牙折裂达龈下、或龋坏导致的残根达龈下时,修复常难以进行,残根往往被拔除。然而,若对残根进行完善的根管治疗,再采用一定的方法使牙断缘暴露出来,则残根可以被保留并可进行修复。在暴露残根断缘的方法中,有学者采用牵引方法,将儿童和青少年外伤牙的残根牙缘牵至龈上,但这需要 Dentures subdermal or subgingival, or decay caused by residual subgingival subgingival, often difficult to repair, the root is often removed. However, if the residual root is treated with a sound root canal, and then a certain method is used to expose the broken edge of the tooth, the residual root can be retained and can be repaired. Among the methods of exposing the broken root, some scholars use a traction method to pull the residual tooth edge of children and adolescent traumatic teeth to the gingiva, but this requires