Purpose: The aim of this retrospective study was to evaluate the clinical performance of two implants supporting mandibular overdentures by means of clinical and radiologic parameters, and also to explore the relationship of marginal bone loss with implant-/patient-related factors and soft tissue parameters.

Materials and methods: Data of patients who had undergone insertion of two implants into the interforaminal region between November 2012 and December 2016 using three different implant systems were retrieved from the archival records. Age, sex, implant length, implant diameter, observation period, mobility, and soft tissue parameters were recorded. Marginal bone levels and interimplant distances were measured with computer software on panoramic radiographs obtained at 3 months and at the recall session.

Results: A total of 43 patients with 86 implants were included in the study. Patients were evaluated with an average observation period of 41.79 months. Among the evaluated parameters, Gingival Index, Bleeding Index, and implant diameter were found to have significant effects on the marginal bone loss (P < .05). However, no significant effects of sex, age, implant length, observation period, and interimplant distance were observed on the marginal bone loss. No implants showed peri-implantitis or mobility, while eight implants showed peri-implant mucositis.

Conclusion: Within the limitations of this study, it can be concluded that peri-implant soft tissue health and the diameter of the implant have an important effect on the marginal bone loss as well as the success of two-implant-supported mandibular overdentures.