Enamel cavosurface bevels finished with ultraspeed instruments

Sixteen extracted human premolars that had been stored in a glycerin/peroxide solution were selected for this study. The occlusal enamel was removed from each tooth with an arbor band to create a flat nrclusal table at approximately the junction of the occlusal and middle third of the crown (Fig. 1). The four instruments selected for this study were (1) a straight fissure carbide bur (FG 57, Sybron/Kerr, Romulus, Mich.); (2) a superfine tapered diamond stone (FG 8858, Brassler, USA, Inc., Lombard, Ill.); (3) a needle la-fluted finishing carbide bur (FG 7903, Midwest American Dental Div., American Hospital Supply Corp., Des Plaines, Ill.); and (4) a needle-fine 40-fluted finishing carbide bur (FG 9905, Midwest American Dental Div., American Hospital Supply Corp.) (Fig. 2). Each bur was used to place a single 45-degree cavosurface bevel on four extracted teeth. The bevel was prepared on the buccal surface of each tooth at the cavosurface angle formed by the occlusal table and the unprepared (intact) enamel using ultraspeed instrumentation. The crowns were then separated from the roots, cleaned in an ultrasonic cleaner, and mounted on aluminum stubs. The specimens were then slowly