Nonsubmerged Implants in the Treatment of the Edentulous Lower Jaw: A 5-Year Prospective Longitudinal Study of ITI Hollow Screws

Background: Although most implant systems have been designed for a two‐stage surgical technique, a one‐stage surgical technique has always been advocated for the ITI Dental Implant System (Straumann AG, Waldenburg, Switzerland). A new generation of ITI implants was presented in 1988 and included a hollow cylinder, a hollow screw, and a solid screw. Purpose: The goal of this study was to evaluate the one‐stage surgical technique in connection with the ITI hollow screw in a longitudinal study over 5 years. Materials and Methods: Forty‐six patients with edentulous lower jaws were supplied with ITI hollow‐screw implants. Patients who requested an overdenture (n = 18) had four implants inserted; those who requested a fixed bridge (n = 28) had five to six implants. The patients have been followed annually for 5 years. There was a dropout of three patients (6.5%); one patient did not want to cooperate, one moved from the area, and one was deceased. The clinical examinations included bridge removal for evaluation of the individual implant stability in connection with the 1‐, 3‐, and 5‐year examinations. Radiographic examinations were performed with intraoral radiographs and the long‐cone technique. Results: The survival rate after 5 years was 95.7%. The success rate (in which implants undergoing treatment of peri‐implantitis were not counted as successes) was 91.4%. The mean marginal bone loss between the baseline and the 1‐year examination was 0.1 mm and between the 1‐ and 5‐year examinations was 0.1 mm. These changes in marginal bone level were not significant. Conclusions: The success rate of ITI hollow‐screw implants in the edentulous mandible was 91.4% after a 5‐year observation period. There was no significant change in mean bone level between the loading of the implants and the 5‐year examination. Peri‐implantitis was diagnosed in three patients with poor oral hygiene, and it affected six implants. Five of these failed in spite of treatment.     

A prospective 15‐year follow‐up study of mandibular fixed prostheses supported by osseointegrated implants. Clinical results and marginal bone loss.

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

Long‐term stability of osseointegrated implants in bone regenerted with the membrane technique. 5‐year results of a prospective study with 12 implants.

The purpose of the present clinical study was to evalutate the 5‐year results of the first 12 implants inserted at the University of Berne in regenerated bone following successful ridge augmentation with the membrane technique. The patients were recalled and examined with clinical and radiographic paramenters routinely utilized in prospective studies with standard implants in non‐regenerated bone. Based on clinical and radiographic findings, all 12 implants were considered successfully integrated according to strict criteria of success. The detailed analysis of clinical parameters revealed no differences to results of prospective studies on standard implants in non‐regenerated bone. All implants demonstrated ankylotic stability which was confirmed by a mean Periotest value of ‐2.08. The radiographic analysis showed stable bone crest levels with a mean bone loss between the 1‐ and 5‐year examination of 0.30 mm. However, 2 implants exhibited a bone loss of more than 1 mm between the 1‐ and 5‐year examination. Therefore, the prognosis of these 2 implants seems questionable at the present time. It can be concluded that bone regenerated with the membrane technique reacts to implant placement like non-regenerated bone, since all 12 implants achieved successful tissue integration with functional ankylosis. Furthermore, this bone is also load‐bearing, since all 12 implants maintained osseointegration over a 5‐year period.     

A three-year follow-up report of a comparative study of ITI Dental Implants and Brånemark System implants in the treatment of the partially edentulous maxilla

