Effect of moist vs. dry bonding to normal vs. caries-affected dentin with Scotchbond Multi-Purpose Plus

Recent research in dentin bonding demonstrated the superiority of moist bon ding over dry bonding on normal dentin, but it is unclear if this technique is also superior in bonding to caries-affected dentin. The purpose of this study was to evaluate the SEM appearance and bond strength of Scotchbond M ulti-Purpose Plus (SMPP) to normal vs. caries-affected dentin bonded under moist vs. dry conditions, with and without polyalkenoic acid in the primer. Extracted carious human third molars were ground down by means of 600-grit SiC paper until the carious dentin no longer stained with caries detector solution, The flat surfaces were then primed, bonded, and built up with res in composite. After soaking in water for 1 day, the teeth were serially sec tioned vertically into 5 or 6 slabs 0.7 mm thick. The bonded caries-affecte d areas were isolated by means of an ultrafine diamond bur to create an hou rglass configuration with a cross-sectional area of 0.9 mm(2). Bonded norma l dentin was isolated the same way. Each specimen was attached to a Bencor device and tested in tension to failure. SMPP bonds to dry, normal dentin w ere only half as strong (21 +/- 10 MPa, (x) over bar +/- SD) as those made to moist, normal dentin (42 +/- 9 MPa, p < 0.01). There was no significant difference between bonds made to normal vs. caries-affected dentin by means of the moist technique (42 +/- 9 vs. 48 +/- 4 MPa, respectively). Removal of the polyalkenoic acid from the primer lowered (p < 0.05) the bond streng th of SMPP to caries-affected dentin (38 +/- 8 MPa). The benefits of moist bonding extend to caries-affected dentin. The polyalkenoic acid in the SMPP primer contributes to the high bond strength that can be achieved ta carie s-affected dentin.