This project aims to investigate the permeability of mineralized and demineralized dentin against different solvents when used as carriers of hydrophobic monomers and elucidate the HEMA wet-bonding concept. Six hundred (600) sound human third molars will be collected and used for the production of powdered dentin. The dentin powder (25 cm3) will be placed in a glass column (30.0 cm x 1.0 cm) that will be used for size-exclusion chromatography and elution of large (blue dextran and albumin) and small molecules (HEMA, TEGDMA, and BIS-GMA). Initially it will be evaluated using mineralized dentin in the presence of Tris buffer (control), acetone, ethanol and HEMA. Then, the column will be completely demineralized with formic acid 0.1 M (pH 2.3) over three days at 4°C and the permeability of demineralized collagen will be analyzed as described for the mineralized dentin. The monomers will be separated and quantified by HPLC. Finally, the column will be equilibrated with 5, 10, 15 or 20% water, and all tests will be repeated to ascertain the minimum water concentration for monomer permeation.When the demineralized dentin powder in the column is equilibrated with water, the endogenous proteases of dentin (MMPs and cysteine cathepsins) will release telopeptide fragments as collagen degradation products that will be identified by ICTP and CTX assays. Data set of response variables will be evaluated for adherence to the normal curve and homoscedasticity of variance. Compliance with the requirements of normality and homogeneity among groups, will allow the application of parametric tests considering paired data; otherwise the alternative nonparametric tests will be used. All statistical inferences will be considered at 5% significance level.
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