An experimental fibre-reinforced dental resin composite

Abstract

Fibre-reinforced dental resin composites (FRCs) have shown increased fracture resistance and tensile strength compared with particulate filled composites (PFC). However, clinically successful restorative materials require adequate bond strength and wear resistance along with high strength. An experimental FRC (ST) was developed and tested as a dentine replacement. It has randomly distributed E-glass fibres above their critical length of 0.5-1.6 mm. This work aimed to evaluate the possibility of using ST as a single restorative material by assessing its three-body wear resistance and surface contact fatigue. The polymerisation shrinkage, water sorption, and bond strength of ST were also assessed. Two commercially available materials; an FRC (Build It FR) and PFC (Z250) were used as comparators. ST showed significantly lower wear resistance and higher contact fatigue. No significant difference was found regarding polymerisation shrinkage but ST had significantly higher water sorption, lower shear bond strength (SBS) to human dentine. SBS of the interfacial layers within and between the dental resin composites was evaluated after 24 hours and 1 year of water storage in the absence of an oxygen inhibition layer. Build It/Z250 showed a significantly higher SBS at both time intervals. The presence of an oxygen inhibited layer increased the interfacial strength in all groups except ST/Z250. ST formulations were varied in resin/diluent (Bis-GMA/TEGDMA) ratios, filler loading and fibre lengths for development. Wear testing found changing the Bis-GMA/TEGDMA ratio from 60/40 to 70/30 decreased the wear resistance regardless of filler loading and fibre length. In summary, wear resistance of ST and its variants was insufficient to recommend its use as a single restorative material without a surface veneer of PFC. As a dentine replacement, ST was only comparable with Z250 and Build It in polymerisation shrinkage and SBS between composites in the absence of an oxygen inhibition layer.