Bonding of polymers to enamel: influence of deposits formed during etching, etching time and period of water immersion.

A technique for measuring the shear bond strength of composites to etched enamel was developed. The importance of thorough washing of the enamel surface to remove deposits formed during etching was demonstrated by measurements of bond strength and by scanning electron microscopy. One of three orthodontic adhesive systems showed a highly significant increase in bond strength after immersion in water for three months. Etching times as short as five seconds gave a bond strength not significantly different from that obtained after a one-minute etch.