The effects of varied etching time and etching solution viscosity on bond strength and enamel morphology.

The effects of varied etching time and etching solution viscosity on bond strength were evaluated by measuring the tensile bond strength of a composite resin to bovine enamel. Also, six enamel surfaces were examined to evaluate the effect of acid treatment on the morphology of etched enamel using scanning electron microscopy. There was no significant difference in tensile bond strength between three etchants of differing viscosity or between etch times. Light microscopy revealed that most bond failures were cohesive in nature. When the three etchants of differing viscosity were compared under the scanning electron microscope, the liquid and the thin gel produced a more even etch pattern than the thick gel. In addition, the thin gel appeared to produce the most well-defined pattern of the three conditioners.