The effects of differential torque of maxillary posterior teeth with clear aligner of tooth extraction correc-tion on anterior teeth 3D mechanics in vitro
10.3969/j.issn.1001-3733.2025.01.017
- VernacularTitle:无托槽隐形拔牙矫治上颌后牙不同转矩对前牙三维力学影响的体外实验
- Author:
Yongjie FAN
1
;
Junting WEI
;
Bingle WANG
;
Gang WU
;
Sensen YANG
;
Xingxing WANG
Author Information
1. 014030 包头,内蒙古医科大学第四附属医院正畸科
- Publication Type:Journal Article
- Keywords:
Clear aligner;
Torque of posterior teeth;
3D mechanics of anterior teeth
- From:
Journal of Practical Stomatology
2025;41(1):104-109
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the effects of differential torque of maxillary posterior teeth with clear aligner on anterior teeth 3D mechanics.Methods:4 maxillary models were designed for differential torque of posterior teeth on the basis of 3D me-chanical test model with first premolar extraction.The stereolithography models were made with the same size as the standard model by 3D printing.According to the torque of the 6 keys to normal occlusion of Andrews,the standard torque of Andrews was used in group A1.The posterior teeth with lingual-crown torque of 5° were used in groups A2,and those with buccal-crown torque of 5° and 10° were respecitvely used in group A3 and A4.4 sets of corresponding clear aligners were fabricated with a 0.75 mm thick thermoplastic material.Each group had 12 pairs of the same clear aligners.The anterior teeth underwent 0.25 mm activation for en-mass retraction.The six-axis force/torque transducer measurement system was used to measure the force applied by the clear align-ers on the anterior teeth in the 3D directions.Results:In buccolingual direction:in group A1,the 4 incisors received lingual force,in groups A2-A4,the anterior teeth received labial force,and the force on the central incisors was greater than that on later-al incisors.In mesiodistal direction:in group A1-A4,4 incisors received mesial force,and the force on lateral incisors was greater than that on central incisors;in group A1-A4,the canines received distal force;the force on canine in group A4 was greater than that in A2 or A3 groups(P＜0.05).The force in the vertical direction on the anterior teeth among the 4 groups(P＞0.05).Conclu-sion:When en-mass retraction of the anterior teeth with clear aligner,attention should be taken to the torque of the incisors and the tip of the canines.When the posterior teeth with standard torque,the activation of labial-crown overcorrection of the anterior teeth should be increased.When the posterior teeth with lingual-crown torque or buccal-crown torque,the activation of labial-crown over-correction of the anterior teeth should be appropriately reduced.Increasing the mesial overcorrection design of canines may avoid the extrusion of anterior teeth and the deepening of o-verbite due to the distal inclination of canines.
