Bone and soft tissue outcomes, risk factors, and complications of implant-supported prostheses: 5-Years RCT with different abutment types and loading protocols.

BACKGROUND: Data on risk factors and complications after long-term implant treatment is limited. The aims were to evaluate the role of various fixation modes and to analyze complications and risks that affect long-term use of implant-supported partial fixed dental prostheses. MATERIALS AND METHODS: Fifty partially edentulous subjects received three Brånemark TiUnite™ implants. Superstructures were attached directly at implant level (IL) or via abutments: machined surface (AM) and an oxidized surface (AOX, TiUnite™). Implants were immediately loaded (test) or unloaded for 3 months (control). Examinations occurred over a 5-year period. RESULTS: Forty-four subjects were re-examined after 5 years. Cumulative survival rates in test and control groups were 93.9% and 97.0%, respectively. Marginal bone loss (MBL; Mean [SEM]) was significantly lower at superstructures connected to AM (1.61 [0.25] mm) than at sites with no abutment IL (2.14 [0.17] mm). Peri-implantitis occurred in 9.1% of subjects and in 4.0% of implants. Multiple linear regression indicated that increased probing pocket depth (PPD), periodontal disease experience, deteriorating health, and light smoking (≤10 cigarettes/day) predict greater MBL, whereas increased buccal soft tissue thickness and higher ISQ predict lower MBL. CONCLUSIONS: The results show that MBL was influenced by the connection type. A machined abutment, instead of connecting the superstructure directly at the implant level, was beneficial. The following factors influenced MBL: PPD, periodontal disease experience, deteriorating health, light smoking, buccal soft tissue thickness, and ISQ. The results on peri-implantitis underscore the need for long-term maintenance care. Further, the abutment material surface properties constitute additional target for strategies to minimize MBL.

Bone Response and Soft Tissue Changes Around Implants With/Without Abutments Supporting Fixed Partial Dentures: Results From a 3-Year, Prospective, Randomized, Controlled Study.

BACKGROUND: Diverging opinions exist regarding rough surface abutment usage, and abutment exclusion effects are unstudied. PURPOSE: The study aims to: (1) assess tissue response to oxidized or machined abutments or no abutment; and (2) evaluate immediate implant-loading effects. MATERIALS AND METHODS: In a 2005-2008 parallel-group randomized, clinical trial, 50 partially edentulous subjects received three Brånemark TiUnite™ (Nobel Biocare®, Gothenburg, Sweden) implants. Superstructures were attached via abutments (one with a TiUnite surface - AOX, and one with a machine-milled surface - AM) or directly at implant level (IL). Implants were immediately loaded (test) or unloaded for 3 months (control). Postoperative examinations were done up to 3 years. RESULTS: Forty-seven subjects were reexamined after 3 years. Four and two implants were lost in test and control groups, respectively, during the first year. Thereafter, no implant loss occurred (95.7% survival). After 1 year, mean (SEM) peri-implant marginal bone loss (MBL) was 1.33 (0.08) mm (test) and 1.25 (0.08) mm (control). Between 1 and 3 years, a nonsignificant MBL occurred: 0.36 (0.08) mm (test) and 0.33 (0.06) mm (control). Similar MBL was found at IL (1.81 [0.93] mm) and AOX (1.77 [0.14] mm) after 3 years and was significantly lower at AM (1.42 [0.17] mm) than at IL (groups merged); 42% of the implants displayed mucosal bleeding at 3 years and probing pocket depths varied between 2.13 (0.12) mm and 3.62 (0.15) mm, significantly lower buccally. Bleeding on probing (BoP) in minute amounts was found in 30-45% of the sites and abundant BoP at about 20% of the sites. Soft tissue retracted mostly during year 1 and was more pronounced buccally. Regression analyses revealed significant effects from smoking, periodontal disease, abundant BoP, and a low initial implant stability quotient on MBL. CONCLUSIONS: No further significant MBL was found between 1 and 3 years, irrespective of loading protocol. Use of machined abutments may benefit marginal bone stability over time.

Changes of Marginal Bone Level in Patients with "Progressive Bone Loss" at Brånemark System® Implants: A Radiographic Follow-Up Study over an Average of 9 Years.

