Saudi Cultural Missions Theses & Dissertations
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Item 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 0Item Restricted Assessment of the Dentin Bond Strength Values of Resin Modified Glass Ionomer Restorative Material using Different In Vitro Test Methods(Carolina Digital Repository, 2016-05) Kensara, Anmar; Ko, Ching-Chang; Boushell, LeeObjective: To assess whether the in vitro dentin bond strength values of a resin modified glass ionomer restorative material (RMGI) are affected by different in vitro test methods. Methods: Mid-depth occlusal dentin of 36-extracted human third molars free of defects was exposed and finished with wet 600-grit silicon carbide paper for 10s. A commercially-available RMGI (Fuji II LC, GC America) was applied to all specimens according to manufacturer’s instructions, after which specimens were stored in 100% humidity at 37 °C for 24 h. Specimens were then randomly divided into three different test groups (n=12): shear bond strength (SBS), microtensile bond strength (μTBS), and four-point bending bond strength (4PBBS). Specimens were loaded to failure using universal testing machines and test-specific parameters: Instron for SBS and 4PBBS tests, EZ-Test for the μTBS test. The mode of bond failure (adhesive, cohesive or mixed) was qualitatively assessed with optical stereomicroscopy. Data were analyzed using one-way ANOVA and descriptive statistics. Results: There was a statistically significant difference between bond strength values for the different test methods (p<0.05). The mean bond strength values (± SD, in MPa) were 15.7 (±7.1) for SBS, 9.7 (±5.3) for μTBS and 37.3 (±12.8) for 4PBBS. With respect to the mode of failure, most SBS failures were adhesive in nature (83%), while the majority of μTBS and 4PBBS failures were mixed (69% and 47% respectively). Several μTBS and 4PBBS specimens failed during processing (before testing). Conclusion: The in vitro dentin bond strength values of a resin-modified glass ionomer material are greatly affected by the test method. The mode of bond failure is also affected by test method. The SBS test method demonstrated the highest percentage of adhesive failure and proved to be less technique sensitive. The majority of μTBS and 4PBBS failures were mixed. Use of the μTBS and 4PBBS may not be optimal laboratory test methods for comparison of the relative bond strength of RMGI materials to dentin. Use of the SBS test may allow more controlled comparison of the adhesive dentin bond among various RMGI formulations, whether already commercially available or under development.24 0