Ultrastructure of the resin-dentin interface following reversible and irreversible rewetting

Purpose: This study investigated the effect of reversible and irreversible rewetting on the application of One-Step, single-bottle, water-free, acetone-based primer/adhesive. Materials and Methods: Thirty 1 mm dentin discs prepared from third molars were each conditioned with 10% H ₃PO ₄ for 20 seconds and rinsed for 20 seconds. They were randomly divided into five groups: Group 1 (positive control): conditioned dentin bonded visibly moist; Group 2: bonded after drying for 3 seconds; Group 3: drying for 3 seconds and rewetting with distilled water; Group 4 (negative control): drying for 3 seconds, stored in 8% glutaraldehyde for 15 minutes, rinsed with distilled water and dried for 3 seconds; and Group 5: drying for 3 seconds, stored in glutaraldehyde for 15 minutes, rinsed with distilled water and bonded visibly moist. One-Step was applied in two coats according to the manufacturer's recommendation and discs in each group were further bonded together to form a disc-pair using a chemical cure resin, demineralized in EDTA and prepared for TEM examination. Results: Complete resin infiltration into the zone of demineralized dentin was observed in Group 1 and 3. In Group 2, resin infiltration was limited to the surface and base of the demineralized network apparently along the lateral branches of the dentin tubules. A middle zone of suboptimal infiltration was observed. In Group 4 and 5, minimal resin infiltration was only observed along the base of the demineralized network upon their fixation in a collapsed state with glutaraldehyde.