Holt M H, Nanda R S, Duncanson M G
Department of Orthodontics, College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City.
Am J Orthod Dentofacial Orthop. 1991 Apr;99(4):287-93. doi: 10.1016/0889-5406(91)70010-T.
The purpose of this study was to determine the fracture resistance of commercially available ceramic brackets during arch wire torsion. Lingual root torque was applied at the distal side of upper central incisor brackets with 0.022-inch slots by means of a 0.0215 x 0.028-inch arch wire. A specially designed apparatus was used to test six types of ceramic bracket in sample groups of 30. The amount of torque and degrees of torsional rotation at fracture were measured. The ceramic brackets could be separated into three statistically different groups with mean torques at fracture ranging from 3,706 to 6,177 gm-mm. The mean torsional rotation at fracture ranged from 9.5 degrees to 17.8 degrees. The single-crystal alumina bracket had the most intragroup variation. Eight to ten degrees of torsional rotation of the arch wire produced sufficient orthodontic force to achieve the torque. The fracture resistance of the ceramic brackets appears to be adequate for clinical use. The Starfire, Allure III, and Transcend brackets had the highest fracture resistance values.
本研究的目的是确定市售陶瓷托槽在弓丝扭转过程中的抗断裂性。通过一根0.0215×0.028英寸的弓丝，在上颌中切牙托槽的远中侧施加舌侧根转矩，该托槽带有0.022英寸的槽沟。使用一种专门设计的仪器对6种类型的陶瓷托槽进行测试，每组30个样本。测量了断裂时的转矩量和扭转旋转度数。陶瓷托槽可分为三个统计学上有显著差异的组，断裂时的平均转矩范围为3706至6177克毫米。断裂时的平均扭转旋转度数范围为9.5度至17.8度。单晶氧化铝托槽在组内的变化最大。弓丝扭转8至10度可产生足够的正畸力以实现转矩。陶瓷托槽的抗断裂性似乎足以满足临床使用。Starfire、Allure III和Transcend托槽具有最高的抗断裂性值。
