Retrograde peri-implantitis: evaluation and treatment protocols of a rare lesion.

Objective Retrograde peri-implantitis (RPI) is defined as bone loss around an osseointegrated implant apex that usually appears within the first few months of its placement. This retrospective study aimed to evaluate the relationships between RPI and demographic factors, local bone and intraoral factors, and implant and surgery-related factors. Method and materials A retrospective study was conducted in 116 patients with a total of 369 implants placed between January and June 2019. The associations between RPI and the following data were evaluated: location of the recipient site, bone quality, reason for previous tooth loss, condition of adjacent teeth, marginal bone loss, immediate or late placement of implants, implant brand and size, activation of lesions, and treatment modality. Results: Among the 14 (3.8%) implants that showed RPI, 10 (5.8%) were in the maxilla and four (?2.0%) were in the mandible, which were detected before prosthetic loading. There was no significant difference in terms of RPI between the arches. Of the 14 RPI implants, four (28.?6%) were placed into a previously periapical lesion site, three (21.4%) had endodontically treated adjacent teeth, two (14.3%) were immediately placed following extraction, three (?21.4%) revealed marginal bone loss, and one (7.1%) was lost at the abutment connection. Eight RPI implants healed spontaneously, while the remaining six were subjected to treatment (P = .05). Conclusion: Local bone and intraoral factors, particularly the reason for tooth loss at the recipient site and the condition of the adjacent teeth, had stronger effects on RPI than other factors. (Quintessence Int 2021;52:112-121; doi: 10.3290/j.qi.a45264).