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.

Effect of a calcium-silicate-based restorative cement on pulp repair.

In cases of pulp injury, capping materials are used to enhance tertiary dentin formation; Ca(OH)(2) and MTA are the current gold standards. The aim of this study was to evaluate the capacity of a new calcium-silicate-based restorative cement to induce pulp healing in a rat pulp injury model. For that purpose, cavities with mechanical pulp exposure were prepared on maxillary first molars of 27 six-week-old male rats, and damaged pulps were capped with either the new calcium-silicate-based restorative cement (Biodentine), MTA, or Ca(OH)(2).

Langerhans cells express matrix metalloproteinases 9 and 2 and tissue inhibitors of metalloproteinases 1 and 2 in healthy human gingival tissue and in periodontitis.

Background: As antigen-presenting cells, Langerhans cells may play an important role in the initiation and maintenance of periodontal disease. This study is the first report that extends our knowledge of the expression of matrix metalloproteinases and their endogenous tissue inhibitors by Langerhans cells in healthy and diseased gingival tissues.

Methods: Single and double immunolabeling procedures were carried out using monoclonal antibodies against CD1a, matrix metalloproteinases 2 and 9, and tissue inhibitors of matrix metalloproteinases 1 and 2, and analyzed by conventional and confocal microscopes.

Vascular wall remodeling in patients with supravalvular aortic stenosis and Williams Beuren syndrome.

Supravalvular aortic stenosis (SVAS) and Williams Beuren syndrome (WBS) can be considered as inherited diseases affecting the whole arterial tree and causing narrowing of the vessels. It has been reported that abnormal deposition of elastin in arterial walls of patients with SVAS and WBS leads to increased proliferation of arterial smooth muscle cells (SMC), which result in the formation of hyperplastic intimal lesions. In this work, we conducted morphological and morphometrical analysis with stenotic aortas from patients suffering from SVAS and WBS and from healthy control subjects and demonstrated that the amount of elastic fibers and the loss of integrity of vascular elastic fibers in the aortas reflect similar changes in the skin of patients with SVAS or WBS, as reported in our previous work conducted on skin in these pathological states.

Possible involvement of gelatinase A (MMP2) and gelatinase B (MMP9) in toxic epidermal necrolysis or Stevens-Johnson syndrome.

Toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS) are considered to be drug-induced diseases, and are characterized by extensive mucocutaneous disorder and epidermal necrosis which result in the detachment of the epidermis. Inactive and active forms of metalloproteinases (MMP2 and MMP9) secreted by skin explants maintained in organ culture for 72 h and in blister fluid from two TEN and three SJS patients were investigated. Interestingly, lesional skin from both the TEN and the SJS patients cultured for 3 days in conditioned medium showed high levels of both 72 kDa progelatinase A and 66 kDa activated gelatinase A, and the 66 kDa activated form was not observed in cultures of skin from control individuals.

Validation of a morphometric method for evaluating fibroblast numbers in normal and pathologic tissues.

The aim of this work was to validate an image analysis method, based on cell nuclei form factor determination, for counting fibroblasts within human dermis. We first used reconstructed dermal equivalents in which fibroblasts can also be counted directly after lysis of the collagen matrix. We found a good correlation between the results of direct counting and those of image analysis from day 10 to day 28 of culture.

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.

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).

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.

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.

Human dermal and gingival fibroblasts in a three-dimensional culture: a comparative study on matrix remodeling.

Free-floating collagen lattice is considered a useful tool for assessing wound healing in vitro. This work compared extracellular matrix remodeling in collagen lattices populated by gingival or dermal fibroblasts. For 21 days we followed gel contraction and changes in cell number of collagen lattices seeded with l.

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.

Effect of avocado and soybean unsaponifiables on gelatinase A (MMP-2), stromelysin 1 (MMP-3), and tissue inhibitors of matrix metalloproteinase (TIMP- 1 and TIMP-2) secretion by human fibroblasts in culture.

Background: In inflamed periodontal tissues, gingival fibroblasts are able to express matrix metalloproteinases (MMPs) and their natural inhibitors, tissue inhibitors of matrix metalloproteinases (TIMPs). They can also respond to growth factors and cytokines. In this study, the in vitro effects of avocado and soybean unsaponifiable residues (ASU), their fractions (avocado unsaponifiable [ASF] or soy unsaponifiable [SSF]) on MMP-2 and MMP-3, and the activity and secretion of their inhibitors TIMP-1 and TIMP-2 were investigated using cultured human gingival fibroblasts.

Morphometric analysis of elastic skin fibres from patients with: cutis laxa, anetoderma, pseudoxanthoma elasticum, and Buschke-Ollendorff and Williams-Beuren syndromes.

