Microshear bond strength of self-etching adhesives to caries-affected dentin identified using the dye permeability test.

Abstract

The aim of this study was to compare microshear bond strength (µSBS) of different adhesives to normal dentin (ND) and caries-affected dentin (AD) as differentiated using the dye permeability test. One hundred freshly extracted carious teeth were ground to expose normal and cariesaffected dentin. Differentiation between both substrates was carried out using microhardness and a new dye permeability method. Ground teeth were divided into 5 groups according to the adhesive tested; Clearfil SE Bond (SE), Clearfil DC Bond (DC) (Kuraray), Bond Force (BF) (Tokuyama), AdheseOne (AH) (Ivoclar), Adper Prompt-L-pop (PR) (3M ESPE). Adhesives were applied to selected substrate, and composite cylinders (0.9 mm diameter x 0.7 mm length) were formed. After 24 h, specimens were subjected to microshear testing at a crosshead speed of 0.5 mm/min. Failure modes were determined using a stereomicroscope at 40X magnification. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests. Normal dentin was permeable for the dye, while caries-affected dentin was impermeable. Vickers hardness numbers (VHN) for normal and caries-affected dentin were 63.98 ± 3.24 and 62.40 ± 3.49 respectively, which were not significantly different (p > 0.05). µSBS values were: SE-ND = 22.34 ± 6.4, SE-AD = 18.70 ± 4.0, BF-ND = 24.52 ± 4.9, BF-AD = 18.31 ± 4.9, DC-ND = 24.49 ± 8.0, DC-AD = 18.97 ± 9.4, AH-ND = 17.21 ± 6.8, AH-AD = 17.03 ± 10.3, PR-ND = 13.67 ± 4.4, PR-AD = 7.31 ± 2.4 MPa. A statistically significant difference was found among the adhesive systems to both normal (p < 0.01) and caries-affected dentin (p < 0.001). However, µSBS of SE, DC, and AH adhesives to normal dentin were not significantly different from those of caries-affected dentin (p > 0.05). The permeability test was an effective tool to differentiate between normal and caries-affected dentin. Some adhesive systems showed no significant difference in their bond to normal or affected dentin.