A radiographic evaluation of bone healing around submerged and non-submerged dental implants in beagle dogs

Background: The rehabilitation of the oral cavity with dental implants has become a predictable treatment modality However, there have been only a few direct comparisons evaluating the submerged and nonsubmerged placement tec hniques. The purpose of this study was to characterize radiographic peri-im plant bone changes following the insertion of submerged and nonsubmerged im plants in the beagle dog. Methods: At the end of the extraction healing phase, 19 submerged and 19 no nsubmerged implants were randomly placed in a split-mouth study design and observed over an 18-week period. For submerged implants, a second stage sur gery and transmucosal abutment attachment was performed at week 12. Standar dized dental radiographs taken at baseline, week 12, and week 18 were used to measure peri-implant bone changes. The radiographs were analyzed with a simple computer assisted method. Results: A total of 43 standardized radiographs were exposed to evaluate th e 38 implants. During the study period, all submerged and nonsubmerged impl ants demonstrated peri-implant bone loss. At baseline, both submerged and n onsubmerged implants had similar bone levels (P greater than or equal to 0. 05). When the mean peri-implant bone levels for submerged and nonsubmerged implants were compared from baseline to week 12, nonsubmerged implants had a significantly greater amount and rate of bone resorption than submerged i mplants (P less than or equal to 0.05). Following week 12, the initially su bmerged implant had a significantly higher rate and amount of peri-implant bone loss than the nonsubmerged implants (P less than or equal to 0.05). Ho wever, by the end of the study period, week 18, both submerged and nonsubme rged implants had comparable bone levels (P greater than or equal to 0.05). Conclusions: The study indicates that, although the temporal patterns of pe ri-implant bone resorption differed, there were no differences between subm erged and nonsubmerged implants in the overall amount and rate of peri-impl ant bone loss.