the facial marginal soft tissue, i.e., lack of an attached portion of masticatory mucosa, was observed at 61% of all implants. No major differences in the clinical parameters examined were found between sites with and without an “adequate” width of masticatory mucosa. Multiple regression analyses revealed that neither the width of masticatory mucosa nor the mobility of the border tissue had a significant influence on (i) the standard of plaque control or (ii) the health condition of the peri‐implant mucosa, as determined by bleeding on probing. Hence, the study failed to support the concept that the lack of an attached portion of masticatory mucosa may jeopardize the maintenance of soft tissue health around dental implants.
Fixed implant‐supported prostheses in the edentulous maxilla. A five‐year follow‐up report.
Authors: Jemt T.
Published: March 2003

Seventy‐six patients were consecutively treated with fixed prostheses supported by osseointegrated implants in the edentulous maxilla and followed up for 5 years. The mean bone quality and resorption indices were 3.1 and 2.7 at the time of implant placement, respectively. Altogether, 449 standard Brånemark implants were placed. Two patients resumed to complete dentures, and the cumulative implant and prosthesis survival rates were 92.1% and 95.9% for 5 years, respectively. The mean marginal bone level was 0.6 mm below the reference point at the time of placement and 1.2 mm below the same point 5 years later. Speech problems was the most frequent complaint during the first year of function, while resin fractures caused most adjustments during the follow‐up period. No implant, abutment or gold alloy screws were found to be fractured, and only 4 patients had their prostheses re‐tightened due to loose gold alloy screws.
The effect of smoking on early implant failure
Authors: De Bruyn H. , Collaert B.
Published: March 2003

This retrospective study describes the effect of smoking on initial fixture failure before functional loading with fixed prosthetic restorations. Of 208 installed Brånemark fixtures in the mandible, only 1 failed (0.5%) and no detrimental effect of smoking on fixture survival could be detected. In the maxilla, 101244 fixtures failed (4%); 7778 fixtures failed in smokers and 31166 in nonsmokers. The failure rate before loading was 9% in smokers versus 1% in nonsmokers and was statistically significant, despite the fact that bone quality in both groups was comparable. Failed fixtures occurred in 31% of the smokers, despite often excellent bone quality, long fixture length or good initial stability. Only 4% of the nonsmokers had failures, in most cases related to poor bone quality. It is concluded that smoking is a significant although not the only important factor in the failure of implants prior to functional loading. Prospective studies are needed to assess the risk of implant failure in conjunction with smoking. In the mean time, patients should be informed of the adverse effect of smoking.
Vertical load distribution on a three‐unit prosthesis supported by a natural tooth and a single Brånemark implant. An in vivo study.
Authors: Rangert B. , Gunne J. , Glantz P.‐O. , Svensson A.
Published: March 2003

In vivo bite forces, implant axial forces and bending moments were measured on 5 patients with fixed posterior prostheses supported by a natural tooth and a single Brinemark implant. The results demonstrate that the vertical loads applied to the prostheses are shared between the tooth and the implant. The maximum bending moment transferred to the implant (10–15N.cm) was well below the acceptable load limits for the mechanical components (50–60N.cm), even at bite forces exceeding 100 N. The main reason for this load sharing seems to be the inherent bending flexibility of the implant screw joint, which matches the axial flexibility of the periodontal ligament of the tooth.
Registration of localization, occlusion and occluding materials for failing screw joints in the Brånemark implant system
Authors: Wie H.
Published: March 2003

This study is based on data from routine follow‐up registration following functional loading of a consecutive number of osseointegrated prostheses at the Dental School, University of Oslo. Fifty‐six patients with 240 Brånemark implants were examined 24 months after the implants were loaded, and a protocol form for collecting information about the status of the treatment was completed. The examinations included registration of oral hygiene, pathological alterations in soft and hard tissues, type of material used in contacting occlusal surfaces, occlusal design and technical and mechanical failures. All superstructures, except CeraOne single‐tooth prostheses. were unscrewed for inspection of implant and screw joint mobility. Eighty‐three per cent of the implants were found in the upper and lower frontal segments of the jaws. The survival rate for individual implants in this study was 94%. which is well within the generally accepted level for osseointegrated implant systems. Plaque and soft tissue complications were low and could not be associated with the early losses of implants. Group function was the preferred design of the occlusal contact pattern (53.4%), followed by 37% for canine guidance and about 9% for balanced articulation. Fourteen abutment screws and 7 gold screws loosened during the period between permanent loading and the first follow‐up registration. A majority of the failures occurred in osseointegrated bridges occluding with complete dentures in the opposite jaw. The failing screw joints were found in 25% of the patients, which means that one fourth of the patients needed extra mending appointments. The failures are assumed to be iatrogenic, and measures to avoid them are discussed.
Threshold of tactile sensitivity perceived with dental endosseous implants and natural teeth
Authors: Hämmerle C. H. F. , Wagner D. , Brägger U. , Lussi A. , Karayiannis A. , Joss A. , Lang N. P.
Published: March 2003

