Background The COVID-19 pandemic has become a global health issue and has had a major impact on education. Consequently, half way through the second semester of the academic year 2019/2020, learning methods were delivered through distance learning (DL). We aimed to evaluate the student perspective of DL compared to classroom learning (CL) in the undergraduate dentistry study program at the Faculty of Dentistry Universitas Indonesia. Methods An online questionnaire was sent at the end of the semester. A total of 301 students participated in the study. Results Duration of study influenced student preference. Higher number of first-year students preferred DL compared to their seniors (p < 0.001). Students preferred CL for group discussion, as DL resulted in more difficult communication and gave less learning satisfaction. Only 44.2% students preferred DL over CL, although they agreed that DL gave a more efficient learning method (52.6%), it provided more time to study (87.9%) and to review study materials (87.3%). Challenges during DL included external factors such as unstable internet connection, extra financial burden for the internet quota and internal factors such as time management and difficulty to focus while learning online for a longer period of time. Conclusion Despite some challenges, dental students could adapt to the new learning methods of full DL and the majorities agreed blended learning that combined classroom and distance learning can be implemented henceforth. This current COVID-19 pandemic, changes not only the utilization of technology in education but the pedagogy strategies in the future.

The gingival epithelium acts as a physical barrier to separate the biofilm from the gingival tissue, providing the first line of defense against bacterial invasion in periodontal disease. Disruption of the gingival epithelial barrier, and the subsequent penetration of exogenous pathogens into the host tissues, triggers an inflammatory response, establishing chronic infection. Currently, more than 700 different bacterial species have been identified in the oral cavity, some of which are known to be periodontopathic. These bacteria contribute to epithelial barrier dysfunction in the gingiva by producing several virulence factors. However, some bacteria in the oral cavity appear to be beneficial, helping gingival epithelial cells maintain their integrity and barrier function. This review aims to discuss current findings regarding microorganism interactions and epithelial barrier function in the oral cavity, with reference to investigations in the gut, where this interaction has been extensively studied.

Several studies have demonstrated the remarkable properties of microbiota and their metabolites in the pathogenesis of several inflammatory diseases. 10-Hydroxy-cis-12-octadecenoic acid (HYA), a bioactive metabolite generated by probiotic microorganisms during the process of fatty acid metabolism, has been studied for its protective effects against epithelial barrier impairment in the intestines. Herein, we examined the effect of HYA on gingival epithelial barrier function and its possible application for the prevention and treatment of periodontal disease. We found that GPR40, a fatty acid receptor, was expressed on gingival epithelial cells; activation of GPR40 by HYA significantly inhibited barrier impairment induced by Porphyromonas gingivalis, a representative periodontopathic bacterium. The degradation of E-cadherin and beta-catenin, basic components of the epithelial barrier, was prevented in a GPR40-dependent manner in vitro. Oral inoculation of HYA in a mouse experimental periodontitis model suppressed the bacteria-induced degradation of E-cadherin and subsequent inflammatory cytokine production in the gingival tissue. Collectively, these results suggest that HYA exerts a protective function, through GPR40 signaling, against periodontopathic bacteria-induced gingival epithelial barrier impairment and contributes to the suppression of inflammatory responses in periodontal diseases.

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