The purpose of this experiment was to investigate the tissue irritation induced by GP-Solvent, a newly designed solvent for removing the guttapercha point in the root canal. In this study, the degree of inflamatory response in the skin was observed after intradermal injection of “GP-Solvent” and other existing solvents into the dosal skin of guinea pig. The results may be summarized as follows: 1. When Evans blue was used to evaluate the serum protein leakage, it was proved that the increased vascular permeability induced by “GP-Solvent” was comparatively weak, corresponding to 1/2 or less than that of chloroform and xylene. 2. “GP-Solvent” and chloroform were injected into the skin of guinea pigs, and after that, the tissue reactions were observed for 25 days. With both solvents, an ulcer appeared on the injected site after 24 hours, but the one induced by “GP-Solvent” was undoubtedly mild compared to that produced by chloroform. Furthermore, the tissue injury produced by “GP-Solvent” was repaired in a shorter time than that induced by chloroform. From the above results, it was concluded that the tissue irritation of “GP-Solvent” was significantly weaker than that of chloroform.
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