Treatment outcome and efficacy of an aligner technique--regarding incisor torque, premolar derotation and molar distalization

Mareike Simon, Ludger Keilig, Jörg Schwarze, Britta A Jung, Christoph Bourauel, Mareike Simon, Ludger Keilig, Jörg Schwarze, Britta A Jung, Christoph Bourauel

Abstract

Background: The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy.

Methods: We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®.

Results: The overall mean efficacy was 59% (SD = 0.2). The mean accuracy for upper incisor torque was 42% (SD = 0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD = 0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD = 0.2).

Conclusion: Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy.

Figures

Figure 1
Figure 1
Laser scanner used in this study.
Figure 2
Figure 2
Superimposition of the scans. a) The plaster cast models of the beginning conditions are digitised using a laser scanner. b) The models are segmented into single teeth. c) The predicted tooth movement in the ClinCheck (extracted from the dataset from Align Technology). d) Superimposition of the plaster cast of the beginning conditions with the ending conditions in the ClinCheck to determine the predicted tooth movement.
Figure 3
Figure 3
Definition of the coordinate system used in this work. The distalization is described as a translation on the x-axis, incisor torque as a rotation around the y-axis, and premolar derotation is described as a rotation around the z-axis.
Figure 4
Figure 4
Box– whisker plots showing the treatment efficacy of incisor torque, premolar derotation and molar distalization. w. Att = with Attachment, w/o Att = without Attachment, w. PR. = With Power Ridge.

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Source: PubMed

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