Preliminary Study to Evaluate Marginal Bone Loss in Cases of 2- and 3-Implant-Supported Fixed Partial Prostheses of the Posterior Mandible.

Purpose: The purpose of this study was to evaluate, by radiographic examinations, the marginal bone resorption around implants in cases of 2 and 3 implant-supported fixed partial prostheses (FPPs) at the posterior mandible. Methods: A retrospective study of 41 patients (23 males, 18 females) of an average age of 67 years (range, 53-85), with 2 and 3 implants-supported FPPs in the posterior mandible that were treated during 2006 to 2015. The mean follow-up time was 6.32 years (range, 2-10). Twenty-four patients had FPPs on 2 implants (a total of 48 implants). Seventeen patients had FPPs on 3 implants (a total of 51 implants). Clinical and radiographic follow-up examinations were performed. All radiographs were analyzed for changes in marginal bone height surrounding the implants. Results: The mean marginal bone loss around the most mesial implant was slightly higher in the 2-implant group (0.833 mm) compared with the 3-implant group (0.431 mm). The correlation between the mean marginal bone loss around the most mesial implant and the number of implants was of borderline value (P = 0.055). Conclusions: Considering the limitations of this preliminary study, the authors found that the mesial implant in the 2-implant group is more susceptible to marginal bone loss.