BACKGROUND: Patients have in many studies been identified with progressive bone loss and peri-implantitis problems, but few studies are available where these groups of patients have been followed up. PURPOSE: The purpose of this paper is to study further progression of bone loss in a cohort of 182 patients that have been reported to suffer from "progressive" bone loss and peri-implantitis. MATERIALS AND METHODS: Altogether, 182 patients that have earlier been identified to suffer from "progressive" bone loss formed the present study group. Data from patients' files have been retrieved, and intraoral radiographs have been analyzed for further bone level changes. Bone loss has been measured from time of inclusion into the present group to last available radiographs. Within each patient, one or several implants were diagnosed to suffer from "progressive" bone loss (affected), whereas others are not (unaffected). RESULTS: Altogether, 145 patients (80%) were radiographically followed up on an average of 9.1 years (SD 3.77) after inclusion. Twenty-four implants (3.1%) were lost in 16 patients (11%). Marginal bone loss was on an average 0.3 mm (SD 0.75) at stable implants with only small differences between "affected" and "unaffected" implants. In total, 67 implants (8.6%) presented an annual bone loss of >0.2 mm. Oral hygienist treatment and/or peri-implantitis surgery did not neither reduce implant failure rate nor marginal bone loss in 88 treated patients as compared with untreated patients. CONCLUSIONS: Less than one-third of the patients identified with "progressive bone loss" showed one or more implants as failures or with high annual bone loss (>0.2 mm) during follow-up (11.6% of implants). Treated patients (oral hygienist and/or surgery) did not perform better than untreated patients with regard to bone loss or implant failure.

Immediately loaded implants with or without abutments supporting fixed partial dentures: 1-year results from a prospective, randomized, clinical trial.

PURPOSE: To evaluate 1-year implant survival and marginal bone loss around implants that support fixed partial dentures loaded immediately or after 3 months, and effects from abutment usage. MATERIALS AND METHODS: In this 2005 to 2009 randomized, parallel-group, clinical trial, 50 partially edentulous patients each received three Brånemark TiUnite™ implants (Nobel Biocare®, Göteborg, Sweden), mostly in the posterior maxilla. Two implants were fitted with abutments: a TiUnite™ surface and a machine-milled surface; the suprastructure was attached directly at implant level for the third implant. After randomized allocation, implants were immediately loaded with a fixed temporary bridge (test group) or left unloaded for 3 months (control group). A permanent fixed suprastructure replaced the temporary bridge after 6 months (test). Hard and soft tissues were examined during pretreatment and surgery plus 2 days, 14 days, 4 weeks, 3 months, and 1 year after surgery. RESULTS: After 1 year, four implants were lost in the test and two in the control groups (1-year survival rates of 94.9% [test] and 97.2% [control], with no significant intergroup difference). Resonance frequency analysis values indicated a similar pattern in both groups, with implant stability quotient (ISQ) reduction between 2 and 4 weeks. The test group had a significantly lower ISQ than the control group at these appointments. After 1 year, marginal bone losses around the implants were, on average, 1.32 mm (test, standard error of the mean [SEM] 0.08) and 1.24 mm (control, SEM 0.08), with no significant intergroup difference. Significantly larger marginal bone loss was observed at implants without abutment compared with implants with abutment. CONCLUSIONS: For both groups, this study showed similar implant survival rates and marginal bone loss. Larger bone loss was found at implants loaded without attached abutments.

Implant survival and marginal bone loss at turned and oxidized implants in periodontitis-susceptible smokers and never-smokers: a retrospective, clinical, radiographic case-control study.

BACKGROUND: Little is known about the long-term outcome of oxidized surface oral implants, especially in periodontitis-susceptible smokers. The aim of this study is to determine implant survival and marginal bone loss at turned and oxidized implants in smokers and never-smokers with periodontitis. METHODS: Forty smokers and 40 never-smokers with experience of advanced periodontal disease, treated with implants 5 years previously, are included in this study. Groups were matched for sex, oral hygiene, and implant distribution, and patients were subgrouped by implant surface type (turned or oxidized). RESULTS: The overall implant survival rate was 96.9% in never-smokers and 89.6% in smokers. Compared with oxidized implants, turned implants failed more frequently in smokers. In smokers, mean (standard error of the mean) marginal bone loss at 5 years was 1.54 (0.21) mm at turned and 1.16 (0.24) mm at oxidized implants. In never-smokers, significantly greater bone loss was found at oxidized implants, 1.26 (0.15) mm, than at turned implants, 0.84 (0.14) mm. Oxidized implants demonstrated similar bone loss for both groups. Turned implants lost significantly more bone in smokers. Compared with never-smokers, the smokers' likelihood ratio for implant failure was 4.68, 6.40 for turned and 0.00 for oxidized implants. CONCLUSIONS: The results of the study underscore the need for prevention and cessation of smoking. Turned implants failed more frequently and lost more marginal bone in smokers. In contrast, oxidized implants showed similar failure rates and bone loss in smokers and never-smokers. Turned implants displayed less bone loss than oxidized implants in never-smokers. Oxidized surface implants are more suitable for patients susceptible to periodontitis who smoke.

