MTA를 이용한 직접치수복조술과 치수절단술 후 형성된 수복상아질의 조직학적 연구

Abstract

Regenerative pulp treatment include two therapeutic approaches: indirect pulp capping in cases of deep dentinal cavities and direct pulp capping/pulpotomy in cases of pulp exposures. The ultimate goal of a regenerative pulp treatment strategy is to reconstitute normal tissue continuum at the pulp-dentin border, regulating tissue-specific processes of reparative dentinogenesis. However, little is known about the molecular mechanism of reparative dentinogenesis. The purpose of this study was to investigate the pulpal response of dog's teeth after direct pulp capping and pulpo- tomy with mineral trioxide aggregate (MTA). Twelve teeth were treated with MTA. The animals were sacrificed and specimens were removed and prepared for histological analysis. All sections were histologically examined at 1 week, 2 weeks, and 4 weeks after treatment. The expression of dentin sialoprotein (DSP) and bone sialoprotein (BSP) was also observed in all sections by immunohistochemistry. The results were as follows; 1. There were continuous reparative dentin bridge formation at 2 weeks after treatment with MTA without inflammation and tissue necrosis in both pulp capping and pulpotomy group. 2. The cells in pulp capping group showed typical odontoblast characteristics, while the cells of reparative dentin in pulpotomy group were round in shape, lost their polarity, organized as a sheet of cells, and trapped in osteodentin- like mineralized tissue. 3. In pulp capping group, upper layer of the reparative dentin showed cell lacunae indicating osteoblastic characteristics, whereas lower layer of the reparative dentin contained predentin and dentinal tubule-like structures as normal dentin. However, there was osteodentin formation in pulpotomy group. 4. DSP protein was expressed at 4 weeks in odontoblasts of pulp capping group, while BSP was expressed at 4 weeks after pulpotomy. Interestingly, there were transient co-expression of BSP and DSP protein in differentiating cells around the dentinal chip at 2 weeks after pulp capping. These results suggest that two different types of reparative dentin formation, dentin-like and bone-like dentin, maybe depend, partly at least, on the type and extent of the injury and the effect of the associated defense reaction on the structural and functional integrity at the dentin-pulp border. Key words: pulp capping, pulpotomy, MTA, reparative dentin, DSP, BSP