published_or_final_version / Dentistry / Master / Master of Dental Surgery

published_or_final_version / abstract / Dentistry / Doctoral / Doctor of Philosophy

published_or_final_version / Dentistry / Master / Master of Dental Surgery

Indiana University-Purdue University Indianapolis (IUPUI) / Both quaternary ammonium bromide (QAB) and furanone derivatives were synthesized, characterized and formulated into dental resin composites for improved antibacterial properties. Compressive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antibacterial activity of the restoratives. The effects of chain length, loading, saliva and aging on CS and S. mutans viability were investigated. Chapter 2 describes how we studied and evaluated the formulated antibacterial resin composites by incorporating the synthesized QAB-containing oligomers into the formulation. The results show that all the QAB-modified resin composites showed significant antibacterial activity and mechanical strength reduction. Increasing chain length and loading significantly enhanced the antibacterial activity but dramatically reduced the CS as well. The 30-day aging study showed that the incorporation of the QAB accelerated the degradation of the composite, suggesting that the QAB may not be well suitable for development of antibacterial dental resin composites or at least the QAB loading should be well controlled. Chapter 3 describes how we studied and evaluated the formulated antibacterial resin composite by incorporating the synthesized furanone derivative into the formulation. The results show that the modified resin composites showed a significant antibacterial activity without substantially decreasing the mechanical strengths. With 5 to 30% addition of the furanone derivative, the composite kept its original CS unchanged but showed a significant antibacterial activity with a 16-68% reduction in the S. mutans viability. Further, the antibacterial function of the new composite was found not to be affected by human saliva. The aging study indicates that the composite may have a long-lasting antibacterial function. In summary, we have developed a novel QAB- and furanone-containing antibacterial system for dental restoratives. Both QAB- and furanone-modified resin composites have demonstrated significant antibacterial activities. The QAS-modified experimental resin composite may not be well suitable for development of antibacterial dental resin composites due to its accelerated degradation in water unless the QAB loading is well controlled. The furanone-modified resin composite shows nearly no reduction in mechanical strength after incorporation of the antibacterial furanone derivative. It appears that the furanone-modified resin composite is a clinically attractive dental restorative that can be potentially used for long-lasting restorations due to its high mechanical strength and permanent antibacterial function.