Aligner-induced tooth movements in three dimensions using clinical data of two patients

TL;DR

This study demonstrates a method to precisely measure three-dimensional crown movements in orthodontic treatments using intraoral scans, providing insights into actual tooth movement versus planned movement.

Contribution

It introduces a novel approach for quantifying tooth movements in 3D with micrometer accuracy using clinical intraoral scan data from two patients.

Findings

Up to 1 mm tooth movement observed in nine weeks

Canines and incisors moved more than premolars and molars

Movement lag behinds the treatment plan

Abstract

The effectiveness of a series of optically transparent aligners for orthodontic treatments depends on the anchoring of each tooth. In contrast with roots, the crowns' positions and orientations are measurable with intraoral scans, thus avoiding any X-ray dose. Exemplified by two patients, we demonstrate that three-dimensional crown movements could be determined with micrometer precision by registering weekly intraoral scans. The data show the movement and orientation changes of the individual crowns of the upper and lower jaws as the result of the forces generated by the series of aligners. During the first weeks, the canines and incisors were more affected than the premolars and molars. We detected an overall tooth movement of up to about 1 mm during a nine-week treatment. The data on these orthodontic treatments indicate the extent to which actual tooth movement lags behind the treatment plan as represented by the aligner shapes. The proposed procedure can not only be used to quantify the clinical outcome of the therapy, but also to improve future planning of orthodontic treatments for each specific patient. The study should be treated with caution because only two cases have been investigated and the approach should be applied to a reasonably large cohort to reach strong conclusions regarding efficiency and efficacy of the therapeutic approach.