Evaluation of Microshear Bond Strength ofLight and Chemically-Cured Composite Resinsto Light-Cured Glass-Ionomer Using VariousBonding Systems

This study was conducted to compare the microshear bond strength (MSBS) of chemicallycured and light cured composite to resin-modified glass-ionomer (RMGI) based on different types of adhesive systems. Thirty-two discs of Vitrebond RMGI were prepared and randomly divided into 8 groups. Four cylinders of composite resin were placed on each RMGI sample. Z250 composite was bonded to the RMGI discs with Single-Bond, Clearfil SE-Bond, and Clearfil S3-Bond adhesive agent in groups 1, 2 and 3, respectively. Group 4 was considered to be the control group without any adhesive. In groups 5-8, the procedures were the same as those in groups 1-4, except that a chemically-cured composite (Master Dent) was used. All the samples were kept at 37˚C for 24 hours and tested for MSBS by a mechanical testing machine at a strain rate of 0.5 mm/min. Failure mode was assessed under a stereomicroscope. Data analysis was carried out by two-way ANOVA, independent t test, one-way ANOVA and Tukey honestly significant difference test. Application of a bonding agent significantly increased MSBS (P=0.0001). MSBS was significantly higher in samples with light cured composite resin compared to the chemically-cured composite (P=0.0001). Application of an adhesive system significantly increased the MSBS of composite resins to RMGI. The bond strength of composite resin to RMGI could vary depending on the type of the composite resin and the adhesive system.