CORRELATION OF BOND STRENGTH WITH SURFACE-ROUGHNESS USING A NEW ROUGHNESS MEASUREMENT TECHNIQUE

Objectives. The correlation between shear bond strength and surface ro ughness was investigated using new surface measurement methods. Method s. Bonding agents and associated resin composites were applied to set amalgam after mechanically roughening its Surface. Surface treatments were none (as set against glass), 80 grit, and 600 grit abrasive paper . Surface roughness (R(a)) as measured parallel (I) and perpendicular (+) to the direction of the polishing scratches and true profile lengt h were measured. A knife-edge was applied (rate = 2.54 mm/min) at the bonding agent/amalgam inter face of each sample until failure. Results . Coefficients of determination for mean bond strength vs. either surf ace roughness (R(a)) or profile length were significantly higher for m easurements in (I) directions than for those measurements in (+) direc tions. The shear bond strength to set amalgam for a PENTA-containing a dhesives system (L.D. Caulk Division) was not significantly different from that of a PENTA-free adhesive (3M Dental Products Division), even though PENTA has been reported to increase bond strength to nonprecio us metals. Significance, The shear bond strength of resin composite to amalgam is correlated to surface roughness when it is measured parall el to the polishing scratches. This correlation is significantly lower when surface roughness is measured in the typical manner, perpendicul ar to the polishing scratches.