Effects of different orthodontic retainers on dental arch stability and periodontal health: a systematic review with pairwise meta-analysis and network meta-analysis.

Authors

Xiaochen Zhang, Ying Li, Zhen Zhang, Jianwei Liu, Qinfeng Sun

Published in

BMC oral health. Jul 15, 2026. Epub Jul 15, 2026.

Abstract

Orthodontic retainers play a crucial role in maintaining dental arch stability and periodontal health; however, the relative advantages of different retainer types remain inconsistent. This study aimed to systematically evaluate the comparative effectiveness of different retainers by integrating both direct and indirect evidence.
A systematic search of PubMed, Web of Science, Embase, and the Cochrane Library was conducted up to January 2026. Randomized controlled trials (RCTs) comparing different types of retainers were included. Pairwise meta-analysis was performed to compare fixed retainers and removable retainers. A Bayesian framework-based network meta-analysis (NMA) was further conducted to explore comparative patterns among conventional fixed retainers (FRs), computer-aided design/computer-aided manufacturing fixed retainers (CAD/CAM FRs), vacuum-formed retainers (VFRs), and Hawley retainers (HRs).
A total of 18 studies (n = 1,471) were included. Pairwise meta-analysis showed no statistically significant differences between the two types of retainers in periodontal indices, including gingival index (GI) and plaque index (PI), as well as in most stability outcomes. However, removable retainers were associated with greater increases in arch length (AL), while the observed reduction in intercanine distance (ICD) was statistically borderline and clinically small. The NMA similarly revealed no statistically significant differences. Ranking probabilities suggested exploratory, outcome-specific patterns: FRs ranked highest for AL, CAD/CAM FRs for Little's irregularity index (LII), HRs for ICD, and VFRs for interpremolar distance (IPD); however, these rankings should be interpreted cautiously because most network estimates were imprecise and statistically non-significant.
Overall, the available evidence did not demonstrate definitive superiority of any retainer type. Ranking results suggested possible outcome-specific patterns, but these findings remain exploratory because of sparse networks, imprecise estimates, and limited certainty of evidence. Further well-designed randomized trials are needed.

PMID:
42458363
Bibliographic data and abstract were imported from PubMed on 16 Jul 2026.

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