Retrospective evaluation of crestal bone changes around implants with reduced abutment diameter placed mnon-submerged and at subcrestal npositions: The effect of bone grafting at implant placement

Background: There is limited information regarding the effect of grafting of the osteotomy after subcrestal implant placement. The primary aim of this study is to retrospectively evaluate theeffect of bone grafting of the defect between the bone crest and the coronal aspect of implants with reduced abutment diameter placed non-submerged and at subcrestal positions. Methods: Records of50 consecutive patients treated with subcrestally placed dental implants grafted with a xenograft (Group A) and 50 consecutive patients with subcrestally placed dental implants without any grafting material (Group B) were reviewed. For each implant, the radiographs after placement were compared to images from the last follow-up visit and evaluated regarding the following: 1) degree of subcrestal positioning of the implant, 2) changes ofmarginal hard-tissue height over time, and 3) whether marginal hard-tissue could be detected on the implant platform at the follow-up visit. Results: The mean marginal loss of hard tissues was 0.11 - 0.30 mm for Group A and 0.08 - 0.22 mm for Group B. Sixtynine percent of the implants in GroupAand 77% of the implants in Group B demonstrated hard tissue on the implant platform. There were no statistically significant differences between the groups regarding marginal peri-implant hard-tissue loss. Conclusion: The present study fails to demonstrate that grafting of the remaining osseous wound defect between the bone crest and the coronal aspect of the implant has a positive effect on marginal peri-implant hard-tissue changes.