The Efficacy and Predictability of Maxillary First Molar Derotation with Invisalign: A Prospective Clinical Study in Growing Subjects

Roberta Lione,Francesca Chiara De Razza,Paola Cozza,Chiara Pavoni,Valeria Paoloni

doi:10.3390/app12052670

Roberta Lione, Francesca Chiara De Razza + Show 3 more

Open Access

https://doi.org/10.3390/app12052670

Copy DOI

Abstract

To analyze the derotation of maxillary mesio-rotated first permanent molars in subjects with Class II edge-to-edge dental malocclusion in mixed dentition treated with Invisalign Clear Aligners (CA). In total, 36 patients (16 males, 20 females, 9.9 ± 1.9 years) treated with CA are enrolled from the Department of Orthodontics. Inclusion criteria are the following: Caucasian ancestry, mixed dentition, molar Class II edge-to-edge, no tooth/craniofacial anomalies, no caries/periodontal diseases. Pre-treatment (T1) and post-treatment (T2) digital casts, and final ClinCheck representations (T2ClinCheck) are acquired. The Henry’s angle (HA) is used to assess maxillary first molars rotation. The molars with an HA > 11° are taken (53 teeth). Five measurements are performed at T1, T2, and T2ClinCheck: Henry’s angle (HA), mesiobuccal-expansion (MBE), distobuccal-expansion (DBE), mesiobuccal-sagittal (MBS), and distobuccal-sagittal (DBS). A paired t-test was used to compare T2-T1 and T2ClinCheck-T2. The T2-T1 shows a distal-rotation (difference −6.3°) with an expansion of 2.2 mm for MBE and 1.5 mm for DBE. At T2, the mesiobuccal cusps show a distal movement of 1.0 mm and the distobuccal cusps of 0.9 mm. The HA’s T2ClinCheck-T2 difference is −4.2°. In the sagittal plane, the difference is 0.9 mm for the MBS and 0.7 mm for the DBS. The expansion showed the highest predictability (60% HA, 52.6% MBS, and 56.25% DBS). The CA effectively produces an arch expansion and upper molars’ distal rotation. Upper molar derotation provides a 1 mm of gain in arch perimeter and occlusal improvement.

Highlights

Publisher’s Note: MDPI stays neutralThe correct molar position and occlusal relationship have been described by Andrews as one of the six keys essential to achieving a successful orthodontic treatment [1,2]
This rotation is caused by the mesiolingual cusp of the upper first molar, which firmly occludes in the central fossa of the lower first molar and acts as a center of rotation, causing a mesial movement of the mesiobuccal cusp [4]
The patients were selected according to the following inclusion criteria: Caucasian ancestry, mixed dentition, Class II edge-to-edge first molar occlusal relationship assessed through clinical evaluation, and good compliance with aligners

Summary

Introduction

Publisher’s Note: MDPI stays neutralThe correct molar position and occlusal relationship have been described by Andrews as one of the six keys essential to achieving a successful orthodontic treatment [1,2]. Due to its rhomboidal shape with a wider buccolingual diameter than mesiodistal, a rotated upper first molar occupies more space, creating a situation unreceptive to obtain a normal occlusion with more crowding between adjacent teeth [2,4]. This rotation is caused by the mesiolingual cusp of the upper first molar, which firmly occludes in the central fossa of the lower first molar and acts as a center of rotation, causing a mesial movement of the mesiobuccal cusp [4]. The tooth occupies excessive space in the dental arch and its buccal cusps occlude with a tendency of Class II molar relationship [5].

Objectives

Methods

Results

Discussion

Conclusion