The Effect Of Octadecyltrichlorosilane Modification On Dentin Bonding

Caries has always been a hot area of dental research.Clinically,minimally invasive tooth preparations and esthetic tooth-colored restorations are performed when dental caries is observed.With the continuing advances in dentin bonding technology and dental material,the immediate resin-dentin bond strength of current adhesives has been shown to be satisfactory.However,NIDCR 2009-201 reported that the average replacement time of esthetic tooth-colored restorations is only 5.7 years.A great number of labour power and medical resources are spent in the replacing defective dental fillings.Therefore,it is important to improve the durability of resin-dentin bond.The degradation at the interface between dentin and restorative is the main reason of substantial decreases in resin-dentin bond strength after aging.Nowadays,dentin surface is kept totally hydrated throughout the "wet bonding" procedure.Nevertheless,the current adhesives could not displace the water within the interfibrillar spaces completely.Incomplete infiltration of adhesives/resin monomers could lead to the exposure of the non-infiltrate collagen underlying.These denuded collagens are susceptible to denaturation,creep,cyclic fatigue rupture or be hydrolyzed by endogenous and exogenous collagenolytic enzymes after long-lasting function.Moreover,hydrophilic components contained in adhesives exhibit high water affinity at resin-dentin interface,and would result in rapid deterioration of their mechanical?properties.In this study,octadecyltrichlorosilane(OTS)in ethanol/diethyl ether/toluene solution was used to modify the exposed collagen in acid-etched dentin to create a relative hydrophobic interface for dentin bonding,with the aim of promoting the durability of resin-dentin bonds.Infrared spectrum and water contact angle analysis showed that OTS was successfully grafted onto the exposed dentin collagen fibrils to create a hydrophobic interface.The use of OTS in ethanol/diethyl ether/toluene solution enhanced the immediate microtensile bond strength(?TBS)in Prime&Bond NT,but had no apparent effect on Optibond S.However,nanoleakage was reduced with the application of OTS in ethanol/diethyl ether/toluene solution in both adhesive systems.After storage for 3 months,in the OTS-ethanol/diethyl ether/toluene-treated groups,?TBS was maintained in both adhesive systems and no increase in nanoleakage was observed.Conversely,in the other two groups,?TBS decreased and the nanoleakage increased significantly.The use of OTS in ethanol/diethyl ether/toluene solution creates a relative hydrophobic resin-dentin interface,enhances adhesive-dentin interfacial compatibility,and promotes infiltration of adhesive resin monomers into the demineralized collagen exposed by acid-etching.The technique forms a relative hydrophobic resin-dentin interface that improves the durability of resin-dentin bond.