COVID-19 and Dentistry in 72 Questions: An Overview of the Literature.

The outbreak of Coronavirus Disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has significantly affected the dental care sector. Dental professionals are at high risk of being infected, and therefore transmitting SARS-CoV-2, due to the nature of their profession, with close proximity to the patient's oropharyngeal and nasal regions and the use of aerosol-generating procedures. The aim of this article is to provide an update on different issues regarding SARS-CoV-2 and COVID-19 that may be relevant for dentists. Members of the French National College of Oral Biology Lecturers ("Collège National des EnseignantS en Biologie Orale"; CNESBO-COVID19 Task Force) answered seventy-two questions related to various topics, including epidemiology, virology, immunology, diagnosis and testing, SARS-CoV-2 transmission and oral cavity, COVID-19 clinical presentation, current treatment options, vaccine strategies, as well as infection prevention and control in dental practice. The questions were selected based on their relevance for dental practitioners. Authors independently extracted and gathered scientific data related to COVID-19, SARS-CoV-2 and the specific topics using scientific databases. With this review, the dental practitioners will have a general overview of the COVID-19 pandemic and its impact on their practice.

Lupinus albus, a novel vegetable extract with metalloproteinase inhibitory properties: a potential periodontal therapy.

BACKGROUND: In this study we examine the properties of a vegetable extract from seeds of Lupinus albus (LU 105). In previous works we demonstrated that LU 105 reduced the expression, by gingival fibroblasts, of both matrix metalloproteinase (MMP)-2 and MMP-9. We decided to study the impact of LU 105 on cell proliferation and morphology. Using organ culture media we also studied the MMP and tissue inhibitors of metalloproteinases (timp) expression AND THE cytokines secretion. METHODS: Healthy and inflamed gingival biopsies were placed in appendage culture with or without LU 105. The organ culture media were analyzed using Western blottings (MMP-1, MMP-2, MMP-3, MMP-7, MMP-9, MMP-13, TIMP-1, and TIMP-2) and gelatine zymography. A reverse transcription polymerase chain reaction (RT-PCR) was also performed on healthy and inflamed gingival biopsies, which were maintained in culture with or without LU 105 0.1%. Then, we decided to determine the amount of cytokines present in the organ culture media such as interleukin (IL)-1 beta, IL-4, IL-6, transforming growth factor (TGF)-beta, and tumor necrosis factor (TNF)-alpha. RESULTS: When gingival biopsies derived from inflamed tissues were cultured with LU 105 0.1% in the culture media, the MMP and TIMP expression and activity decreased significantly when compared to cultures without LU 105. Moreover, we did not note any statistical difference in the cell proliferation compared with human gingival fibroblast cultures without LU 105. Furthermore, IL-1 beta, IL-6, TGF-beta, and TNF-alpha amounts in the culture media decreased significantly, whereas IL-4 increased significantly when LU 105 0.1% was added to the culture media. CONCLUSION: LU 105, a novel metalloproteinase inhibitor with few consequences on cell proliferation and morphology, is a vegetable extract with potential clinical capacity.

Decrease in the total antioxidant activity of saliva in patients with periodontal diseases.

This study examined the role of free radical-induced tissue damage and the antioxidant defense mechanism of saliva in periodontal disease. Antioxidant activity of saliva was compared in 20 healthy individuals and 17 patients with periodontal diseases. We measured the scavenging capacity of saliva against free radicals generated in vitro by electrolysis, xanthine-xanthine oxidase, or stimulated polymorphonuclear leukocytes. Total protein content and total antioxidant activity of saliva were also determined. The results indicate that stimulated saliva of healthy individuals is significantly more effective (40-50%) than that of patients with periodontal diseases in scavenging a wide variety of free radicals generated in vitro. Under these conditions it appears that the total antioxidant activity of saliva is significantly decreased in these patients despite the fact that the levels of the three main antioxidants (uric acid, ascorbic acid, and albumin) are not significantly affected. We conclude that periodontal diseases are associated with an imbalance between oxidants and antioxidants in favor of the former due to both an increase in free radical production and a defect in the total antioxidant activity of saliva.

Expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in healthy and diseased human gingiva.

BACKGROUND: The purpose of this study was to quantify the amount of matrix metalloproteinases such as MMP-1, MMP-2, MMP-3, MMP-7, MMP-9, and MMP-13 and tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2 expressed by human gingival explants in culture media and the area fraction (AA%) of gingival collagen fibers according to the degree of inflammation, to investigate a possible correlation between these enzymes and collagen loss. METHODS: Gingival tissue specimens from 6 healthy controls (group 1), 17 patients with mild gingival inflammation (group 2), 10 patients with moderate gingival inflammation (group 3), and 9 patients with severe gingival inflammation (group 4) were placed in organ culture for 3 days. The MMPs and TIMPs in the culture media were quantified using zymography, dot blotting, and Western blotting. Paraffin gingival sections were stained with sirius red F3Ba for visualization of collagen fibers, then the area fraction (AA%) occupied by the gingival fibers was determined by automated image analysis. RESULTS: The AA% occupied by collagen fibers significantly decreased from group 1 (53%) to group 4 (35%). The decrease in collagen fibers was inversely correlated with the significant increase in MMP-1, MMP-9, and MMP-13 (dot blotting analysis), with the increase of the active form of MMP-2, and with the active form and proform of MMP-9 (zymography analysis). CONCLUSION: The present study showed that metalloproteinases, particularly MMP-2, MMP-9, MMP-1, and MMP-13, are involved in the gingival extracellular matrix degradation during periodontitis.

