Development of Antibacterial-releasing Dental Composites with High Strength and Dentine Bonding

The thesis aim is to develop a dental composite with (1) high conversion/ depth of cure to provide good strength, (2) water sorption to compensate shrinkage and promote antibacterial release, and (3) added re-mineralising components and acidic monomers to enhance bonding. Conversion/ shrinkage, depth of cure, water sorption, and antibacterial (polylysine & chlorhexidine) release into distilled water versus simulated body fluid were assessed using FTIR, ISO 4049 (scraping test), gravimetrical studies, and UV spectroscopy respectively. Flexural strength/ modulus was assessed up to 6 months of water storage. Similarly bonding to moist ivory and human dentine was assessed via a push out and shear bond test. Factorial analysis was used to analyze the data. The results showed that a major factor affecting the conversion, and shrinkage was sample thickness. Similarly a major factor affecting the depth of cure was duration of light cure. In water sorption studies the major factors enhancing water sorption were use of distilled water, and polylysine. The chlorhexidine release was enhanced by the use of distilled water, while a higher polylysine release percentage was seen with lower levels of drug in the filler phase. The strength and modulus were decreased with the addition of reactive fillers. Lastly, adhesion was improved with the use of adhesive, and acidic monomers. The materials produced could potentially reduce bacterial micro leakage, which is the most common reason for failure.