Micromorphologic relationship between resin and dentin in Class II restorations: an in vivo and in vitro investigation by scanning electron microscopy.

The wetting property of dentinal bonding systems may play an important role in the mechanism of adhesion to dentin. Some studies have observed that tags penetrate 100 microns or more in nonvital teeth and less than 10 microns in vital teeth. This investigation was designed to evaluate the micromorphologic relationship between in vivo and in vitro dentin after application of two new dentinal bonding systems in Class II restorations. Class II cavities were restored in vitro and in vivo with Gluma 2000 adhesive and Pekafill hybrid resin or Scotchbond Multi-purpose adhesive and Z100 composite resin. After dissolution of dental structures, the restorations were observed with a scanning electron microscope. No morphologic differences were found between in vivo and in vitro specimens with either of the new dentinal adhesive systems tested. Short resin tags were often found in vivo, particularly at the cavity walls. Only a few areas in vivo had deep resin tags (longer than 100 microns) and these were always at the cavity floor.