Actual contribution ratio of maxillary and mandibular molars for total molar relationship correction during maxillary molar sequential distalization using clear aligners with Class II elastics: A finite element analysis

作者：Xulin Liu, Zhiyuan Wang, Jie Gao, Wen Qin, Yi Wen, Houzhuo Luo, Yanning Ma, Zuolin Jin · 发表于：American Journal of Orthodontics and Dentofacial Orthopedics · 年份：2023 · DOI：10.1016/j.ajodo.2023.07.007 · 被引用次数：26 · 研究领域：Orthodontics and Dentofacial Orthopedics、Dental Implant Techniques and Outcomes、Temporomandibular Joint Disorders

INTRODUCTION: Class II elastics, in combination with clear aligners (CA), are efficient for molar distalization. However, the effects of this combination on intermaxillary molar relationship correction have yet to be investigated. This study aimed to investigate the actual contribution ratio of the maxillary and mandibular molars for total molar relationship correction during maxillary molar distalization using Class II elastics with CA and further explore therapeutic recommendations for clinical practice. METHODS: Finite element models (FEMs) were established, including the distalization of the second molars (Set I), followed by the distalization of the first molars (Set II). Model A simulated elastics attached by precision cutting, whereas Model B simulated elastics attached to buttons. Force magnitudes of 100 g, 150 g, and 200 g of force were applied. We recorded the contribution ratio of the maxillary and mandibular molars for total molar relationship correction, effective distalizing distance in 0.25 mm step distance, tipping and rotation angles, and the hydrostatic stress in the periodontal ligament. RESULTS: During maxillary molar distalization, mesialization of the mandibular molar had a notable contribution ratio for molar relationship correction. The mandibular first molar was mesialized with mesiolingual rotation tendency. Approximately half of the 0.25 mm step distance was occupied by maxillary molar distalization; the remainder was occupied by anchorage teeth mes...