Susceptibility Testing Of The Combination Of Calcium Hydroxide And Dimethyl Sulfoxide Against E.faecalis In Vitro

Objective:To evaluate the antibacterial effect of calcium hydroxide combined with Dimethyl Sulfoxide against E.faecalis in therapy-resistant apical periodentitis and within root canals of teeth with failed root-canal treatment in vitro and the chemical effect after the combination.Method:The checkerboard macrodilution method recommended by the Nation Committee for Clinical Laboratory Standards(NCCLS,USA)was applied to evaluate the antibacterial effect; MICs of calcium hydroxide combined with Dimethyl Sulfoxide were determined by macrodilution method; the FIC index was calculated according to MIC results. And the pH values of combinants were measured. Results: The MIC of calcium hydroxide was reduced when combined with Dimethyl Sulfoxide. FICI=0.8,after the combination. FICI=0.35, with hydroxyl ions taken into account. The MIC of calcium hydroxide against E.faecalis was 3.5mg/ml (pH=10.03), MBC=4.5mg/ml (pH= 11.05); MIC of Dimethyl Sulfoxide against E.faecalis was 20% (pH=7.50), MBC=40% (pH=8.20). The pH value of calcium hydroxide combined with 10% Dimethyl Sulfoxide or 30% Dimethyl Sulfoxide increases compared with the pH value of calcium hydroxide combined with distilled water(P<0.05). Conclusion: Synergitic and additive interactions existed between calcium hydroxide and Dimethyl Sulfoxide Against E.faecalis without antagonism in vitro.Aqueous dimethyl sulfoxide does not decrease the pH value of calcium hydroxide.