Conclusion When M/F is about 8 and two equal forces are added on both buccal and palatal sides, there are the uniform stress in the molar and controlled translatory movement.

• 结论下颌第二恒磨牙近中移动时，颊舌侧同时加力并且施加适当的近远中向的力矩，有利于牙齿的整体平行移动。