Factors and clinical outcomes for standard and mini-implants retaining mandibular overdentures: A systematic review and meta-analysis

Statement of problem. Standard-diameter dental implants are not always applicable because of anatomic limitations of the residual ridge. Thus, mini-implants have been increasingly used and offer an alternative. However, data regarding prosthetic complications, maintenance factors, and clinical outcomes are limited.Purpose. The purpose of this systematic review and meta-analysis was to compare prosthetic complications and maintenance events and clinical outcomes in residual ridges rehabilitated with mandibular implant overdentures (IODs) by using standard implants or mini-implants.Material and methods. Nine electronic databases were searched. Quantitative analyses to measure the risk ratio (RR) and standardized mean difference (SMD) were applied. Those methods were used to assess prosthetic complications and maintenance events (abutment adjustments, replacement of retentive element, occlusal adjustment, and overdenture fracture) and clinical outcomes related to postoperative pain, probing depth (PD), plaque index (PI), marginal bone loss (MBL), and implant survival rate. Results. Altogether, 7 publications were selected. Mini-implants presented reduced abutment adjustments (RR 0.23 [0.07, 0.73], P=.01), replacement of retentive element (RR 0.41 [0.31, 0.54], P<.001), occlusal adjustment (RR 0.53 [0.31, 0.91], P=.02), and overdenture fracture (RR 0.46 [0.23, 0.94], P=.03) compared with standard implants. Additionally, mini-implants presented lower values for PI at 6 months (SMD-0.27 [-0.47, -0.08], P=.006) and 12 months (SMD-0.25 [-0.46,-0.05], P=.01). No additional tangible differences were noted.Conclusions. Mini-implants might be an alternative choice based on the number of prosthetic complications and maintenance events. This was also confirmed by the comparable clinical data between standard implants and mini-implants. (J Prosthet Dent 2023;130:677-89)