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. 2025 Jul 25;55(4):266-275.
doi: 10.4041/kjod24.223. Epub 2025 Jun 4.

In vitro analysis of mandibular arch response to canine distalization with aligners at varying initial angulations

Fan Yongjie  1 , Lv Xin  2 , An Le  2 , Wang Bingle  1 , Liu Gebing  1 , Guo Baoxiong  3 , Yang Sensen  4
Affiliations

In vitro analysis of mandibular arch response to canine distalization with aligners at varying initial angulations

Fan Yongjie et al. Korean J Orthod. .

Abstract

Objective: The purpose of this research was to analyze the three-dimensional forces acting on the mandibular teeth with aligner activation for distalization and an antitipping design of the mandibular canines, based on various pretreatment canine tips in vitro.

Methods: Five sets of clear aligners were designed to produce the same 0.25 mm distalization forces, with/without the 2° antitipping design, and were applied to canines with three initial angulations. Each group consisted of 12 aligners. Aligner forces were measured in real time using a force transducer measurement system.

Results: In the mesial group, the canines mainly received distal and extrusive forces; labial and intrusive forces were observed on the incisors, and the second premolar received mesial forces. In the upright and distal groups, the canines were subjected to distal and intrusive forces, while the incisors were subjected to lingual and extrusive forces. Greater mesial forces on the second premolars were also observed. In the upright and distal groups, the distal and intrusive forces on the canines, and the lingual and extrusive forces on the incisors, were reduced by adding a 2° antitipping design to the canines; however, the mesial and intrusive forces on the second premolars increased.

Conclusions: With clear aligners, the "bowing effect" is aggravated when the initial angulation of the canines is distal. This effect can be partially relieved by implementing an antitipping design on the canines, although greater attention should be paid to posterior anchorage control.

Keywords: Aligner; Antitipping design; Canine distalization; Initial canine tip.

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Conflict of interest statement

CONFLICTS OF INTEREST

The equipment used in this study was provided by Shanghai Smartee Denti-Technology which had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors declare that there is no conflict of interest.

Figures

Figure 1
Figure 1
Illustration of the five study protocols. A, Mesially inclined canine with activation of 0.25 mm; B, Upright canine with activation of 0.25 mm distalization; C, Upright canine with activation of 0.25 mm distalization and 2° antitipping design; D, Distally inclined canine with activation of 0.25 mm distalization; E, Distally inclined canine with activation of 0.25 mm distalization and 2° antitipping design. CA, clear aligner.
Figure 2
Figure 2
Measurement and design device. A, The computer linked with the measurement system. B, The force/moment measuring system. C, The digital software used to design study protocols. D, The force data collected in the computer.
Figure 3
Figure 3
Setting up of the teeth and aligner inserted onto the force/moment sensor. A, Sagittal view. B, Lingual view.
Figure 4
Figure 4
Force diagram of canines with mesially or distally inclined during canine distalization. A, From sagittal view, the distalization force applied on mesially inclined canine was decomposed into a distal force and an extrusive force. B, From occlusional view, the distalization force applied on mesially inclined canine was decomposed into a distal force and a lingual force. C, From coronal view, the mesially inclined canine was subjected to a lingual force. Likewise, D–F illustrate force analysis of distally inclined canine.
See this image and copyright information in PMC

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