The aim of this study was to determine the threshold of tactile perception of endosseous dental implants and to assess the relative difference of that threshold between implants and teeth. Twenty‐two subjects with implants of the ITI® Dental Implant System were included in the study. All implants served as abutments for single tooth crowns and had been in function for a minimum of 1 year. A strain gauge glued to the shaft of an amalgam plugger served as a force sensor. It transformed the elastic deformation exerted onto the shaft into an electronic signal for recording. By use of the amalgam plugger, a continuously increasing force was exercised on the implants or teeth until the first sensation of touch was indicated by the patient. Statistical analysis revealed threshold values for the implants ranging from 13.2 to 189.4g (1g=0.0lN)(mean 100.6; SD 47.7), while a range of 1.2 to 26.2g (mean 11.5; SD 11.5) was found for control teeth. Thus, the mean threshold values for implants were 8.75 times higher than for teeth. This difference was highly statistically significant. A general linear models procedure was applied to determine the influence of patient age, jaw, implant position and the threshold values of teeth on the measurements obtained for implants. Only gender and the threshold values for contralateral teeth had a significant influence. These 2 parameters together explained 27% of the variability in threshold measurements. It is concluded that a more than 8‐fold higher threshold value for tactile perception exists for implants compared with teeth.
A study of 184 consecutive patients referred for single‐tooth replacement
Authors: Andersson B. , Ödman P. , Carlsson G. E.
Published: March 2003

The aim of this investigation was to study the acceptance and the rejection of patients referred for single implant restorations based on data from referral, case history. clinical examination and therapy planning. The referrals comprised 184 patients with 251 missing single teeth. Sixty‐four per cent of the referred patients were accepted for treatment. There was difference in acceptance between men and women (75% and 54%, respectively). A negative relationship was noticed between age and acceptance. External trauma (33%), root fractures (16%) and congenitally missing teeth (15%) were the main reasons for lost or missing teeth. Anatomical limitations was the most frequent reason for rejection (76%). Most fillings and crowns on adjacent teeth to the edentulous space did not serve as a contraindication for an implant single‐tooth restoration, and thus extensive fillings or not acceptable crowns was the cause of rejection only for a minor group (13%). The great majority of the partially dentate patients showed a very high interest in treatment with single‐tooth implants, but some of the patients (4% in all, 11% of those rejected for treatment) did not want implant treatment after having received further information at the specialist clinic.
Single‐tooth replacement by osseointegrated Brånemark implants. A retrospective study of 82 implants.
Authors: Engquist B. , Nilson H. , Åstrand P.
Published: March 2003

The aim of the study was to evaluate the outcome of single‐tooth restorations on Brånemark implants performed during the period 1986–1989. The material comprised 58 consecutive patients with 82 implants. The observation period varied from 1 to 5 years. Two implants were lost. both of them before loading. The overall survival rate was 97.6%. Radiographic follow‐up was performed for 72 implants after 1 year and for 51 implants after 2 years. The bone loss during the first year was on average 0.6±0.1 mm and during the second year 0.1±0.1 mm. Although the observation time for most of the patients was only 2 years, the results indicate that the outcome of single‐tooth restorations may be as favorable as for implants in edentulous jaws.
In vivo measurements of some functional aspects with mandibular fixed prostheses supported by implants
Authors: Mericske‐stern R. , Zarb G. A.
Published: March 2003

