Influence on peri-implant bone loss of different fixed partial dentures retained on 2 implants.

STATEMENT OF PROBLEM: Marginal bone loss is key to determining the success of dental implants. However, how different factors, including the extension or span of implant-supported restorations and implant position, affect bone loss is unclear. PURPOSE: The purpose of this prospective clinical study was to analyze peri-implant bone loss 3 years after loading by evaluating the influence of implant position and prosthetic type and comparing splinted crowns and 3- or 4-unit fixed partial dentures (FPDs) to determine whether 2 dental implants can achieve comparable success when replacing 2, 3, or 4 missing teeth. MATERIAL AND METHODS: Sixty-two adjacent dental implants in 23 participants were investigated. The implants supported noncantilevered restorations: 2 splinted crowns or 3- or 4-unit FPDs. Bone loss was evaluated 3 years after loading from periapical radiographs using AutoCAD software. Nonparametric comparisons were made. The Wilcoxon test was applied to determine homogeneity of related samples. The Mann-Whitney test was applied to measure homogeneity of bone loss in 2 independent samples and the presence/absence of a pontic in the restoration (alpha=.05). RESULTS: Mean +/-standard deviation peri-implant bone loss was 0.9 +/-0.7 mm. The peri-implant bone loss of the restorations analyzed was similar to the average values of 1.1 +/-0.8 mm for 3- and 4-unit FPDs and 0.8 +/-0.6 mm for splinted crowns. The type of prosthodontic restoration and implant position did not show significant influences on bone loss (P>.05). CONCLUSIONS: Mean bone loss values were within an acceptable range. Statistically significant relationships were not found between the restoration types, suggesting that 3 or 4 missing teeth can be replaced by 2 implants. Further studies with longer follow-ups are needed to obtain clinically applicable conclusions.