Research progress on the dentin adhesion of Enterococcus faecalis and its influencing factors / 口腔疾病防治

@#Enterococcus faecalis is the main pathogen causing refractory apical periodontitis (RAP). This bacterium can tolerate harsh environments and trigger periapical immune inflammatory responses that result in persistent infection inside and outside the root canal. Adhesion to the dentin wall of root canals and the subsequent formation of biofilms significantly enhances the drug resistance and anti⁃erosion ability of Enterococcus faecalis, which is the key factor medi⁃ ating its pathogenesis. The adhesion of Enterococcus faecalis to dentin involves non⁃specific adhesion and specific adhe⁃ sion, and the latter is mediated by adhesion⁃related virulence factors, mainly including the adhesin of collagen from en⁃terococci (Ace), extracellular surface protein (Esp), gelatinase (GelE), serine protease (SprE), endocarditis and biofilm associated pilus (Ebp) and aggregation substance (AS), which is regulated by multiple two⁃component systems. The two⁃ component system Fsr can promote the expression of gelE and sprE when the cell population density increases. GelE can further reduce Ace, while the two⁃component system GrvRS directly downregulates ace expression in response to the serum environment. The two⁃component systems CroRS and WalRK may also promote and inhibit the expression of vari⁃ ous virulence factors, including ace and gelE, thus affecting the adhesion of Enterococcus faecalis. In addition, the mech⁃ anochemical preparation and the internal environment of the root canal can also influence the adhesion of Enterococcus faecalis to dentin. Avoiding the introduction of Enterococcus faecalis and using adhesion⁃interfering medications during root canal treatment can effectively prevent the adhesion of Enterococcus faecalis, and a variety of activated irrigation protocols can also be effective at increasing the clearance of Enterococcus faecalis from the root canal. The design of ra⁃ tional drugs targeting key factors involved in and regulators of the adhesion of Enterococcus faecalis to dentin is expected to provide new ideas and strategies for root canal infection control. The present paper reviews the adhesion of Enterococ⁃ cus faecalis to dentin and its influencing factors.

Research progress on oxidative stress regulatory mechanisms in Streptococcus mutans / 口腔疾病防治

@#The oral microecological balance is closely associated with the development of dental caries. Oxidative stress is one of the important factors regulating the composition and structure of the oral microbial community. Streptococcus mutans is closely related to the occurrence and development of dental caries. The ability of S. mutans to withstand oxidative stress affects its survival competitiveness in biofilms. The oxidative stress regulatory mechanisms of S. mutans include the synthesis of reductase, the regulation of iron and manganese uptake by metalloregulatory proteins, transcription regulator Spx, extracellular uptake of glutathione and other related signal transduction systems. The current research focuses on how S. mutans adapts to a complex external environment through an oxidative stress response and its influence on oral microecology. We can design targeted small molecular compounds for key signaling pathways to inhibit oxidative stress and weaken the virulence of S. mutans, which is important for oral microecological modulation and dental caries prevention and treatment.

Research progress on antimicrobial peptides in terms of the prevention and treatment of dental caries / 口腔疾病防治

@#Antimicrobial peptides have antibacterial effects on various pathogenic microorganisms, including natural antimicrobial peptides and synthetic antimicrobial peptides. According to the structure of natural antimicrobial peptides, synthetic antimicrobial peptides can be obtained by recombining different functional domains, adjusting the original amino acid sequence, or completely redesigning the peptides from scratch. Antimicrobial peptides can inhibit the growth of various cariogenic microorganisms and the formation of microbial biofilms. They also reduce acid production and acid resistance of microorganisms. Natural antimicrobial peptide genes can be used as genetic susceptibility markers for predicting the development of caries, thus, showing potential applications in the prevention and treatment of dental caries. The instability of natural antimicrobial peptides and the inability to achieve targeted sustained release limit their application in the prevention and treatment of oral caries. Synthetic antimicrobial peptides can enhance their stability and the antibacterial effect. Synthetic antimicrobial peptides can also be polymerized with common oral adhesives to reduce the incidence of microleakage after filling treatment for caries and to prevent the occurrence of secondary caries. The pH-sensitive antimicrobial peptides are slowly released to promote remineralization in the process of caries. However, the safety and biocompatibility of synthetic antimicrobial peptides are worse than those of natural antimicrobial peptides. Moreover, the combined effect of antibacterial peptides and anticaries drugs, such as fluoride, is still uncertain. Therefore, in this paper, we will review the design methods, application and underlying mechanisms of antimicrobial peptides to introduce novel methods and ideas for the prevention and treatment of dental caries.