Factors affecting the efficacy of Invisalign in anterior tooth rotation

Abstract

The objectives of this study were to evaluate the clinical efficacy of SmartTrack aligner in rotational movement of the anterior tooth by 15°-30°, and to analyze the factors influencing anterior tooth rotational movement. A total of 212 teeth, including 4 tooth types (maxillary central incisor, maxillary lateral incisor, mandibular central incisor, and mandibular canine) that require anterior tooth rotational movement by 15°-30° were selected from 123 patients, with a mean age of 25.6 years. Rotational movements were calculated from the superimposition of the initial and predicted models (predicted rotational movement) and from the superimposition of the initial and achieved models (achieved rotational movement) using the best-fit alignment tool in NX Imageware. The difference between the predicted and achieved rotational movements (DPARM) was calculated. Univariate analysis, categorical regression analysis, and subgroup analysis were performed on 7 variables: age, gender, tooth type, predicted rotational movement, attachment type, interproximal reduction (IPR), and the total number of active aligners. The mean DPARM when the anterior tooth was rotated 15°-30° was 4.46° (range, -3.52° to 25.28°). Regression analysis showed that the patient's age, IPR, tooth type, and predicted rotational movement affected DPARM (P<0.01). Factors influencing the DPARM of the anterior tooth include the patient's age, tooth type, the magnitude of the predicted rotational movement, and whether or not IPR was prescribed.