Does planned molar intrusion with aligners assist with closure of anterior open bite?

Introduction

This study aimed to determine whether prescribed molar intrusion, with or without virtual occlusal bite-blocks (BB), resulted in actual molar intrusion and assisted with anterior open bite (AOB) correction in adult patients treated with Invisalign clear aligners (Align Technology, Santa Clara, Calif).

Methods

A retrospective study was conducted with 36 adult patients with AOB. Subjects were divided into 2 treatment groups: planned molar intrusion (PMI) and no-PMI (No-PMI). PMI was obtained from the tooth movement tables in the ClinCheck software. Patients with PMI were further categorized by the presence or absence of virtual posterior BB (PMI-BB and PMI-No BB, respectively). Treatment success was determined on the basis of positive vertical incisor overlap in posttreatment cephalograms. Treatment changes were assessed using pretreatment and posttreatment cephalometric radiographs (Welch 2-sample t test, 95% confidence interval, P = 0.05). Finally, treatment stability was assessed at least 1-year posttreatment using the Photographic Open Bite Severity Index (POSI).

Results

There were 15 patients with No-PMI and 21 without PMI (total n = 36). The mean overbite change was 2.5 ± 1.0 mm for No-PMI and 3.2 ± 1.8 mm for patients with PMI (P = 0.12). All patients had positive vertical incisor overlap in posttreatment cephalograms, indicating 100% treatment success. Open bites were corrected primarily by incisor retroclination and extrusion in both treatment groups. The average measured molar intrusion for the PMI group was 0.71 mm greater than the change for the No-PMI group, but the difference was not statistically significant after controlling for potentially confounding variables (P = 0.074). A total of 14 patients from the original sample were assessed for stability using the POSI analysis. Of those, 12 (85.7%) had a POSI score of 0.

Conclusions

Regardless of whether the molar intrusion was planned or not, the modality of AOB correction with Invisalign clear aligners was primarily incisor extrusion and retroclination. Overall, aligners are an effective appliance for the treatment of adult AOB. Based on our limited sample, treatment stability was similar to that reported for fixed appliances.