An Experimental Study of the Periapical Healing after Apexification on the Immature Pulpless Teeth

对根尖诱导成形术后根尖周伤口愈合情况进行组织学评价。本研究对3只4岁左右的食蟹幼猴的健康恒牙进行了研究。在全身和局部麻醉下，用橡胶坝隔离牙齿，然后拔除冠髓。用高频电灼凝残根髓，随机分为感染组和非感染组，1周后开始感染根管治疗，根管消毒后用氢氧化钙或FR-Ca糊剂充填根管。实验结束后1个月、3个月、5个月，用中性福尔马林灌流处死动物。制备脱钙石蜡切片，苏木精-伊红染色，光镜下观察，结果如下：1.与电极接触的牙髓组织凝结，但在距离其一定距离处仍有活体牙髓组织存在。根管壁较薄的未成熟牙的牙周韧带和牙槽骨内可见根尖温度升高引起的灼伤，可见牙根外吸收和/或与骨性强直。非感染组氢氧化钙根管引流术后，根尖区可见严重的骨性牙本质填充根管间隙。观察到骨性牙本质牙根的持续发育，但出现根尖的异常形成和严重的根管钙化。这些结果将与感染组进行比较，细节有待进一步调查。

Periapical wound healing after apexification on immatured non-vital permanent teeth with bulunderbass canals were evaluated histologically. This investigation was undertaken on sound permanent teeth in three crab-eating young mondeys aged four approximately.Under general and local anesthesia, access openings of the teeth were performed with rubber-dam isolation, then the coronal pulps were extirpated. Remnant root pulps were cauterized and coagulated with high frequency current, and then divided to two groups, one was infected group, and other was non-infected groop.One week later, infected root canal treatment was started, and calcium hydroxide or FR-Ca paste was applicated to the canal after root canal disinfection. At the conclusion of the experimental period, 1,3,5 months, the animals were sacrificed by perfusion with neutral formalin. Decalcified serial paraffin sections were prepared and stained with hematoxylin-eosin, and observed by light microscopy.The results obtained were as follows :1. The pulp tissue which contacted with eletrode was coagulated, but at some distance from it vital pulptissues were still existent in alive.2. The burn caused by a rise in temperature of the root conal was observed in the periodontal ligaments and alveolar bone on the immature tooth with thiner root canal wall, and external root resorption and/or ankylosis with the bone were observed.3. After the apexification with calcium hydroxide on non-infected group, addition of severe osteo-dentin which filled up the canal space was observed at apex area.4. Continual development of the root by osteo-dentin was observed, but abnormal formation of root apex and severe calcified of root canals were appeared.In future, these results will be compared with infected groop, and details will be investigated further.