ABSTRACT
Bonding agents are one of the most important materials in adhesive dentistry. Sixth generation bondings have more simple application than fifth generation, but despite this, it has been addressed by some articles that adhesive strength of sixth generation gradually decreases over time. The aim of this study was to compare the shear bond strength of a resin composite with application of two bonding agents [fifth and sixth generation] after three months storage in normal saline. This invitro study was conducted on 40 anterior bovine teeth. After complete removal of enamels, the samples were randomly divided into four groups based on the use of acid etch technique and the type of bonding agents [Excite or Prompt L-pop]. After applying Z250 composite resin, the samples were immersed in normal saline for 90 days and then were thermocycled and subjected to shear bond testing with Dartec universal testing machine. Statistical analysis was performed using one-way ANOVA and Tukey's test. In non-etched groups, Prompt L-pop showed significant higher bond strength than Exite, but in etched groups Excite had significantly higher bond strength [p<0.005]. There were no significant differences in Prompt L-pop subgroups with or without etching meanwhile in Excite subgroups, significant differences were found. The use of Excite with acid etching technique provide more reliable bonding than Prompt L-pop to dentin