Computed morphometric analysis of elastic skin fibres in patients with cutis laxa, anetoderma, Williams-Beuren syndrome, pseudoxanthoma elasticum (PXE), and Buschke-Ollendorff syndrome, all clinically ascertained, was performed and compared with data obtained from healthy individuals of the same age. The diameters, area fractions (AA%) and volume fractions (VV%) occupied by pre-elastic fibres and dermal elastic fibres were determined. Irrespective of age the diameter of dermal elastic fibres followed a Gaussian distribution for all groups studied.

Effect of heparin on the production of matrix metalloproteinases and tissue inhibitors of metalloproteinases by human dermal fibroblasts.

The influence of heparin and a heparin fragment devoid of anticoagulant activity on the production of matrix metalloproteinases and tissue inhibitors of metalloproteinases by human dermal fibroblasts was studied. Doses (0.1-400 microg/ml) responses were performed and data obtained were similar whatever heparin or fragment was used.

Skin elastic fibers in Williams syndrome.

The elastin gene is consistently deleted in Williams syndrome and as this protein represents the major component of the elastic fibers of the dermis, we sought to investigate skin elastic fibers in Williams syndrome as a key to unraveling extracellular matrix disorganization in this condition. Both morphometric parameters analyzed by using automated image analysis and immunofluorescence labeling with monoclonal antibodies against elastin and fibrillin 1 showed a disorganized pre-elastic (oxytalan and elaunin) and mature elastic fibers in the dermis of 10 Williams syndrome patients compared with five healthy children and one patient with isolated supravalvular aortic stenosis. Skin biopsies in Williams syndrome patients provide a simple mean to elucidate extracellular matrix anomalies.

Morphometric analysis of human gingival elastic fibres degradation by human leukocyte elastase protective effect of avocado and soybean unsaponifiables (ASU).

Degradation of preelastic fibres (oxytalan and elaunin) and mature elastic fibres by human leukocyte elastase (HLE) was investigated using automated image analysis. Specimens from two young healthy adults were used. Although HLE hydrolyzed both fibre types, mature elastic fibres exhibited greater susceptibility to this effect than preelastic fibres.

Influence of heparin(s) on the interleukin-1-beta-induced expression of collagenase, stromelysin-1, and tissue inhibitor of metalloproteinase-1 in human gingival fibroblasts.

Here, we describe the influence of heparin(s) on the interleukin-1-beta (IL-1beta)-induced expression of collagenase (matrix metalloproteinase-1, MMP-1), stromelysin-1 (matrix metalloproteinase-3, MMP-3) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in human gingival fibroblasts (HGF). Amounts of secreted enzymes and inhibitors as well as their mRNA steady-state levels increased significantly following supplementation of HGF culture medium with 2 ng/mL of IL-1 beta1. Addition of heparin to cell culture medium 1 hour following IL-1beta decreased MMP and TIMP-1 expression in a dose-dependent manner.

Measurement of the amounts of elastic fibers in the skin and temporal arteries of healthy aged individuals by automated image analysis.

Background: A quantitative study of dermal and arterial elastic fibers as a function of age was carried out by computerized image analysis.

Objective: We investigated whether any parallelism can be established between the morphometric parameters of elastic fibers from the skin and the temporal artery in elderly subjects.

Methods: we quantitated the skin elastic fibers of the reticular dermis and the elastic fibers of the temporal artery using a specific staining procedure followed by automated image analysis in 16 subjects of age range 63-87 years.

Morphometric studies of collagen and fibrin lattices contracted by human gingival fibroblasts; comparison with dermal fibroblasts.

Cell shape variations and substratum re-organization during contraction of floating collagen and fibrin lattices seeded with human gingival fibroblasts were determined by computerized image analysis of light and scanning electron microscopic images. Data were compared with those obtained with lattices populated with human dermal fibroblasts. The extent of collagen lattice contraction was similar with both cell types, resulting in a two-fold decrease in the area fractions occupied by collagen fibers.

Morphometric analysis of collagen and elastic fibers in normal skin and gingiva in relation to age.

The morphometric parameters of the human gingival elastic fiber network were determined by image analysis and compared with human skin elastic fibers in relation to age. Similarly, collagen fibers were also investigated in both tissues. In this study, 47 healthy patients, 10-75 years old were studied for gingiva and another 50 patients in the same age range were included for skin biopsies.

Antiproliferative polysaccharides modulate distribution and phenotypic expression of collagens by gingival fibroblasts.

Gingival fibroblasts are particularly involved in the physiologic maintenance and repair of periodontium. During these processes, cell proliferation and synthesis of a collagen-rich gingival matrix should be controlled. A dextran derivative, namely, carboxy methyl dextran benzylamide sulfonate (CMDBS), considered to be a functional analog of heparin, was previously described to regulate proliferation of different types of cells and independently to modulate the expression of collagen biosynthesis.

A point mutation in the bulge of the iron-responsive element of the L ferritin gene in two families with the hereditary hyperferritinemia-cataract syndrome.

The molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome is the presence of a mutation in the iron-responsive element (IRE) of the L ferritin gene, located on chromosome 19q13.3-13.4.