Indiana University-Purdue University Indianapolis (IUPUI) / A novel antimicrobial dental composite system has been developed and evaluated. Both alumina and zirconia filler particles were covalently coated with an antibacterial resin and blended into a composite formulation, respectively. Surface hardness and bacterial viability were used to evaluate the coated alumina fi ller-modif ed composite. Compressive strength and bacterial viability were used to evaluate the coated zirconia ller-modi ed composite. Commercial composite Kerr was used as control. The specimens were conditioned in distilled water at 37 °C for 24 h prior to testing. Four bacterial species Streptococcus mutans, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli were used to assess the bacterial viability. Effects of antibacterial moiety content, modif ed particle size and loading, and total fi ller content was investigated. Chapter 2 describes how we studied and evaluated the composite modi fed with antibacterial resin-coated alumina llers. The results showed that almost all the modi ed composites exhibited higher antibacterial activity along with improved surface hardness, as compared to unmodi fed one. Increasing antibacterial moiety content, particle size and loading, and total fi ller content generally increased surface hardness. Increasing antibacterial moiety, fi ller loading, and total fi ller content increased antibacterial activity. On the other hand, increasing particle size showed a negative impact on antibacterial activity. The leaching tests indicate that the modiChapter 3 describes how we studied and evaluated the composite modif ed with antibacterial resin-coated zirconia fi ller. The results showed that almost all the modif ed composites exhibited higher antibacterial activity along with decreased compressive strength, as compared to the unmodif ed control. It was found that with increasing antibacterial moiety content and modi fedfi ller loading, yield strength, modulus and compressive strength of the composite were decreased. In addition, the strengths of the composite were increased with increasing powder/liquid ratio. On the other hand, with increasing antibacterial moiety content, fi ller loading and powder/liquid ratio, antibacterial activity was enhanced. In summary, we have developed a novel antibacterial dental composite system for improved dental restoratives. Both composites modif ed with the antibacterial resin-coated alumina and zirconia fi ller have demonstrated signi cant antibacterial activities. The composite modi fed with the alumina fi ller showed improved hardness values, but the composite modif ed with the zirconia fi ller showed decreased compressive strength values. It appears that the developed system is a non-leaching antibacterial dental composite. ed experimental composite showed no leachable antibacterial component to bacteria.

Resin based composite is currently one of the most popular dental restoratives. Used as a direct restorative material, it displays many beneficial properties such as excellent micromechanical bonding to enamel, polishability and aesthetics. Despite many advances in dentine bonding agents, dentine bonding remains problematic with microleakage and recurrent caries, being frequent clinical sequelae. The open sandwich technique was developed to overcome two problems: deficient bonding of resin composites to dentine, and inadequate strength and fracture toughness of conventional glass-ionomers (GI). GI displayed excellent cavity sealing abilities by virtue of their chemical adhesion to tooth structure. Resin-modified glass-ionomers (RMGI) were developed to improve on the weaknesses of conventional GI during early setting i.e. setting rate, water sensitivity and strength. Recently literature has reported the use of ultrasonic activation to set conventional GI, opening the possibility of improving the initial properties of the material and suitability for use in the open sandwich technique. The aim of this study was to compare microleakage of Ketac Molar, Ketac Molar set by ultrasound (US), Vitremer and Ketac N100 used in the open sandwich technique, with the control of a resin based composite, Filtek Z250. Two hundred Class II cavities were prepared in a hundred caries free, human, molar teeth, with half of the cervical margins placed apical and the rest coronal to the cemento-enamel junction. For each material, twenty restorations were placed for each cervical position. The sandwich materials were placed to fill the interproximal box level with the pulpal floor, and a final two layers of resin composite was then placed to complete the restoration. Restored teeth were stored in a laboratory oven for 7 days at 37 °C; margins were then finished initially with a medium grit Sof-Lex disc and finally with a fine diamond drill. Material groups were separated into two halfs to commence microleakage testing or thermocycling. Thermocycling was conducted for 500 cycles between 5 °C and 55 °C, with a dwell time of 30 seconds. Restored teeth were then covered with nail varnish around the restoration margins, and immersed in 0.5% basic fuchsin solution for 24 hours. They were then cleaned, embedded in clear self-curing acrylic and sectioned 3 times with an Accutom-2 precision saw, at 2 mm intervals. Sections were evaluated using a light microscope under 4 time’s magnification and microleakage scores given as: 0 = no leakage; 1 = < ½; 2 = > ½ distance to the axial wall/pulpal floor; 3 = leakage up to axial wall/pulpal floor. Statistical analysis was undertaken using Analysis of Variance (ANOVA) for the cervical and occlusal microleakage scores; p-values <0.05 were considered significant. The cervical microleakage results of cavity margins in dentine showed that Ketac Molar (US) performed better than Ketac Molar, and Ketac N100 performed better than Vitremer. Results in enamel showed no significant differences. The use of the open sandwich technique effectively reduced microleakage of cervical cavity margins placed in dentine but failed to reduce occlusal microleakage of Filtek Z250. Copyright / Dissertation (MSc(Odont))--University of Pretoria, 2008. / Odontology / unrestricted

A novel antimicrobial dental composite system has been developed and evaluated.Both alumina and zirconia filler particles were covalently coated with an antibacterial resin and blended into a composite formulation, respectively. Surface hardness and bacterial viability were used to evaluate the coated alumina filler-modified composite.Compressive strength and bacterial viability were used to evaluate the coated zirconia filler-modified composite. Commercial composite Kerr was used as control. The specimens were conditioned in distilled water at 37°C for 24 h prior to testing. Four bacterial species Streptococcus mutans, Staphylococcus aureus, Pseudomon asaeruginosa and Escherichia coli were used to assess the bacterial viability. Effects of antibacterial moiety content, modified particle size and loading, and total filler content were investigated.<div><br><div>Chapter 2 describes how we studied and evaluated the composite modified with antibacterial resin-coated alumina fillers. The results showed that almost all the modified composites exhibited higher antibacterial activity along with improved surface hardness, as compared to unmodified one. Increasing antibacterial moiety content, particle size and loading, and total filler content generally increased surface hardness. Increasing antibacterial moiety, filler loading, and total filler content increased antibacterial activity. On the other hand, increasing particle size showed a negative impact on antibacterial activity. The leaching tests indicate that the modified experimental composite showed no leachable antibacterial component to bacteria.<br></div><div><br></div><div>Chapter 3 describes how we studied and evaluated the composite modified with antibacterial resin-coated zirconia fillers. The results showed that almost all the modified composites exhibited higher antibacterial activity along with decreased compressive strength, as compared to the unmodified control. It was found that with increasing antibacterial moiety content and modified filler loading, yield strength,modulus and compressive strength of the composite were decreased. In addition,the strengths of the composite were increased with increasing powder/liquid ratio.On the other hand, with increasing antibacterial moiety content, filler loading and powder/liquid ratio, antibacterial activity was enhanced.<br></div><div><br></div><div>In summary, we have developed a novel antibacterial dental composite system for improved dental restoratives. Both composites modified with the antibacterial resin-coated alumina and zirconia fillers have demonstrated significant antibacterial activities.The composite modified with the alumina fillers showed improved hardness values, but the composite modified with the zirconia fillers showed decreased compressive strength values. It appears that the developed system is a non-leaching antibacterial dental composite.<br></div></div>