A scanning electron microscopy evaluation of different root canal irrigating solutions.

The efficacy of solutions to remove the smear layer from human teeth was evaluated. One and 2.5% sodium hypochlorite, 1 and 5% calcium hydroxide, 0.2% (solution) and 2% (gel) chlorhexidine gluconate, 1% tea and distilled water as control were assessed. Fifty-six freshly extracted permanent human incisors were selected. Access cavities, conductometric measurements and apical sealing with wax were performed. Root canals were instrumented up to a #40 file at the apical level and with the step-back technique up to #60 file and irrigated with 25 ml of each solution. Roots were longitudinally cut and cleaning of dentinal walls in the coronal, middle and apical thirds was evaluated by scanning electron microscopy. The ANOVA test showed no statistically significant differences between the thirds treated with the same solution (p = 0.562), but showed differences between solutions (p = 0). Although none of the solutions showed complete elimination of the smear layer, sodium hyplochlorite solutions were the most efficientfollowed by calcium hydroxide solutions and chlorhexidine. Tea and distilled water were less effective.