Effect of different tips of posteriors in extraction treatment on three-dimensional forces of teeth with clear aligners
10.13591/j.cnki.kqyx.2023.02.002
- VernacularTitle:无托槽隐形矫治拔牙病例的后牙不同轴倾度对牙齿三维力学影响
- Author:
FAN Yongjie
1
;
KOU Yating
Author Information
1. Department of Stomatology, Fourth Affiliated Hospital of Inner Mongolia Medical University, Baotou 014030, China
- Publication Type:Journal Article
- Keywords:
orthodontics, clear aligner； extraction； tips of posteriors； three-dimensional forces
- From:
STOMATOLOGY
2023;43(2):104-109
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the three-dimensional forces in real-time at different tips of the posteriors created by clear aligners on maxillary teeth during en-masse retraction of anteriors after 2 first premolars extraction treatment.
Methods:Four groups of maxillary models with different tips of posteriors(T1-upright of posteriors, T2-posteriors with distal inclination of 5°, T3-posteriors with mesial inclination of 5°, T4-posteriors with mesial inclination of 10°) undergoing 0.25 mm en-masse retraction treatment using clear aligners were simulated on a multi-axis force/torque transducer measurement system. When each clear aligner was inserted, a computer connected to the transducer collected and recorded the three-dimensional force of every tooth in real-time. Each group included 12 aligners.
Results:Incisors received smaller lingual and extrusive forces; canines received greater distal forces; smaller mesial forces were observed on the posteriors, and molars received greater buccal and extrusive forces in T2,compared with T1,which showed statistically significant differences(P<0.05). Incisors received smaller lingual and extrusive forces; canines received greater distal forces; greater mesial forces were observed on the posteriors, and molars received greater buccal and extrusive forces in T3 and T4,compared with T1,which showed statistically significant differences(P<0.05).
Conclusion:Posteriors with distal inclination contributed to the torque of the anterior and anchorage of posteriors. In group T2 posterior teeth experienced larger buccal forces and extrusive forces than in group T1. When the posteriors crown inclined mesially, the anterior teeth were more prone to lingual tip and caused overbite. The more mesially inclined the posterior teeth were, the more serious overbite was, and the posterior teeth were more prone to anchorage loss.
