Mini-implant mandibular overdentures under a two-step immediate loading protocol: A 4-6-year retrospective study

Objectives: This retrospective study to evaluate the treatment outcomes of mandibular mini--implant overdentures (MIODs) placed under a two--step immediate loading protocol. Background: The mini--implant overdenture emphasises the advantages of simplicity using flapless surgery and immediate loading. However, some mini--implant have lowe initial stability. Materials and Methods: A total of 30 participants who used mandibular MIODs and maxillary removable complete dentures (RCDs) over 4 years were included. Four one-piece mini--implants (<3 mm in diameter) were placed by a flapless surgical approach after fabrication of new RCDs, and the O--ring attachment was attached at least 8 weeks after implant placement. Results: The average observation period was 58.9 +/- 9.2 months after mini--implant loading. The survival rate of the implants was 100.0%, and the overall change in mean marginal bone level (Delta MBL) was -0.9 +/- 1.1 mm. The implant success rate was 83.3% at the implant level, and 66.7% at the patient level. The mean initial Periotest value was 0.9 +/- 3.1, and it was positively associated with Delta MBL and implant success (P <.05). Patient satisfaction improved after conversion from RCDs to MIODs (P <.05), and mastication and pain showed greater satisfaction with longer loading time (P <.05). Conclusions: The mandibular MIODs could be chosen as an alternative treatment under a two--step immediate--loading protocol in edentulous patients with limited alveolar bone volume. To ensure superior treatment outcomes of MIODs, initial stability of implant must be obtained using as wide a diameter as possible within the anatomically allowable limits.