Background Coronavirus disease (COVID-19) was first reported on 31 December 2019 and has rapidly been spreading day by day. Dental patients and professionals have a high risk of the coronavirus infection and also have a huge responsibility to prevent its spread during emergency dental treatment over the period of the COVID-19 outbreak. Aim Informing patients and dental practitioners about the novel coronavirus in an accurate and effective way is very important. Therefore, this study aimed to evaluate the quality of dentistry-related medical information about COVID-19 on YouTube as educational resources for dental practitioners. Methods YouTube was queried for the search phrases 'COVID-19 and dental practice', 'SARS-Cov-2 and dental practice' and '2019-COV-2 and dental practice'. The first 100 videos for each term were viewed and analysed by 3 independent investigators. The scope was limited to videos in English. Results The search phrases yielded 1102 videos, among which 802 videos were excluded and 300 videos screened. Fifty-five videos were included in the final analysis. Of the 55 videos, only 2 videos (3.6%) were found to be of good quality, while 24 videos (43.6%) were found to be of poor quality. Conclusion YouTube is a popular video broadcast site and can provide both relevant educational information and the spreading of misinformation. Health professionals should play a more active role with regard to educative information given on social media, especially YouTube, during global disease outbreaks.

INTRODUCTIONCigarette users are more susceptible than non-smokers to periodontitis, a bacterial-induced, inflammation-driven, destructive disease of the supporting tissues of the teeth. We hypothesized that clinical periodontal findings and microbiological and/or inflammatory marker levels would be intermediate in those exposed to environmental tobacco smoke compared to active smokers and non-smokers.METHODSSixty individuals were recruited from a University periodontal clinic and assigned as non-smokers, active smokers or passive-smokers according to their self reports. Clinical periodontal measurements, comprising plaque index, probing depth (PD), clinical attachment level (CAL) and bleeding on probing, were recorded at six sites per tooth. Cotinine levels were determined in whole saliva samples by EIA. Treponema denticola and Porphyromonas gingivalis infection was determined by PCR, while matrix metalloproteinase-8 (MMP-8) and interleukin-8 (IL-8) concentrations were determined by ELISA.RESULTSStudy groups were subsequently reassigned in accordance with the cotinine data. The smoker group exhibited higher mean PD and CAL values compared to the non-smoker group (p<0.05). Passive-smokers exhibited PD and CAL values smaller than those of the active smokers and greater than those of the non-smokers, but the differences were not statistically significant. PD and CAL values correlated with cotinine concentrations (p<0.05). P. gingivalis infection was noted in most subjects, irrespective of smoking status. T. denticola infection was noted in 4/23 (17.4%) smokers, 0/16 (0%) environmentally-exposed recruits and 2/21 (9.5%) non-smokers. Salivary MMP-8 and IL-8 levels were lower in smokers compared to both non-smokers and passive-smokers but the differences were not significant (all p>0.05).CONCLUSIONSThe present clinical periodontal findings provide further support for a negative, dose-related effect of tobacco exposure on periodontal health. The tendency for a more prevalent detection of T. denticola and for a suppressed inflammatory response observed in the smokers may partly explain the increased susceptibility to periodontal tissue destruction, but needs to be verified in larger scale studies.

Background:To evaluate possible effects of smoking on clinical, biochemical, and microbiological outcomes of non-surgical periodontal treatment in patients with periodontitis Stage III or IV and Grade C. Methods:Conventional quadrant-wise non-surgical periodontal treatment was performed and whole-mouth periodontal measurements were recorded at baseline, 1, 3, and 6 months after completion of treatment. Saliva, gingival crevicular fluid, subgingival plaque, and blood samples were obtained at the same time points.Inflammatory cytokine levels, presence, and quantities of 11 different bacterial species were determined. Smoking status was validated by cotinine assay.Results: Fourteen smoker and 13 non-smoker patients completed the study protocol and revealed similar clinical findings except for the higher plaque scores in the nonsmokers at 6 months (P <0.01). Significant differences were found between the study groups in biofluid cytokine levels at 1 and 3 months (P <0.01). Gram-negative bacteria were more abundant in the smokers at baseline and so were Gram-positive bacteria in the non-smokers (P <0.01). Gram-negative bacteria repopulated in the smokers faster than in the non-smokers (P <0.01). Conclusions:The present findings suggest that smoker patients with periodontitis Stage III and IV, Grade C respond well to the non-surgical periodontal treatment during the 6-month follow-up. However, smokers exhibit faster repopulation of Gram-negative bacteria. K E Y W O R D Sbacteria, cytokines, gingival crevicular fluid, periodontitis, smoking 442

Basic clinical periodontal parameters for periodontal diagnosis as well as evaluation of prognosis and treatment outcomes are probing depth and clinical attachment level, gingival inflammation, and level of oral hygiene. Endpoints of active periodontal treatment have been recently revisited during the World Workshop for Classification of Periodontal and Peri-implant Diseases 1 . It was found that periodontitis patients with a low proportion of deep residual pockets after active periodontal therapy are more likely to be stable in long follow-up periods.

Periodontal diseases are among the most common chronic inflammatory diseases worldwide, whereas periodontitis is characterized by attachment loss and destruction of alveolar bone. The cardinal signs of inflammation are rubor (redness), tumor (swelling), calor (heat), dolor (pain), and functio laesa (loss of function). Some or all of these signs of inflammation can be seen in periodontitis cases, and advanced disease may cause tooth loss (Highfield, 20 09). Periodontitis continues to be a major global oral health problem that causes partial or complete edentulism in approximately 5%-20% of the adult population (Watt & Petersen, 2000). Apart from the functional problems, premature tooth loss is regarded as an important cause of decreased self-esteem. Moreover, restoration of lost teeth by dentures creates tremendous financial burden for the individual patient as well as for the government or insurance companies. Clearly, having access to proper information about periodontal disease etiology and its clinical signs is of vital