Clinical and radiographic outcomes of mini-implant-retained maxillary and mandibular overdentures: a systematic review and meta-analysis.

OBJECTIVE: To assess the clinical and radiographic outcomes of overdentures and their retaining dental mini-implants, based on a single-arm systematic literature review. METHODS: Electronic search was undertaken in three databases, last updated in October 2023, plus manual search of journals. Cumulative implant survival rate (CSR) and the estimated marginal bone loss (MBL) under different follow-up times were calculated. RESULTS: Thirty-nine studies were included, with 3,787 mini-implants supporting 1,026 overdentures (109 maxilla, 896 mandible) in 1,005 patients, with a mean follow-up of 28.1 +/- 19.8 months (min-max 0.3-84.0). 202 mini-implants failed, after a mean of 9.4 +/- 11.8 months (7-year CSR 91.4%). The implant survival was lower in the maxilla in comparison to the mandible (p < 0.001), lower for early/delayed-loaded in comparison to immediately-loaded implants (p = 0.005) and lower for 2-mini-implant in comparison to 4-mini-implant-retained mandibular overdenture (p < 0.001; Log-rank test). A high rate of transversal fracture of the prosthesis and wear of the attachment parts was observed. The estimated mean MBL gradually increased from 0.518 (</= 6 months) to 1.260 mm (58.8-90 months). There was an estimated MBL increase of 0.011 mm per additional month of follow-up. CONCLUSION: Although presenting a high 7-year CSR, mini-implant-retained overdentures may require frequent maintenance follow-ups, due to the high rate of technical complications. The estimated MBL of mini-implants over 80 months is low. CLINICAL RELEVANCE: The ability to anticipate outcomes is an essential part of risk management in clinical practice. The findings reported herein set some recommendations and potential strategies for minimizing failures and complications commonly associated with this mini-implant-retained overdentures.