Background: Many longitudinal studies of different implant systems have been published but few controlled randomized investigations have been reported. A 1‐year report of a comparative study of ITI Dental Implant System® implants (Straumann AG, Waldenburg, Switzerland) and Brånemark System® implants (Nobel Biocare AB, Gothenburg, Sweden) has been published by the present authors. This paper is a 3‐year follow‐up of that randomized study. Purpose: The aim of the study was to compare the outcome of fixed partial prostheses supported by ITI or Branemark implants. The outcome was evaluated primarily in terms of survival rates and changes in marginal bone level. Material and Methods: The study group comprised 28 patients with anterior residual dentition in the maxilla. The patients were provided with two to four implants on each side of the dentition and were randomly allocated to Brånemark implants or ITI implants; 77 ITI implants and 73 Brånemark implants were inserted. After 6 months abutment connections were made to both ITI and Brånemark implants. All patients were provided with fked partial prostheses of gold‐ceramic. The patients were followed up annually with clinical and radiographic examinations for 3 years. Results: Two Brånemark implants and two ITI implants were lost. The Brånemark implants were lost before loading whereas the ITI implants were lost because of periimplantitis. The survival rate for both groups was 97.3%. The mean marginal bone level of the Brånemark implants was situated 1.8 mm from the reference point at both the baseline and the 3‐year examinations. The corresponding values for the ITI implants were 1.4 mm at baseline and 1.3 mm after 3 years. There was no significant difference between the implant systems with regard to bone level or bone level change. A steady state of the marginal bone level was calculated to have been reached after 3 years for 95.5% of the Brånemark implants and 87.1% of the ITI implants. Periimplantitis (infection including pus and bone loss) was observed with seven ITI implants but with none of the Brånemark implants. This difference was statistically significant. Conclusions: No statistically significant differences were found between the implants studied, except for the frequency of periimplantitis, which was higher for the ITI implants. The survival rates were high, and the marginal bone loss was small for both systems.     

Some clinical and radiographical features of submerged and non‐submerged titanium implants. A 5‐year follow‐up study.

The present study reports on the results of a follow‐up examination of patient material, 5 years after the installation of the fixed supraconstruction. The patient group comprised 11 individuals. Briefly, a split‐mouth technique of treatment was used. In the right side of the mandible the traditional 2‐step surgical approach for implant installation was used. In the left jaw quadrant a l‐step surgical procedure was used. A clinical and radiographical examination was performed 5 years after the initial connection of the supra‐construction to the implants. At the 5 year follow‐up examination all 61 implants examined at the 1 month follow‐up were still in service and found to be clinically stable irrespective of the surgical procedure used. Furthermore, the results of the present clinical and radiographical follow‐up study demonstrate that the marginal bone level at implants placed anteriorly in the edentulous mandible and supporting fixed supraconstructions is stable between 18 and 60 months irrespective of whether placed according to a l‐step or 2‐step surgical procedure.     

Nonsubmerged and submerged implants in the treatment of the partially edentulous maxilla

Background: Dental implants vary in design and surfaces. In addition, different surgical techniques have been used for implant insertion. The ITI Dental Implant System (Straumann AG, Waldenburg, Switzerland) has always required a one‐stage technique, whereas the Brånemark System (Nobel Biocare AB, Gothenburg, Sweden) requires a two‐stage technique. Purpose: The aim of this study is to compare the outcome of fixed partial bridges in the maxilla supported by both ITI and Brånemark implants in a split‐mouth design. Materials and Methods: Twenty‐eight patients with a residual anterior dentition in the maxilla were included in this split‐mouth study. The Brånemark implants were used on one side and the ITI implants on the other side of the residual dentition according to a randomization procedure. A blocking size of four was used, giving equal probability of placing ITI or Brånemark implants in the right or left side of the jaw. The surgical and prosthetic procedures followed the guidelines given by the manufacturers. The prosthetic treatment with the two‐implant systems was performed at the same time, and for that reason the healing period was 6 months for both systems. The observation period for all patients was 1 year after loading. Results: Two Brånemark implants (in one patient) were lost before loading, and one ITI implant was lost 1 year after loading. There was no significant difference in survival rate. Radiographie examination of the bone level was performed at the time of delivery of the bridge and after 1 year. The mean marginal bone level at baseline was situated 1.9 mm from the reference point for the Brånemark implants and 1.5 mm for the ITI implants. With regard to the insertion depth used, these bone levels indicate that bone loss had taken place before baseline. However, between baseline and the 1‐year examination, there was no significant change of the marginal bone (0.2 ± 0.08 mm at the Brånemark implants and 0.1 ± 0.11 mm at the ITI implants). The difference between results with the two implants was not statistically significant. Crater‐form bone destructions were seen at some ITI implants, indicating periimplantitis. However, at only two implants were there clinical signs of periimplantitis. Conclusions: No significant difference in survival rate or in marginal bone change could be demonstrated between the two systems. At some ITI implants (18%), crater‐form bone loss was observed.     

