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 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 0Item Restricted The Etiology of Peri-implantitis: Microbiological Profile Within and Around Dental Implants and the Associated Human Immune Response(2023) Kensara, Anmar; Masri, RadiObjectives: To characterize the microbiome composition within and around dental implants of peri-implantitis subjects and within and around healthy implants using 16S rRNA gene sequencing, and to profile salivary inflammatory mediators associated with peri-implantitis compared to healthy controls from the same subjects. Methods: A total of 24 subjects (peri-implantitis n=14, healthy n=10) were enrolled in the study. From the 24 subjects, 24 endosseous implants from affected (peri-implantitis) and 14 healthy controls were included in this cross-sectional study. Samples for microbiological analysis were obtained from the internal surfaces of dental implants and peri-implant sulcus using sterile paper points. DNA was extracted and 16S rRNA gene was amplified using universal primers targeting the V3-V4 regions. Amplicons were sequenced using Illumina MiSeq platform. Alpha and beta diversity, core microbiome, and taxa differential abundance were assessed. Saliva was collected from the same subjects for immunology-based assays. Salivary inflammatory mediators in peri-implantitis and healthy implant subjects were profiled using antibody arrays. Results: A significant increase in microbial diversity was observed in the internal implant surface of healthy implants compared with the internal surfaces of peri-implantitis (Shannon P= 0.02), and no significant differences in microbial diversity between healthy implants sulci and peri-implantitis pockets (Shannon P= 0.82). Bacterial community structure was significantly different within implant in both healthy and peri-implantitis groups (P= 0.012) but not significantly different around implants in both healthy and peri-implantitis (P= 0.18). Enterococci is the predominant bacteria within peri-implantitis (LD >2.0, P< 0.05). Abundant species in peri-implantitis were C. leadbetteri, T. maltophilum, Peptostreptococcus, Neisseria, P. gingivalis, and P. endodontali, L. lactis and F. alocis (P < 0.05). Gram-positive bacteria such as S. salivaris, P. melaninogenica, L. wadei, and Actinomyces spp were more abundant in the peri-implant healthy sulcus. Around 48% of detected bacteria were cultivable in general media. In addition, out of 105 analytes examined in saliva, we found that 29 mediators were upregulated in subjects with peri-implantitis (P < 0.001). Conclusions: Our results indicate that microbial colonization of the internal implant surface may act as a major contributor to the etiology of peri-implant disease. Multiple inflammatory mediators were significantly elevated in the saliva of peri-implantitis patients compared to healthy implant patients.30 0