Adhesion to Dentin Promoted by Contemporary Bonding Agents

Objectives: The aim of this in vitro study was to analyze the morphology of resin-dentin interfaces (RDI) and bond strength (BS) of three adhesive systems to human dentin.

Methods: Thirty-nine human third molars had their occlusal enamel removed with a diamond saw (Buehler Ltd) to expose the middle-depth dentin. The dentin surfaces were abraded with SiC 600 paper, under water cooling for 10 seconds, to standardize the smear layer and planning of the dentin surface. For microtensile BS and for scanning electron microscopy (SEM) analysis, the teeth were randomly divided into three experimental groups (n=10 and n=3, respectively): Gluma 2Bond (G2B - Heraeus Kulzer), Clearfil SE Protect (CSP - Kuraray Med.) and Peak Universal Bond (PUB - Ultradent Prod.). The adhesives were applied following the instructions of each manufacturer. Filtek Supreme composite (3M ESPE) were incrementally built-up on dentin surfaces (6 mm thickness) and the teeth were stored for 24h at 37^oC. The teeth were vertically and serially sectioned with a diamond saw under water lubrication to obtain bonded specimen (area of approximately 1.0 mm²), which were tested in a universal testing machine (EZ Test, Shimadzu). Data were analyzed by one-way ANOVA and Tukey test (α=5%). For SEM observations, composite block of 2mm thick was placed after bonding, teeth were sectioned to obtain slices of 1.5 mm thick and the slices were 

Results: The BS means (SD) were (in MPa): G2B: 35.0(5.4)a; CSP: 27.8(9.0)a and PUB: 46.6(8.2)b;  The CSP self-etching primer presented thin hybrid layer and short resin tags when compared to etch-&-rinse systems (G2B and PUB).

Conclusions: The PUB adhesive showed highest BS to dentin. The morphology of RDI did not influence the BS.