Chlorhexidine and ethanol influence on long-term bond strength of adhesive systems to sound, caries affected and intraradicular dentin

Abstract

The aim of this study is to investigate the influence of ethanol and chlorhexidine on bond strength of adhesive systems over time to the sound and caries-affected dentin. Project 1 - The aim of this study is to verify the influence of chlorhexidine application time and concentration on long-term bond strenght to dentin of conventional and self-etching adhesive systems. Will be used 80 third human molars with occlusal medium and flat dentine exposure. Dentin will be subjected to various pretreatments (n = 8) according to the concentration of chlorhexidine solution (2% or 0.12%) and application time (30 or 60 seconds) after the phosphoric acid application to etch-rinse adhesive system and prior to self-etching adhesives. Two control groups (one for each adhesive system) will be made following the manufacturer's recommendation. Next, the teeth will restored with composite resin and will be obtained microtensile specimens submitted to the test immediately or after water storage for 180 days. Project 2 - This study will evaluate the effects of ethanol and chlorhexidine application on long term bond strength of conventional adhesive system to sound and caries affected dentin. Will be used 60 fragments of sound and caries affected-dentin restored with conventional adhesive system according to the manufacturer's recommendation (control) or associated with the surface treatment with chlorhexidine and ethanol after acid etching (n = 10). Midle coronal dentin will be exposed and 30 teeth will be submitted to the procedures for obtaining caries-affected dentin. Then, the surface treatments with ethanol and chlorhexidine and restoration with composite resin will be performed according to the experimental groups. The microtensile specimens will be submmited to the microtensile test immediately or after water storage for 180 days. Project 3 - This study will evaluate the bond strength over time of dual and self-adhesive resin cement used for cementation of fiber glass associated with root canals irrigations solutions: chlorhexidine, sodium hypochlorite and distilled and deionized water. Ninety single-rooted premolars will be divided into 6 groups (n=15) from the combination of resin cement: dual and self-adhesive and irrigation solutions: 1% sodium hypochlorite, 2 % chlorhexidine gel and distilled and deionized water (control). After cementing of glass fiber pin, the roots will be radially sectioned obtaining two slices of each third of the root. The root slices will be stored for 48 hours or 180 days. At the especific time the slices will be submmited to the push-out test to evaluate the bond strength. The data will be tabulated and evaluated according to the appropriate statistical method (parametric and nonparametric) adopting a significance level of 5%. (AU)