RESUMEN
Background and objective: Retrograde peri-implantitis (RPI) is a periapical radiolucent lesion developed around the implant apex. This study aimed to investigate the Incidence of RPI in a single university dental hospital training center. Materials and Methods: All records of patients who received single Implants between 2016-2020 were screened. For cases that met inclusion criteria, clinical and radiographic data were analyzed. Results: A total of 215 were included and categorized as follows, Category A: implants were placed next to endodontically treated teeth (n = 58, 27%); category B, implants placed at the sites with previous endodontic involvement within 6 months of tooth extraction (n = 25, 11.6%); Category AB: implants placed at sites that fulfill the criteria of groups A and B (n = 18, 8.4%); and Category C: Implants that were placed next to vital teeth and at a site with no previous endodontic treatment or a site that was allowed to heal for more than six (n = 114, 53%). Categories A, B and AB served as the endodontically involved (EI) group, while category C served as non- endodontically involved (NEI) group. Only two sites (0.9%) were confirmed as RPI, both from group A (3.4%). Comparing all groups studied showed no statistically significant difference in RPI incidence. Conclusions: The incidence of RPI is low; however, endodontically treated teeth with periapical lesions (PALs) next to an implant site could contribute to RPI.