Maximal occlusal force and oral tactile sensibility were recorded in 21 edentulous patients wearing maxillary complete dentures and mandibular fixed prostheses supported 1 by Brånemark implants. Bite force was measured with a miniature force transducer between antagonistic molars and premolars, and the passive tactile sensibility of the fixtures was recorded in the horizontal and vertical directions with spring balances. The active tactile sensibility was tested using steel foils 100 to 10 . The range of maximal occlusal force recorded was from 35 to 330N with highest values observed on the second premolars (mean 143N). Significantly lower forces were found on molars and first premolars (p<0.01). The detection threshold of minimal pressure was about 330g in the horizontal, and 388g in the vertical direction. This difference was not statistically significant. The average number of incorrect assessments when testing steel foils was 16.6 errors, out of 100 recordings. Similar results when using these 3 test modalities had been found on overdentures supported by two mandibular implants and occluding with maxillary complete dentures. The results of this study suggest that mandibular implants supporting fixed prostheses are not likely to improve oral tactile sensibility and maximal occlusal force in the presence of maxillary complete dentures.
Marginal bone levels at Brånemark system implants used for single tooth restoration. The influence of implant design and anatomical region
Authors: Malevez C. H. , Hermans M. , Daelemans P. H.
Published: March 2003

In this retrospective study of Brånemark™ system oral implants, 75 consecutive patients were treated with 84 implants for single‐tooth replacement from 1988 to 1993. Two implants were lost and not replaced: the first one before the abutment connection, the latter during the first year in function. The cumulative failure rate reached 2.4%during the 5‐year period. Seventy‐one percent of the implants were located in the incisor/canine region of both jaws. Twenty‐six per cent of the implants were inserted in special presurgical or surgical conditions. The mean annual bone loss as scored on radiograph, was 0.8mm during the first year and 0.1mm the following years. Different implant designs were used, a more pronounced bone loss was observed for the conical implant. The present data shows that the cumulative failure rate for single Brånemark™ implants and the radiographic bone loss is similar to that found around implants used for the treatment of complete and partial edentulism.
The peri‐implant hard and soft tissues at different implant systems. A comparative study in the dog.
Authors: Abrahamsson I. , Berglundh T. , Wennström J. , Lindhe J.
Published: March 2003

The aim of the present experiment was to study the marginal peri‐implant tissues at intentionally non‐submerged (1‐stage implants) and initially submerged and subsequently exposed implants (2‐stage implants). 5 beagle dogs, about 1‐year‐old, were used. 3 months after the extraction of the mandibular premolars, fixtures of the Astra Tech Implants Dental System®, the Brånemark System® and the Bonefit®‐ITI System were installed. In each mandibular quadrant, 1 fixture of each implant system was installed in a randomised order. The installation procedure followed the recommendations given in the manuals for each system. Thus, following installation, the bone crest coincided with the fixture margin of the Astra Tech Implants Dental System® and the Brånemark System®, whereas the border between the plasma sprayed and the machined surface of the Bonefit®‐ITI implant system was positioned at the level of the bone crest. Following a healing period of 3 months, abutment connection was carried out in the 2‐stage systems (the Astra Tech Implants Dental System® and the Brånemark system®). A 6‐month period of plaque control was initiated. The animals were sacrificed and biopsies representing each implant region dissected. The tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. The mucosal barrier which formed to the titanium surface following 1‐stage and 2‐stage implant installations comprised an epithelial and a connective tissue component, which for the 3 systems studied, had similar dimensions and composition. The amount of lamellar bone contained in the peri‐implant region close to the fixture part of the 3‐implant systems was almost identical. It is suggested that correctly performed implant installation may ensure proper conditions for both soft and hard tissue healing, and that the geometry of the titanium implant seems to be of limited importance.
Quantitative determination of the stability of the implant‐tissue interface using resonance frequency analysis
Authors: Meredith N. , Alleyne D. , Cawley P.
Published: March 2003

Bone anchored implants are now being used in dentistry for supporting intraoral and craniofacial prostheses. Although high success rates have been reported, a small number of implants may fail during the early healing phase or later in function. Currently available clinical methods to determine implant stability and osseointegration are relatively crude and may entail percussing a fixture with a blunt instrument. Radiographs are of value, but a standardised technique is necessary to ensure repeatability. This investigation was designed to study the application of a non‐invasive test method using resonance frequency analysis to make quantitative measurements of the stability of the implant tissue interface in‐vitro and in‐vivo. The resonance frequency of a small transducer was measured when attached to implants embedded at different heights in an aluminium block. A strong correlation (r=0.94, p<0.01) was observed between the observed frequency and the height of implant fixture exposed. The change in stiffness observed in the bone surrounding an implant during healing was modelled by embedding implants in self‐curing polymethylmethacrylate and measuring the resonance frequency at periods during polymerisation. A significant increase in resonance frequency was observed related to the increase in stiffness. Resonance frequency measurements were also made on implants in‐vivo and the results correlated well with the in‐vitro findings.
The influence of periodontitis on the subgingival flora around implants in partially edentulous patients
Authors: Papaioannou W. , Quirynen M. , Van Steenberghe D.
Published: March 2003

