Effectiveness of varying alternating rapid maxillary expansions and constrictions (Alt-RAMEC) durations on maxillary protraction in noncleft Class III malocclusion: A systematic review and meta-analysis

Abstract

Background

This systematic review aims to assess whether extending Alt-RAMEC (Alternating Rapid Maxillary Expansions and Constrictions) protocols from four to nine weeks yields superior skeletal, dental, and soft-tissue outcomes in growing noncleft Class III patients when compared to conventional rapid maxillary expansion (RME).

Methods

A systematic literature search was conducted across the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Scopus, Embase, Web of Science, Google Scholar, Ovid MEDLINE, EBSCOhost, and LILACS databases over the past 20 years up to 7 January 2025. Clinical trials comparing cephalometrically conventional RME with Alt-RAMEC-assisted maxillary protraction in growing noncleft Class III subjects were included. Risk of bias was assessed using the Methodological Index for Nonrandomized Studies (MINORS) and the Cochrane Risk of Bias (RoB 2) tool. A random-effects meta-analysis using RevMan was conducted for quantitative synthesis.

Results

Out of 1847 articles screened, 24 studies were included for qualitative synthesis and 11 studies for meta-analysis. The five-week Alt-RAMEC protocol showed a statistically significant improvement in the ANB angle compared to RME (mean difference 1.37°; 95% confidence intervals 0.85–1.89; P < 0.01; c² = 2.14; I² = 0%). However, both 7-week and 9-week protocols demonstrated no significant advantage over conventional RME/facemask.

Conclusions

Only the five-week Alt-RAMEC protocol offers a statistically significant but clinically negligible improvement in maxillofacial, dental, and soft-tissue outcomes over conventional RME-assisted protraction in managing growing noncleft Class III malocclusion using a Hyrax-type expander. However, this is supported by only moderate to weak evidence.