Comparison of Clear Aligner Treatment in First-Treatment and Re-Treatment Patients: A Retrospective Cohort Study

Abstract

This retrospective real-world study aimed to evaluate the outcomes of clear aligner treatment (CAT) and patient demographics of patients seeking orthodontic re-treatment who had previously received orthodontic treatment in childhood or adolescence. The study was conducted using anonymized data from DrSmile (Berlin, Germany), a CAT provider in Europe. Data were collected from a total of 2080 patients in Germany (71.5% female, 28.5% male, ranging from 18–70 years, median 29.0 years), who completed their CAT between 1 June and 30 June 2022. Patients were divided into two groups: adult first-treatment patients (n = 1587) and adult re-treatment patients (n = 493). Results showed that re-treatment patients had a shorter treatment duration (p < 0.05), required fewer interproximal reductions (IPR) (p < 0.001), and had fewer clinical visits (mean 2.96 versus 4.14 visits) than first-treatment patients (p < 0.001). Data collected from adult orthodontic re-treatment and first-treatment patients indicated that the demographic characteristics of these two groups were very similar. No significant differences were found between re-treatment patients and first-treatment patients in terms of motives for orthodontic treatment (p = 0.068), types of insurance (p = 0.615), and treatment satisfaction (p = 0.673). The study highlights the need for orthodontists and dentists to provide adequate information to patients about long-term retention and decision-making for orthodontic treatment, especially for re-treatment.