Kinetic cavity preparation: protection of the cavo-surface enamel

A significant defect of kinetic cavity preparation systems is damage to cavo-surface sound tooth enamel. The purpose of this study is to establish a protective method for cavo-surface sound tooth enamel during air-powder abrasive system cavity preparation, using protective varnish. A total of 39 extracted human primary teeth were used for this experiment. Protective varnish was applied to the tooth surface in single, double and triple coats. The kinetic instrument was used for cavity preparation. Class V cavities were prepared on the border area of varnish coated and intact tooth surface. After removal of varnish with a supersonic washer, specimens were dried and gold plated with ion-spatter, following which cavity margin enamel was observed through a SEM. Tooth surface enamel where coated with varnish appeared intact and the cavo-surface margin remained at a right angle form. However, tooth surface enamel without varnish coating appeared rough, and the cavo-surface margin exhibited a round shape. It seems likely that kinetic energy was absorbed by the soft varnish coating, thereby protecting the enamel. Protective varnish was found to provide a protective effect for cavo-surface sound enamel, and was also found to promote a sharp edge at the cavo-surface margin, during kinetic cavity preparation.