Effects of C-factor on bond strength to floor and wall dentin

This study evaluated the effect of C-factor on the bond strength of a resin composite to floor and wall dentin using two adhesive systems. Box-form cavities were prepared on human molars, following the walls of half of the cavities were removed to create flat dentin surfaces for bonding. Each specimen was then restored using one of two adhesives (Clearfil SE Bond or Clearfil tri-S Bond) and filled or built up using Z100 resin composite. After light-curing, the specimen was cut perpendicular to the bonded surface parallel to the floor or wall to obtain beams. The micro-tensile bond strength to the flat floor, flat wall, cavity floor, or cavity wall was determined. Resin composite bonded more strongly to the flat wall dentin than to the flat floor dentin, regardless of the adhesive system used. Bonding to the cavity wall was higher affected by C-factor than to the cavity floor.