Tip, torque and rotation of maxillary molars during distalization using Invisalign: a CBCT study

Abstract

Abstract Background: Desirable molar distalization by bodily movement is challenging and can be difcult to achieve. This study investigated changes in molar angulation (mesiodistal tipping), molar inclination (buccolingual torque) and rotation during distalization using clear aligner therapy (CAT).

Materials and methods: This retrospective study included 38 cone beam computed tomographic images (CBCTs) taken for patients treated with molar distalization using CAT. The study evaluated pre- (T0) and post-treatment (T1) CBCTs of 19 adult patients (36.68±13.50 years) who underwent maxillary molar distalization using Invisalign® align ers (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization. Changes in maxillary molar tip, torque and rotation were measured for 61 molars (183 roots). Paired t-test was used to evaluate the diferences between pre- and post-treatment readings. The level of signifcance was set at p≤0.05. The reproducibility of meas urements was assessed by the intraclass correlation coefcient (ICC).

Results: Molar angulation did not show signifcant change after distalization (p=0.158) however, there was signifcant increase in buccal molar inclination (p=0.034) and mesiobuccal molar rotation (p<0.001).

Conclusion: Molar distalization of 2 mm did not cause signifcant molar tipping. Maxillary molars showed signifcant buccal inclination (increased torque) and mesiobuccal rotation after distalization.