Physicochemical properties, cytotoxicity, and penetration into dentinal tubules of calcium hypochlorite with or without surfactants

Abstract

Since the root canal irrigants may contact with the periapical tissues, it should be taken into consideration its possible cytotoxic effects. In addition, the physicochemical properties and the ability to penetrate areas not reached by the instruments are essential for the disinfection of the root canal system. Calcium hypochlorite [Ca(OCl)2] has been suggested as a potential alternative irrigant to sodium hypochlorite (NaOCl). The aim of this study will be to assess the physicochemical properties (part 1), cytotoxicity and effect on the biology of osteoblasts (part 2) and penetration into dentinal tubules (part 3) of Ca(OCl)2 with or without surfactants compared to NaOCl. In part 1, the physicochemical properties of NaOCl and Ca(OCl)2 with or without the surfactants Tween 80 (T80), Triton X-100 (TRX), benzalkonium chloride (BAK) or cetrimide will be evaluated. The pH will be assessed by using digital pH-meter, the surface tension by pendant drop method and the free active chlorine by spectrophotometry. In part 2, L929 fibroblasts or osteoblasts-like Saos2 in culture will be exposed to NaOCl and Ca(OCl)2 in association or not to with surfactants. The cell viability will be evaluated by means of the methyltetrazolium (MTT) and neutral red assays, the cytoskeleton by means of actin labeling, the type of cell death by flow cytometry, the ultrastructure by transmission electron microscopy and the activity of phosphatase alkaline by the calculation of thymolphthalein release. In part 3, single-rooted human teeth will be instrumented, stained with crystal violet and irrigated with NaOCl or Ca(OCl)2 associated or not with surfactants. The penetration into dentin will be evaluated at the cervical, middle and apical thirds. The statistical analysis of the results will be carried out using a significance level of 5%. The statistical tests will be chosen according to the distribution and homoscedasticity of the data. Ultimately, it is our expectation to obtain information to understand more deeply the mechanism of action of Ca(OCl)2 on eukaryotic cells, its physicochemical properties and penetration into dentinal tubules to provide subsidies for its indication or not in the endodontic clinic. (AU)