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1978年Shifman等根据牙齿的测量制定了比较客观的牛牙症诊断标准,即髓室顶的最低点(A)至髓室底最高点(B)的距离,除以A至根尖(C)的距离等于或大于0.2 mm,从B至牙釉质牙骨质界(D)的距离大于2.5 mm时即为牛牙症。牛牙症这种牙齿异常最多见于磨牙,偶尔见于前磨牙。前磨牙牛牙症必须具备以下解剖学特点:①牙颈部轻度缩窄,②具有明显的棱形牙根,牙根的颈部及根尖部变粗,③牙根轻度内陷和髓室及根分叉部膨大。
In 1978, Shifman et al. Developed an objective diagnostic criteria for bovine spondylosis based on measurements of the teeth, that is, the distance from the lowest point on the medullary column (A) to the highest point on the medullary cavity (B), divided by A to apical (C) Is equal to or greater than 0.2 mm, and from B to enamel cementum (D) is greater than 2.5 mm. Dentinosis This type of tooth abnormalities is found most often in molars and occasionally in premolar teeth. Anterior premolars must have the following anatomical features: ① narrow neck and neck dentition, ② have obvious prism root, root and root apical thickening, ③ mild root depression and medullary cavity and Root bifurcation enlargement.