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Background: Coronavirus disease 2019 (COVID-19) has received marked attention globally. A worldwide call for social distancing occurred. Although the reduction of face-to-face consultation is required in order to reduce the risk of infection, dermatological services must be maintained in action and 'teledermatology' should be the solution.Materials & methods: We introduce a cross sectional observational study, demonstrating the patients' behavior regarding dermatological consultations in Cairo, Egypt in both private and Public practice. Synchronous (live interaction via What's app and Zoom) and asynchronous (What's app, emails) teledermatology models were used. After the end of the teleconsultation, patients were asked to fill a questionnaire adapted from the Telehealth Usability Questionnaire (TUQ). Results: There was an overall satisfaction and future use score among the interviewed patients that received Teledermatology services of 91.0%, a usefulness score of 93.7%, interface and interaction quality scores of 85.9% and 87.0%, ease and use learnability score of 87.8% and reliability score of 86.7%. Conclusion: Teledermatology was efficient in triaging and treatment, hence, decreasing risk of COVID-19 exposure for the physician, the patient and the paramedical personel in heavily populated third world countries. Legislation is needed to sanction physician compensation for tele dermatology where this does not exist.

Toothpastes arguably are the most common preparations used in the treatment of dentine hypersensitivity. Evidence for efficacy largely comes from clinical trials, and supports the role of the contained so-called "active" ingredient. How such compounds produce therapeutic benefit has received limited attention. This study measured the availability and uptake onto dentine of fluoride and metal ions contained in commercial and test toothpastes. The effects of exposure of dentine sections to these toothpastes, and abrasive only pastes in particular, was investigated by scanning electron microscopy and X-ray microanalysis. Aqueous extracts of the different toothpastes contained measurable concentrations of the incorporated metal and or fluoride, but usually considerably below that incorporated by the manufacturer. Extraction of dentine sections exposed to toothpaste slurries revealed levels of fluoride and metal ions, although post-treatment washing in water reduced these levels. Surface changes at 1 and 10 h were not consistent with the uptake of fluoride or metals. These changes were almost certainly produced by the contained abrasives, including calcium carbonate, dicalcium phosphate, alumina and silica. In particular fume silica progressively accumulated on the dentine surface to narrow and occlude dentinal tubules. Unlike other abrasives fume silica was resistant to removal by washing. It would appear that insufficient attention has been given to the therapeutic potential of toothpaste ingredients, particularly abrasives, to produce benefit by occlusion of dentinal tubules.

Dentine has been shown to possess affinity for a large number of varied compounds, many of which have been shown effective in clinical trials, for the treatment of dentine hypersensitivity. The mode of action of these compounds is unclear. The aim of this study was to investigate the uptake of metal ions, fluoride and formaldehyde in solution onto dentine in vitro and determine whether therapeutic effects could be mediated through occlusion of dentinal tubules. Etched dentine sections were exposed for 1 h to 1000 ppm solutions of fluoride and metal salts. Levels of fluoride and respective metals could be extracted and measured from the specimens. Saliva pretreatment had a variable but small effect on uptake of each ion, but post treatment washings reduced all levels of retained fluoride and metals. X-ray microanalysis indicated surface or immediate subsurface deposits of metals. However, surface changes were only consistently produced by zinc and more particularly tin salts. Both zinc and tin salts produced covering or obturation of tubules. The surface effects of zinc could largely be reversed by washing, but not those of tin. Formaldehyde alone or in the presence of saliva produced no effects. A 4-week study involving twice daily exposure of specimens to saliva and fluoride, metals or formaldehyde yielded essentially the same results. It is unlikely that, except for tin, the compounds tested achieve their apparent clinical effects mediated by direct occlusion of dentinal tubules.

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