Marginal tissue response adjacent to Astra Dental Implants® supporting overdentures in the mandible. A 2‐year follow‐up study.

The aim of this study was to evaluate the marginal tissue response adjacent to implant supported overdentures. Twenty edentulous patients had 2 Astra Dental Implants® placed in the canine region of the lower jaw. New overdentures were retained by individual ball attachments in 11 patients and by a bar attachment in 9 patients. Periodontal registrations were recorded 0 months, 6 months, 12 months and 24 months after the overdentures were inserted. One of the 40 fixtures was lost at the stage of abutment connection. No fixtures were lost during the 2‐ to 4‐year observation period and no fixtures showed any periodontal signs of failure. At the 2‐year examination, no pocket depths adjacent to the implants exceeded 4 mm and no bone loss exceeded 3 mm. The mean annual bone loss was less than 0.2 mm during the first 2 years. The preliminary results from this limited study were promising and showed that two osseointegrated Astra Dental Implants® could successfully retain an overdenture in the lower jaw. However, long‐term observation is needed for a definate evaluation of this treatment concept.     

Implant-supported fixed prostheses in the edentulous maxilla. A 2-year clinical and radiological follow-up of treatment with non-submerged ITI implants

OBJECTIVES: To evaluate the survival rate of non-submerged solid-screw ITI dental implants with a rough (titanium plasma sprayed, TPS) surface in the edentulous maxilla after 1 and 2 years of loading. MATERIAL AND METHOD: Twenty-five patients (mean age 64 years) with edentulous upper jaws received five-seven implants and, after a mean healing time of 6.9 months, screw-retained implant-supported fixed prostheses. A total of 146 ITI solid screw TPS implants were inserted. The diameter of 56% of the implants was smaller (3.3 mm) than the standard (4.1 mm) and the diameter of the rest (44%) was standard. The bone quantity of the majority of the patients was low and the bone quality poor. Clinical parameters were registered at baseline and at two annual follow-ups. Radiological examinations and assessments were also made at these times. RESULTS: Mean marginal bone level at baseline was measured at a point 4.52 mm (range 1.45-7.70, SD 1.2) apical of the reference point. Mean bone loss from baseline to 1 year of loading was 0.24 mm (SD 0.9, P=0.002) and from 1 year to 2 years of loading 0.15 mm (SD 0.4, P<0.001). Five implants failed, four of which were early failures prior to loading. One implant failed shortly after bridge installation. The cumulative survival rate was 96.6% after 1 and 2 years. CONCLUSION: ITI TPS solid-screw implants in combination with fixed prostheses had successful survival rates and were found to be a viable treatment alternative in the edentulous maxilla.     

Comparison of Brånemark fixture integration and short‐term survival using one‐stage or two‐stage surgery in completely and partially edentulous mandibles

The aim of this prospective study was to compare the clinical integration and survival of Brånemark fixtures when using the conventional 2‐stage surgical procedure to a 1‐stage surgical approach in completely and partially edentulous mandibles. A total of 85 patients were consecutively treated for partial ( n =35) or complete ( n =50) mandibular edentulousness. Fixtures removed because of mobility, pain or infection were counted as failures. The first 10 patients of each group were selected for radiographical analysis of crestal bone changes 1 year after prosthesis insertion. In 33 patients with edentulous mandibles, 170 fixtures were placed in a 1‐stage approach. In this group, 4 fixtures (2.4%) were lost prior to prosthetic restoration. Seventeen edentulous patients received a total of 70 fixtures in a 2‐stage procedure. Out of these, 5 fixtures (7.1%) were lost at abutment connection. In 17 partially edentulous patients, 41 fixtures were inserted in a 1‐stage approach. Two fixtures (5%) were lost in this group. Finally, 18 partially edentulous patients received a total of 49 fixtures in a 2‐stage procedure. Out of these, 6 fixtures (12%) were lost at abutment connection. In total 313 of the 330 installed mandibular implants were loaded between 6 and 12 months (94.8% success). No further losses occurred in the implants functioning at least 1 year (267 implants) or at least 2 years (59 implants). Statistical analysis (Chi square test) revealed no difference in fixture survival between the treatment modalities. Radiographical analysis after 1 year of functional loading showed the typical bone resorption changes up to the most coronal implant thread in both modalities. Although this study pertains to relatively early loading of 2 years, the results seem to indicate that in the mandible a 1‐stage surgical approach with Brinemark fixtures may be as predictable as the conventional 2‐stage procedure.     

