The overall study of the pulp and periodontal ligament of replanted tooth - The change of sensory nerve and the development of root end filling material -

在间脑的腹后内侧核（VPM）、丘脑后群（PO）和齿状回（ZI）记录到对牙齿、口腔粘膜或面部皮肤伤害性刺激产生反应的伤害性感受神经元。这些神经元分为低阈值机械感受神经元、宽动态范围神经元和伤害感受特异性神经元。这些伤害性感受神经元在核内和核间的功能分离不明显，在三叉神经尾侧核和延髓网状亚核也有伤害性感受神经元的记录。这些神经元根据它们的反应模式分为三组，（1）潜伏期小于30毫秒的神经元，（2）潜伏期大于30毫秒的神经元和（3）潜伏期均小于30毫秒的神经元。伤害感受神经元均表现出上述反应模式，但低阈值机械感受（LTM）神经元的反应模式为（1），提示A纤维传入。结果表明，实验用植骨石膏为半水磷酸钙。实验植骨石膏的砷浓度低于检测限（0.2ppm），低于其他材料，并在再植大鼠切牙根尖周部进行生物相容性测试。对照组采用增强丁香酚水门汀作为根端充填材料。骨水泥在术后4周才被吸收，术后4周仍观察到炎症。实验组用实验植骨石膏作为根端充填材料。实验性植骨石膏术后2周吸收，术后4周炎症消退。

The nociceptive neurons responding to noxious stimuli of the tooth, oral mucous or facial skin were recorded in the ventral posteromedial nucleus (VPM), and the posterior thalamic group (PO) and the zona incerta (ZI) in the diencephalon. These neurons were classified into the low threshold mechanoreceptive neurons, wide dynamic range neurons and nociceptive-specific neurons. Functional segregation of these nociceptive neurons was not apparent within the nucleus or between nuclei.The nociceptive neurons are also recorded at the trigeminal caudal nucleus and the reticular subnuclei in the medulla oblongata. These nurons were divided into three groups depending their response pattern, (1) neurons with a latency of less than 30 msec, (2) those with a latency of more than 30 msec and (3) those with both latency. The nociceptive neurones showed all these response pattern, but the low threshold mechanoreceptive (LTM) neurons responded with the pattern of (1) suggesting the input from A-fiber.The composition and properties of experimental and commercial bone grafting gypsum was evaluated. The experimental bone grafting gypsum was revealed that was calcium phosphate hemihydrate. The arsenic concentration of experimental bone grafting gypsum was under the detection limit (0.2 ppm) and lower level than the other materials.The biocompatibility of the experimental bone grafting gypsum was tested at the periapical portion of the replanted rat incisor. In the control group, the reinforced eugenol cement was filled as root end filling material. The cement was not absorbed until four weeks after operation and the inflammation was still observed until four weeks after operation. In the experimental group, the experimental bone grafting gypsum was filled as root end filling material. The experimental bone grafting gypsum was absorbed until two weeks after operation and the inflammation went out until four weeks after operation.