EFFECT OF PRIMERS ON BONDING AGENT POLYMERIZATION

The aim of the present study was to evaluate the effect of primers on the polymerization of bonding agent. We measured the degree of convers ion (radical production) and mechanical properties (surface hardness a nd direct tensile strength) of various adhesives/primers mixed at diff erent ratios and the effect of varying the visible-light curing time. With and without primer treatment, the tensile bond strength of adhesi ve resin to micacious glass ceramic and human enamel was measured. Aft er the tensile bond test, using the Image Capture System, the failure patterns of adhesive resin bonded to micacious glass-ceramic were anal ysed. The results show that the mixtures containing the higher amounts of primer yielded a lower degree of conversion and inferior mechanica l properties when compared with the mixtures containing a lower propor tion of primer, except in the experimental bonding system. The adhesiv e/primer mixtures inhibited free radical polymerization. The value for the Knoop hardness number and the direct tensile strength of the adhe sive/primer mixtures were significantly decreased compared with those of the adhesive bonding agent alone with no primer added. The tensile bond strength of adhesive resin bonded to micacious glass-ceramic or h uman enamel without primer treatment was significantly greater than th at of adhesive resin with primer treatment in certain cases. Most of t he fractures of ceramic surfaces were cohesive (within resins) and/or interface (at the ceramic surface) failure.