A novel type of dental tube implant for areas with limited bone height. Clinical and radiographic data from three patients with 5-year follow-up.

BACKGROUND: Alternative implant designs may reduce the need for complicated and costly bone augmentation procedures in situations with limited bone height. PURPOSE: Wide dental tube implants have been manufactured and tested in three patients and followed for 5 years to evaluate if such implants are capable to support fixed prosthetic constructions with good prognosis in areas with limited bone height. MATERIALS AND METHODS: Four machined-tube implants with a height of 6 mm, an outer diameter of 7.4 mm, and an inner diameter of 6.0 mm were placed in three patients. After a healing period of 3 months, ceramometal suprastructures were constructed to supply the implants. Annual clinical and radiographical follow-ups were done up to 5 years. At the 5-year follow-up, all three patients were examined with a cone beam computed tomography technique. RESULTS: All implants and the suprastructures were clinically stable after 5 years. In one patient, vertical bone loss and a 6-mm deep pocket appeared after 1 year. The pocket has remained throughout the observation period and has been regularly debrided and kept it free from clinical signs of inflammation. In the other two patients, the soft tissue surrounding the implants was in good health with no or only slight inflammation throughout all observations. Pocket probing revealed no or slight bleeding and pocket depths amounting to less than 3 mm. CONCLUSION: It was shown that this new type of implant will function excellent during follow-up times of several years. Further studies should be done to explore in more detail indications for such implants.

Long-term evaluation of Astra Tech and Brånemark implants in patients treated with full-arch bridges. Results after 12-15 years.

AIM: To study the long-term outcome of implant survival rate, soft and hard tissue conditions and prosthetic status in a group of individuals treated with either Astra Tech TiOblast or Brånemark turned implants supporting a full-arch bridge. MATERIAL AND METHODS: Edentulous patients treated with either Astra Tech TiOblast surface or Brånemark turned implants were recalled for examination after 12-15 years. Out of initially 66 patients 46 were available for examination. Intra-oral radiographs were taken for bone level assessments. Clinical prosthetic conditions, number of surviving implants, implant stability, plaque scores, probing pocket depths, bleeding and pus after probing were recorded. Analyses of bone level changes during the total observation period were performed. RESULTS: Three patients in the Astra Tech group lost totally eight implants and five patients in the Brånemark group lost 10 implants during the total observation period. No statistically significant difference in implant loss or bone level change was found. Sixteen per cent of Astra Tech and 29% of Brånemark patients showed at least one implant with ≥2 mm bone loss after the first year in function. The corresponding prevalence on implant level was 6% and 5% respectively. No significant differences were found between the other examined variables. Two patients showed prosthetic complications of the supra construction in need of repair. Seven bridges had minor ceramic chippings. CONCLUSION: Treatment with Astra Tech TiOblast implants and Brånemark turned implants supporting full-arch bridges showed generally good clinical results with low numbers of implants with marginal bone loss indicative of peri-implantitis. No significant differences were found between the implant systems after 12-15 years in function.

Cone beam computed tomography evaluations of marginal alveolar bone before and after orthodontic treatment combined with premolar extractions.

