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. S tudy design. Standardized voids of 0.50 and 0.22 mm in diameter were c reated in 60 human roots: specimens were divided into five groups. Fou r groups were subjected to a 2% filtered aqueous methylene blue dye so lution under different conditions of atmospheric pressure for 7 days a nd reduced pressures of a 10 torr, a 260 torr, and a 510 torr for 30 m inutes. The conditions for the fifth group were similar to the last gr oup except that ethyl alcohol was substituted for water in the dye. Re sults. All positive control specimens showed complete dye penetration. The least linear dye penetration was observed in passively immersed s pecimens. The results were significantly different from those when red uced pressure had been used (p < 0.001). There were no significant dif ferences among the groups with reduced pressure. No significant differ ence was found at any pressure level between the means of dye diffusio n 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 b y the group of the least reduced pressure of 510 torr, with the use of the tincture dye solution. Conclusions. A 10-torr reduced pressure an d an application of the tincture dye solution would provide an improve d method for microleakage studies.