Are cytokines linked to collagen breakdown during periodontal disease progression?

BACKGROUND: Evidence of the role of cytokines produced by resident and inflammatory cells during inflammation is well established. The aim of this study was to quantify in healthy and diseased human gingiva the area fraction (AA%) occupied by collagen fibers and the amount of cytokines such as interleukin (IL)-1beta, IL-4, IL-6, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and epidermal growth factor (EGF) to investigate a possible correlation between such cytokines, collagen degradation, and the gingival index. METHODS: Gingival tissue specimens from 6 healthy controls (group 1), 6 patients with mild gingival inflammation (group 2), 6 patients with moderate gingival inflammation (group 3), and 6 patients with severe gingival inflammation (group 4) were cultured for 72 hours, and the cytokines present in the culture media were quantified using an enzyme-linked immunosorbent assay (ELISA). Paraffin gingival sections from the 24 subjects were stained with sirius red F3Ba for visualization of collagen fibers, then the area fraction (AA%) occupied by the gingival fibers was determined by automated image analysis. RESULTS: The present study revealed significant differences (P < 0.05) between means of AA% in group 1 (53%), group 2 (41%), group 3 (39.5%), and group 4 (35%) for collagen fibers. Compared to controls, there were significant increases of IL-1beta (groups 3 and 4), IL-6, and TNF-alpha (group 3); a significant decrease of IL-4 (groups 2, 3, and 4) and TGF-beta (groups-2 and, 3); and no change of EGF. The collagen AA% was significantly correlated with the amounts of IL-4 and TGF-beta, and significantly inversely correlated with the amounts of IL-1beta for all 3 inflamed groups and IL-6 and TNF-alpha for groups 2 and 3. CONCLUSION: The present study showed that EGF was not changed in inflamed gingival tissue and that IL-1beta and IL-4 were particularly and intensively correlated with collagen loss. These 2 cytokines could be markers of clinical severity during active periodontitis.

Langerin+ versus CD1a+ Langerhans cells in human gingival tissue: a comparative and quantitative immunohistochemical study.

Langerhans cells (LC) are dendritic cells of the immune system able to capture intraepithelial pathogens and migrate to regional lymph nodes to present them to naive T cells. Up to now immunohistological studies on human gingival LC have been carried out using antibodies against HLA-DR or CD1a molecules. A new marker of LC called Langerin (CD207) and described, among other subcellular localisations, in the Birbeck granules is now available in immunohistochemistry. The purpose of this in situ study was to quantify and to compare Langerin+ versus CD1a+ LC number in order to show differences in the expression of these molecules, if any, and to determine which marker is the most specific. The present study was conducted using nine frozen healthy gingival samples. Double immunofluorescence procedures were performed with an anti-Langerin antibody revealed by FITC and with an anti-CD1a-PE antibody. Mounted slides were analysed by fluorescence microscopy and quantifications were performed on projected slides associated with a grid of 0.015 mm(2). Our results have shown that 1/ the number of CD1a+ LC was significantly increased (P=0.01) when compared with Langerin+ LC 2/ 92% of Langerin+ LC co-expressed CD1a 3/ only 82% of CD1a+ cells co-expressed Langerin 4/ a positive correlation was noted between CD1a+ and Langerin+ LC numbers. The present study has revealed the heterogeneity in the phenotype of gingival LC population and shown that Langerin seems the most specific marker for the study of LC.

Anetoderma: an altered balance between metalloproteinases and tissue inhibitors of metalloproteinases.

The amount of elastic fibers from lesional and healthy skin areas of five patients with anetoderma was determined by automated image analysis. Dermal elastic fibers were almost completely absent in anetodermic skin and preelastic fibers were undetectable or extremely rare. Organ cultures were performed using explants from affected and unaffected skin areas of the same patient. We identified and quantified proteases in the culture media of explants: MMP-1 (collagenase 1), MMP-2 and MMP-9 (gelatinases A and B), MMP-3 (stromelysin 1), MMP-7 (matrilysin 1), and tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-2. The data were compared with those of two healthy donors. For the five samples of anetodermic skin, MMP-1 levels were significantly higher compared with the uninvolved cultures and the two healthy samples. A significant increase of TIMP-1 expression was also observed in the affected cultures. We demonstrated a significant increase in the production of gelatinase A in lesional skin when compared with nonlesional skin and healthy donor samples. We found no significant production of TIMP-2 in the five samples of anetodermic skin compared with the samples from the two healthy donors. There was a significant decrease in TIMP-2 expression in the five nonlesional samples compared with the control samples. These data are in favor of an altered balance in anetodermic patients between MMP-2 and TIMP-2. Levels of MMP-9, MMP-3, and MMP-7 were significantly higher in the culture-conditioned media of the anetodermic skin samples than the nonlesional skin cultures. Because MMP-3, MMP-7, MMP-9 are known to degrade elastin, and MMP-3 can activate the latent forms of MMP-7 and MMP-9, we propose that these metalloproteinases also participate in the degradation of elastic fibers in anetodermic skin.