Using cone beam computed tomography (CBCT) we investigated the distance between the cemento-enamel junction (CEJ) and the marginal bone crest (MBC) at buccal, lingual, mesial, and distal surfaces of incisors to first molars in adolescents before (baseline) and after extractive orthodontic treatment (study end point). Patients with Class I malocclusion, crowding and an overjet of ≤ 5 mm were examined with a CBCT unit using a 60 × 60-mm field of view and a 0.125-mm voxel size. Large differences in marginal bone height were found at baseline, particularly between tooth surfaces. There was a slight correlation between age and CEJ-MBC distance. From baseline to the study end point, large bone-height changes among teeth and tooth surfaces could be seen. Lingual surfaces, followed by buccal surfaces, showed the largest changes. Eighty-four per cent of lingual surfaces of mandibular central incisors exhibited a bone-height decrease of > 2 mm. The bone-height decrease was larger at lingual surfaces in the mandible than in the maxilla, and larger in girls (mean=1.8 mm) than in boys (mean=1.5 mm). Fewer than 1% of proximal surfaces exhibited changes of > 2 mm. It is unknown whether the changes in marginal bone height are transitory. A high-quality CBCT technique may help to determine this by providing a deeper insight into the long-term side effects of orthodontic treatment.

E.A.O. guidelines for the use of diagnostic imaging in implant dentistry 2011. A consensus workshop organized by the European Association for Osseointegration at the Medical University of Warsaw.

Diagnostics imaging is an essential component of patient selection and treatment planning in oral rehabilitation by means of osseointegrated implants. In 2002, the EAO produced and published guidelines on the use of diagnostic imaging in implant dentistry. Since that time, there have been significant developments in both the application of cone beam computed tomography as well as in the range of surgical and prosthetic applications that can potentially benefit from its use. However, medical exposure to ionizing radiation must always be justified and result in a net benefit to the patient. The as low a dose as is reasonably achievable principle must also be applied taking into account any alternative techniques that might achieve the same objectives. This paper reports on current EAO recommendations arising from a consensus meeting held at the Medical University of Warsaw (2011) to update these guidelines. Radiological considerations are detailed, including justification and optimization, with a special emphasis on the obligations that arise for those who prescribe or undertake such investigations. The paper pays special attention to clinical indications and radiographic diagnostic considerations as well as to future developments and trends.

Frequency of errors and pathology in panoramic images of young orthodontic patients.

The aims of this study were to evaluate the frequency of errors in panoramic radiographs in young orthodontic patients, to register pathologic and abnormal conditions, and to compare these findings with the patient's record. A total of 1287 panoramic radiographs of children and adolescents (530 boys and 757 girls; mean age 14.2 years) were analyzed. The radiographs were obtained of patients referred for orthodontic treatment during a 1 year period. Four observers evaluated the radiographs for 10 common errors, pathologies, and/or anomalies. Cohen's kappa was used for the calculations of inter- and intraobserver variability. Five of the errors were divided into clinically relevant or not clinically relevant errors, i.e. errors influencing diagnosis. Only those pathological findings with a possible influence on orthodontic treatment were compared with the patient's record. Of the 1287 radiographs, 96 per cent had errors. The number of errors in each image varied between 1 and 5, and in 24 per cent of these images, the errors could be of importance for clinical decision making. The most common error was that the tongue was not in contact with the hard palate. Pathologies or anomalies were found in 558 patients and a total of 1221 findings were recorded. Findings of possible relevance for orthodontic treatment were 63, and 12 of those were registered in the patient records. Pathological findings outside the dental arches were low and could be an argument for minimizing the radiation field.

Apical root resorption during orthodontic treatment. A prospective study using cone beam CT.

OBJECTIVE: To investigate the incidence and severity of root resorption during orthodontic treatment by means of cone beam computed tomography (CBCT) and to explore factors affecting orthodontically induced inflammatory root resorption (OIIRR). MATERIALS AND METHODS: CBCT examinations were performed on 152 patients with Class I malocclusion. All roots from incisors to first molars were assessed on two or three occasions. RESULTS: At treatment end, 94% of patients had ≥1 root with shortening >1 mm, and 6.6% had ≥1 tooth where it exceeded 4 mm. Among teeth, 56.3% of upper lateral incisors had root shortening >1 mm. Of upper incisors and the palatal root of upper premolars, 2.6% showed root shortenings >4 mm. Slanted surface resorptions of buccal and palatal surfaces were found in 15.1% of upper central and 11.5% of lateral incisors. Monthly root shortening was greater after 6-month control than before. Upper jaw teeth and anterior teeth were significantly associated with the degree of root shortening. Gender, root length at baseline, and treatment duration were not. CONCLUSION: Practically all patients and up to 91% of all teeth showed some degree of root shortening, but few patients and teeth had root shortenings >4 mm. Slanted root resorption was found on root surfaces that could be evaluated only by a tomographic technique. A CBCT technique can provide more valid and accurate information about root resorption.

