The effect of smear layer removal on permeability of dentinal tubules in human by dye penetration method

The effect of smear layer on dentinal tubules is remarkable in endodontic treatments. The aim of this study was measuring the range of dye penetration in dentinal tubules with and without smear layer.

Thirty extracted human teeth used in this study. At first, segments e prepared with 5 mm length from each tooth's root and then their canals widened by a 1/4 mm diameter bur, so that the smear layer appeared. The external, superior and inferior surfaces of the segments covered by 2 layers of nail varnish. The segments divided to 2 groups of 15 samples. The first group samples immersed in 17% EDTA for 2 minutes and then in 5.25% NaOCl for 20 minutes to remove the smear layer. After that the samples immersed in 2% basic fushin for 24 hours. The second group samples immersed in 2% basic fushin without removing the smear layer. After water rinse,all samples sectioned horizontally from middle of the root and photographs was taken of each samples surfaces. After transmitting the photographs to a computer, the percentage of the dye penetration into dentinal tubules of each sample calculated by Photoshop software.

Due to results, the range of dye penetration in dentine tubules of the teeth with and without smear layer had no statistically significant difference (P-Value=0.120).

According to the result, smear layer removal have no effect on dentin permeability to dye penetration and dentin sclerosis is an important factor in this subject. Performing studies on the teeth with certain age and using other methods such as microbial permeability evaluation are needed.