Immediate loading of splinted locking-taper implants: 1-year survival estimates and risk factors for failure.

PURPOSE: The purpose of this study was to estimate the 1-year survival rate of immediate vertical-load splinted locking-taper implants and to identify risk factors for implant failure. MATERIALS AND METHODS: To address the research aim, the investigators implemented a retrospective cohort study design and enrolled a sample derived from the population of patients who had received immediate vertical-load splinted implants (Bicon, Boston, MA). The predictor variables were the sets of exposures associated with implant failure and classified as demographic, health status, anatomic, implant specific, prosthetic, and surgical. The primary outcome variable was implant failure, which was defined as implant removal. Descriptive, univariate, and multivariate analyses using clustered marginal approach of the Cox proportional hazards models were computed. The level of statistical significance was set at P < .05. RESULTS: The study cohort was composed of 209 patients who received 477 implants. The overall 1-year Kaplan-Meier survival estimate was 90.3% (95% CI: 86.9%, 93.7%). In the multivariate model, implant placement in a delayed manner versus implantation the same day as extraction (hazard ratio = 3.7, P = .002), uncoated implants versus coated implants (hazard ratio = 22.1, P < .001), and an increased per-unit number of pontics involved in the temporary prosthesis (hazard ratio = 1.8, P < .001) were statistically associated with an increased risk of implant failure. CONCLUSIONS: An overall 1-year survival estimate of 90.3% (95% CI: 86.9%, 93.7%) was calculated for immediately loaded splinted implants. After controlling for other variables, 3 variables-timing of implant placement relative to extraction (delayed implant placement after tooth extraction), coating of implant (uncoated), and increased number of pontics-were associated with an increased risk for implant failure.

Changes in crestal bone levels for immediately loaded implants.

PURPOSE: The authors' objective was to measure crestal bone level change in subjects with immediately loaded implants and to identify risk factors associated with changes in bone level. MATERIALS AND METHODS: A retrospective cohort study design was used. The sample comprised subjects who had had endosseous implants placed and immediately loaded between July 2001 and July 2003. Demographic, health status-related, anatomic, implant-specific, prosthetic, and surgical variables were examined. The primary outcome variable was change in crestal bone level over time. Appropriate uni-, bi-, and multivariate statistics were computed. RESULTS: The sample comprised 174 subjects who received 347 immediately loaded implants. The mean duration of radiographic follow-up was 6.9 +/- 4.0 months, respectively. Mean changes in radiographic bone level were -0.5 mm and -0.6 mm on the mesial and distal surfaces, respectively, after a mean of 6.9 months of radiographic follow-up. Using least squares methods, it was estimated that radiographic bone levels would be -1.0 mm and -0.8 mm on the mesial and distal surfaces, respectively, at 12 months. The multivariate model revealed that radiolucency at or adjacent to implant site was associated with an increased risk of crestal bone loss (odds ratio, 1.88; 95% CI, 1.00 to 3.60). Twelve months after placement, 92.5% of implants had had < or = 1.5 mm of crestal bone loss. DISCUSSION: The results of this study were comparable to the results of other studies comparing immediate loading to delayed loading. Further research to estimate long-term changes in crestal bone loss and to identify risk factors for bone loss with immediate loading is recommended. CONCLUSION: This study suggests that crestal bone level changes with immediately loaded implants were within the recommended range for 92.5% of the evaluated implants. The mandible showed a higher risk for crestal bone loss compared to the maxilla.