The epidemic of coronavirus disease 2019 , originating in Wuhan, China, has become a major public health challenge for not only China but also countries around the world. The World Health Organization announced that the outbreaks of the novel coronavirus have constituted a public health emergency of international concern. As of February 26, 2020, COVID-19 has been recognized in 34 countries, with a total of 80,239 laboratory-confirmed cases and 2,700 deaths. Infection control measures are necessary to prevent the virus from further spreading and to help control the epidemic situation. Due to the characteristics of dental settings, the risk of cross infection can be high between patients and dental practitioners. For dental practices and hospitals in areas that are (potentially) affected with COVID-19, strict and effective infection control protocols are urgently needed. This article, based on our experience and relevant guidelines and research, introduces essential knowledge about COVID-19 and nosocomial infection in dental settings and provides recommended management protocols for dental practitioners and students in (potentially) affected areas.

Non-syndromic cleft lip with palate (NSCLP) is the most serious sub-phenotype of non-syndromic orofacial clefts (NSOFC), which are the most common craniofacial birth defects in humans. Here we conduct a GWAS of NSCLP with multiple independent replications, totalling 7,404 NSOFC cases and 16,059 controls from several ethnicities, to identify new NSCLP risk loci, and explore the genetic heterogeneity between sub-phenotypes of NSOFC. We identify 41 SNPs within 26 loci that achieve genome-wide significance, 14 of which are novel (RAD54B, TMEM19, KRT18, WNT9B, GSC/DICER1, PTCH1, RPS26, OFCC1/TFAP2A, TAF1B, FGF10, MSX1, LINC00640, FGFR1 and SPRY1). These 26 loci collectively account for 10.94% of the heritability for NSCLP in Chinese population. We find evidence of genetic heterogeneity between the sub-phenotypes of NSOFC and among different populations. This study substantially increases the number of genetic susceptibility loci for NSCLP and provides important insights into the genetic aetiology of this common craniofacial malformation.

Clefts of the palate are common birth defects requiring extensive treatment. They appear to be caused by multiple genetic and environmental factors during palatogenesis. This may result in local changes in growth factors, extracellular matrix (ECM), and cell adhesion molecules. Several clefting factors have been implicated by studies in mouse models, while some of these have also been confirmed by genetic screening in humans. Here, we discuss several knockout mouse models to examine the role of specific genes in cleft formation. The cleft is ultimately caused by interference with shelf elevation, attachment, or fusion. Shelf elevation is brought about by mesenchymal proliferation and changes in the ECM induced by growth factors such as TGF-betas. Crucial ECM molecules are collagens, proteoglycans, and glycosaminoglycans. Shelf attachment depends on specific differentiation of the epithelium involving TGF-beta3, sonic hedgehog, and WNT signaling, and correct expression of epithelial adhesion molecules such as E-cadherin. The final fusion requires epithelial apoptosis and epithelium-to-mesenchyme transformation regulated by TGF-beta and WNT proteins. Other factors may interact with these signaling pathways and contribute to clefting. Normalization of the biological mechanisms regulating palatogenesis in susceptible fetuses is expected to contribute to cleft prevention.

Periodontal regeneration is defined as regeneration of the tooth-supporting tissues including cementum, periodontal ligament, and alveolar bone. Guided tissue regeneration (GTR) has been demonstrated to be an effective technique to achieve periodontal regeneration. In the GTR procedures, various kinds of membranes play important roles. Chitosan, a deacetylated derivative of chitin, is biocompatible, biodegradable, and antimicrobial. It acts as hydrating agent and possesses tissue healing and osteoinducing effect. Chitosan can be easily processed into membranes, gels, nanofibers, beads, nanoparticles, scaffolds, and sponges forms and can be used in drug delivery systems. Here, we review the bioproperties of chitosan and report the progress of application of chitosan as membranes in GTR and guided bone regeneration (GBR), which indicates that chitosan could be a good substrate candidate as the materials for the GTR/GBR membranes.

Dens invaginatus is a malformation with varying anatomical features, posing challenges to treatment. Early and accurate diagnosis plays a significant role in selecting the appropriate treatment. The diagnosis of teeth with a complex root canal system including dens invaginatus has made progress with the application of three-dimensional imaging techniques in endodontics. Advanced treatment options provide hope for teeth that could not be saved before. This review discusses diagnostic methods and treatment options for teeth with dens invaginatus, and provides guidelines for the management of dens invaginatus cases in clinic. Current as well as traditional diagnostic techniques are summarized. Treatment options including state-of-the-art alternatives are presented for coronal dens invaginatus and radicular dens invaginatus.

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In the course of embryonic development skeletal elements form either through intramembranous or endochondral ossification. Wnt proteins play diverse roles during vertebrate skeletal development. Wnt16 is a key factor in developing long bones, but its exact role in craniofacial bone formation remains unclear. This study was initially undertaken to investigate the expression of Wnt16 during craniofacial bone development in mouse embryos. Wnt16 expression in the osteoid of calvaria, maxilla, and mandible started later than that of ALP and osteocalcin (OCN), but before mineralization of the craniofacial bones, suggesting that Wnt16 is involved in intramembranous ossification in the head. To confirm this, MC3T3-E1 cells were transfected with an adenovirus containing Wnt16 (Ad-Wnt16). Ad-Wnt16 cells showed decreased ALP activity and less mineralized nodule formations compared with control cells. In addition, the mRNA levels of osteogenic markers were reduced. Moreover, Wnt16 activated β-catenin signaling in MC3T3-E1 cells at both transcription and protein levels as shown by a TOPflash luciferase reporter gene assay and western blot analysis. On the other hand, Wnt/β-catenin pathway blockade by Dickkopf 1 abrogated the suppression of mineralization by Wnt16. Our findings suggest that Wnt16 is involved in intramembranous ossification and suppresses osteoblast differentiation through the Wnt/β-catenin pathway.

Atmospheric volatile organic compounds (VOCs) measurement was carried out using gas chromatography-flame ionization detector (GC-FID) technique (Airmo VOCs online analyzer) in a typical urban area in Beijing from April 2014 to January 2015. Ambient levels, variation characteristics and influential factors contributing to the formation of near-ground-ozone and secondary organic aerosols as well as health risk assessment of VOCs were analyzed. Based on these analyses, the important VOC species that should be given more attention for pollution control were identified and the source apportionment of VOCs was made. Suggestions for VOCs pollution control countermeasures were put forward. The annual average concentration of 84 VOCs was 119 µg·m −3 and the hourly mean concentration was 9.11-567 µg·m −3 . Ambient level of VOCs in Beijing has been alleviated in recent years, but is still severe compared to some other cities. VOCs with the largest proportion were alkanes in spring and halogenated hydrocarbons in summer, autumn and winter. The variation of 84 VOCs concentrations was consistent with that of the ambient air quality index, indicating that VOCs had a strong influence on ambient air quality. Influenced by the concentration and activity of VOCs, the largest contribution to ozone formation potential and secondary organic aerosol formation potential came from alkenes and aromatic hydrocarbons, respectively. Five VOCs species such as benzene pose carcinogenic risk to exposed populations. Contrary to some previous studies, benzene was found to have potential cancer risk in some urban areas in China. The main sources of VOCs in the study area were vehicle exhaust, solvent usage, and industrial processes. In order to improve air quality in Beijing and reduce the infection rate of air pollutant related diseases, it is necessary to strengthen the control the emission of VOCs from those three sources.