Influence of Antibacterial Copper Glass Particles on Surface and Mechanical Properties of Flowable Composites

Copper oxide containing phosphate glasses showed an antibacterial action against streptococcus sanguis, streptococcus mutans and staphylococcus epidermidis. This study aimed to investigate the effect of adding copper glass particles (0- 25 wt%) into flowable composites (Filtek Z350XT flowable and Fusio liquid dentin dental flowable) to induce antibacterial properties. Surface (contact angle and Vicker hardness number) and mechanical (flexure strength, strain and modulus) properties of modified composites have been tested throughout this study; the antibacterial action will be tested in the future. The results showed that both surface and mechanical properties were dependent on the original composite as well as the added filler content. Lower contact angles, indicating higher wettability of the composites, observed with the higher loading of copper glass particles in both resin composites; this high wettability was obvious with Fusio flowable composites. This would be beneficial in bacterial adhesion to the composite surface and hence the expected antibacterial activity of copper glass against the adherent bacteria during biofilm formation. Surface hardness was not negatively affected by adding copper glass particles, except at higher loading levels (25 wt%) particularly when added to Z350 composites. This could indicate that the copper glass at low wt% had no adverse effect on monomer conversion. Generally, the rigidity (indicated by flexure modulus) and strain % of both composites were not affected by the presence of copper glass particles. Finally, it can be concluded that addition of low wt% of copper glass particles (up to 10 wt%) could provide a restorative material with antibacterial action without compromising their surface and mechanical properties. Addition of high wt% of copper glass to Fusio flowable in particular could be beneficial in producing a more hydrophilic material that could potentially encourage bacterial adhesion and hence a significant antibacterial action of copper glass against adherent bacteria will be expected.