Serious tooth defect which involved cuspid, incisal Angle, marginal ridge and occlusal surface can't be filled and need occlusal reconstruction.
各种严重的牙体缺损已涉及牙尖、切角、边缘嵴以及合面，需要咬合重建而不能使用一般充填修复者。
2
An alternative rest-seat preparation, on the marginal ridge of the canine crown, conserves tooth structure and provides a rest seat of adequate length and depth to ensure support for a cast framework.