Mouse Subcutaneous Tissue Reaction to Calcium Hydroxide-based Root Canal Filling Material

Abstract

Mouse subcutaneous tissue reaction to an embedded calcium hydroxide-based root canal filling material was analyzed histopathologically. After the material was placed within the mouse dorsal subcutaneous tissues, we performed examinations using histopathological, histochemical and immunohistochemical techniques. Two weeks after embedment, the proliferation of granulation tissue had already begun to surround the calcification. Most of the cells observed were macrophages. Likewise, multinucleated giant cells increased significantly. The multinucleated giant cells were observed as two types. In one, the centers of the giant cells were vacuoles, while in the others there were deeply stained calcifications with hematoxylin. Twelve weeks after embedment of the materials, further growth of multinucleated giants cells were sighted. Histochemically, von Kossa-stainpositive granules were observed within the macrophages and multinucleated giant cells as black fine granules. According to the TRAP stained specimens, the multinucleated giant cells especially reacted strongly at 4 weeks. However, the reaction became very weak at 12 weeks. CD68 immunohistochemical staining showed positive reactions in the cytoplasm of the proliferating macrophages and multinucleated giant cells. These results suggest that multinucleated giant cells are present in the surrounding tissues due to implantation of the calcium hydroxidebased root canal filling material, and that the presence of ACP in the cells is due to ingested calcium during active phagocytosis, which would disappear later on.

Reactions of the Dentin-Pulp Complex to Calcium Hydroxide Paste in Rats

“…Regarding the small vacuole-like structures in the pulp, these were probably derived from the silicone oil which is the basic component of Vitapex. The same description was mentioned in a study where a similar material was implanted in the subcutaneous tissue 18) . In addition, irregular bone-like dentin was formed due to the formation of large amount of dentin in a very short period of time.…”

“…The present study examined the subsequent tissue reactions in dentin-pulp complex following the direct application of Vitapex®. As previously mentioned [13][14][15][16][17][18] , Vitapex is a root canal filling material dispense in a syringe and mainly consists of calcium hydroxide. It became popular since it is convenient to use (no kneading required) and offers favorable results.…”