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(4) 根据牙齿X线片推断年龄:Demirjian et al(1973)根据上颌左侧7颗牙齿的X线片,进行年龄推断。其方法: ①拍摄上颌左侧七颗牙的X线片; ②根据分级标准,对X线片上的每个牙齿进行分级。其分级标准如下: A、在齿槽中,可见牙尖的钙化点,但尚未融合; B、牙尖钙化点融合,形成一个闭合的表面; C、牙冠表面形成完整的釉质,或闭合式的髓腔已经形成; D、牙冠完全形成,已向下达到釉牙骨质界,或髓腔下缘达到牙颈部,并出现髓角,外观呈伞状,或开始形成针状牙根; E、单根牙:髓室壁呈直线状,出现髓角顶,而呈转折状,髓角比以前大,或牙根长度小于牙冠长度; 磨牙:根分叉开始形成,或呈点状钙化或呈新月
(4) Extrapolating age from dental radiographs: Demirjian et al. (1973) deduced age based on the radiographs of the seven maxillary left teeth. The method: ① shoot the left upper seven teeth X-ray film; ② according to the grading standards, each tooth on the X-ray film grading. The grading standards are as follows: A, in the alveolus, showing the calcification of the cusp point, but not yet fusion; B, cusp calcification point fusion to form a closed surface; C, the formation of a complete enamel crown surface, or closed Of the medullary cavity has been formed; D, the crown is completely formed, has reached the lower enamel cementum, or the lower edge of the medullary cavity reached the cervical, and appear medulla, the appearance of umbrella, or began to form acicular roots; E, a single tooth: the medullary wall was linear, the top of the medulla there, and was turning, the marrow larger than before, or the length of the root is less than the length of the tooth crown; molars: root furcation began to form, Or crescent