Effect of osseous ankylosis in immature permanent teeth on jaw development (dynamics of periodontal membrane collagen fibers)

为探讨未成年恒牙骨性强直对牙齿萌出的影响，对10只幼犬的右上第一、第二切牙进行再植实验。将实验牙齿取出，从整个圆周上剥离牙周膜后，将它们浸入2%酸化磷酸盐氟化钠溶液中20 min。去除牙髓后，通过将氢氧化钙施加到根管中并再植牙齿来实验性地诱导未成熟牙齿的强直，临床观察发现，实验牙有内翻和磨耗，且牙根发育不全的第二切牙比第一切牙更明显。从再植后6周开始，可以在标准化X线片上对骨强直进行评级。从再植后6周起，实验牙的活动度最小 关于我们 组织病理学检查证实所有实验牙均发生骨性关节强直，对侧牙周膜胶原纤维的走行消失。骨强直被证实包括一种类型，其中根牙本质被吸收，并迅速进展，和一种类型，其中强直被观察到，但不伴有快速根吸收。实验牙的牙槽嵴低于对照牙，实验牙唇侧颈部附近的牙槽骨比对照侧凹陷。由于关节强直的进展，牙槽间隔增宽，中央小梁稀疏。在实验侧，指示骨形成的荧光提取区域比对照侧宽，并且相对荧光强度更高。这种变化在再植后的前3周更为显著，并且牙颈部侧的相对荧光强度值更高，但在再植后12周观察到接近对照侧的趋势。结果表明，在发育期发生的骨性关节强直，由于缺乏牙周膜，抑制了牙齿萌出，抑制了颌骨向唇侧和垂直方向的发育。少

In order to elucidate the effect of osseous ankylosis of immature permanent teeth on tooth eruption, we conducted a replantation experiment on the right upper first and second incisors of 10 juvenile dogs. The experimental teeth were removed, and after detaching the periodontal ligament from the entire circumference, they were immersed in 2% acidulated phosphate sodium fluoride solution for 20 min. After removing the pulp, ankylosis was experimentally induced in the immature teeth by applying calcium hydroxide to the root canal and replanting the teeth, and the teeth were compared with the healthy opposite side.The clinical evaluation revealed infraversion and attrition of the experimental teeth, and they were more marked in the second incisor, whose root is immature, than in the first incisor. It was possible to rate the bony ankylosis on standardized X-ray films beginning 6 weeks after replantation. From 6 weeks after replantation onward the mobility of the experimental teeth was les … More s than that of the control teeth, and a metallic sound was confirmed by percussion.We confirmed the development of osseous ankylosis in all of the experimental teeth by histopathological evaluation, and the coursing of the periodontal ligament collagen fibers seen on the opposite side was absent. The osseous ankylosis was confirmed to consist of a type in which the root dentin is resorbed and which rapidly progresses, and a type in which ankylosis is observed but is not accompanied by rapid root resorption. The alveolar crest was lower in the experimental teeth than in the control teeth, and the alveolar bone in the vicinity of the necks of the experimental teeth on the labial side was more concave than on the control side. The septum interalveolare widened as a result of progression of the ankylosis, and the central trabecula had rarified. On the experimental side the fluorescence extraction region, which indicates bone formation, was wider than on the control side, and relative fluorescence intensity was higher. This change was more marked in the first 3 weeks after replantation, and the relative fluorescence intensity values were higher on the tooth neck side, but at 12 weeks after replantation a tendency to approach the control side was observed. The median palatine suture was interposed, and bony ankylosis of the experimental teeth seldom affected the opposite side.The above findings suggested that osseous ankylosis that occurs in the developmental period inhibits tooth eruption because of the lack of a periodontal ligament and that it inhibits development of the jaw in the labial and vertical direction. Less