Three-dimensional finite element study on the effects of maxillary anterior two-step retraction and en-masse retraction with clear aligners.
10.3760/cma.j.cn112144-20221222-00628
- VernacularTitle:无托槽隐形矫治上颌前牙分步内收和整体内收的三维有限元分析
- Author:
Xin Yue TANG
1
;
Min Yi XU
2
;
Ying Jie HUA
2
;
Yu Yang WANG
2
;
Ting JIANG
1
;
Guo Hua TANG
1
Author Information
1. Department of Orthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine & College of Stomatology, Shanghai Jiao Tong University & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai 200011, China.
2. Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
- Publication Type:Journal Article
- From:
Chinese Journal of Stomatology
2023;58(7):670-676
- CountryChina
- Language:Chinese
-
Abstract:
Objective: To investigate the effects of two-step retraction and en-masse retraction on tooth movement pattern of anterior teeth and posterior anchorage with clear aligners using three-dimensional finite element analysis. Methods: A finite element model of maxillary first premolar extraction case undergoing clear aligner treatment was established based on maxillofacial cone-beam CT data of a 24-year-old adult male with individual normal occlusion, who visited Department of Oral Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine for impacted mandibular third molar in June, 2022. The initial tooth displacement of five anterior retraction protocols (two-step with canine retraction, two-step with incisor bodily retraction, two-step with incisor retraction-overtreatment, en-masse bodily retraction, and en-masse retraction-overtreatment) were evaluated. Results: Two step with canine retraction caused distal tipping of the canine and labial tipping of the incisors (0.18° for central incisor and 0.13° for lateral incisor). Two step with incisor retraction caused mesial tipping of the canine. In two step with bodily retraction protocol, uncontrolled lingual tipping was found in central incisor (0.29°) and lateral incisor (0.32°). In two-step with incisor retraction-overtreatment protocol, the movement pattern of the incisors didn't change, but the inclinations reduced to 0.21° and 0.18°. En-masse retraction caused distal tipping of the canine. In en-masse bodily retraction protocol, uncontrolled lingual tipping was also found in central incisor (0.19°) and lateral incisor (0.27°). In en-masse retraction-overtreatment protocol, the central incisor showed controlled lingual tipping (0.02°) and the lateral incisor showed palatal root movement (0.03° labial inclination). Posterior teeth exhibited mesial tipping in all five protocols. Conclusion: En-masse retraction with incisor overtreatment was beneficial to incisor torque control in clear aligner treatment.