Root resorption diagnosed with cone beam computed tomography after 6 months of orthodontic treatment with fixed appliance and the relation to risk factors.

OBJECTIVES: To investigate root resorption after 6 months of active orthodontic treatment and its relation to possible risk factors. MATERIALS AND METHODS: Ninety-seven patients (10-18 years) with a Class I malocclusion and crowding treated with fixed appliance and premolar extractions were examined with cone beam computed tomography before and after 6 months of active treatment. The exposure covered all teeth from first molar to first molar in both jaws. The Malmgren index was used to evaluate the degree of root resorption. Irregular root contour (score 1) was seen in most teeth already before active treatment, and therefore resorptions were registered only as score 2 (<2 mm, minor resorption) or higher. RESULTS: Minor root resorption was noted in 10% of the patients and severe root resorption, >2 mm (score 3) was found in four patients. Root resorption was more frequently seen in the upper jaw, especially the incisors. There was no statistically significant correlation of root resorption with any of the selected risk factors. CONCLUSIONS: After 6 months of treatment, clinically significant resorption was diagnosed in 4% of the patients, ie, in 96% of the patients the radiographic examination did not reveal any significant information. The selected risk factors did not have any impact on the amount of resorption after 6 months of active treatment.

Evaluation of subjective image quality in relation to diagnostic task for cone beam computed tomography with different fields of view.

AIMS: To evaluate subjective image quality for two diagnostic tasks, periapical diagnosis and implant planning, for cone beam computed tomography (CBCT) using different exposure parameters and fields of view (FOVs). MATERIALS AND METHODS: Examinations were performed in posterior part of the jaws on a skull phantom with 3D Accuitomo (FOV 3 cm×4 cm) and 3D Accuitomo FPD (FOVs 4 cm×4 cm and 6 cm×6 cm). All combinations of 60, 65, 70, 75, 80 kV and 2, 4, 6, 8, 10 mA with a rotation of 180° and 360° were used. Dose-area product (DAP) value was determined for each combination. The images were presented, displaying the object in axial, cross-sectional and sagittal views, without scanning data in a random order for each FOV and jaw. Seven observers assessed image quality on a six-point rating scale. RESULTS: Intra-observer agreement was good (κw=0.76) and inter-observer agreement moderate (κw=0.52). Stepwise logistic regression showed kV, mA and diagnostic task to be the most important variables. Periapical diagnosis, regardless jaw, required higher exposure parameters compared to implant planning. Implant planning in the lower jaw required higher exposure parameters compared to upper jaw. Overall ranking of FOVs gave 4 cm×4 cm, 6 cm×6 cm followed by 3 cm×4 cm. CONCLUSIONS: This study has shown that exposure parameters should be adjusted according to diagnostic task. For this particular CBCT brand a rotation of 180° gave good subjective image quality, hence a substantial dose reduction can be achieved without loss of diagnostic information.

Severity and pattern of peri-implantitis-associated bone loss.

OBJECTIVE: The purpose of the present study was to describe the severity and pattern of peri-implantitis-associated bone loss. MATERIAL AND METHODS: Intra-oral radiographs from 182 subjects were analysed. Bone-level measurements were performed in 419 implants with a history of bone loss. All radiographs obtained in the interval from the 1-year follow-up to the end-point examination (5-23 years) were analysed. The amount of bone loss that occurred from 1 year after prosthesis insertion was assessed and the pattern of bone loss was evaluated. RESULTS: The average bone loss after the first year of function was 1.68 mm and 32% of the implants demonstrated bone loss > or =2 mm. The multilevel model revealed that the bone loss showed a non-linear pattern and that the rate of bone loss increased over time. The model also revealed that the pattern of peri-implantitis associated bone loss was similar within the same subject. CONCLUSION: It is suggested that peri-implantitis-associated bone loss varies between subjects and is, in most cases, characterized by a non-linear progression, with the rate of loss increasing over time.

Cone beam computed tomography for assessment of root length and marginal bone level during orthodontic treatment.

