Abstract
The purpose of this study was to evaluate the
generation of enamel cracks and gaps at the
cavosurface margin of resin composite restorations
using various burs. Saucer-shaped cavities with a
bevel were prepared on mid-coronal buccal or lingual
surfaces of extracted human molars using a
regular-grit round diamond bur, a fine-grit diamond
bur, a superfine-grit diamond bur or a sixbladed
tungsten carbide bur with an air turbine
handpiece. The enamel margin of the cavity in each
group was observed by a light microscope.
Cavities were restored with a self-etching adhesive
and a light-cured composite resin. After thermocycling,
enamel cracks and gaps at the cavosurface
margins were observed and scored. Specimens
were sectioned longitudinally in two halves, and the
resin-cavity interface was observed by means of a
light microscope. In cavity preparation, the regulargrid
diamond bur and the tungsten carbide bur
caused more cracks in the marginal enamel than
other groups. From the surface and sectioned
surface observation of restored teeth, the
superfine-grit diamond bur generated fewer
cracks and gaps than the other burs.
