Treatment outcomes of different TAD patterns in clear aligner therapy for maxillary incisor retraction after premolar extraction.

Abstract

Objective: The integration of temporary anchorage devices (TADs) to aid clear aligner therapy (CAT) represents an evolving strategy that has gained expanding application over the past decade. This retrospective cohort study aimed to investigate the treatment outcomes of CAT cases involving maxillary incisor retraction following premolar extraction, managed with assistance of various TAD patterns.

Subjects and methods: Adult premolar extraction CAT cases were included in this retrospective cohort study. The maxillary central incisors (U1) were grouped based on the TAD pattern for their retraction: Non-TAD (n = 54), posterior TADs only (P-TADs; n = 50), or combined anterior and posterior TADs (AP-TADs; n = 46). Pretreatment and post-treatment CBCTs quantified U1 lingualization, intrusion, retroclination and potential side effects such as apical root resorption (ARR), pulp chamber reduction and palatal dehiscence incidence.

Results: P-TADs and AP-TADs patterns achieved greater U1 lingualization than the Non-TAD group. Vertical control differed markedly: AP-TADs achieved U1 intrusion (1.07 ± 1.64 mm), whereas P-TADs and Non-TAD showed U1 extrusion (-0.46 ± 1.12 mm and -1.51 ± 1.29 mm, respectively). U1 retroclination was over 10° in all three groups. AP-TADs exhibited greater ARR (1.31 ± 0.91 mm) and a higher proportion of Grade III ARR than the other groups. In regression analysis, the intrusion achieved was the strongest independent predictor of ARR. Pulp chamber reduction and palatal dehiscence incidence was similar among groups.

Limitations: Residual confounding may persist due to the inherent limitations of retrospective study designs.

Conclusions: In CAT cases involving maxillary incisor retraction following premolar extraction, P-TADs and AP-TADs patterns were associated with notable clinical treatment outcomes. These preliminary findings may provide prognostic indication for the management of such cases in the future.