Influence of implant microstructure on the osseointegration of immediate implants placed in periodontally infected sites - A histomorphometric study in dogs

The aim of this study was to evaluate the influence of implant microstructure on the osseointegration of immediate implants placed into infected sites. During 12 weeks, periodontitis was induced in six dogs in the areas of the first to fourth mandibular premolars of both sides. The teeth were extracted and the implants were placed immediately. Implant placement was randomly assigned so that for each side in the mandible a different implant surface, a new grit-blasted/acid-etched group 1 or titanium plasma spray surface group 2 was used, totaling 36 implants in the experiment. The animals were killed 12 weeks after implant placement. Two histomorphometric analyses were performed: percentage of bone/implant contact (BIC) and analyses of the bone density in adjacent and distant areas from the implant surface. The results showed that the percentages of BIC were 52.7% and 42.7% for groups 1 and 2, respectively. The bone density analysis revealed that the percentages of bone in the adjacent areas were 66.6% and 58.8%, and in the distant areas from the implants were 58.7% and 55.8% for groups 1 and 2, respectively. The mean differences of BIC were verified through the Mann-Whitney test and differences in bone density through the Kruskal-Wallis test. The differences were not statistically significant (P>0.05). In conclusion, osseointegration of implants placed into a more challenging healing situation such as immediate implants into periodontally compromised sites was successful for both surfaces; however, the grit-blasted/acid-etched surface, although not statistically significant, had a slightly better performance when compared to the titanium plasma spray surface for all the parameters studied.