The ridge-preservation approach using porcine bone in combination with collagen membrane significantly limited the resorption of hard tissue ridge after tooth extraction compared to extraction alone. Furthermore, the histologic analysis showed a significantly higher percentage of trabecular bone and total mineralized tissue in ridge-preservation sites compared to extraction-alone sites 7 months after tooth removal.

This study clearly points out that an alveolar ridge preservation technique performed with collagenated porcine bone and a resorbable membrane--according to the procedure reported in this study--was able to limit the contour changes after tooth extraction. Finally, the test sites showed a better preservation of facial keratinized tissue when compared to control sites; grafted sites allowed the placement of longer and wider implants when compared to implants inserted in non-grafted sites.

This study suggests that circumferential defects could heal clinically without any guided bone regeneration (GBR) in both experimental groups, and that the procedure was virtually free from complications in the postoperative period, probably because of the absence of barrier membranes and/or grafting materials. Histologically, peri-implant defects of over 1.5 mm heal by connective tissue apposition, rather than by direct bone-to-implant contact, but clinically this healing may be very successful. No histological analysis was carried out in the present study, but even the largest residual gaps were filled with hard tissue that could not be probed. Thus, such outcomes can be considered clinically successful. The different rate of bone remodeling around immediate or delayed implants could have implications for the preferred timing of implant placement in sites of high esthetic concern.

The results of this study seem to indicate that inadequate oral hygiene and the presence of bleeding from the gingiva/mucosa in patients with dental implant were associated with an higher prevalence of peri-implantitis; moreover, in the patients affected by peri-implantitis, the lack of sufficient height keratinized mucosa (<2 mm) and bone regenerative procedures at implant level were also associated to higher prevalence of peri-implantitis as well.