Use of 5‐mm‐diameter implants: Periotest® values related to a clinical and radiographic evaluation

A modified design of the original Brånemark implant consisting of a cp. Titanium 5.0‐mm‐diameter self‐tapping implant threaded up to the marginal platform has been proposed for specific indications. From February 1992 to November 1995, a total of 185 machined screw implants (Nobel Biocare, Gothenburg, Sweden) were installed in 45 patients to withstand 58 prostheses. Of these, 91 were 3.75mm diameter and 94 were 5.0mm wide. Most of the implants were placed in type B and C bone quantity and type 2 and 3 bone quality. A retrospective evaluation with regard to indications, marginal bone remodelling, Periotest® values (ID) and survival rate is presented. PTv and radiographic measurements were made at abutment connection and repeated 3, 6 and 12 months later and thereafter every year. The follow‐up ranged from 16 to 55 months (mean 32.9 months) post‐loading. Three patients with 8 5.0mm implants dropped‐out of the study at different stages. Out of the wide implants, 1 was expelled during the healing period; 3 were found mobile at the abutment connection; 1 lost its osseointegration suddenly after 2 years of function; 4 belonging to 1 patient did not meet the success criteria due to continuous marginal bone loss. The cumulative success rate of 5.0mm implants (CSR) after 1 year of function was 97.2% for upper jaws and 88.4% in mandibles, whereas the CSR in maxilla after 48 months was 97.2% and 83.4% in mandibles. The obtained PTv from 5.0mm‐wide fixtures in maxilla and mandibles were respectively 1.1 and 0.6 units lower than those obtained PTv for 3.75mm‐diameter implants in the same patients. The hypothesis that there are differences in the damping capacity of the bone surrounding a 5.0mm‐wide implant compared to the 3.75mm‐diameter implant is supported by the PTv results.     

Peri‐implant mucosal aspects of ITI implants supporting overdentures. A five‐year longitudinal study.

Sixty‐six ITI implants placed in the mandible of 33 edentulous elderly patients (mean age: 69 years) were observed longitudinally for 5 years. The implants served as overdenture anchorage either by means of a connecting bar or single spherical attachments. During the study period, 2 implants failed (one because of a peri‐implant lesion and one because of a fracture) and had to be removed. At the beginning of the study, all implants were osseointegrated and had successfully been in function for 335 months. Oral hygiene practices and the peri‐implant mucosal status were assessed according to the criteria of conventional periodontal parameters. Approximately 50% of the implants had been installed into lining mucosa and hence were to surrounded by keratinized mucosa. The peri‐implant mucosal tissue was maintained healthy during the whole observation period, and no or only minimal loss of attachment was observed. The probing depths averaged approximately 3 mm. At the end of the study, orthopantomographic radiographs were obtained from all patients to assess the peri‐implant bony structures. Small local angular bony defects were detected on 16 implants (22%) in 12 patients. Slightly increased probing depths were observed when angular bony defects were present. Loss of attachment was significantly less frequent when the implants had been placed following a prolonged period of edentulousness (<5 years). This study demonstrated that advanced age, reduced dexterity of elderly patients and environmental conditions of overdentures do not represent a 1 higher risk for the development of peri‐implant lesions.     

Orthodontic anchorage capacity of short titanium screw implants in the maxilla. An experimental study in the dog.

