Bond Strength of Resin-composite to Fibre-reinforced-composite With IPN Polymer Systems

Objectives: To evaluate the effects of polymer matrix of interpenetrating-polymer-network (IPN) on bonding strength of UDMA-based fibre-reinforced-composite (FRC) using with E-glass-fibres and AR-glass-fibres.
Methods: Urethanedimethacrylate (UDMA)-methylmethacrylate (MMA) monomer system in ratio of 90:10 was used. IPN-forming polymer of IPN was PMMA or PMMA-copolymer. IPN-forming polymer was added to UDMA-MMA with photocuring initiator/activator of 0.7wt% camphorquinone and DMAEMA. PMMA (0.5%,2%,5%) and PMMA-copolymer (0.5%,2%) were added to each group of UDMA-MMA resin. No IPN-forming group was used as control. Thus, 6 different contents of matrix resin were prepared. For FRC specimens, one roving of E-glass-fibres and AR-glass-fibres were impregnated with each resin and light cured to use as bonding substrate. Oxygen inhibition layer was removed by grinding. Ceramic Primer 2 (CeP, GC) and Composite Primer (CoP, GC) were used for surface treatment of the FRC. Application time for primer CeP and CoP was 5min, and CoP specimen was light cured for 20s. No primer (NP) group was also prepared. Composite (GradiaCore, GC) was filled to plastic mold 3.6mm diameter and 2mm height onto the fiber specimens, and light cured for 40s. After 24h water storage at 37degrees-C, bond strength (so-called shear-bond strength test, SBS) was measured (n=10/group) crosshead-speed of 1.0mm/min. The results were analyzed (two-way ANOVA).
Results: Mean SBS value is given in Table. ANOVA showed that there were significant differences of priming agent: NP/CeP (p<0.01) and NP/CoP (p<0.01) in E-glass-FRC, and NP/CoP (p<0.01) in AR-glass-FRC. By increased quantities of PMMA to matrix resin, SBS of all tested groups increased in AR-glass-FRC.
Conclusions: This study showed that increasing of IPN component with fibre-reinforcement increased bonding strength when using both priming agents. However, the increased quantities of PMMA-copolymer were not influenced on the increasing of bonding strength in the same primer group.