A quantitative study of enamel acid etch patterns on surfaces used for retention of resin-bonded fixed prostheses

This study investigated the quality of in vivo etch patterns on the bonding surfaces of 46 abutment teeth following acid etching with 37% phosphoric acid for 30 seconds. Two-stage putty and light bodied addition cured silicone impressions of the etched lingual surfaces were used to form replicas that were then viewed using the scanning electron microscope. Over 69% of the lingual bonding surface area of incisors, canine and premolars were unetched, 16% barely etched, 7% etched and less than 2% ideally etched. There was no significant difference in the quality of etch between different tooth types. There was a significantly greater proportion of poorly etched enamel towards the cervical margin in comparison with the occlusal half. This may have implications in retention of resin bonded bridges.