INFLUENCE OF EXTRACTION VERSUS NON-EXTRACTION TREATMENT ON REFINEMENT FREQUENCY IN CLEAR ALIGNER THERAPY

Abstract

The objective of this research is to investigate the association between space management requirements and refinement frequency in clear aligner treatment. This retrospective cohort study analyzed 190 patients who completed clear aligner treatment in Bangkok, Thailand from 2016-2025. Space management was categorized as < 6 mm (n = 155, 81.58%), representing non-extraction cases and ≥6 mm (n = 35, 18.42%) representing extraction cases. Modified Poisson regression was employed, adjusting covariants, reporting results as risk ratios with 95% confidence intervals, with p<0.05 considered statistically significant. The results revealed that closing space ≥ 6 mm was the strongest independent predictor of increased refinement frequency (adjusted RR = 1.37, 95% CI: 1.02-1.82, p = 0.034), indicating 1.37 times higher refinement risk. The overall refinement rate was 92.1%, with all patients requiring ≥ 6 mm space closure undergoing at least one refinement. Space closure in extraction cases represents the primary predictor of refinement frequency. Therefore, enhanced treatment planning incorporating auxiliary mechanics, optimized attachment design, and strategic overcorrection may improve treatment predictability and reduce both refinement frequency and overall treatment time.

Keywords: Clear Aligner Treatment, Refinement, Extraction, Non-extraction, Space Management