INFLUENCE OF DIFFERENT FACTORS ON BOND STRENGTH OF HYBRID IONOMERS

A new generation of filling materials, the hybrid-ionomer cements, has been introduced recently. In many clinical situations these hybrid io nomers may be an alternative to conventional glass-ionomer cements and resins bonded with dentin bonding agents. During the past years resea rch has focused on factors influencing bond strength of dentin bonding systems, but there is not much knowledge about the bond strength of h ybrid- and glass-ionomer filling materials under different conditions. Bond strengths of four hybrid ionomers, one conventional glass-ionome r cement, and one cermet cement were determined in superficial and dee p, dry and moist dentin using a simplified pulp chamber model. All mat erials showed significantly higher bond strength to superficial compar ed to deep dentin. Moisture showed no significant influence on any mat erial neither in deep nor in superficial dentin. Bond strengths of Fuj i II LC, Variglass, and Vitremer were distinctly higher than those of the conventional glass-ionomer cement (Ketac-Fil) and the cermet cemen t (Ketac-Silver), while that of Photac-Fil was not significantly diffe rent. Ionomer samples failed cohesively in superficial dentin in over 60% of the samples. The bonding interfaces between Fuji II LC and Vari glass and the treated dentin surface showed tags but no distinct hybri d layer. Bond strength is not only dependent on the pretreatment of th e dentin, but also on the glass-ionomer resin composition of the mater ial.