OBJECTIVE: To evaluate the accuracy and precision of cone beam computed tomography (CBCT) with regard to measurements of root length and marginal bone level in vitro and in vivo during the course of orthodontic treatment. MATERIALS AND METHODS: Thirteen patients (aged 12-18 years) from an ongoing study and a dry skull were examined with CBCT using multiplanar reformatting for measurements of root length and marginal bone level. For in vivo evaluation of changes in root length, an index according to Malmgren et al was used, along with a modification of this method. RESULTS: The in vitro mean difference between physical and radiographic measurements was 0.05 mm (SD 0.75) for root length and -0.04 mm (SD 0.54) for marginal bone level. In vivo the error was <0.35 mm for root length determinations and <0.40 mm for marginal bone level assessments. CONCLUSION: Despite changes in tooth positions, the CBCT technique yields a high level of reproducibility, enhancing its usefulness in orthodontic research.

Placement of Brånemark implants in the maxillary tuber region: anatomical considerations, surgical technique and long-term results.

BACKGROUND: Fixture placement in the tuber area is one way to overcome the problem of insufficient bone volume for routine implant surgery in the posterior maxilla due to severe resorption of jawbone and an extensive enlargement of the maxillary sinus. However, little is known about the long-term results. PURPOSE: The aim of this study was to retrospectively evaluate the survival rate and marginal bone conditions at fixtures placed in the tuber region of the maxilla. MATERIAL AND METHODS: Twenty-one patients previously treated with at least one implant in the tuber region of the maxilla were included in this retrospective analysis. A total of 23 standard Brånemark System fixtures with a turned surface had been surgically placed in the tuber regions and 71 additional implants in adjacent areas to support fixed dental bridges. All implants were allowed to heal for 6-8 months before abutment connection and following prosthetic treatment. The patients were radiographed after 1-12 years for evaluation of marginal bone levels. In addition, the relation between the apex of the fixture in the tuberosity area and the posterior border of the maxilla was measured. RESULTS: Twenty of the 21 patients representing 22 tuber and 64 additional implants were radiographically evaluated. No implants in the tuber areas were lost during the follow-up whereas two fixtures in the anterior region had to be removed, one before loading and the other after 4 years of loading not interfering with the prosthesis stability. The mean marginal bone level at tuber implants was situated on average 1.6 mm (SD 1.1, n=22) from the abutment-fixture junction, whilst the other implants showed an average bone level of 1.9 mm (SD 0.8, n=64). The results were similar when comparing partially and totally edentulous patients. CONCLUSION: The present retrospective study shows good clinical outcome with standard Brånemark fixtures placed in the tuber region of the posterior maxilla using a two-stage procedure. In appropriate cases where bone of adequate volume and density is available, our data indicate that the technique can be used as an alternative to more extensive surgery and especially to the sinus lift procedure. However, prospective comparative studies are needed in order to evaluate the efficacy of the described technique for this purpose.

Radiographic analyses of "advanced" marginal bone loss around Brånemark dental implants.

BACKGROUND: Dental implant failures have a multifactorial background; dependency within patient/jaw exists. Failures caused by bone loss are rare. Lately, advanced bone loss around implants has been discussed. PURPOSES: Our aim was to study advanced bone level changes (>or=2 mm) regarding "clustering effect," prediction, and dependency. Further, we also aimed to study if the number of radiographs/radiographic examinations could be reduced. MATERIALS AND METHODS: Six hundred and forty patients (3,462 Brånemark implants) with radiographic follow-ups >or=5 years were included, whereas patients with overdentures and augmentation procedures were excluded. RESULTS: Progression rate for implants with advanced bone loss was largest during the first year; thereafter, slow. A cluster effect was found with more advanced bone loss in few patients. Position was important for lower jaw implants with larger bone loss for implants placed close to midline. Age, jaw type, and implant placement were identified as predictors. The longer the follow-ups, the more bone loss around a randomly selected and examined implant, and the more implants per patient, the higher the risk for bone loss >or=2 mm around any other implant. Still, it seems safe to exclude radiographic follow-ups during the first 5 years. Dependency within the patient was found, hence the "one-implant-per-patient technique" can be applied. CONCLUSION: The number of intraoral radiographs per examination and, more importantly, radiographic examinations can be reduced without jeopardizing good clinical management, a statement valid even for Brånemark implants with advanced bone loss.

