The enamel bonding ability of three composite resin systems including a self-etching primer was evaluated and compared in vitro. Also, enamel bonding was compared between the enamel conditioning using the conventional phosphoric acid (Scotchbond^TM Etchant/3 M) and that using the self-etching primer for each product.
The composite resin systems used for this experiment were Clearfil® Liner Bond II / Clearfil® APX (Kurare): LB, Mac Bond System/ Palfique® Light Posterior (Tokuyama): MB, and Fluorobond/Lite-fil II P (Shofu): FB. After standardized cavities were prepared on extracted human molars, the composite resins were filled according to the manufacturers' instructions except for the comparative use of phosphoric acid for the control groups. The thermal cycling test followed by the dye penetration test was performed to evaluate marginal microleakage at the enamel-composite interface.
Based on the findings in this study, the following conclusions were drawn,
1. A significantly better enamel bond was obtained by the use of phosphoric acid when compared with that using the self-etching primer for all of the experimental composite resin systems.
2. The LB and MB groups showed significantly better enamel bond than the FB group for either conditioning using phosphoric acid or a self-etching primer. Also, the MB group provided better results than the LB group.
Further improvement, therefore, is necessary for the enamel bond for the experimental systems including the self-etching primer.