Saudi Cultural Missions Theses & Dissertations
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Item Restricted Novel Bioactive Low-Shrinkage-Stress Composite with Antibacterial and Remineralization Properties(Saudi Digital Library, 2023-11-28) Alhussein, Abdullah; Huakun, Xu; Michael, D. Weir; Abraham, Schneider; MaryAnn, Jabra-Rizk; Jirun, SunMethacrylate-based resin composites are frequently employed in dentistry for their aesthetic qualities, durability, and adhesive properties. Nevertheless, these restorations generally exhibit a lifespan of 5 to 10 years, with recurrent caries and tooth fractures being primary failure factors. Marginal integrity and the absence of bioactivity at the tooth-restoration junction contribute to recurrent caries development. Consequently, this dissertation endeavors to introduce a novel bioactive low-shrinkage-stress nanocomposite, featuring dimethylaminododecyl methacrylate (DMADDM) as an antibacterial agent, as well as remineralization nanoparticles of calcium fluoride (nCaF2) and nanoparticles of amorphous calcium phosphate (NACP), with the potential of increase the longevity of dental restoration and protect tooth structure. All novel formulations of low-shrinkage-stress composite were subjected to a series of mechanical, antibacterial, cytocompatibility, and ion release assessments. First, we investigated the optimum concentration of DMADDM that can be incorporated with a low-shrinkage-stress composite without compromising mechanical properties. We found that incorporation of up to 5% DMADDM into a low-shrinkage stress composite efficiently inhibited Streptococcus mutans (S. mutans) biofilm commonly associated with secondary caries. This potent antibacterial effect is achieved while maintaining excellent mechanical properties and minimizing polymerization shrinkage stress, potentially improving the long-term success of dental restorations. Next, we investigated the antibacterial and cytocompatibility of the incorporation of 3% DMADDM with 20% nCaF2 or 20% NCAP into a low-shrinkage-stress nanocomposite. We found that incorporating DMADDM with either nCaF2 or NACP into a low-shrinkage-stress nanocomposite provides a potent antibacterial effect against S. mutans biofilm while maintaining excellent mechanical properties. In addition, the novel formulations demonstrated excellent biocompatibility against human gingival fibroblasts and dental pulp stem cells. Lastly, we investigated the ions release and antibacterial properties against a salivary biofilm for our innovative formulations. The innovative mixture of DMADDM, NACP, and nCaF2 demonstrated strong antibiofilm effects on salivary biofilm, while concomitantly releasing a significant amount of remineralizing ions. This nanocomposite is a promising dental material with antibiofilm and remineralization capacities, with the potential to reduce polymerization-related microleakage and recurrent caries.23 0Item Restricted Surface Characteristics of Novel Dental Composite Materials Incorporating Fluorhydroxyapatite Crystals(Saudi Digital Library, 2020-11-04) Alhussein, Abdullah; Chang, Sywe-Ren; Yaman, Peter; Dennison, Joseph; Clarkson, BrianObjective: To investigate the hydrophobicity of composite surfaces, surface roughness and micro-hardness of three resin composites with and without fluorohydroxyapatite (FA). Material and methods: Three composite materials bisGMA, TMES/DNBPA and TMES/TNTATO with and without FA crystals were used. Five samples for each resin composite group were prepared as discs then finished using 600-grit wet silicon carbide paper for 5 seconds. All samples were polished using Sof-Lex™ Spiral Wheels in one direction for 15 seconds according to the manufacturer instructions. The hydrophobicity of composite surfaces were evaluated using a Ramé-Hart 200-F1 goniometer. Measurement of surface roughness was evaluated using the three-dimensional laser- measuring microscope. Micro-hardness test was used to determine the Vickers hardness number (VHN). Results were analyzed using 1-way ANOVA/ Tukey’s multiple comparison. Results: The Incorporation of the FA reduced the contact angle for the 3 composites, but this was statistically significant for only bisGMA/TEGDMA + glass + FA versus its non-FA control. All experimental composites had statistically smaller contact angles than those of bisGMA/ TEGDMA with or without FA. There was no significant different in surface roughness in bisGMA/TEGDMA + glass + FA versus its non-FA control, while in TMES/DNBPA and TMES/TNTATO group there was a significant increase in surface roughness value when FA was incorporated into the composites. The incorporation of the FA did not cause any significant difference in surface hardness in each composite group. Conclusion: The incorporation of FA reduced the contact angle value in all resin composites and increased the surface roughness of the experimental novel composites but not for the bisGMA/TEGDMA+ glass + FA group. Surface hardness was not affected by incorporation of FA.11 0