• Nanotechnology-Based Dental Materials for Root Caries Management: Design Concepts and Advanced Strategies to Modulate Dysbiotic Patient-derived Oral Biofilms

      Balhaddad, Abdulrahman Abubaker; Melo, Mary Anne; Xu, Huakun H.; 0000-0001-6678-7940 (2021)
      The distinctive challenges associated with root caries demand innovative interventions to preserve the tooth structure and surrounding soft tissues. This dissertation is composed of a set of manuscripts aiming to advance the anti-biofilm approaches to prevent root caries from two perspectives: (i) invasive approach via novel bioactive resin composites, and (ii) non-invasive approach via magnetic field-guided antimicrobial photodynamic therapy (MF-aPDT). The first chapter provided a general introduction concerning the clinical burden of root caries, current treatment modalities, and their limitations. In the second chapter, I provided an overview of contact-killing monomers and bioactive fillers in restorative dentistry. Then, in chapter three, we developed bioactive resin composite formulations containing dimethylaminohexadecyl methacrylate (DMAHDM) antibacterial monomer and 20% nano-sized amorphous calcium phosphate (NACP) and subjected them to a series of mechanical/physical tests and antibacterial assays. We found that the DMAHDM-NACP resin composites were associated with a potent antibacterial action against cariogenic and periodontal biofilms, as 2 to 6-log reduction was observed. Other virulence factors, as lactic acid production, and polysaccharide production, were also reduced. The mechanical properties, physical characteristics, surface features, and polymerization behavior were comparable to the commercial control at baseline testing and after one year of aging. We concluded that the designed bioactive formulations might present a pathway to preven recurrent caries and the onset of periodontal diseases around dental restorations. In chapter four, we reviewed the most recent updates related to the implementation of nanotechnology to enhance antimicrobial photodynamic therapy (aPDT). Then, in chapter five, we investigated the impact of encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) and toluidine blue ortho (TBO) inside a microemulsion, named MagTBO, to enhance the TBO’s penetration and antibacterial action against S. mutans and saliva-derived biofilms. Besides, the ability of magnetic field (MF) navigation to serve as a biofilm penetration strategy was also investigated. The MagTBO microemulsions were synthesized successfully and demonstrated excellent biocompatibility and thermodynamic stabilities. Furthermore, the MagTBO microemulsions demonstrated more remarkable and significant antibacterial action than conventional aPDT, especially when the MF is applied. Thus, this approach can be an adjunctive technique to control dental caries and other oral diseases.