Marginal bone loss at implants: a retrospective, long-term follow-up of turned Brånemark System implants.

BACKGROUND: Lately, presence of progressive bone loss around oral implants has been discussed. PURPOSE: The aim of this study was to report in a large patient group with different prosthetic restorations marginal bone level and its change as measured in radiographs obtained from prosthesis insertion up to a maximum 20 years in service. Further, it also aimed to study the impact of gender, age, jaw, prosthetic restoration, and calendar year of surgery. MATERIALS AND METHODS: Out of 1,716 patients recorded for clinical examination during 1999, 1,346 patients (78.4%) could be identified. A total of 640 patients (3,462 originally installed Brånemark System implants, Nobel Biocare, Göteborg, Sweden) with a follow-up of >or=5 years were included in the study, while patients with continuous overdentures and augmentation procedures were not. Distance between the fixture/abutment junction (FAJ) and the marginal bone level was recorded. RESULTS: The number of implants with a mean bone level of >or=3 mm below FAJ increased from 2.8% at prosthesis insertion to 5.6% at year 1, and 10.8% after 5 years. Corresponding values after 10, 15, and 20 years were 15.2, 17.2, and 23.5%, respectively. Implant-based bone loss was as a mean 0.8 mm (SD 0.8) after 5 years, followed by only minor average changes. Mean bone loss on patient level followed a similar pattern. Disregarding follow-up time, altogether 183 implants (107 patients) showed a bone loss >or=3 mm from prosthesis insertion to last examination. Significantly larger bone loss was found the older the patient was at surgery and for lower jaw implants. CONCLUSIONS: Marginal bone support at Brånemark implants was with few exceptions stable over years.

Cone-beam CT for preoperative implant planning in the posterior mandible: visibility of anatomic landmarks.

BACKGROUND: The technical development has given a new type of modality, cone-beam computed tomography (CBCT). This technique has a high potential to solve different diagnostic problems among which is preoperative planning for implants in the posterior mandible. PURPOSE: The aim of this retrospective study was to evaluate the visibility of the mandibular canal and the marginal bone crest and the agreement between observers in images from one CBCT technique. MATERIALS AND METHODS: Thirty consecutive patients were examined with 3D Accuitomo (J. Morita Mfg. Corp., Kyoto, Japan) in one side of the mandible, where the second premolar and molars were lost. The examined volume was 30 by 40 mm. Seven observers evaluated the visibility and the location of the mandibular canal and the marginal crest by visually deciding if the structures were clearly visible, probably visible, or invisible in one cross-sectional image, approximately 1 cm posterior to the mental foramen. In a later session, the observers also marked the two anatomic structures. If the decision was not "clearly visible" or if the anatomic structures were difficult to identify, the observers had to use other cross-sectional, axial, and/or sagittal images in the volume. RESULTS: The confidence among the observers evaluating the marginal bone crest was high. Two observers never used any other images, and the rest took help in two to seven cases. When marking the mandibular canal, the observers, in general, used more images. In five cases (17%), all the observers only used the single cross-sectional image. The agreement on the position of the canal was also high. CONCLUSION: With this CBCT modality (3D Accuitomo), the visibility of the mandibular canal and the marginal crest, as well as the observer agreement of the location of these structures, was high. Hence, the 3D Accuitomo can be recommended for implant planning in the posterior mandible.

Limited cone-beam CT and intraoral radiography for the diagnosis of periapical pathology.

OBJECTIVE: To compare intraoral periapical radiography with 3D images for the diagnosis of periapical pathology. STUDY DESIGN: Maxillary molars and premolars and mandibular molars with endodontic problems and examined with periapical radiographs and a 3D technique (3D Accuitomo) were retrospectively selected and evaluated by 3 oral radiologists. Numbers of roots and root canals, presence and location of periapical lesions, and their relation to neighboring structures were studied. RESULTS: Among 46 teeth, both techniques demonstrated lesions in 32 teeth, and an additional 10 teeth were found in the Accuitomo images. As regards individual roots, 53 lesions were found in both techniques, and 33 more roots were found to have lesions in Accuitomo images. Artefacts were sometimes a problem in Accuitomo images. In 32 of the 46 cases, all observers agreed that additional clinically relevant information was obtained with Accuitomo images. CONCLUSIONS: A high-resolution 3D technique can be of value for diagnosis of periapical problems.