Morphology of the dentin-resin interface yielded by twostep etch-and-rinse adhesives with different solvents

Abstract

Aim: The study aimed to analyze the morphology of the dentin- resin interface yielded by two-step etch-and-rinse adhesive systems with different solvents and compositions. Materials and methods: A total of 32 dentine disks were prepared and randomly assigned to four groups of one-bottle etchand- rinse adhesive systems containing different solvents: group I, Adper Scotchbond-1XT™ (ethanol/water); group II, XP-Bond™ (tertiary butanol); group III, Prime and Bond NT® (acetone); and group IV, One Coat bond® (5% water). Adhesive systems were applied onto dentin disks, which were then thermal cycled, divided into two hemi-disks (n = 16), and prepared for field-emission scanning electron microscopy to examine the dentin-resin interdiffusion zone. Microphotographs were scanned and data were processed. Data were compared with analysis of variance multivariant test after Kolmogorov-Smirnov and Shapiro-Wilk tests using Statistic Package for the Social Sciences. Results: The adhesive layer thickness average found was group I: 45.9 ± 13.41 μm, group II: 20.6 ± 16.32 μm, group III: 17.7 ± 11.75 μm, and group IV: 50.7 ± 27.81 μm. Significant differences were found between groups I and IV and groups II and III (p < 0.000). Groups I (3.23 ± 0.53 μm) and II (3.13 ± 0.73 μm) yielded significantly thicker hybrid layers than groups III (2.53 ± 0.50 μm) and IV (1.84 ± 0.27 μm) (p < 0.003). Group III presented a less homogeneous hybrid layer, with some gaps. Tag length average was greater in groups II (111.0 ± 36.92 μm) and IV (128.9 ± 78.38 μm) than in groups I (61.5 ± 18.10 μm) and III (68.6 ± 15.84 μm) (p < 0.008). Conclusion: Adhesives systems with different solvents led to significant differences in the dentin-resin interface morphology. Solvents role in adhesives bond strength should be considered together with the other adhesive system components. Clinical significance: The adhesive containing tertiary butanol, in addition, seems to originate a good-quality hybrid layer and long, entangled tags and also appears to have greater ability to originate microtags, which may indicate higher bond strength.