The Impact of Mini-Screws and Micro-Implants on Orthodontic Clinical Outcomes: An Umbrella Meta-Analysis

This umbrella meta-analysis aimed to answer the clinical question: Do mini-screws and micro-implants improve specific orthodontic outcomes such as intermolar width, interpremolar width, suture expansion, molar movement, and skeletal width compared to conventional anchorage methods?

A systematic search was performed in PubMed, Scopus, ISI Web of Science, and Google Scholar up to October 2024. Systematic reviews and meta-analyses on mini-screws and micro-implants in orthodontic treatment were included. Methodological quality was assessed using AMSTAR 2, and a random-effects model was used to calculate effect sizes (ESs) and 95% confidence intervals (CIs). Heterogeneity was evaluated using the I² statistic and Cochrane's Q-test, with subgroup and sensitivity analyses conducted to identify sources of heterogeneity.

Eleven meta-analyses comprising 50 data sets were included. The results indicated that mini-screws significantly increased intermolar width (ES: 2.61 mm, 95% CI: 0.29-4.92, p = 0.02) and skeletal width (ES: 3.33 mm, 95% CI: 1.37-5.29, p = 0.001). However, no significant impact was found on interpremolar width or alveolar width before and after MARPE. Micro-implants significantly reduced molar movement (ES: -1.13 mm, 95% CI: -1.99 to -0.26, p = 0.01). Substantial heterogeneity was noted across several outcomes (I² > 50%), which persisted despite subgroup analyses.

Mini-screws and micro-implants enhance skeletal and intermolar width and control molar movement in orthodontic treatment. However, their effects on other outcomes are inconsistent, warranting further high-quality studies to strengthen clinical recommendations.

PROSPERRO (CRD42023447137).