Peri-implant health and patient-reported outcomes in mandibular two-locator overdentures: A 1- to 9-year retrospective cohort study.

This study aimed to clinically and radiographically evaluate peri-implant health and to analyze patient satisfaction with two implant-supported overdentures (IODs) with locator attachments in the mandible. This retrospective cohort study included 50 patients with 100 implants who underwent functional loading for 1-9 years with IODs. Patient demographic variables were recorded. Clinically, modified plaque index (mPI), modified gingival index (mGI), bleeding on probing (BoP), and probing depth (PD) were recorded. Radiographically, marginal bone level changes (ΔMBL) and inter-implant distance were measured. Patient satisfaction was assessed using a visual analog scale (VAS). Multiple linear regression analysis was used for statistical analysis. Patients with good cleanability had higher satisfaction. Mesial ΔMBL was correlated with PD (r = 0.354, p < 0.001) and BoP (r = 0.223, p = 0.026), while distal ΔMBL was correlated with PI (r = 0.232, p = 0.020), PD (r = 0.308, p = 0.002), and BoP (r = 0.214, p = 0.032). At the same time, the inter-implant distance was statistically significantly correlated with mGI (r = -0.209, p = 0.037). Linear regression analysis showed that when the maxilla was fixed with a prosthesis, the mesial, distal, and maximum ΔMBL increased by 1.17, 0.93, and 0.96 mm, respectively, compared with a conventional complete denture. Furthermore, when PD increased by 1 mm, mesial, distal, and maximum ΔMBL increased by 0.39, 0.37, and 0.43 mm, respectively. The implant brand had a significant effect on mesial, distal, and maximum ΔMBL. Locator-retained mandibular IODs demonstrated favorable long-term peri-implant outcomes and high patient satisfaction. Peri-implant ΔMBL was associated mainly with PD, BoP, implant brand, and opposing dentition, while good cleanability was associated with higher satisfaction. These results emphasize the importance of inflammation control and prosthesis-related planning to preserve peri-implant bone and optimize long-term success. Peri-implant health around mandibular overdentures is shaped by patient-, implant-, and prosthesis-related factors, as well as clinical measurements, highlighting the importance of prosthetic planning and maintenance.