2010 Volume 53 Issue 2 Pages 174-181
The aim of this study was to evaluate the function of Chloramine-T as a root canal irrigant. Varying concentrations of Chloramine-T and hydrogen peroxide (H2O2) were examined for tissue dissolution activity using rat rectus muscles, pH changes, free radical generation by means of electron spin resonance (ESR) spin trapping, tissue damaging activity using rat rectus muscles, and cytotoxicity in cultured human periodontal ligament cells. When 5.0% and 10.0% Chloramine-T or 3.0% H2O2 were applied to rat rectus muscles for 1 hour, the weight of rat rectus muscles decreased. However, the weight of rat rectus muscles was not changed when 0.5% and 1.0% Chloramine-T or 1.0% H2O2 were applied. The pH values of 0, 0.5, 1.0, 5.0 and 10.0% Chloramine-T were 6.22, 6.85, 7.83, 9.33 and 9.97, respectively. When these concentrations of Chloramine-T were applied to rat rectus muscles, each pH changed to 6.30, 7.07, 7.45, 7.52 and 7.51. Also, the pH values of 0, 1.0 and 3.0% H2O2 were 6.22, 5.20 and 4.65, respectively. When H2O2 was applied to rat rectus muscles, each pH changed to 6.54, 6.84 and 6.72. ESR spin trapping revealed that DMPO-X was detected from Chloramine-T in the order of 0.5%>1.0%>5.0%>10.0%>0%, and hydroxyl radical (OH・) was detected from H2O2 in order of 3.0%>1.0%>0%. When Chloramine-T was applied to rat rectus muscles, the DMPO-X signals were diminished. However, the ESR signals showed no changes when H2O2 was applied to the rat rectus muscles. Histological observation of Chloramine-T and H2O2 exposed rat rectus muscles demonstrated atrophy of muscle fibers, dissolution of connective tissues and disappearance of striations in a does-dependent manner. H2O2 caused stronger damages as compared with Chloramine-T. In the cytotoxicity experiments, the survival rate of human periodontal ligament cells decreased in a dose-dependent manner with Chloramine-T and H2O2. The survival rate was 100, 38.5, 33.6, 33.6 and 23.0%, when 0, 0.5, 1.0, 5.0 and 10.0%, respectively, of Chloramine-T was applied. The survival rate with 0, 1.0 and 3.0% H2O2 was 100, 14.9 and 14.7%, respectively. These results suggested that Chloramine-T is a milder root canal irrigant than H2O2.
