Vertical and Horizontal Crestal Bone Levels in Root-Analog Stepped Implants-A 10-Year Prospective Study.

PURPOSE: The aim of this study was to evaluate bone levels with root-analog stepped implants by radiographic analysis over a 10-year period. MATERIALS AND METHODS: One hundred fifty-three implants placed in 93 patients were examined after 10-year follow-up. The implant diameters were 3.8 to 6.5 millimeters (mm), whereas the lengths were 10 to 15 millimeters (mm). One hundred seven implants were restored with single crowns or fixed partial dentures, 46 with bar or ball-retained overdentures. Radiographs were taken after surgery, after the insertion of the prosthesis, after 5 and 10 years of loading. Vertical and horizontal bone levels were measured at each control. RESULTS: After 10 years, the mean vertical bone defect (VBD) for all implants was 1.8 mm, whereas the horizontal bone loss was 0.4 millimeters (mm). Implants inserted in the mandibular frontal area lost statistically significant more bone (3.1 ± 1.9 millimeters [mm]) than implants placed in the maxillary frontal area (1.4 ± 1.8 millimeters [mm]; P-value [P] = 0.00). The VBD of implants placed in the mandibular (1.6 ± 2.2 millimeters [mm]) and maxillary posterior region (1.9 ± 2.0 millimeters [mm]) did not show significant differences (P-value [P] = 0.06). CONCLUSION: The implants showed VBD a moderate range (mean 1.8 mm after 10 years) depending of the implant sites (maxillary frontal area less than mandibular frontal area).

Peri-implant bone changes in immediate and non-immediate root-analog stepped implants-a matched comparative prospective study up to 10 years.

BACKGROUND: The purpose of this retrospective long-term study was to evaluate the peri-implant bone changes in immediate implants and matched non-immediate implants as a control group using a specific and proven measurement protocol over a 10-year period, because there are no similar studies published. METHODS: One hundred and thirty-three patients received 174 implants (immediate implants (IM) n = 87; control group (CG) n = 87). The two groups were matched following specific criteria for comparison: implant length, diameter, site of the implant, and patient's gender. For the evaluation, radiographic images were taken, digitalized, and assessed using the "coronal bone defect (CBD)". RESULTS: The differences between the means and medians showed a statistically significant difference at the time of insertion, while to the other control dates, no significant differences could be concluded. The median CBD for the control group was 0 mm at the time of insertion and increased to 1.7 mm after 10 years while the CBD for the IM group was 0.7 mm at the time of insertion and increased to 1.5 mm over the 10 years. CONCLUSIONS: Both surgical protocols lead in our study to similar outcomes regarding the loss of bone around dental implants.

Anterior Loop of the Mandibular Canal-A Source of Possible Complications.

INTRODUCTION: Recognizing the radiographic position of the mental foramina is not sufficient to avoid complications during dental implant surgery. In many cases, the inferior alveolar nerve extends mesially as an "anterior loop" (AL). The aim of this study was to investigate the prevalence and spatial extension of the AL on computed tomography (CT). MATERIALS AND METHODS: Thirty-seven human mandibles from an anatomical collection underwent CT analysis. Cross-sectional views and panoramic reconstructions were obtained. Prevalence and length of the AL were investigated. RESULTS: Recognition of the AL on CT was 100%. Prevalence of the AL was 97.3% (n = 36). AL mean length was 2.26 mm (maximum: 7.0 mm). CONCLUSION: Recognition of the AL on CT scans (100%) is higher compared with data in literature for detection on panoramic radiographs (38.2%). To avoid complications, it is important to detect the AL presence and its mesial extension from the mental foramen. Safety distance of at least 2 mm from the mesial extend of the AL is recommended. Therefore, 3D imaging techniques are advised for loops which courses are not clearly identifiable on panoramic radiographs.

Reliability of findings around healthy implants in association with oral hygiene measures: a clinical, microbiological, and immunological follow-up in edentulous patients.

