Takeda Y, Kuroda M, Amari E, Yanagisawa T
Int J Oral Maxillofac Surg. 1987 Jun;16(3):376-82. doi: 10.1016/s0901-5027(87)80163-7.
Complete absence of root formation of the upper incisors, canine and first premolar was reported in a 27-year-old female who had received radiation therapy for a retinal glioma of the right eye at age of 3 years 1 month. Ground and decalcified sections showed no remarkable changes in enamel and dentin of the crowns, but the pulp floor was closed by irregular dentin deposit despite the absence of root formation. The outer surface of the irregular dentin was covered by acellular cementum, and the periodontal membrane was undeveloped. A slight degree of fibrosis was seen in the pulp, but the coronal part of the dentin was lined by odontoblasts. The theory that tooth eruption is caused by the growth of the root is not substantiated by the observation in this case.
据报道，一名27岁女性的上颌切牙、尖牙和第一前磨牙完全没有牙根形成。该女性在3岁1个月时因右眼视网膜胶质瘤接受了放射治疗。磨片和脱钙切片显示，牙冠的釉质和牙本质没有明显变化，但尽管没有牙根形成，牙髓底部却被不规则的牙本质沉积封闭。不规则牙本质的外表面覆盖有无细胞牙骨质，牙周膜未发育。牙髓中可见轻度纤维化，但牙本质的冠部由成牙本质细胞排列。在该病例中的观察结果并未证实牙根生长导致牙齿萌出这一理论。
