Diffusion of hydroxyl ion on external root surface using different irrigating solutions: An In vitro study

The aim of this study was to evaluate the diffusion of hydroxyl ion to the external root surface using different irrigating solutions and intracanal medication with calcium hydroxide.

Sixty bovine tooth roots were randomly divided into six experimental groups (n = 10), according to the irrigating substance used during biomechanical preparation: 12% glycolic propolis extract (PROP); 20% glycolic ginger extract (GENG); 2% sodium hypochlorite with surfactant (NaOClS); 2% chlorhexidine gel (CLX); 2.5% sodium hypochlorite (NaOCl); and physiological saline solution. After filling the root canals with calcium hydroxide paste, pH measurements were taken directly at the external cavities over time intervals of up to 30 days.

Data were submitted to two-way ANOVA and Tukey's test (P < 0.05).

The pH of the external root surface was increased when the surfactant associated with NaOCl was used. However, the pH values were very close for the different groups. Hydroxyl ion diffusion up to the external root surface did not exceed the pH value of 8.5, and in the hollow passage of the canal, the pH was higher than 12.

Hydroxyl ion diffusion of calcium hydroxide paste through the dentinal tubules up to the external root surface allows minimal alkalinization of this surface, and it is greater when using NaOCl with surfactant during biomechanical preparation.