Surface Treatment Effect on Bond Strength of Repaired Core Build-up

Purpose: To evaluate the tensile bond strength between different surface treatments of two different composite core build-up materials (Build-It FR and ParaCore) covered with light-cured resin composite (Z250). Methods: The cylindrical shaped (8 mm in diameter, 5 mm in height) of each composite core build-up materials were prepared. The specimen-surfaces were polished with 600 grit of SiC paper and stored in distilled water at 37 degree Celsius for 30 days. Later, each of two cylindrical- shaped specimen materials was divided into 4 groups concerning the surface treatment methods: 1) sandblasted with 50 micron aluminum oxide particle; 2) sandblasted and applied ethyl acetate solution; 3) sandblasted and applied methyl methacrylate monomer; and 4) no surface treatment (control group). All specimen- surfaces were then coated with adhesive and covered with light-cured resin composite (Z250). After 40 seconds light curing, thermocycling was performed between 5 degree Celsius and 55 degree Celsius for 20,000 cycles.  Mini-dumbbell test specimens were achieved according to ISO/TS 11405 (n=15/group). The tensile bond strength was measured using Universal testing machine at crosshead speed of 1.0 mm/ min and data were statically analyzed by ANOVA.  Results: Means and standard deviations of tensile bond strength are shown in the table.

  The groups of sandblasting and sandblasting following with chemical reagents applying showed tensile bond strength significantly higher than the control group (p<0.05). Yet, tensile bond strength was not significantly different among the different surface treatments of repaired core build-up materials (p>0.05). Conclusion: Sandblasting enhanced the tensile bond strength between the repaired core build-up material and the light-cured resin composite. Methyl methacrylate monomer and ethyl acetate solution did not improve the tensile bond strength.