Mandibular overdenture retained by four one-piece titanium-zirconium mini implants: A 2-year RCT on patient-reported outcomes

Aim: The positive impact of implant interventions on dental patient-reported outcomes is an essential parameter of treatment effectiveness. This study assessed the 2-year changes in patient satisfaction and oral health-related quality of life (OHRQoL) of edentulous patients treated with a four mini implant mandibular overdenture (IOD) Methods: The study was planned as a 2 x 2 factorial randomized clinical trial that tested two surgical approaches (flapped or flapless) and two loading protocols (immediate and delayed) using a titanium-zirconium mini implant (Straumann Mini Implant System (R)) and a PEEK retentive system (Straumann (R) Optiloc (R) Retentive System). Outcome measures (OHIP-Edent scores and the McGill Denture Satisfaction questionnaire) were assessed before treatment and at the 3-, 6-, 12-, and 24-month follow-ups. The Friedman test and multiple regression using Generalized Estimating Equations (GEE) were used for data analysis, considering the perprotocol (PP) and intention-to-treat (ITT) approaches Results: Seventy-four patients were randomized to the study groups. No implant failure occurred during the study period. Marked improvement in all post-treatment periods compared to baseline were observed for the two outcomes. No significant effect of patient's gender, age, and surgical protocol on the study outcomes. The effect of treatment provision was significant for the two outcomes in the PP and ITT approaches (p < 0.001). A barely significant positive effect of the immediate loading was observed for OHIP-Edent in the PP approach (p = 0.020) Conclusion: IOD treatment significantly improved patient-reported outcomes measures, with sustained benefits over the two years of overdenture use, and can be considered a promising treatment option in for the edentulous mandible.