The overall aim of this study, divided into three experiments, will be to evaluate the solubility of the enamel and dentin of deciduous and permanent teeth, as well as the influence of the time of acid etching on the infiltration of the demineralized dentin and on the immediate bond strength of resin-dentin bonds produced on noncarious and carious dentin. Experiment #1: To comparatively evaluate the product of solubility of enamel and dentin obtained from deciduous and permanent teeth in buffer solutions with distinct pH. Also in that study, it will be evaluated the dissolution of dentin after three different phosphoric acid times. Deciduous and permanent crowns will be dehydrated and pulverized. The powder will be fractionated and the substrates (enamel and dentin) separated in a bromoform-acetone solution. Samples will be dispensed into containers containing acetate buffer solutions with different pH and the solubility will be estimate by means of calcium (Ca) and inorganic phosphorous (Pi) concentrations. Also, the dentin solubility will be evaluated after 5s, 10s and 15s of phosphoric acid etching. Experiment #2: To investigate the effect of acid etching time on the demineralized dentin infiltration by resinous monomers. Flat dentin surfaces will be produced on deciduous and permanent sound teeth. The surface will be divided in the center and each half (mesial and distal) will be phosphoric acid etched for 5s or 15s. The teeth will be randomly assigned to one of the adhesive systems, Prime&Bond NT or Prime&Bond 2.1. Specimens including the adhesive interface will be produced and prepared for light microscopy evaluation after been stained with Goldner's Thricome. The thickness of the non-infiltrated collagen zone at the bottom of the hybrid layer will be quantified. Experiment #3: to evaluate the effect of acid etching time on the bond strength of resin-dentin bonds produced on noncarious and carious dentin of deciduous and permanent teeth. Flat dentin surfaces will be produced and half of the deciduous and permanent teeth will be submitted to an artificial caries protocol. After removing the carious tissue or on the noncarious dentin, the adhesive system Prime&Bond NT will be applied. Resin blocks will be constructed and beam specimens with nearly 0.64 mm2 cross-sectional area will be produced for the microtensile bond strength testing. The statistical tests for all the experiments will be selected after analyzing the characteristics of the data. Since adherence to the normal curve and homocedasticity are respected, parametric tests will be chosen according to the number of independent variables of each study. Otherwise, corresponding nonparametric tests will be selected. All the statistical tests will be considered at the preset level of significance of 5%. (AU)
Articles published in Agência FAPESP Newsletter about the research grant:
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
SALLES SCHEFFEL, DEBORA LOPES;
CURY, JAIME APARECIDO;
ANDALO TENUTA, LIVIA MARIA;
SCHEFFEL, REGIS HENKE;
SOARES, DIANA GABRIELA;
BASSO, FERNANDA GONCALVES;
DE SOUZA COSTA, CARLOS ALBERTO;
PASHLEY, DAVID HENRY;
Proteolytic activity, degradation, and dissolution of primary and permanent teeth.
International Journal of Paediatric Dentistry,
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