Effect of reduced air pressure on dye penetration in standardized voids

Objective. This study determined the correlation between the degree of dye penetration in standardized voids to various reduced pressures. Study design. Standardized voids of 0.50 and 0.22 mm in diameter were created in 60 human roots: specimens were divided into five groups. Four groups were subjected to a 2% filtered aqueous methylene blue dye solution under different conditions of atmospheric pressure for 7 days and reduced pressures of a 10 torr, a 260 torr, and a 510 torr for 30 minutes. The conditions for the fifth group were similar to the last group except that ethyl alcohol was substituted for water in the dye. Results. All positive control specimens showed complete dye penetration. The least linear dye penetration was observed in passively immersed specimens. The results were significantly different from those when reduced pressure had been used (p < 0.001). There were no significant differences among the groups with reduced pressure. No significant difference was found at any pressure level between the means of dye diffusion in the 0.50 and the 0.22 mm voids. The smallest standard deviations were observed for the most reduced air pressure of 10 torr, followed by the group of the least reduced pressure of 510 torr, with the use of the tincture dye solution. Conclusions. A 10-torr reduced pressure and an application of the tincture dye solution would provide an improved method for microleakage studies.