Comparison of conventional vs self-etching adhesive bonds to caries-affected dentin

The mechanism of resin adhesion to caries-affected dentin is still unclear, This study evaluated the interfacial morphology of two bonding systems to caries-affected dentin, coupled with the measurement of microtensile bond s trengths (mu TBS). Carious human molars were prepared as previously describ ed in Nakajima and others (1995) and were bonded with Single Bond (SB) or F luoroBond (FB) according to the manufacturer's instructions, followed by cr eation of AP-X composite buildups, After one day of storage in 37 degrees C water, the teeth were serially sectioned vertically into 0.8 mm slabs, tri mmed to yield a 1 mm(2) test area, and tested to failure in a Bencor device used in an Instron machine operated at 1 mm/min. Resin-dentin interfaces w ere observed with SEM before or after acid/base challenge, Bonding to norma l dentin with the two bonding systems (SB and FB) showed tensile bond stren gths significantly higher than those to caries-affected dentin, The moist b onding technique significantly increased bond strength of SE to normal and caries-affected dentin, SEM examination revealed that typical hybrid layer and resin tags could not be formed to caries-affected dentin, The results s uggested that resin penetration may be prevented by occlusion of dentinal t ubules by mineral deposits that may also impart acid-resistance to the inte rtubular matrix of caries-affected dentin.