178例儿童埋伏多生牙拔除难度的临床分级

目的： 探讨儿童埋伏多生牙（embedded and multiple teeth in children,EMTC）的拔除难度及方法。方法： 对178例250颗EMTC进行锥形束CT （cone-beam CT,CBCT）检查,根据埋伏多生牙与恒牙的相邻关系分为3型。I型为多生牙位于恒牙的冠端,Ⅱ型为多生牙位于恒牙的体部,Ⅲ型为多生牙位于恒牙的根端。根据埋伏多生牙牙体形态分为2类。A类,与牙冠-根中轴形成的畸形角度<90°,牙体直形畸形;B类,与牙冠-根中轴形成的畸形角度>90°,牙体钩形畸形。根据各型埋伏多生牙的位置和畸形分类、恒牙的发育状态、拔除难度,选择时机拔除。结果： 拔除难度Ⅰ-Ⅱ级为Ⅰ型、Ⅱ型的A类l76颗,在相邻恒牙尚未完全发育时,作即刻拔除。拔除难度Ⅲ级为Ⅱ型A类12颗、Ⅲ型B类62颗,在相邻恒牙基本发育后,作延期拔除。本组EMTC均完全拔除,无相邻恒牙损伤。结论： 根据EMTC的临床位置分型、牙冠-根畸形的临床分类预测拔牙的手术难度分级,具有一定的临床指导意义。

Clinical classification of extraction difficulty for embedded multiple teeth in 178 children

PURPOSE: To investigate the clinical classification of extration difficulty for embedded multiple teeth in children(EMTC). METHODS: Two hundred and fifty teeth of 178 children with embedded multiple teeth were examined by cone-beam CT(CBCT）. According to the relationship between adjacent embedded multiple teeth and permanent teeth, they were divided into 3 types. Type I:embedded multiple teeth located on the crown of permanent teeth; type Ⅱ: embedded multiple teeth located to the body of permanent teeth; type Ⅲ: embedded multiple teeth located to the root apex of the permanent teeth. The embedded multiple teeth were further divided into 2 classes. Class A: the angle of malformation was<90° with the axis of the crown and root, and the tooth was of straight deformity. Class B: the malformation angle was >90° with the crown-root axis, and the tooth was hook-shaped. The embedded multiple teeth were extracted accordingly based on the different type and class. RESULTS: ：One hundred and seventy-six teeth belonging to type Ⅰ, type Ⅱand class A were removed immediately when the adjacent permanent teeth were not fully developed. Twelve teeth belonging to type Ⅱ, class A, and 62 teeth belonging to type Ⅲ and class B were removed secondly when the adjacent permanent teeth were fully developed. All 250 teeth were removed without damage to the adjacent permanent teeth. CONCLUSIONS: This classification based on teeth morphology is of certain clinical usefulness in predicating extraction difficulty and guidance of operation.