Saudi Cultural Missions Theses & Dissertations
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Item Open Access In vitro Antibiofilm Activity of Cold Atmospheric Plasma on Enterococcus Faecalis(Univeristy of Liverpool, 2024) ALqahtani, Omar; Jarad, Fadi; Walsh, James; Longridge, Nicholas; Horsburgh, MalApical periodontitis is an infection primarily caused by bacteria that invade the dental pulp and periapical tissues, necessitating effective management to preserve tooth function and aesthetics through endodontic procedures. E. faecalis is one of the most significant bacteria implicated in endodontic treatment failure. Effective disinfection of the root canal system is crucial for reducing the bacterial load and ensuring long-term treatment success. Traditionally, NaOCl has been the gold standard for root canal disinfection due to its broad-spectrum antimicrobial properties. However, NaOCl presents several significant drawbacks, including potential safety concerns, adverse effects on dentine mechanical properties, and limited penetration into the dentinal tubules. These limitations necessitate the exploration of alternative or adjunctive disinfection methods that can offer enhanced efficacy and safety. Atmospheric plasma jet (APJ) technology has emerged as a promising alternative in various fields due to its potent antimicrobial properties. APJ has been investigated in areas such as food safety, industrial sanitation, medical sterilisation, and more recently, dentistry. The APJ generates reactive oxygen species (ROS), which are believed to play a critical role in its antimicrobial activity. Although the precise mode of action of APJ is not yet fully understood, its broad-spectrum antimicrobial effectiveness highlights its potential as a significant area of interest for researchers aiming to enhance endodontic treatment disinfection. The primary aim of this research was to investigate the antimicrobial efficacy of APJ against E. faecalis biofilms on hydroxyapatite (HA) discs. A secondary aim was to determine whether adding NaOCl 0.5% to APJ treatment would enhance its antimicrobial efficacy, thereby testing the synergistic potential of the combined treatment. In addition, phosphate-buffered saline (PBS) was used as the liquid medium and tested in two ways to evaluate its antimicrobial efficacy. The first method involved applying APJ to PBS without the HA disc sample for a determined period. The sample was then inserted into the activated PBS without further application of APJ to observe any antimicrobial activities generated by the APJ. This group was referred to as Plasma-Activated PBS (PAPBS). The second method involved exposing the sample to continuous APJ application while it was in the PBS medium. This approach aimed to enhance the disinfection process by utilising both APJ and the ROS generated in the PBS. The PBS media treated the sample with APJ during its time in PBS, resulting in a group termed Plasma-Enhanced PBS (PEPBS). The objective of comparing these two methods was to determine which technique would result in more significant bacterial reduction, thus guiding future clinical applications. The methodology involved culturing E. faecalis biofilms on HA discs in10 BHI broth under anaerobic conditions at 37°C. Biofilms were grown for different periods: 24 hours, 1 week, and 3 weeks, to represent varying stages of biofilm maturity. Treatment groups comprised a negative control PBS, a positive control (1% NaOCl), and various combinations involving APJ alone, PEPBS, PAPBS and APJ with 0.5% NaOCl. Biofilms were exposed to the antimicrobial agents for 1, 5, and 10 min. Bacterial reduction was assessed using CFU counting. For statistical analysis, a three-way ANOVA was employed to evaluate the significance of the results. The results demonstrated that while 1% NaOCl exhibited the highest reduction rate for immature biofilms, the mature biofilm showed higher resistance. In contrast, APJ showed superior performance in killing mature biofilms. APJ alone, PEPBS, and PAPBS provided significant differences compared to the control group. Notably, the combination of APJ and 0.5% NaOCl achieved 100% eradication of E. faecalis biofilms regardless of their age, highlighting a synergistic effect that significantly enhances antimicrobial efficacy, indicating the potential of APJ to improve the performance of various irrigants.16 0Item Restricted The Interaction Between Hydroxyapatite and Citric Acid(The Catholic University of America, 2014) Alhubaysh, Abeer Abdullah; Wilson, OttoHydroxyapatite (HAp) [Ca10(PO4)6(OH)2] is an inorganic compound which has similar chemical composition as bone and citric acid (CA) [C6H8O7 ] is an weak organic acid. In this work the complex (HAp-CA) formed by their interaction is characterized by X-ray diffraction (XRD) analysis and Zeta potential (ZP) measurement as a function of pH of the complex solution. The results of XRD analysis have revealed a monoclinic pattern of the HAp-CA complex with the most pronounced diffraction line, observed at a 2θ of 32.179°. In ZP measurement experiments, the isoelectric point (IEP) for the complex was found to be 1.6 which is well shifted from that of HAp alone (IEP for HAp = 6.5, measured in several previous studies). Also the measured values of ZP in acid medium was found to be higher than that in alkaline medium due to particle size reduction of HAp with increased concentration of CA. The present study can be potentially applied in cancer therapies and drug deliveries.9 0Item Restricted Altering the Morphological Properties of Nano-Scale Hydroxyapatite Via Sol-Gel Synthesis.(Saudi Digital Library, 2023-11-03) Alnasr Allah, Fahad; Miller, Cheryl; Harrison, Caroline; Joshi, ShivaniBackground: Bone defects and infections are significant clinical challenges facing maxillofacial and orthopaedic surgeons. These conditions can arise from trauma, cancer or infections, leading to bone tissue loss and structural changes requiring intervention and treatment. Traditional approaches to bone regeneration and infection management have limitations (e.g., immunological rejection by the host, transmission of diseases and costs); this highlights the need for innovative solutions to overcome the clinical obstacles associated with traditional treatment of bone defects. Nano-hydroxyapatite biomaterials have shown promising effects when used as bone graft substitutes because they promote bone tissue growth, making them candidates for addressing bone defects. Materials and Methods: Nano-scale hydroxyapatite was synthesised via the sol-gel method, three with different stirring speeds overnight and the fourth batch with 5 g of 3-Aminopropyltriethoxysilane (APTES) stirred at medium stir speed overnight. After that, the supernatant was poured off, and the nHA was washed until the conductivity was stable. The suspensions were dried to a powder (for characterisation) in the oven at 60°C overnight. The samples were characterised using x-ray diffraction (XRD) to identify the crystal phases, transmission electron microscopy (TEM) to image the particle shapes and zeta potential to analyse the surface charge. Results: All samples were successfully crystallised based on the XRD results. The main crystal phase of all the experimental samples was identified precisely and matched those specified in (pure hydroxyapatite, JCPDS card #09-0432), but the samples prepared had a lower degree of crystallinity than the ReproBone® novo. In addition, the stirring speed and/or the addition of APTES affected the size, morphology, particle aggregate and surface charge. Conclusion: Within the study's limits, it was concluded that the difference in the stirring speeds and/or the addition of APTES affect intense crystallisation. In addition, that affects the size, morphology, aggregate of particles and the surface charge of the particles. Thus, knowing the causes and effects of these changes may contribute to the synthesis of HA with better biocompatible and mechanical properties.24 0