Comparison of Shear Bond Strength and Compatibility of Dual-Cure Resin Composite Core Build-Up Materials Using Various Adhesive Systems: An In Vitro Study

Objectives: The primary aim of this study was to measure the shear bond strength (SBS) of various dual-cure resin composite core build-up (CBU) materials bonded to caries-free dentin via their self-curing mechanism(s) of action using different self-etching universal adhesives (SEUA). This study also examined the translucency, radiopacity, and microhardness of the tested dual-cure resin composite core build-up materials.

Methods: Non-carious molars and premolars were mounted into acrylic blocks. A flat dentin bonding surface was obtained by grinding the specimens with a model trimmer and sanded to 320-grit with a polishing wheel. The specimens were assigned to a dual-cure CBU material group (Table 1) and assigned to a SEUA subgroup (Table 2). Within 4 hours of surface preparation, the SEUA corresponding to the specimen’s subgroup (Table 2) was applied and light cured per manufacturer’s IFU. Composite buttons for the assigned dual-cure CBU material of each group were placed using a bonding clamp apparatus and allowed to self-cure for 2 hours in an incubator at 37 °C. The bonded specimens were unclamped and stored in water in an incubator at 37 °C for 24 hours to allow for bond maturation. The specimens were mounted to a testing clamp, and a universal testing machine with a fixture featuring a circular notched-edge blade was used to apply load at a crosshead speed of 1mm/min until bond failure. The load (MPa) at the time of bond failure was recorded. The data was analyzed via 2-way ANOVA, 1-way ANOVA, and Tukey’s post-hoc analyses.

Results: Analysis of SBS via 2-way ANOVA determined statistically significant differences in SBS between the adhesives, the CBU materials, and their interaction (p<.05). Individual 1-Way ANOVAs determined significant material groups for each self-etching universal adhesive.

Conclusions: The results of this in vitro study suggest a material incompatibility can exist between self-etching universal adhesive systems and dual-cure resin composite CBU materials when utilizing their self-curing mechanism(s) of action.