Antibacterial activity of a glass ionomer containing silver nanoparticles against Streptococcus mutans and Streptococcus sanguinis.

AIM: Nano-sized metal particles exhibit special biological, chemical, and physical properties. The aim of this study was to evaluate the effect of incorporating silver nanoparticles into a resin-modified glass ionomer (GI) on its antimicrobial property. MATERIALS AND METHODS: Antibacterial action of GI samples containing 0, 40, 80 ppm silver nanoparticles against standard strains of Streptococcus sanguinis and Streptococcus mutans were assessed by agar diffusion and direct contact tests. Data were analyzed using analysis of variance and Duncan test (P < 0.05). RESULTS: Agar diffusion test showed no bacterial inhibition zone, but direct contact test exhibited significant antimicrobial activity against S. sanguinis and S. mutans in resin containing 80 ppm of nanosilver. CONCLUSION: Incorporation of a certain amount of silver nanoparticles into GI can increase its antimicrobial activity compared to the original material.

Nano-hydroxyapatite could Compensate the Adverse Effect of soft carbonated Drinks on Enamel.

INTRODUCTION: Since one of the most important disadvantages of soft drinks includes their adverse effect on mineral content of enamel because of their low pH, this study examined the microhardness of enamel before and after exposure to a soft drink containing different concentrations of nano-hydroxyapatite (nano-HA) as an additive. MATERIALS AND METHODS: Sixty caries free human premolars were mounted in epoxy resin. After polishing, the baseline micro-hardness was recorded three times for each specimen using a Vickers indenter at 50 gm load. Subsequently, the samples were divided into six groups, which were treated for 5 minutes at 9°C by a cola-based drink contacting 0, 0.5, 1, 5, and 10 wt.% of nano-HA while the control group was immersed in artificial saliva. Ultimately, the final microhardness was assessed three times again for each specimen. RESULTS: Paired t-test showed that in groups containing 0 and 0.5 wt.% of nano-HA, the microhardness was significantly reduced after treatment protocol (p = 0.00 and 0.01 respectively). Whereas in the other groups the microhardness was not significantly changed after treatment (p > 0.05). CONCLUSION: Pure cola-based drink has a pronounced adverse effect on enamel microhardness, while admixing it with nano-HA could act as a protective factor. CLINICAL SIGNIFICANCE: Although soft beverages are hazardous to tooth structure, some additives could compensate their adverse effect.