The hypothesis that teeth act as reservoirs of micro‐organisms for the colonization of oral implants has recently been stated several times. The present study aimed at examining, in partially edentulous patients with severe periodontitis, whether pockets around teeth and implants harbored a comparable micro‐flora. In 6 patients (3 with refractory periodontitis and 3 with advanced chronic adult periodontitis), plaque samples were taken from a deep and shallow pocket around both teeth and implants for differential phase contrast microscopy and DNA probe analysis. The results showed important differences in the sub‐gingival flora between the 2 disease groups, as well as between deep and shallow pockets, around both implants and teeth. On the other hand, when pockets around teeth and implants with equal depths were compared a striking similarity was observed in the microbial composition. These observations confirm the hypothesis that pockets around teeth act as a reservoir and highlight the importance of periodontal health when oral implants are planned.
Healing around implants placed in bone defects treated with Bio‐Oss®. An experimental study in the dog.
Authors: Berglundh T. , Lindhe J.
Published: March 2003

The aim of the present experiment was to (i) study the healing after 3 and 7 months of bone defects filled with cancellous bovine bone mineral and (ii∥ compare the healing around implants placed in normal bone and in defects filled with bovine bone mineral. 5 beagle dogs, about l‐year‐old, were used. At baseline, extractions of all mandibular left and right premolars were performed. Bone defects were prepared in the left mandibular quadrant. The defect was immediately filled with natural bovine cancellous bone mineral particles (Bio‐Oss®, Geistlich Sons Ltd. Wolhusen, Switzerland). No resective surgery was performed in the right jaw quadrant. In both quadrants the flaps were adjusted to allow full coverage of the edentulous ridge and sutured. 3 months later, 2 dogs (group I) were euthanized and biopsies from the premolar regions obtained and prepared for histologic analysis. The 3 remaining dogs (group II) were at this time interval (3 months) subjected to implant installation in the premolar region of both the right and left mandibular jaw quadrants. 2 fixtures of the ITI Dental Implant System (Straumann, Waldenburg, Switzerland; solid‐screw; 8 x 3.3 mm) were installed in each side. The fixtures in the test side were placed within the previously grafted defect area, while the fixtures in the control side were placed in normally healed extraction sites. A 4 month period of plaque control was initiated. At the end of this period, a clinical examination including assessment of plaque and soft tissue inflammation was performed and radiographs obtained from the implant sites. Biopsies were harvested and 4 tissue samples were yielded per dog, each including the implant and the surrounding soft and hard peri‐implant tissues. The biopsies were processed for ground sectioning or “fracture technique” and the sections produced were subjected to histological examination. The volume of the hard tissue that was occupied by clearly identified Bio‐Oss® particles was reduced between the 3‐ and 7‐month intervals. This indicates that with time, Bio‐Oss® becomes integrated and subsequently replaced by newly formed bone. In other words, this xenograft fulfils the criteria of an osteoconductive material. It was also observed that 4 months after implant installation, the titanium/hard tissue interface at test and control sites exhibited, from both a quantitative and qualitative aspect, a similar degree of “osseointegration”.
Patient's opinion and treatment outcome of fixed rehabilitation on Brinemark implants. A 3‐year follow‐up study in private dental practices.
Authors: De Bruyn H. , Collaert B. , Lindén U. , Björn A. L.
Published: March 2003

