Hybrid-type artificial root of tooth with cementum and periodontal ligament

本研究的目的是延长再植牙裸露牙根的再生。将经三步层析法部分纯化的牛骨形态发生蛋白（BMP）与流式细胞术（FCM）结合。Beagle犬的前磨牙在根管治疗后小心地被拔除。在再植前，部分去除PL和牙骨质，用FCM/BMP覆盖根面牙本质裸露区。在一组中，去除了根表面的顶半区域，而在另一组中，去除了根中部周围的带状区域。6周后，在带状缺损中，在新形成的牙骨质和牙槽骨之间组织学上观察到特征性的垂直胶原纤维，其频率约为治疗根的75%。但在根尖半缺损中，这种情况发生的频率低于30%，主要是引起牙根的强直和吸收。对照组无缺损再植牙基本恢复到原始PL状态，而无FCM/BMP的脱髓牙无论是根尖半型还是带状型，均以强直和吸收为主。结论：再植牙牙周膜和牙骨质的带状缺损是BMP应用于组织工程牙周再生定量研究的一个有用的系统。

The aim of this study is to extend the regeneration in the denuded roots of replanted teeth. Bovine BMP partially purified by three-step chromatography was combined with FCM as reported (FCM/BMP). Premolars of beagle dogs were carefully extracted after their root canals were treated. Before replantation, their PL and cementum were partially removed and the denuded areas of root dentin were covered with FCM/BMP.Removal of the PL and cementum was done in two ways. In one group, the apical half area of the root surface, and in the other, a belt-type area around the middle part of the root, were removed. After 6 weeks, in the belt-type defects, characteristic perpendicular collagen fibers were histologially observed between the newly formed cementum and alveolar bone, with a frequency of about 75% of the treated roots. Butin the apical-half defects this occured with less than 30% frequency, mostlyinducing ankylosis and resorption of roots. The control replanted teeth without defects recovered almost to be original PL states, while in the denuded teeth without FCM/BMP,either in the apical-half or belt-type, ankylosis andresorption were dominant. It was concluded that the belt-type defect of PL and cementum in the replanted tooth is a useful system for quantitative studies of periodontal regeneration by BMP-applied tissue engineering.