Studies on the biological responses to mechanical stress on jaw bone and periodontium, and their clinical applications.

为了研究颌骨和牙周组织在机械应力作用下的生物学反应，我们将正畸力施加到牙齿上，以扩大牙周韧带的间隙，从而在移植前方便拔牙和减少牙周韧带的损伤。实验组右上颌磨牙施加正畸力，7d后再植或拔除上颌第二磨牙，14 d后处死再植动物，检查拔除的牙是否附着PDL及根面外露。正畸力施加7 d后，PDL的间隙增大，牙槽槽宽度增大，拔牙根表面附着PDL丰富。在未预施正畸力的对照组中，在恢复后14天，牙根吸收的增强可能与PDL的破坏同时发生。结果提示，在供牙上预施正畸力可增加供牙PDL宽度，使拔牙更加容易，从而抑制再植后牙根吸收。研究了牙合负荷对牙槽骨重建及血管活性肠肽（VIP）和降钙素生成肽（CGRP）免疫反应纤维（IR）分布的影响。第5天，与未咬合组相比，咬合负荷诱导破骨细胞数量和成骨细胞表面显著增加。成骨细胞层旁可见VIP-IR纤维，与未闭塞组相比，闭塞组成骨细胞层旁VIP-IR纤维的分布在第5天明显增强。虽然牙周韧带和牙槽骨尖部对CGRP有免疫反应，但在分节处未检测到CGRP- ir纤维。上述结果提示，大鼠牙齿再植后，咬合负荷诱导破骨细胞和成骨细胞形成增加，VIP可能在成骨细胞中发挥功能作用。少

In order to investigate the biological responses to mechanical stress on jaw bone and periodontium, we aimed to apply the orthodontic force to the teeth in order to enlarge the space of periodontal ligaments (PDL), which may ease extraction and minimize the damage of PDL before transplantation. The orthodontic force was applied to the right upper molars for the experimental group, and after 7days, upper second molars were replanted or extracted, where replanted animals were then sacrificed after 14 days and those extracted teeth were examined for the attached PDL and exposed root surface. The application of orthodontic force for 7 days increased the PDL space and also the width of the alveolar socket, which resulted in the rich attached PDL to the root surface of the extracted teeth. And enhanced root resorption that may have been coincided with the disruption of the PDL was detected in the root of the control group without pre-application of orthodontic force at the 14 days after repl … More antation. These results suggested that the pre-application of orthodontic force to the donor teeth increased the PDL width and ease the extraction, which may inhibit the root resorption after replantation. The influences of occlusal loading on the alveolar bone remodeling and the distribution of vasoactive intestinal peptide (VIP)- and calcitonin generelated peptide (CGRP)-immunoreactive (IR) fibers were investigated after tooth replantation in rats. At day 5, occlusal loading induced a significant increase in osteoclast number and osteoblast surface compared to those in the non-occluded group. VIP-IR fibers were observed beside osteoblastic layers and their distribution was significantly enhanced at day 5 in the occluded group, compared to the non-occluded group. Although there was immunoreactivity for CGRP in the periodontal ligament and alveolar bone apically, CGRP-IR fibers were not detected above the furcation. These results suggest that, after tooth replantation in rats, occlusal loading induced an increase in osteoclast and osteoblast formation, and that VIP might play a functional role in osteoblasts. Less