Determination of the etching surface of metal frameworks in resin-bonded prostheses

The aim of electrolytic etching of the metal framework of resin bonded retainers is a microretentive surface. The results of metal etching depend on various factors such as metal alloy, casting conditions, etching solution, and constant electrolytical conditions. Precise knowledge of the inner metal surface is necessary for an exact setting of the current density per time unit. The indirect method of copying the contours from tinfoil to graph paper reduced the error rate to a mean value of +/- 2.3 mm2. This practical method of determining the metal surface before etching can be accomplished without complicated equipment.