Effect of Enamel Preparation on the Microtensile Bond Strength of Self-etching Primers

Objective: To evaluate the effects of enamel surface preparation method on the microtensile bond strength (µtbs) using two commercially available self-etching primer adhesive systems (SEP) Methods: Nine bovine incisors were randomly divided into 3 experimental groups according to surface preparation. Group 1 polished surface (non-smear layer) group, Group 2 carbide bur, and Group 3 medium grit diamond bur. For group 1 the buccal surfaces of the teeth were polished to remove the smear layer with 600- and 800- grit sand paper then 6 µm, 1µm, and 0.5 µm diamond polishing compound with polishing cloths using an Ecomet polisher (Buehler Ltd.). Groups 2 and 3 were prepared with their respective cutting instrument then all groups were treated with SEPs; Clearfil SE Bond, Kuraray (CSE) and Prompt L-Pop, 3M-ESPE (LP); and a conventional total-etch three-step adhesive system, Optibond, Kerr (OB) (control) before composite buildups (Prodigy, Kerr). Four specimens were obtained per tooth (n = 4). Specimens were trimmed, resulting in a cylindrical cross-sectional area of 0.5mm² and subjected to tensile force at 1 mm/min until failure. Differences between surface preparation within adhesives were determined by the Kruskal-Wallis test (a=0.05). Results: The µtbs of OB was not affected by surface preparation (p=0.75). The µtbs of CSE and LP was affected by surface preparation (p=0.017 & 0.021 respectively). Conclusion: The data suggests that the type of burs used can influence the enamel bond strength of these bonding systems. There is a tendency that the bond strength decreased when enamel surfaces has been prepared with diamond burs. The influence of the type of bur used to prepared enamel on resin-enamel bond strength depends upon the type of adhesive system used.