Solvent content and dentin bond strengths using water-wet, ethanol-wet and deproteinization bonding techniques.
OBJECTIVE
To evaluate the impact of solvent content in two-step, etch-and-rinse adhesives on the dentin bond strengths obtained via water-wet, ethanol-wet or deproteinization techniques.


METHODS
A model photocurable Bis-GMA/HEMA blend was diluted in ethanol (7.5, 15 or 30 mass%) or acetone (15, 30 or 60 mass%) (low, medium or high solvent content, respectively). Viscosity of the solutions was measured with an oscillatory viscometer and data analyzed using ANOVA on Ranks (5%). Dentin bond strengths were evaluated using microshear bond test. After acid-etching and rinsing, the dentin was kept wet (water-wet), treated with ascending ethanol concentrations (ethanol-wet) or with 10% NaOCl solution (deproteinization). Composite cylinders built-up on the surfaces for the microshear test. Data from each bonding technique were submitted to two-way ANOVA and Fisher's LSD method (5%). Failure modes were classified under magnification and data analyzed using chi-square tests (5%).


RESULTS
Viscosity of ethanol-based agents was remarkably higher than acetone solutions. For the water-wet technique, lower bond strength was observed for the low compared with medium and high ethanol contents. For the ethanol-wet technique, the bond strength for both solvents types was low < medium = high solvent content. For the deproteinization technique, no significant differences were observed among groups. Significant differences in failure modes were observed between the bonding techniques. The ethanol-wet technique had more adhesive failures, whereas the other techniques showed a predominance of mixed failures.


CONCLUSIONS
The solvent content may interfere with the dentin bond strengths for the conventional and ethanol bonding techniques.
Department of Dentistry, Federal University of Sergipe, Aracaju, SE, Brazil. faria_silva@ufs.br
André Luis
AL
Faria-e-Silva
José Everton
JE
Araújo
Gilliane Pereira
GP
Rocha
Aline da Silva
Ada S
de Oliveira
Rafael Ratto
RR
de Moraes
D000704:Analysis of Variance; D003804:Dentin / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D008422:Materials Testing; D011506:Proteins / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D011506:Proteins; D012997:Solvents; D014867:Water; D000431:Ethanol