Examining the Influence of the Smear layer on Permeability of Dentin Tubules in Human Teeth Using Dye Penetration Method

Abstract

Background and aim: The influence of the smear layer on human dentin tubules has been a considerable issue in endodontic treatments. This study aims to measure the dye penetration depth into dentin tubules in the presence and absence of smear layer.

Materials and methods: Thirty healthy human teeth were used in this experimental study. First, a block with a length and diameter of 5 mm was prepared from the tooth roots. Then, their canals were widened using a burr with 1.4 mm diameter to form the Smear layer. The lateral, upper and lower surfaces of the blocks were coated with 2 layers of nail polish except for the entrance of the canals. Blocks were divided into two groups of 15. Specimens of the first group were placed in %17 EDTA for two minutes and then in 25.5% sodium hypochlorite for 20 minutes to remove the Smear layer. The Smear layer was not removed in the second group. Then, both groups’ specimens were placed in 2% basic Fuchsin dye. After removing the specimens from the dye and washing them in water, they were all divided into two halves by a horizontal cut and images were taken from their upper surface. Images were then transferred to the computer and dye penetration was calculated by the Photoshop program. The results were analyzed using the Mann-Whitney Test.

Results: No significant difference was found in penetration into dentinal tubules in the presence or absence of the Smear layer (p=0.120).

Conclusion: Results of the study showed that removal of the Smear layer has no effect on dentinal penetration depth and dentinal sclerosis plays an important role in this regard. More studies are recommended using other methods such as microbial penetration into the teeth with specific age.