Bone Loss Before and After Peri-implantitis Surgery: A 7-Year Retrospective Observational Study.

PURPOSE: This study aimed to report changes in implant bone levels before and after peri-implantitis surgery (P-IS). MATERIALS AND METHODS: Patients were treated with P-IS from 2003 to 2010 and thereafter followed up until the last available radiographic examination (study termination: October 2018). Bone loss was measured before and after P-IS, and the numbers of clinical examinations post-P-IS were determined. The Student t test was used to compare the bone loss between examinations and reference populations, and correlations between different variables were calculated using the Pearson correlation coefficient (r). RESULTS: One hundred thirty-four consecutive patients (137 arches) underwent P-IS during the inclusion period (2.3%). A total of 122 patients (125 arches) were followed up for a mean period of 6.9 (SD: 5.54) and 7.3 (SD: 3.39) years from the first annual examination to before P-IS, and from the time of P-IS to after P-IS, respectively. The mean bone loss during the aforementioned durations was 0.18 (SD: 0.23) and 0.26 (SD: 0.28) mm/year, respectively (P < .05). Bone loss per year was also greater for unaffected implants after (0.29 [0.34] mm/year) compared with before P-IS (0.06 [0.10] mm/year; P < .05). No difference in bone loss was observed between peri-implantitis affected and unaffected implants or between implants with a turned or moderately rough surface after P-IS. A greater amount of bone loss was associated with increasing numbers of clinical examinations and shorter follow-up times after P-IS (P < .05). CONCLUSION: Average bone levels decreased from the time of prosthesis placement to termination of the study. Bone loss increased after P-IS in the total and unaffected group, and edentulous patients compared unfavorably with partially and single implant conditions. Increased bone loss was associated with higher numbers of clinical examinations per year of followup after P-IS (P < .05).