In this study, patient opinion on oral rehabilitation by means of Brånemark implants was investigated. All patients were referred to a periodontal clinic for implant installation and treated by one and the same operator. Prosthetic restorations were performed by dentists, who had no previous experience with prostheses on implants, but had completed a postgraduate training course. Patient opinion was obtained through questionnaires, pertaining to satisfaction and oral function. A comparison was made between pre‐implant situation, short‐term (<4 months) and long‐term functioning )3 years( with the implant‐restorative rehabilitation. In total, 61 patients participated in the study; 23 received a full lower arch bridge and 18 a full upper arch bridge, while 20 patients got partial bridges. Of 298 installed implants, 7 failed at abutment connection (2.3%) and 1 during the 3‐year follow‐up interval (0.3%). The study results indicated that a great majority of patients were very satisfied with the treatment. Comfort with eating, aesthetics, phonetics and overall satisfaction improved significantly and nearly all patients said that they would undergo the treatment again or recommend it to others. Patients experienced their implants as “natural” teeth. The conclusion is that rehabilitation ad modum Brånemark, even in the hands of non‐specialized dentists, can be of high quality, improving oral function and satisfying the needs and demands of patients.
A histomorphometric evaluation of screw‐shaped implants each prepared with two surface roughnesses
Authors: Wennerberg Ann , Hallgren Carin , Johansson Carina , Danelli Stefano
Published: March 2003

Four different surface modifications were designed. Forty screw‐shaped implants were divided into 4 groups, 10 screws in each. Every screw was prepared with 2 different surface topographies. The surface topography was measured with a confocal laser scanning profilometer and the surface roughness was characterized using 1 height, 1 spatial and 1 hybrid descriptive parameter. After 12 weeks in rabbit bone all screws were histomorphometrically evaluated. Blasted surfaces demonstrated more bone in contact to implant surface compared with turned surfaces. Most bone in close contact to implant surface was found for a surface blasted with 75 pm sized particles, numerically characterized with an average height deviation (S,) of 1.4 pm, an average wavelength (Sdr) of 11.6 pm and a developed surface area 1 ratio (Sdr) of 1.5.
Effect of different microstructures of e‐PTFE membranes on bone regeneration and soft tissue response: a histologic study in canine mandible
Authors: Simian Massimo , Dahlin Christer , Blair Kerry , Schenk Robert K.
Published: March 2003

The purpose of the present study was to compare the effect of 3 types of titanium reinforced e‐PTFE membranes (GTRM #l, #2, and #3) on bone regeneration and tissue integration. GTRM #l was a standard titanium reinforced membrane, GTRM #2 was a prototype characterized by a more open total surface microstructure and GTRM #3 was a prototype characterized by two extremely porous external layers separated by a totally occlusive internal layer. The membranes were used to cover saddle type ridge defects surgically created in the mandible of 6 dogs. After a healing period of 6 months, all the membrane protected sites demonstrated almost complete osseous healing of the defects. GTRM #3 specimens showed the most favourable biologic response. in fact they were characterized by a larger surface of contact between the membrane and the regenerated bone, but from a clinical point of view GTRM #3 material was too difficult to remove. The results of this study suggest that an extremely open porous microstructure, in combination with a totally occlusive barrier, may provide significant improvements in regenerative outcomes. However, these design characteristics may be applied only to resorbable devices, which do not require removal.
Implant‐retained mandibular overdentures compared with complete dentures; a 5‐years' follow‐up study of clinical aspects and patient satisfaction
Authors: Meijer Henny J. A. , Raghoebar Gerry M. , Van't Hof Martin A. , Geertman Mariëlle E. , Van Oort Robert P.
Published: March 2003

The aim of this prospective randomized controlled clinical trial was to evaluate and compare clinical aspects and satisfaction during the first year following treatment and consecutively the change in treatment during the next 4 years of follow‐up. Patients were allocated to one of the following treatment modalities: an implant‐retained overdenture (IRO‐group, 2 endosseous implants, n=61) or a complete denture (CD‐group, n=60). One year after placement of the denture, unsatisfied patients of the CD‐group got the opportunity for a retreatment including an implant‐retained overdenture. In the IRO‐group 4 implants were lost during the first year and again 4 implants were lost during the next 4 years (survival rate: 93%). All patients could be re‐operated successfully. In the CD‐group 14 patients (23%) chose an implant‐retained overdenture after 1 year. Patients of the IRO‐group were significantly more satisfied than patients of the CD‐group after 1 year (satisfaction score 8.3 versus 6.6, scale l–10) and after 5 years (7.4 versus 6.4). From this study it can be concluded that endosseous implants have a high survival rate after 5‐years' follow‐up. Satisfaction score of the IRO‐group is diminishing in time, probably because patients get used to an improved situation. After 5 years, the mean satisfaction score of the CD‐group (including patients who got implants) was still lower than of the IRO‐group, in spite of the opportunity to a retreatment and have implant‐retained overdentures.
Microbial findings at failing implants
Authors: Leonhardt Åsa , Renvert Stefan , Dahlén Gunnar
Published: March 2003

