Space closure after premolar extraction using clear aligners: a systematic review with meta-analysis.

Area of Science:

• Orthodontics
• Dental Technology

Background:

• The effectiveness and predictability of clear aligner treatment (CAT) for space closure after premolar extraction (SCaPE) are not well-established.
• Unwanted tooth movements during CAT for SCaPE require further investigation.

Purpose of the Study:

• To systematically review and evaluate the efficacy, predictability, and resistance to unwanted tooth movement of CAT for SCaPE.
• To compare the outcomes of CAT with predicted movements and assess the potential superiority of fixed appliances.

Main Methods:

• Systematic review including pre-post studies and clinical trials, with a comprehensive database search up to November 2024.
• Quality assessment using ROB-2 and ROBINS-I tools, with meta-analysis of predicted versus achieved maxillary tooth movements using the Invisalign® system.
• Effect size estimation via Standardized Paired Difference (SPD) with 95% Prediction and Confidence Intervals, and certainty of evidence evaluated using the GRADE tool.

Main Results:

• Fourteen studies with 510 participants were analyzed; ten studies had a high risk of bias.
• CAT was significantly less effective than predicted for anterior teeth retraction, leading to increased lingual tipping and extrusion.
• Achieved distal canine tipping and mesial first molar tipping were also greater than predicted, with limited evidence comparing CAT and fixed appliances.

Conclusions:

• CAT appears to be less effective and predictable for SCaPE due to limitations in achieving bodily tooth movement and anchorage control.
• Fixed appliances may be superior to CAT for SCaPE, although evidence is limited and of low to very low certainty.
• Future research should focus on enhancing CAT prediction models and exploring accessory use to improve efficacy for SCaPE.