Effects of Different Irrigants on Dentine Hardness

Objectives: The aim of this study was to investigate the effect of different irrigants on dentine hardness. The null hypothesis is that there is no significant effect of irrigants on the hardness of the dentine and that there is no significant changes in the surface hardness of the dentine. Methods: Forty anterior and posterior teeth were randomly selected. Two irrigation solutions were used in this experiment: 5.25% sodium hypochlorite and 2.0% chlorhexidine digluconate. The root of each tooth was sectioned horizontally into three parts; cervical, middle and apical using a water-cooled low speed diamond wheel saw. A 3 ml syringe with a 27-gauge needle was used for irrigation. The irrigant was left for 1 hr and then flushed with sterile water. Microhardness was measured using a Wallace hardness instrument, before and after the application of each irrigant. The hardness of specimens irrigated with 5.25% sodium hypochlorite was statistically significantly different in the cervical and middle root dentine sections, but not in the apical sections. Results: In specimens that were irrigated with 2% chlorhexidine digluconate there was no statistically significant difference in hardness in any section. Conclusions: Sodium hypochlorite was found to reduce the microhardness of dentine in the cervical and the middle aspects of the root canal.