Comparative Analysis of Surface Microhardness and Antimicrobial Activity of Conventional and Bioactive Composite Materials for Dental Restorations

Abstract

This study evaluated the fluoride release capability, antimicrobial activity, and surface microhardness of bioactive composite resins, critical properties for the effectiveness and durability of dental materials in restorative procedures. Conventional and bioactive composite resins with varying viscosities were tested. Specimens of each resin type were prepared and stored in physiological saline solution for 24 hours to simulate oral conditions. Surface hardness was measured using a Knoop hardness test, assessing material resistance to indentation. Antibacterial activity was evaluated by immersing the specimens in a culture medium containing Streptococcus mutants, a common cariogenic bacterium, for 24 hours. After immersion, the specimens were washed to remove non-adherent bacteria, allowing for an accurate count of viable bacterial colonies. Results showed that bioactive composite resins exhibited lower surface microhardness compared to conventional resins lacking Giomer technology. However, bioactive resins demonstrated significant antibacterial activity. This suggests that while bioactive resins may be softer, their ability to inhibit bacterial growth could offer clinical benefits. The integration of Giomer technology in composite resins is a promising strategy to enhance antimicrobial properties and potentially reduce secondary caries. Nonetheless, the observed decrease in surface microhardness highlights a trade-off that may impact the material's longevity and wear resistance. Further research is necessary to optimize the balance between antimicrobial efficacy and mechanical strength in advanced dental materials.