Microshear Bond Strength of Self-etching Adhesives to Caries-affected Dentin Identified Using the Dye Permeability Test

Purpose: 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. Materials and Methods: 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. Results: 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). Conclusions: 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. Keywords: microshear, adhesion, self-adhesives, caries-affected, dentin, staining of caries-affected dentin