Bond strength of self-etch adhesives to dentin prepared with three different diamond burs

To evaluate the micro-tensile bond strength (mu TBS) of a control etch-and-rinse and three self-etch (strong, mild, ultra-mild) adhesive systems to dentin prepared with three different grit size of diamond burs.

Dentin surfaces were created from mid-coronal sound dentin in extracted, human third molars. The teeth were ground with high-speed medium grit (100 microm), fine grit (30 microm), or extra-fine grit (15 microm) diamond bur. Resin composite (Z100) was bonded to the surfaces using Optibond FL, Adper Prompt L-Pop, Clearfil SE Bond, or Clearfil S3 Bond. Rectangular micro-specimens were prepared using the slow-speed diamond saw and tested in tensile to determine the mu TBS. Failure analysis was performed using a stereo-microscope and Fe-SEM. Data were analyzed by two-way analysis of variance and Tukey's HSD test (p<0.05).

The etch-and-rinse adhesive yielded high micro-tensile values (58-69 MPa), irrespective of the diamond burs used. The bond strength values were comparable for Adper Prompt L-Pop and Clearfil SE Bond irrespective of the burs used. The mu TBS values were significantly higher as the particle size of diamond burs is smaller for Clearfil S3 Bond. Most failures were recorded as interfacial failure when the fine and extra-fine diamond burs were used.

Overall, different grit-sized diamond burs did not affect the mechanical properties of the interface, except for the ultra-mild one step self-etch adhesive. This adhesive performed significantly better when a smaller grit size was used to prepare dentin surface.