The aim of this study was to evaluate qualitative differences in the subgingival microbiota at titanium implants, ad modum Bråmnark, demonstrating clinical and radiographic signs of loss of supporting tissues )peri‐implantitis) as compared to implants surrounded by healthy tissues. A total of 37 patients demonstrating 1 or more implants with bone loss ≥3 threads, bleeding on probing and/or suppuration and 51 patients with clinically healthy mucosa and no bone loss were recruited for the study. In each patient subgingival bacterial samples were obtained using paper‐points, and subjected to microbiological analysis by culture. The two types of clinical conditions showed distinct bacterial profiles. For implants with peri‐implantitis putative periodontal pathogens, such as Porphyuonmnas gingivulis, Prevotella intermedial Prevotella nigresscens and Actinobacillus actinomycetemcomitans, were found in 60% of the cases and microorganisms primarily not associated with periodontitis, such as Staphylococcus spp., enterics and Candida spp., were found in 55% of the peri‐implant lesions. In contrast, implants surrounded by healthy tissue demonstrated a microbiota associated with periodontal health. The results indicate that the microbiota of the healthy peri‐implant sulci is similar to that from corresponding conditions around teeth. However, in peri‐implant areas staphylococci, enter& and yeasts were found almost as frequently as periopathogens indicating differences as compared to the microbiota around periodontitis affected teeth. A microbiological diagnosis may therefore be of guidance for the choice of antimicrobial treatment in patients with peri‐implant infection.
Bone density in human dentate and edentulous mandibles using computed tomography
Authors: Bassi Francesco , Procchio Massimo , Fava Cesare , Schierano Gianmario , Preti Giulio
Published: March 2003

Mandibular bone density, vertebral density and resorption of the edentulous ridge were correlated in a group of 17 partially edentulous subjects.Bone density was quantified by Quantitative Computerized Tomography; resorption was evaluated on panoramic radiographs. Mean bone density in dentate areas was significantly higher than that in edentulous areas; mandibular bone density was not found to relate significantly to vertebral bone density, nor to ridge resorption. In programming osseointegrated implants in the partially edentulous mandible, CT may give a more accurate evaluation of trabecular bone. However, further studies are necessary to clarify its clinical utility.
Lack of integration of smooth titanium surfaces: a working hypothesis based on strains generated in the surrounding bone
Authors: Wiskott H. W. Anselm , Belser Urs C.
Published: March 2003

It has been observed that the polished neck of dental implants does not osseointegrate as do textured surfaces. Similar findings were reported in the orthopedic literature on artificial hip endoprostheses. In Dentistry, lack of osseointegration was attributed to increased pressure on the osseous bed during implant placement, establishment of a physiological “biologic width”, stress shielding and lack of adequate biomechanical coupling between the load‐bearing implant surface and the surrounding bone. Among the many variables that may affect osseointegration, this analysis proposes to include stress transfer as a significant one. Therefore the present report discusses the relationship between the stresses applied and bone homeostasis. Any viable osseous structure (Including the tissue that surrounds the polished implant neck) is subjected to periodic phases of resorption and formation. Clinical and experimental data have shown the detrimental effects of lack of function in that bone mass decreases with time. Due to inadequate mechanical stimuli, bone that is resorbed during normal turnover is redeposited in lesser amounts than previously, a process observed clinically as resorption. The stress ranges which cause bone to resorb, maintain or increase its mass and the level that eventually causes bone to fracture have been delimited in the literature. Applying these values to the situation to dental implants, it follows that if it is to be stable, crestal bone must be subjected to suitable levels of mechanical stimulation. We suggest that smooth surfaces will not provide adequate biomechanical coupling with the bone surrounding the implant neck in that the stress range induced by a polished surface is limited. We propose that the surface texture of threaded, plasma‐coated or sandblasted implants generates a heterogeneous stress field around an implant in function. By design, such a stress field includes force levels which are conducive to bone formation. Hence, during the formation phase of bone turnover, osteoblast lineages are much more likely to be stimulated by biomechanical signals of appropriate magnitude.
Biologic width around titanium implants. A physiologically formed and stable dimension over time
Authors: Hermann Joachim S. , Buser Daniel , Schenk Robert K. , Higginbottom Frank L. , Cochran David L.
Published: March 2003

