1338 Indirect Cytotoxicity Of An In-Office Bleaching Agent

Saturday, March 24, 2012: 9:45 a.m. - 11 a.m.
Presentation Type: Poster Session
D.G.S. SOARES, UNESP, Araraquara, São Paulo, Brazil, A.P. RIBEIRO, Department of Dental Materials and Prosthodontics, Universidade Est. Paulista Julio Mesquita, Araraquara, Brazil, F.S. VARGAS, Pathology and Physiology, UNESP, ARARAQUARA, São Paulo, Brazil, J. HEBLING, Dept. de Clinica Infantil, UNESP-Univ Estadual Paulista, Araraquara School of Dentistry, Araraquara Sao Paulo, Brazil, and C.A. DE SOUZA COSTA, Department of Physiology and Pathology, UNESP - Univ. Estadual Paulista, Araraquara, Brazil
Objectives: To evaluate the trans-enamel and trans-dentinal cytotoxic effects caused by a bleaching agent with 35% of hydrogen peroxide (H2O2) (Whiteness-HP, FGM, Brazil) to cultured MDPC-23 odontoblast-like cells after different periods of application on enamel surface. Methods: Enamel/dentin discs were individually adapted to artificial pulp chambers. The following groups were evaluated: G1 – control group (no treatment); G2 and G3 – 1 or 3 applications of a 35% H2O2 gel for 15 min., respectively; G4 and G5 – 1 or 3 applications of a 35% H2O2 gel for 5 min., respectively. Cell metabolism was evaluated (MTT assay) after application of the extracts (culture medium plus bleaching gel components that diffused through the enamel/dentin discs) for 60 min. on the previously cultured cells and the data was submitted to statistical analysis (Kruskal-Wallis/Mann-Whitney; a=0.05). Results: The reduction of cell metabolism observed in G2 and G3 was 0.3% and 30.4%, respectively. In G4 and G5 the cell metabolism increased by 18.3% and 6.3%, respectively. Considering G1 (control group) as 100% of cell metabolism, statistical difference was observed only between G1 and G3 (p<0.05). Time and frequency of application of the bleaching agent with 35% H2O2 used in this in vitro study was directly related to the metabolism of the MDPC-23 cells. Conclusion: The bleaching agent with 35% of H2O2 applied for 45 min. on enamel caused moderate indirect cytotoxicity to the cultured cells. On the other hand, the same dental product increased the MDPC-23 cell metabolism when applied for 5 min.
This abstract is based on research that was funded entirely or partially by an outside source: FAPESP grant # 2009/54315-7

Keywords: Biocompatibility, Bleach, Cell culture, Odontoblasts and Teeth