Bond Strength of Adhesives To Enamel Prepared with Different Burs

Objectives: Previous study showed that some of the all-in-one adhesives produced low bond strengths to dentin prepared by regular-grit diamond bur (J Adhesive Dent 3,129-36,2001). The purpose of this study was to investigate the influence of grinding enamel on tensile bond strength of two all-in-one and one two-step adhesive systems. Methods: Resin composite (Clearfil AP-X, Kuraray) was bonded to the ground enamel surfaces of eighteen extracted human third molars, which were prepared by reducing 0.5 mm from the buccal enamel surfaces using regular- or superfine-grit diamond burs, using randomly either of the three adhesives, Prompt L-Pop (3M/ESPE), Clearfil Megabond (Kuraray), and Xeno CF (Sankin). After 24 h storage in water at 37 Ž, the specimens were sectioned vertically into five or six slabs of 0.7 mm thickness. The slabs were then trimmed using a high-speed diamond bur to create an hourglass configuration with the narrowest portion at the bonded interface. The bonded surface area was approximately 1mm². Micro-tensile bond strength (MTBS) testing was performed at a crosshead speed of 1 mm/min. The data were analyzed by one way ANOVA and Scheffe`s test (p<0.05). Results: The mean MTBSs in MPa (SD) [number of specimens] of Prompt L-Pop, Mega Bond and Xeno CF were 28.61 (12.76) [15], 21.93 (7.58) [18] and 26.82 (9.01) [15] using regular-grit diamond bur, and 31.57 (13.36) [16], 22.74 (10.88) [17] and 31.25 (8.69) [17] by superfine-grit, respectively. For all three adhesives, MTBS to enamel ground with a regular-grit diamond bur was not significantly different from that to enamel ground with a superfine-grit diamond bur. Prompt L- Pop and Xeno CF showed significantly higher MTBS than Mega Bond to ground enamel, irrespective of the burs used. Conclusions: It is concluded that the use of two different burs does not affect the tensile bond strength of the adhesives to enamel.