PubMedDate not supplied
OBJECTIVE: Total dehydration of acid-etched dentin is known to cause the collapse of collagen fiber, which leads to poor hybridization. Dentin-bonding systems with water as a solvent are found to rehydrate the collapsed collagen. Acetone-based adhesives are found to compete with moisture, and the acetone carries the resin deep into the dentin. The question arises whether to dry the dentin and use a water-based adhesive, or to keep the dentin moist and use an acetone- or alcohol-based adhesive. The aim of this study was to compare different bonding systems and techniques to assess which is most successful. A confocal microscope was used to evaluate the amount of hybrid layer formation and the depth of resin tag formation. METHOD AND MATERIALS: Superficial occlusal dentin specimens from 120 noncarious, freshly extracted human premolars were used for the study. The dentin was etched using 36% phosphoric acid for 15 seconds and then rinsed. The specimens were then randomly divided into 4 groups for different drying procedures: group I: air-dried for 30 seconds; group II: air-dried for 3 seconds; group Ill: blotted dry; group IV: overwet. The specimens were further subdivided into 3 groups to be tested with different bonding systems: subgroup A: acetone-based adhesive (Prime & Bond NT); subgroup B: water-based adhesive (Syntac Single Component); subgroup C: water- and ethanol-based adhesive (Single Bond). The resulting resin-dentin interfaces were then examined and categorized via confocal microscopy, and relative values were assigned to each specimen. RESULTS: Group IV (overwet) showed the lowest values, and the highest values were obtained in group III. The highest values were seen in group III, subgroup A (blotted dry, acetone-based bonding agent, Prime & Bond NT). CONCLUSION: Under these conditions, using these three bonding systems, maximum hybridization and resin tag formation was achieved using acetone-based adhesive on etched dentin kept moist by blot drying.