BOND STRENGTH AND INTERFACIAL MORPHOLOGY OF ADHESIVES TO PRIMARY TEETH DENTIN

Purposes: To evaluate (1) the shear bond strength to the dentin of pri mary teeth and failure-site of hydrophilic dentin bonding agents, (2) the interfacial micromorphology of these adhesives on primary teeth. M aterials and Methods: Seventy-six primary noncarious molars stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat wi th hand pressure with a series of SiC paper ending with the 600 grit t o provide a uniform surface on superficial dentin to which the adhesiv es and resin composite could be applied. After preparing the dentin su rface, the teeth were stored in distilled water for 48 hours. They wer e then rinsed and dried with compressed air and divided at random into four groups of 16 specimens each: Group 1: Dentastic; Group 2: One-St ep; Group 3: Prime & Bond 2.0; Group 4: Compoglass SCA. Z100 resin was used in all groups. All specimens were thermocycled (500x) and sheare d in an Instron machine. After shear testing, the debonding sites of a ll samples were examined with a stereomicroscope and selected samples were also examined with the scanning electron microscope. Three additi onal samples per group were used to evaluate the resin adaptation to d entin. Results: The results in MPa were: Dentastic 19.62 (4.67); One-S tep 11.24 (3.67), Prime & Bond 22.38 (6.47), Compoglass SCA 18.88 (4.0 4). ANOVA (P<0.0001) revealed that there was a significant difference between the groups. The Student-Newman-Keuls test (P<0.05) showed no s tatistically significant difference between Dentastic, Prime & Bond an d Compoglass SCA. However, these three groups were statistically signi ficantly higher than One Step. In the Dentastic group, 14 of 16 sample s revealed resin cohesive failure (resin fracture) while two of 16 dis played dentin cohesive failure (dentin fracture). In the One Step grou p, 15 samples failed at the resin and one sample showed dentin cohesiv e failure. In the Prime & Bond group, 12 specimens revealed resin cohe sive failure while four displayed dentin cohesive failure. In the Comp oglass SCA group, 13 samples had resin cohesive failures while three h ad dentin cohesive failures. All samples revealed an intimate adaptati on to the dentin displaying resin tag formation.