OBJECTIVES: To assess the performance of clinical, microbiological, and immunological diagnosis of peri-implant health and the influence of professional hygiene measures on them. MATERIAL AND METHODS: Twenty-one edentulous patients with oral implants supporting a lower overdenture were followed up over 3 months beginning 1 week before their annual recall visit. Hygiene scores, probing depth, bleeding on probing (BOP), implant stability, gingival crevicular fluid (GCF) volume, sulcular interleukin-1beta (IL-1beta) and prostaglandin E2 (PGE2) concentrations, and relative concentrations of five bacterial species (polymerase chain reaction) were investigated. Measurement variation was assessed as a function of (a) intra- and (b) inter-examiner reliability, (c) inter-implant variation in each patient, (d) time, and (e) effect of hygiene measures by accuracy, repeatability, reproducibility, and visualization with the Bland and Altman Plot. RESULTS: Measurement means and accuracy (in parentheses) were as follows: GCF volume 1.5 microl (1.5), Interleukin-1beta 8 ng/ml (26), PGE2 63 ng/ml (185), bacteria sum score 0.2 (0.7), plaque score 1 (1), BOP score 0 (1), Periotest value -4 (3), resonance frequency analysis ISQ 66 (11), and pocket probing depth 2.3 mm (0.7). No finding exhibited any statistically significant measurement variation as explained by accuracy, repeatability, or reproducibility. Bland and Altman Plots revealed insufficient agreement for replicated BOP assessments. A short post-treatment reduction in plaque and BOP scores was visually apparent. Still, professional oral hygiene measures exerted no sustained influence on the clinical and biochemical appearance of the peri-implant tissues. CONCLUSION: All findings except BOP showed statistically acceptable repeatability and moderate vulnerability to influences present 'chairside' in clinical practice.

A comparison of implant-supported, bar- or ball-retained mandibular overdentures: a retrospective clinical, microbiologic, and immunologic study of 10 edentulous patients attending a recall visit.

PURPOSE: Clinical, microbiologic, and immunologic comparisons of the peri-implant health in edentulous volunteers wearing long-standing implant-supported ball- or Dolder bar-retained mandibular overdentures were performed. MATERIALS AND METHODS: Ten age- and gender-matched individuals (mean age, 71 years) with either ball- or bar-retained complete mandibular overdentures, scheduled for an annual implant recall examination, were investigated an average of 7 years after implant placement. Plaque and gingival crevicular fluid samples were obtained from the peri-implant sulcus. The groups were compared with regard to peri-implant probing depth; plaque and bleeding on probing scores; sulcular fluid flow rates; implant stability measurements (Periotest device); relative concentrations of Actinobacillus actinomycetemcomitans, Prevotella intermedia, Fusobacterium nucleatum, Porphyromonas gingivalis, Tannerella forsythensis, and Treponema denticola assessed by polymerase chain reaction analysis; and sulcular concentrations of interleukin-1beta and prostaglandin E2, assessed by enzyme-linked immunosorbent assay. RESULTS: No statistically significant differences were found for any of the examined parameters between both study groups. CONCLUSION: Within the limitations of this study, both ball attachments and Dolder bars can be recommended for overdenture retention, with either one showing satisfying clinical, microbiologic, and immunologic findings in the peri-implant tissues after several years of service in healthy recall patients with good oral hygiene habits.

Resonance frequency analysis and damping capacity assessment. Part I: an in vitro study on measurement reliability and a method of comparison in the determination of primary dental implant stability.

OBJECTIVES: The aims of this in vitro study were to evaluate reliability of the Osstell and Periotest devices in the assessment of implant stability and to perform a method comparison. MATERIAL AND METHODS: Commercial dental implants were inserted into bovine rib segments of different anatomical origins and densities. Repeated measurements were performed, varying (a) the torque-in force of the devices' attachment screw (the Osstell transducer and the ball attachment, insert for the Periotest device), (b) the insertion site bone quality, and (c) the thread exposure in simulated peri-implant bone defects. RESULTS: Both methods were comparably reliable and showed a strong association to each other in the classification of implant stability. As opposed to torque-forced screw attachment, the variations in bone composition, differences in inter-implant stability of adjacent implants, and peri-implant bone reduction were statistically significant for both methods. CONCLUSIONS: Both non-invasive diagnostic devices seem to be useful in the long-term follow-up of implant integration.

Resonance frequency analysis and damping capacity assessment. Part 2: peri-implant bone loss follow-up. An in vitro study with the Periotest and Osstell instruments.

OBJECTIVE: We compared the performance of damping capacity assessment (Periotest device) to resonance frequency analysis (Osstell device) in the assessment of peri-implant bone loss in an in vitro experiment. MATERIAL AND METHODS: Screw-type oral implants were polymerized into acrylic blocks. Peri-implant bone loss was simulated by successively removing defined portions of material surrounding the implants in millimeter increments. Measurement values of both devices were compared by assessing the associated measurement errors, by calculating correlation analyses and drawing scatterplots, and by means of regression analysis referring to increasing bone loss. RESULTS: Both devices produced comparable results suggesting agreement of the measured implant stability values to the actual loss of peri-implant resin. There was a noticeable correlation of the Periotest and Osstell implant stability values. CONCLUSION: The results of this experiment suggest agreement in predicting the actual implant stability with both the instruments with the Osstell instrument being the more precise device.

Accuracy of navigation-guided socket drilling before implant installation compared to the conventional free-hand method in a synthetic edentulous lower jaw model.

