Original Articles of Invisable Aligner Techniques
Three dimensional evaluation of maxillary molar distal movement using invisible aligners
Jingjing Zhang, Yingying Zhang, Yan Liu
Published 2017-06-20
Cite as Chin J Orthod, 2017, 24(2): 70-78. DOI: 10.3760/cma.j.issn.1674-5760.2017.02.003
Abstract
ObjectiveTo investigate the effects of invisible aligners on distalization of maxillary molars in three-dimensions.
MethodsSeven patients who were prescribed with molar distalization were treated by invisible aligners. Dental casts were taken and the digital models were reconstructed before and after molar distalization. The amount and efficiency of distal movement of the molars, the axis inclination of the molars and the positions of central incisors during distalization were measured by Rapidform 2006 software. And results of different distalization designs were compared.
ResultsThree of seven patients were designed with molar distalization combining vertical rectangular attachments on the buccal surface of upper second premolars, the first molars and the second molars. The mean efficiency of the molar distalization were 98.25%, 90.6% and 94.4%, respectively. Two patients' molar distalization were proceeded without upper third molars extraction, and the mean efficiency of the molar distalization were 66% and 78.95% respectively. One of the patients' molar distalization was designed without attachments on upper second molars and the mean efficiency of the molar distalization were 50.65%. Another patient presented with short crown height and the mean efficiency of the molar distalization was 47.85% with first molars distal tipping. The maxillary central incisors had non-significant labial movement but minor extrusion under Class Ⅱ elastics forces during distalization.
ConclusionsMolar distalization can be achieved effectively with the help of Class Ⅱ elastics by invisible aligners. However, molar tipping may exist especially in cases with short clinical crown. Factors including attachments design, crown height and third molar eruptions may affect the efficiency and molar distalization.
Key words:
Invisible aligners; Molar distalization; Three dimensional evaluation
Contributor Information
Jingjing Zhang
Department of Orthodontics, Peking University, School &
Hospital of Stomatology, Beijing 100081, China (Present address: Department of Orthodontics, Hebei Provincial Eye Hospital, Xingtai 054000)
Yingying Zhang
Department of Orthodontics, Peking University, School &
Hospital of Stomatology, Beijing 100081, China
Yan Liu
Department of Orthodontics, Peking University, School &
Hospital of Stomatology, Beijing 100081, China