第二恒磨牙龋与第一恒磨牙龋构成比随年龄增长而上升。
The composition ratio of first and second permanent molars caries increased with the age increasing.
结果保存修复的成功率下颌第一恒磨牙为94％，第二恒磨牙为67％。
Results The successful rate of conservative prosthetics was 94% in the first mandibular molars, while 67% in the second molars.
目的了解下颌第二恒磨牙不同载荷下近中移动时的位移及应力分布情况。
Objective To investigate the displacements and the stress distributions of a mandibular second molar.
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