Immediate versus delayed loading of orthodontic miniscrews: a systematic review and meta-analysis of failure rates

Objectives To evaluate and compare the failure rates of temporary anchorage devices (TADs) subjected to immediate versus delayed orthodontic loading.Materials and methods Six electronic databases (PubMed, Scopus, CINAHL Plus [EBSCO], the Cochrane Library, Dentistry & Oral Science Source, and the Trials Meta Register) were searched up to January 2026. Randomized controlled trials and cohort studies comparing immediate with delayed loading were included; because these protocols were defined differently across studies, the classifications reported by the original authors were adopted. Risk ratios (RRs) with 95% CIs were pooled using a random-effects model.Results Six studies (one RCT, five non-randomized) involving 826 miniscrews (511 immediate, 315 delayed) were analysed. No significant difference in failure rates was observed (RR = 1.03; 95% CI: 0.62–1.71; p = .91). Excluding one outlier gave similar results (RR = 0.91; 95% CI: 0.64–1.31), reducing heterogeneity from 36% to 0%. Findings were robust across risk-difference, Peto odds-ratio, and Hartung–Knapp sensitivity analyses; insertion-site subgroups showed no significant effect modification.Conclusions The currently available evidence is insufficient to determine whether immediate loading alters the risk of miniscrew failure between loading protocols. The evidence is limited, largely observational, heterogeneous in loading definitions, and statistically underpowered; because outcomes were analysed per miniscrew rather than per patient, with within-patient clustering unaccounted for, the confidence intervals are likely narrower than the true uncertainty, and the wide prediction interval remains compatible with both benefit and harm. The certainty of evidence was very low (GRADE). Adequately powered randomized trials with standardized loading definitions are needed.