The aim of this study was to investigate experimentally the effect of long term orthodontic loading on the stability as well as on the peri‐implant bone findings of short titanium screw implants (Bonefit®, submersion depth 6 mm, Ø 4 mm) inserted in regions with reduced vertical bone height. For this purpose, 6 maxillary premolars (₁P₁, ₂P₂, ₃P₃) were extracted from each of 2 foxhounds and reduction of alveolar bone height was performed by osteotomy. After a l6‐week healing period, 8 implants (4 per dog) were inserted in the edentulous areas. Simultaneously, 2 implants (1 per dog) were positioned in the palatal suture (one‐stage surgery). After an 5‐week implant healing period, the fixtures in the Pl/P2 areas ( n = 4) and the palate ( n = 2rpar; were loaded (test implants) by means of transpalatal bars running anteriorly, fixed on the implants in the Pl/P2 areas, and Sentalloy traction springs (‐2 N continuous force) inserted midsagittally between palatal implants and bars (force application period: 26 weeks). The fixtures in the P2/P3 areas served as controls ( n = 4). Clinical measurements and histological evaluation revealed no implant dislocation of the loaded fixtures. These results suggest that short titanium screw implants inserted in the alveolar bone and palatal suture region retain their stability during long‐term orthodontic loading, even following a relatively short unloaded implant healing period. Furthermore, it seems that long‐term orthodontic loading may induce marginal bone apposition adjacent to the implants.     

Periodontal parameters of osseointegrated dental implaits. A 4‐year controlled follow‐up study

The aim of this study was to evaluate the periodontal parameters of osseointegrated dental implants. The condition of the peri‐implant mucosa was assessed using periodontal parameters, i.e., of plaque index, bleeding on probing, probing pocket depth, probing attachment level and Periotest® scores as well as a radiographic parameter, over a 4‐year follow‐up period. 32 non‐submerged ITI dental implants, all placed in the mandible, were studied in 12 patients who had good oral hygiene. All patients were regularly recalled at 6‐month intervals. The overall implant success rate was 100%. None of the implants showed any signs of inflammation, radiographic bone loss or any detectable mobility during the follow‐up period. Methods similar to those used to evaluate the natural dentition were effectively employed to assess the clinical status of the dental implants. The diagnostic value of these parameters could not, however, be determined from this study due to the absence of any peri‐implant tissue complications. The results indicated that some periodontal parameters of healthy peri‐imolant mucosa might be slightly different from healthy periodontal tissue.     

Marginal bone levels at Brånemark system implants used for single tooth restoration. The influence of implant design and anatomical region

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.     

Non‐submerged osseointegrated dental implants with ball attachments supporting overdentures in patients with mandibular alveolar ridge atrophy. A short‐term follow up.

Non‐submerged, hollow screw ITI‐Bonefit dental implants with ball attachments supporting overdentures were used as alternative treatment to combined vestibulo‐lingual‐plasty with free split‐thickness skin graft and removable dentures in 40 consecutive patients with mandibular alveolar ridge atrophy. One hundred and fifty‐six non‐submerged fixtures were installed. Ball attachments were mounted on the fixtures and implant‐supported overdentures inserted 34 months after fixture installation. The observation period after implant activation and prosthesis insertion varied from 1 to 3 years with a median observation period of 2 years. The overall success rate of individual implants was 99%(155/156). The prosthesis function rate was 100%(40/40). The 1‐year success rate of individual implants was 99%(155/156) with a prosthesis function rate of 100% 40/40. No persistent surgical, periodontic or prosthodontic complications were observed. The results indicate that non‐submerged osseointegrated ITI‐Bonefit dental implants with ball attachments supporting overdentures can be a successful alternative to combined vestibulo‐lingualplasty with free split‐thickness skin graft and removable dentures, and as successful as the use of submerged dental implants.     

Implant therapy in periodontally compromised patients

The present study evaluates the outcome of implant therapy in periodontally compromised patients in need of additional functional tooth support. A total of 3 1 Astra® implants and 93 ITI Dental Implant System implants were inserted in 19 and 56 patients, respectively. The length of the implants varied between 8 and 14 mm. with 45% being 8 mm and 21% being 11 mm or more. Most implants were placed in the maxilla, predominantly in the premolar region, while less than 25% were placed in the mandible. The obser vation period ranged between 12 and 40 months for Astra® implants and between 3 and 84 months for ITI implants. At annual recall visits, 4 sites on all implants were assessed for presence of plaque, bleeding on probing, probing depth, and radiographic assessment of bone loss was performed. A total of 3 implants, all ITI implants, failed, yielding a 3‐year survival rate of 95–lOO%, depending on type of implant. After 3 years, 76–86% of all implants remained free from radiographic bone loss 2 1.5 mm. After 5 years, 55% of the ITI implants remained free from such bone loss. These results indicate that periodontally compromised patients, who have experienced a considerable loss of alveolar bony support, can be successfully treated with implants.     

