Vital Pulpotomy in Young Permanent Monkey Teeth with Open Apices

用氢氧化钙预备未发育的猴恒牙行切牙术。在术后愈合过程中，分别于0、6、9、12、24小时检查初始牙本质桥接情况。术后2、3、4、7d光镜、电镜观察。立即用氢氧化钙（Ca(OH)_2）包扎断牙髓后，氢氧化钙产生了一层坏死层，从断牙处顶端延伸到0.5-0.88mm。现实的变化包括细胞细节的丧失，血管充血和频繁的小出血。但是，受影响的地区后来似乎没有扩大。6小时后，在浅牙髓坏死组织内及上方可见少量深嗜酸性小球状体。9小时后，在凝血坏死区和牙髓坏死区出现类似的体。在凝血深层可见大量球状团和电子致密颗粒。球状团簇中的有机基质由细小的针状晶体组成，并在退化的细胞内观察到电子致密的颗粒。此后，聚集发展为粗颗粒，最后形成不规则团块。第7天，成牙细胞样细胞形成混合了细胞成分的胶原纤维牙本质基质。综上所述，本研究结果提示，凝血区、退化细胞区和细胞碎片区在截髓术后初始牙本质桥接中起着重要作用。

The vital undeveloped permanent monkey teeth were prepared for pulpotomy with calcium hydroxide. The initial dentinal bridging during a postoperative healing process was examined at 0,6,9,12,24hr.,2,3,4 and 7days after operation by means of light and electron microscope.Sfter immediately dressing an amputated pulp with Ca(OH)_2, the calcium hydroxide produced a necrotic layer extending to 0.5-0.88mm apically from the amputation site. The ealist changes consisted of loss of cellular detail, engorged blood vessels and frequent small haemorrhages. But, the affected arears later did not appear to extend. After 6 hours, a few of deeply eosinophilic small spherical bodies could be seen in and immediately over the superficial pulp necrotic tissue. After 9 hours, in the necrotic zones of clotted blood and pulp there were similar bodies. Ultrastructurally a number of globular clusters and electron dense granules were observed in the deep layer of clotted blood. The organic matrices in the globular clusters apppeared to be composed of fine needle-like shaped crystals and electron dense granules were also observed within the degenerated cells. Thereafter, gathered togather developing to the gross granules, and finally formed irregulary shaped masses. At 7 days, collagen fibrous dentin matrix mixed with cellular elements was formed by odontoblast-like cells.In conclusin, the results of this study suggested that a zone of clotted blood, degenerated cells and cell fragments had some important role in initial dentinal bridging after pulpotomy.