Shelyn Akari Yamakami

Globally, young women now outpace young men in higher education, accounting for approximately 46% of enrollments compared with 40% for men.1 Yet, despite these gains in education, leadership roles ...

This study evaluated whether an experimental chitosan hydrogel loaded with amine-functionalized nanohydroxyapatite could reduce dentin demineralization and promote remineralization in an in vitro GERD model. A total of 176 bovine dentin specimens were initially eroded with hydrochloric acid and distributed into four treatment groups: untreated control, chitosan gel, experimental hydrogel, and 4% TiF4 varnish, with or without abrasion. The specimens were then exposed to liquid or gaseous hydrochloric acid for 6 days. Remineralization intensity and depth were assessed by swept-source OCT, surface morphology by scanning electron microscopy, and chemical changes by µ-Ramam spectroscopy.OCT showed that the experimental hydrogel produced the highest brightness and greatest mineralized depth, reaching 320–333 µm under gaseous HCl and 255–280 µm under liquid HCl, whereas the untreated control showed the lowest depth values (143–170 µm). TiF4 varnish provided the strongest surface protection, while the experimental hydrogel showed the best depth- related remineralization. Liquid hydrochloric acid caused more severe demineralization than gaseous acid, and abrasion intensified mineral loss, especially in untreated dentin. Morphological analysis showed narrower dentinal tubules and a thin deposited surface layer in the experimental hydrogel and chitosan groups, and the experimental hydrogel also showed stronger phosphate-related Raman bands under liquid acid challenge. However, none of the treatments preserved the organic matrix at the level of sound dentin. Within the limitations of this in vitro study, the experimental hydrogel and TiF4 varnish showed promising but distinct protective effects against dentin erosion: the hydrogel favored deeper remineralization, whereas TiF4 provided stronger superficial protection.

Dental caries is considered one of the most common oral health diseases. The aim of the study was to evaluate the effects of an experimental chitosan/casein gel on enamel demineralization/remineralization in an environment with a high cariogenic challenge. Thirty-six specimens of bovine enamel (4 mm × 3 mm × 2 mm) were ground flat and polished. Then, the specimens were immersed in acetate buffer for 43 h with half of the surface protected (serving as control) and the other half exposed. All demineralized surfaces were randomly assigned into 3 groups (n = 12 per group) according to the type of treatment (G1 - control, G2 - 1.5% chitosan gel with 1.5% casein, and G3 - 1.5% chitosan gel without casein), and the corresponding treatment was applied once a week for 3 weeks. The specimens were also subjected to pH cycles of demineralization/ remineralization and the treatments were performed 3 times at 7-day intervals for a total of 21 days. Surface images were obtained for the analysis of initial roughness and, after the cariogenic challenge, new images were obtained to evaluate the final roughness, volume loss and wear profile using laser confocal microscopy. After the analyses, the specimens were cut and the depth of demineralization was measured. The data were analyzed using the Kruskal-Wallis analysis of variance (ANOVA) and the Tukey's test. While the chitosan gel with casein showed a similar loss to the control group (p > 0.05), both gels resulted in similar volume loss (p > 0.05). There were no statistical differences regarding the wear profile, surface roughness and depth of demineralization between the groups (p > 0.05). The chitosan gel reduced volume loss of the demineralized enamel without significantly impacting the surface smoothness.

Introduction: The advancement of 3D digital scanners has allowed educators to uphold the quality of education whilst implementing novel methods of assessment.Objective: The purpose of this study was to compare two evaluation methods, conventional and digital scanned assessments, on student cavity preparations and students and faculty's perceptions of these assessment methods.Methods: Predoctoral students performed Class II amalgam and Class III resin composite preparations on simulated teeth for their preclinical competency examinations. Two calibrated faculty evaluated the students’ preparations using dental instruments for conventional assessments and 3D scanned images for digital assessments. Faculty scores from both assessment methods were compared and statistically analysed (p < .05). Students also self‐assessed their performance using the digital scanned images and filled out a perception survey.Results: There was no statistically significant difference between the conventional (Class II; 73.3 ± 12.2 and Class III; 82.5 ± 8.9) and the digital assessment with scanned images (Class II; 71.3 ± 11.0 and Class III; 82.2 ± 8.2). Faculty scores from both methods have shown a trend of comparability. Most students agreed that digital ideal preparation models were useful (84.2%) and almost all students agreed that digital technology helped them learn operative dentistry (91.1%). In contrast, most students agreed that conventional assessment should be the main self‐evaluation system (82.2%) and disagreed that digital assessment is more effective than conventional self‐assessment (68.3%).Conclusion: Our study demonstrated that 3D digital technology could be an alternative and/or supplementary educational tool to aid in upholding the quality of dental education.

Key words: Glass-ionomer cement; Adhesion; Molecular structure; Fourier Transform Infrared Spectroscopy; Raman Spectrum Analysis