Scientific Efficacy of a Combined Silica/methacrylate Coupling on the Fiber Post Bonding to Composite Cores

58 INTERNATIONAL DENTISTRY SA VOL. 8, NO. 4 Introduction The clinical success of fiber post-retained restorations depends on the establishment of a reliable bond at the root-post-core interfaces. In spite of the improvements in dental material technology, post to composite adhesion is still considered relatively low. Advances in silane coupling agents enhance bond strength by promoting adhesion between OH-covered inorganic surfaces and polymeric molecules. However, the nature of the fiber post-resin joint is critical: only the exposed fibers (quartz or glass) of the post are available for silane coating and may contribute to retention. Chemical incompatibility between methacrylate-based resins of the core and the epoxy resin matrix of certain types of fiber posts is likely to occur. Alternative approaches, such as the application of an intermediate layer of fluid resin on the post, have been proposed to overcome this limitation. However, the need to create a chemophysical retention has been recognized to ensure a more reliable bond at the postcore interfacial level. Chair-side silica coating techniques (i.e. Co Jet System®), in which the tribochemical effect of air particle abrasion results in superficial deposition of SiO2, have been recently applied for this purpose on fiber posts, with controversial results. Although satisfactory improvements in bond strength were achieved, a weakening effect on the fiber post was reported as a consequence of a perceptible volume loss. In the attempt to simplify clinical procedures, an Department of Restorative Dentistry and Dental Materials, University of Siena, Italy.