Saudi Cultural Missions Theses & Dissertations
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Item Restricted Effect of blood and saliva on the compressive strength and solubility of three Calcium-Silicate based cements.(University of Manchester, 2024) Almousa, Murtadha; Cunliffe, JoanneIntroduction: Apical microsurgery is one of the valuable treatment options in the endodontic field. One of the significant factors that evolved the outcome of apical microsurgery is the calcium- silicate-based cements (CSCs) as retrograde filling. These cements are believed to have high biocompatibility, stimulate hard tissue formation, and better sealing ability. However, the solubility and compressive strength of these cements are important characteristics to prevent bacterial leakage and apical periodontitis. Aim of this study: to evaluate the impact of blood and saliva contamination on the compressive strength and solubility of ProRoot MTA, Biodentine, and MTA Angelus compared to dry condition (no exposure to liquid). Materials and methods: 180 resin moulds were fabricated using a 3D printer. The materials were then condensed in the moulds and incubated for one week in 37 oC with 100% humidity. Each material was then divided into three subgroups (n=10) and exposed to blood, saliva, and dry conditions for one week. Compressive strength was tested using a Universal Testing Machine and the solubility using a weight scale to compare the weight before and after exposure. Results: Regardless of the exposure conditions, Biodentine had the highest compressive strength, followed by ProRoot MTA and MTA Angelus. The highest solubility rate was found in the MTA Angelus group, followed by Biodentine and ProRoot MTA. Saliva positively impacted all materials' compressive strength and solubility rate, with statistical differences compared to other exposure conditions. All materials did not favour the dry conditions as it negatively influenced their compressive strength and solubility. Conclusion: the findings of this study suggested that exposure to blood or saliva did not negatively impact the compressive strength and solubility of all tested materials. This indicated that these materials could maintain their properties even in the presence of oral fluids.10 0Item Restricted Influence of diphenyliodonium hexafluorophosphate salt (DPI) and ion-releasing glass fillers (45S5) on physical, mechanical and chemical properties of model resin composite formulations(University of Manchester, 2024-07-30) Alotaibi, Saad; Silikas, Nick; Watts, DavidRecurrent dental caries is a major reason for resin composite restoration replacement. 45S5 Ion-releasing glass (IRG) fillers are promising for functionalizing resin composites. They aid in hydroxyapatite deposition and remineralization of dental tissues. Diphenyl iodonium hexafluorophosphate (DPI) is a UV light initiator that replenishes Camphorquinone (CQ) by replacing inactive radicals with phenyl active radicals. The aim of this research was to explore the interactive effect of DPI and IRG on short and long-term material properties. Model resin-composites with varying amounts of IRG were prepared using a UDMA/TEGDMA resin system and either a unary or binary (includes DPI) photo-initiator system. Polymerization related properties such as degree of conversion (DC), shrinkage strain (SS) and depth of cure (DoC) were measured. IRG negatively impacted DC and DoC when higher content was used while DPI improved both DC and DoC. The SS was lower in the unary group and with higher IRG content confirming an inverse relation between DC and SS. Martens hardness (HM) and related parameters, indentation modulus (EIT) and creep (CIT), as well as the effect of storage in water or ethanol on these parameters were tested. HM and EIT decreased and CIT increased linearly as the amount of IRG is increased. Deterioration of HM and EIT through aging was more pronounced in specimens containing higher IRG amount. DPI showed higher HM, EIT and lower CIT only at higher IRG content compared to the unary group. Water sorption, solubility, hygroscopic dimensional changes and ions release were assessed. IRG significantly increased water sorption, solubility and hygroscopic expansion. Inclusion of DPI reduced water sorption, solubility and hygroscopic expansion. Release of calcium, sodium and phosphate were dose dependent on IRG. This study concluded that 45S5 IRG, while offering potential means of remineralisation, diminished the material’s overall properties. The inclusion of DPI enhanced the polymerization and overall properties of the tested model resin composites.10 0Item Restricted Temperature Dependent Partition Coefficients of Cyclohexylamine and Ethanolamine Between Octanol and Water Phases.pdf.pdf(2023-05-13) Alhilal, Ahmed Atiah S; Liu, YongThis study has investigated temperature dependence of octanol/water partition coefficients of cyclohexylamine and ethanolamine in temperature ranges of 5 to 25°C for cyclohexylamine and 17.5 to 25°C for ethanolamine. Experiments are largely based on a method developed by a researcher at the University of South Florida, which can help reduce chemical waste, save effort and time, and generate more reliable results. The study has found that the partition coefficient of cyclohexylamine is higher than that of ethanolamine, consistent with literature results. This also indicates that our approach is probably valid. By investigating correlation between chemical descriptors and partition coefficients of more than 1500 amine chemicals theoretically, we have shown that cyclohexylamine has higher values for descriptors that are positively correlated with logP. In addition, it has been found that temperature influences the partition coefficient of ethanolamine more than that of cyclohexylamine, probably due to smaller molecule size of ethanolamine. The partition coefficient of cyclohexylamine has a seemingly inverse relationship with temperature. On the other hand, temperature dependence of ethanolamine is more complicated. Moreover, we have determined thermodynamics of partition process including enthalpy, entropy, and free energy. Overall, these findings could be used to better assess their potential risks to public health.33 0