Studies that evaluate the longevity of bonding mechanism of the restorative materials in dentin after aging modelsare mainly performed in vitro , for at least six months. The aim of the present study will be to evaluate the bonding longevity of three restorative materials in sound and caries affected dentin submitted to both aging processes: six months in vitro after six months and using in situ model for 14 days. Deciduous second molars will be cut to obtain a parallel plain surface the oclusal face. Half of the teeth will be submitted to pH cycling artificial caries induction and the other half will be used sound. They will be randomly assigned in three groups according tothe restorative material: high viscous Glass of Ionomer Cement (GIC) (Ketac Molar Ketac" Easymix - 3M/ESPE), Resin Modified GIC (Vitremer® - 3M/ESPE) and composite resin associate to adhesive system (Z350" and Adper Scotchbond Multi Uso - 3M/ESPE). Each tooth will be sectioned in three parts and randomized in accordance with the aging procedure: Immediate GC- (control group); GV- aging in vitro for 6 months; GS- aging in situ for 14 days. Two cylinders of restorative material will be performed in each fragment. For the GS group, 10 volunteers use a palatal intra-oral device, with three sound dentin blocks and three caries affected at each side of the appliance. The volunteers will use the device all day, removing only for the dripping of sucrose 20% (8x/day) and during meals and cleaning, with non fluoridate dentifrice. After 14 days of experiment, the blocks will be collected and submitted to microshear test in universal testing machine. The data will be analyzed with ANOVA followed to Tukey test, if they show normal distribution.If they show non-normal distribution they will be submitted to Kruskal-Wallis test. The level of significance will be set in 5%.
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