Mk II: the self‐tapping Brånemark implant: 5‐year results of a prospective 3‐center study

The 5‐year result of a prospective 3‐center study is presented, comprising103 patients with 288 Mk II self‐tapping and 275 standard implants of the Brånemark System®. Out of 363 mandibular and 200 maxillary fixtures, one Mk II was lost of the lower jaw and 13 of each implant type failed in maxillae during the study period. Cumulative prosthesis stability was 97%. Five patients accounted for more than 85% of the fixture losses. Marginal bone resorption was similar for both implant designs. Apart from the implant failures and one patient exhibiting disturbed nerve sensation of the mental nerve, no major complications were encountered. Overall, this study revealed equal cumulative success rates for standard and Mk II implants after 5‐years of observation. Mandibular implants exhibited greater success rates (100%) for both tested implant types compared to maxillary implants (87%).     

Osteotome Sinus Floor Elevation without Bone Grafts – A 3‐Year Retrospective Study with Astra Tech Implants

Background: The bone support for implants in the posterior part of the maxilla is often poor. This condition may be treated with augmentation of the maxillary sinus floor. The most common technique used is to elevate the sinus floor by inserting a bone graft through a window opened in the lateral antral wall. In 1994, a less‐invasive technique using osteotomes was suggested by Summers. Purpose: The aim of this study was to evaluate the clinical and radiographic outcome of implants placed in the posterior maxilla with the osteotome sinus floor elevation (OSFE) technique without grafting. Materials and Methods: The study population comprised 36 consecutive patients in whom 53 implants were inserted with the OSFE technique. The indication for sinus floor elevation was that the bone height below the maxillary sinus was considered to be 10 mm or less. Results: The mean height of the alveolar process in the intended implant sites was 6.3 ± 0.3 mm, and the mean elevation of the sinus floor was 4.4 ± 0.2 mm. Two implants in edentulous patients were lost at the 1‐year follow‐up, and one more at the 3‐year examination. The remaining 50 implants inserted were in function, giving a 3‐year cumulative survival rate of 94%. Implants used in single‐tooth replacements and in partially edentulous cases had a 100% survival rate. The marginal bone level at the time of loading of the implants was 0.1 ± 0.04 mm below the reference point. One year later, the corresponding value was 0.5 ± 0.06 mm. The mean bone loss between the two examinations was 0.4 ± 0.05 mm. At the final examination after 3 years, the mean bone level was situated 0.6 ± 0.09 mm below the reference point, indicating a nonsignificant change between 1 year and 3 years. Conclusions: The OSFE technique, without bone grafts, was found to produce predictable results in the treatment of 36 patients with restricted bone volume in the posterior part of the maxilla.     

Inter‐ and intraobserver variability in radiographic bone level assessment at Brånemark fixtures

The aim was to determine inter‐ and intraobserver variability in radiographic bone level assessments at Brånemark fixtures and to study the influence of various factors (radiographic density; projection geometry; jaw in which the fixtures were inserted; degree of bone loss; time after fixture loading; and number of radiographs of each fixture) on the variability. Intraoral radiographs from bridge connection and 1‐ and 3‐year check‐ups from 15 upper and 15 lower jaws (172 fixtures) were assessed by 6 observers. Measurements were taken from a reference point on the fixture to the marginal bone level, and some were repeated by all observers after 1 month. Results showed a small interobserver variation (0.14 mm) with the intraobserver variation (0.08 mm) as its largest component. The radiographic density and the degree of bone loss showed the strongest influence on the interobserver variation. The only variable with a significant effect on the intraobserver variation was the number of radiographs of each fixture. Calculated confidence values showed that measurement reliability can be improved by letting one observer or preferably more make several, independent readings, allowing for the demonstration of minor differences in bone height over time or between implant systems.     

Single‐tooth replacement by osseointegrated Brånemark implants. A retrospective study of 82 implants.

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.