Research in implant dentistry has mainly focused on hard tissue integration with much less data available with regards to soft tissue integration involving epithelium and connective tissue. In the present study, the implantogingival junction of unloaded and loaded non‐submerged titanium implants has been analyzed histometrically in the canine mandible. In 6 foxhounds, 69 implants were placed. Dogs in the unloaded group were sacrificed 3 months after implant placement. Loaded implants were restored with gold crowns and those dogs were sacrificed after 3 months and 12 months of loading. Non‐decalcified histologic sections were analyzed histometrically measuring the dimensions of the Sulcus Depth (SD), the Junctional Epithelium (JE), and the Connective Tissue Contact (CTC). Histometric evaluation revealed that significant changes within tissue compartments (SD, JE, CTC) occurred over time (P<0.05). Sulcus Depth had a mean of 0.49 mm and 0.50 mm after 3 months and 6 months of healing, but after 15 months was 0.16 mm which was significantly different. Similarly, the length of the Junctional Epithelium after 3 months and 6 months of healing was 1.16 mm and 1.44 mm, respectively, and these values were significantly different from measurements taken after 15 months (1.88 mm). The area of Connective Tissue Contact showed a different pattern of change in that after 3 months of healing (1.36 mm) it was significantly different from the same area after 6 months and 15 months which were 1.01 mm and 1.05 mm, respectively. Interestingly, the sum of SD, JE, and CTC, forming the Biologic Width, did not change over the observation period (P>0.05). These data indicate that the Biologic Width is a physiologically formed and stable structure over time in the case of non‐submerged, one‐piece titanium implants as evaluated histometrically under unloaded and loaded conditions. Dynamic changes did occur, however, within the overall Biologic Width dimension. Thus, the use of non‐submerged, one‐piece implants allow for stable overall peri‐implant soft tissues as evaluated under loaded conditions for up to 12 months.
Strength and marginal fit of full and partial porcelain crowns on Brånemark implants
Authors: Kersten S. , Tiedemann Ch.
Published: March 2003

The aim of the present study was to evaluate strength and marginal fit of different designed single crowns screwed on titanium implants (Brånemark) without the usage of any abutment. Seven test groups with 10 specimens each (standardized maxillary central incisor crowns) were fabricated of Empress (staining/veneering technique), metal‐based Empress (staining/veneering technique), metal‐based In‐Ceram and metal ceramic (with/without cervical porcelain margin). The marginal fit of 5 specimens of each group was evaluated (SEM‐Analysis) and the crowns were incisally loaded at a 30° angle in a Zwick testing machine until fracture. The 5 remaining specimens underwent a marginal evaluation (SEM‐analyses) before and after thermo‐mechanical stressing (tms) and were loaded in the Zwick testing machine as well. All Empress ceramic crowns without metal reinforcement fractured during fixing procedure on the implant (32 N cm). The gap medians of the fixed crowns ranged from 11 μm (metal ceramic crowns) to 34 μm (metal ceramic crowns with porcelain margin). No significant differences in gap width were observed before and after tms. In the strength analyses screw‐binding forces (SBF) of about 135 N were registered in all test groups. Fracture failure forces (FFF) reached up to 280 N. The indication of the crown designs presented in this study is limited in clinical use because of low stability and esthetics.
Prospective study on titanium bar‐retained overdentures: 2‐year results
Authors: Walter Michael , Marré Birgit , Eckelt Uwe
Published: March 2003

Within a monometallic concept 29 patients received titanium bar‐retained mandibular overdentures on 2 IMZ implants. The study had a prospective design with 3 months recall intervals. One of 58 implants failed after 11 months. There were no significant differences of the mean plaque scores (Silness, Löe) and the mean sulcus bleeding scores (Mühlemann, Son) at the abutments between baseline, 12 months and 24 months. Less than 40% of the subjects showed plaque score zero at 24 months. However, 89% exhibited sulcus bleeding score zero indicating health of the peri‐implant soft tissues in most cases. Plaque at the basal site of the bar was scored separately at additional measuring points located at the central area and the contact areas between bar and abutments. Bar plaque scores nearly doubled between baseline and 12 months and remained high at 24 months. Median maximal vertical bone loss around the implants was 1.7 mm after 2 years. Bone loss did not exceed one quarter of the implant length in 79%. The monometallic concept in bar‐retained overdentures on 2 implants proved its clinical suitability except for the applicability of pure titanium for bar clips. Plaque formation beneath the bar seems to be one of the major clinical problems.