In this study, the three-dimensional (3D) accuracy of navigation-guided (NG) socket drilling before implant installation was compared to the conventional free-hand (CF) method in a synthetic edentulous lower jaw model. The drillings were performed by two surgeons with different years of working experience. The inter-individual outcome was assessed. NG drillings were performed using an optical computerized tomography (CT)-based navigation system. CF drillings were performed using a surgical template. The coordinates of the drilled sockets were determined on the basis of CT scans. A total of n=224 drillings was evaluated. Inter-individual differences in terms of the surgeons' years of work experience were without statistical significance. The mean deviation of the CF drilled sockets (n=112) on the vestibulo-oral and mesio-distal direction was 11.2+/-5.6 degrees (range: 4.1-25.3 degrees ). With respect to the NG drilled sockets (n=112), the mean deviation was 4.2+/-1.8 degrees (range: 2.3-11.5). The mean distance to the mandibular canal was 1.1+/-0.6 mm (range: 0.1-2.3 mm) for CF-drilled sockets and 0.7+/-0.5 mm (range: 0.1-1.8 mm) for NG drilled sockets. The differences between the two methods were highly significant (P<0.01). A potential benefit from image-data-based navigation in implant surgery is discussed against the background of cost-effectiveness.

Randomized multicenter comparison of 2 IMZ and 4 TPS screw implants supporting bar-retained overdentures in 425 edentulous mandibles.

PURPOSE: Two treatment concepts for implant-supported bar retention of mandibular overdentures-2 intramobile cylinder (IMZ) implants and a Dolder bar and 4 titanium plasma-sprayed (TPS) screw implants and an angulated bar-were compared in a randomized controlled clinical trial with respect to postprosthetic efficacy and safety. MATERIALS AND METHODS: Four hundred twenty-five patients with edentulous mandibles were enrolled; 212 were randomized to TPS implants (control group) and 213 to IMZ implants (test group). Endpoints were occurrences of postprosthetic integration deficiency (ID), functional deficiency (FD), and complications. The trial was sized to detect a 10% difference in 5-year ID-free postprosthetic system lifetime with a power of 80%. RESULTS: With 340 protocol-completed cases, the trial achieved its predetermined power. The 2 systems did not show statistically significant differences in occurrences of postprosthetic ID and FD; 5-year occurrence-free postprosthetic system lifetime probabilities were estimated as 42.5% with IMZ and 42.8% with TPS, for ID; and as 82.6% with IMZ and 87.2% with TPS, for FD. However, at 3 to 6 months after surgery, mean Periotest values were significantly higher (P = .0001 without adjustment) with IMZ implants (5.6, SD 4.2) than with TPS implants (0.8, SD 4.3). TPS implants showed a higher incidence of inflammation and recession, while IMZ implants had a higher incidence of implant fracture after functional loading. DISCUSSION: The system-wise approach overcomes potential bias with implant-wise analyses. A combination of radiographic and clinical criteria distinguishes between desirable integration and functional anchorage. The in situ survival rates at 5 years in this study (95% for IMZ, 92% for TPS) match rates reported in the literature. CONCLUSION: This study demonstrated equivalent efficacy of 2 IMZ cylinders and 4 TPS screws in implant-supported, bar-retained mandibular overdentures and indicated a higher rate of complications with the TPS screw implants.

Randomized multicenter comparison of two coatings of intramobile cylinder implants in 313 partially edentulous mandibles followed up for 5 years.

Intramobile cylinder (IMZ) implants with either of two coatings, hydroxyapatite (HA) or titanium plasma-flame (TPF), as distal abutments for combined tooth implant-supported restorations, were compared in 313 partially edentulous mandibles with respect to postprosthetical failure patterns and complication frequencies in a randomized multicenter clinical trial. Within the treatment protocols, the two coatings do not show evidence of different efficacy with respect to occurrence of postprosthetical integration deficiency (ID) or functional deficiency (FD). Statistical equivalence for an absolute effect of +/-15% in event-free survival could only be demonstrated for FD, not for ID, however. Intent-to-treat and per-protocol population analyses gave consistent results. Hazards of occurrence of ID and FD, adjusted for years of follow-up, were estimated for ID as 7% per year (95%CI 4-10% per year) with HA and 5% per year (95%CI 3-7% per year) with TPF, and for FD as 5% per year (95%CI 3-7% per year) with HA and 4% per year (95%CI 2-6% per year) with TPF. The 5-year cumulative success rates for no ID were 69.5% (95%CI 58-81%) with HA and 82.2% (95%CI 74-91%) with TPF. With respect to frequencies of complications, there was no relevant statistically significant difference between the two coatings.