A confocal microscopic evaluation of resin-dentin interface using adhesive systems with three different solvents bonded to dry and moist dentinan in vitro study.
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.


METHODS
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).


CONCLUSIONS
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.
Department of Conservative Dentistry and Endodontics, Saveetha Denta Co lege and Hospital, Tamilnadu, India. drmohanb@yahoo.com
Bhuvaneswaran
B
Mohan
Deivanayagam
D
Kandaswamy
D000096:Acetone / Q000737:chemistry; D000134:Acid Etching, Dental / Q000379:methods; D000388:Air; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003094:Collagen / Q000737:chemistry; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D003890:Desiccation; D000431:Ethanol / Q000737:chemistry; D005456:Fluorescent Dyes; D006801:Humans; D008422:Materials Testing; D018613:Microscopy, Confocal; D010756:Phosphoric Acids / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry
D017220:Dentin-Bonding Agents; D005456:Fluorescent Dyes; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; D012997:Solvents; C078484:Syntac dentine adhesive; C115612:single bond; D014867:Water; D000096:Acetone; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate; D003094:Collagen