Saudi Cultural Missions Theses & Dissertations
Permanent URI for this communityhttps://drepo.sdl.edu.sa/handle/20.500.14154/10
Browse
2 results
Search Results
Item Restricted Impact of Preparation Designs and Computer-Aided Design/Computer-Aided Manufacturing Materials on the Fracture Resistance of Dental Posterior Indirect Adhesive Restorations(The University of Lowa, 2024-05-14) Alzahrani, Khulood; Leme-Kraus, Ariene; Vargas, Marcos; Restrepo-Kenedy, Natalia; Teixeira, EricaThis study evaluated two Posterior Indirect Adhesive Restorations (PIARs) preparation designs restored with different Computer-aided design and Computer-aided manufacturing (CAD/CAM) materials on the tooth-restoration fracture resistance as compared with sound tooth structure. The tested null hypotheses were: there will be no difference in the fracture resistance between the control group and the different PIAR designs, and there will be no difference in the fracture resistance between the control group and the different CAD/CAM materials. Seventy-five crack-free, sound human molars (n=15/group) were randomly divided into five groups: C (Control, sound tooth), A-Hyb (Design-A preparation with rounded-shoulder finish line) restored with hybrid nano ceramic block, A-LiSi (Design-A prep with rounded-shoulder finish line) restored with lithium disilicate block, B-Hyb (Design-B preparation with butt-joint finish line) restored with hybrid nano ceramic block, B-LiSi (Design-B prep with butt-joint finish line) restored with lithium disilicate block. The cementation process involved selective enamel etch, followed by application a self-adhesive primer and self-adhesive resin cement. The specimens were thermo-cycled (10,000 cycles, simulating approximately 1 year of aging), followed by mechanical cycling (500,000 cycles at 50 N, positioned 90° with the occlusal surface at a frequency of 1 Hz, simulating approximately 2 years of aging). The fracture resistance of the tooth-restoration system was assessed through a compressive test using a Zwick universal machine. The specimens were subjected to compressive load at a 90° angulation using a 5 mm stainless-steel conical-shaped piston in a compression test apparatus until fracture. Statistical analysis was conducted using two-way ANOVA to compare the means among the five groups, and Tukey post hoc tests to compare the mean pairwise if a significant difference was found at α = 0.05. Further statistical analysis was undertaken through linear regression analysis, aimed at explaining the relationships between material types, preparation designs, and the fracture pattern. The control group data was integrated as a reference level within the regression framework enabling the interpretation of coefficients, providing insight into how each variable’s alteration influences the fracture resistance relative to control. All tests were done with the type-1 error rate of α = 0.05. The results revealed that no statistically significant differences were observed among groups considering preparation design (p = 0.972) or materials (p = 0.278) and they were not statistically significant differences in relation to the sound tooth (p > 0.05). The regression analysis showed a significant correlation in the value of the fracture resistance (Fmax) between the cracked group and the other fracture pattern gropes. Specimens with the lowest Fmax values demonstrated crack type of fracture; while type IV had the highest mean Fmax value. In conclusion, PIARs fabricated with CAD/CAM materials achieved comparable fracture resistance to those of sound teeth when applied with precision and adherence to clinical and manufacturing guidelines regardless of the preparation design and the material selection. There were no differences in fracture resistance regardless of the material type and the preparation design.42 0Item Restricted Investigating dental Glass ionomer cement surface hardness and shear bond strength after incorporate it with Chlorhexidine(Saudi Digital Library, 2023-11-28) Alshehab, Bassam Abdullah; Huang, JieThis research project aims to investigate the impact of integrating chlorhexidine (CHX) into glass ionomer cement (GIC) on its surface hardness and shear bond strength. GIC samples were modified with different concentrations of CHX to achieve this objective. The surface hardness of the control and modified samples were measured using the Vickers hardness test. Shear bond strength (SBS) was evaluated using the universal testing machine and shearing jig, employing zirconia and hydroxyapatite (HA) as a substrate. The null hypothesis assumed there was no significant difference on surface hardness and SBS after adding CHX into the GIC. One control group and three variables were examined in this study: the control group (was composed of GIC without the addition of CHX) and the three trial groups were GIC with the addition of 5%, 10% and 20% concentrations of CHX, respectively. To confirm the presence of CHX in the modified samples, Fourier transform infrared spectroscopy (FTIR) analysis was utilised. The results of FTIR shows different peaks for the control group and characteristic peaks of CHX, which represents the presence of CHX in the modified samples. These peaks were not present after 24 hours, suggesting the leaching of CHX. A one-way ANOVA single factor analysis and Tukey’s test indicated significant differences in surface hardness after incorporating CHX into GIC. In terms of SBS, increases of mean values were observed in all modified groups. However, ANOVA single factor analysis indicated no significant difference between the GIC control group and the modified groups with different CHX concentrations (p-value > 0.05) when using zirconia and HA as a substrate. This study concluded that the null hypothesis was partially rejected, because the surface hardness was affected by adding CHX; possible applications of this modified GIC include temporary luting cement or interim restoration between root canal treatment, as of CHX is presence for a short time. Further investigation is needed to evaluate other mechanical properties and antimicrobial activity.23 0