Epigenetic regulation mechanism: roles in enamel formation and developmental defects of enamel / 中华口腔医学杂志

Enamel formation is a series of complex physiological processes, which are regulated by critical genes spatially and temporally. These processes involve multiple developmental stages covering ages and are prone to suffer signal interference or gene mutations, ultimately leading to developmental defects of enamel (DDE). Epigenetic modifications have important regulatory roles in gene expression during enarnel development. New technologies including high-throughput sequencing, chromatin immunoprecipitation sequencing (ChIP-seq), and DNA methylation chip are emerging in recent years, making it possible to establish genome-wide epigenetic modification profiles during developmental processes. The regulatory role of epigenetic modification with spatio-temporal pattern, such as DNA methylation, histone modification and non-coding RNA, has significantly expanded our understanding of the regulatory network of enamel formation, providing a new theoretical basis of clinical management and intervention strategy for DDE. The present review briefly describes the enamel formation process of human beings' teeth as well as rodent incisors and summarizes the dynamic characteristics of epigenetic modification during enamel formation. The functions of epigenetic modification in enamel formation and DDE are also emphatically discussed.

Proposal and thoughts on establishing and improving multi-level dental insurance in China / 中华口腔医学杂志

Oral diseases are highly prevalent in China, while oral health services are generally underutilized and public health resources are wasted. Lacking oral insurance may be one of the leading causes. The basic medical insurance of China does not cover dental care in most cities, which is worthy to further discuss. To better understand the experience of dental insurance from international dental care practice, the dental coverage scope, content, co-pay ratio, and effects of oral insurance on oral health improvement from the abroad countries with typical health insurance systems were summarized by using scoping review. Then, we discussed the coverage scope for dental health of basic medical insurance and private insurance in China. We also analyzed the current issues of dental care coverage and cost-share. At last, we proposed thoughts and suggestions to establish and improve a multi-level oral health insurance system with Chinese characteristics under the basic medical insurance frame. In particular, we gave suggestions on increasing the coverage for high dental care xpenditure by ebasic medical insurance, supplying children and teenagers with preventive dental care, and encouraging private insurance companies to cover dental care expenditure.

Research progress in pathogenesis and control of Enterococcus faecalis with persistent infection in root canals / 中华口腔医学杂志

Root canal therapy is the common treatment for endodontic infections. Successful root canal therapy depends on favorable root canal preparation, root canal medication and three-dimensional obturation of the root canal system. The key to successful root canal therapy is to prevent re-infection of the highly complex root canal systems by removing infecious biofilms and bacterial toxins in the root canal system. The present paper reviews the pathogenic mechanism of the Enterococcus faecalis in the harsh environment of root canal system, the inflammation and immunity of refractory periapical periodontitis and the progress of infection control methods.

Effect of straight-line minimally invasive access cavity on the mechanical properties of maxillary first premolars: a finite element analysis / 中华口腔医学杂志

Objective: To investigate the effects of straight-line minimally invasive access cavity on the mechanical properties of endodontically treated maxillary first premolars using finite element analysis. Methods: Micro-CT data of twenty maxillary first premolars were collected for three-dimensional reconstruction. Three access cavities, including the conventional access cavity (ConvAC), the truss access cavity (TrussAC) and the straight-line minimally invasive access cavity (SMIAC), as well as the root canal treatment procedure, were simulated in all the 20 reconstruction samples of three-dimensional models, respectively. The peak von Mises stress on the cervical area of each model, as well as the stress distribution under vertical and oblique loading circumstances, were subsequently determined by using finite element analysis. Results: In comparison to the stresses of ConvAC [buccal cervical (BC): (188.7±13.4) MPa, palatal cervical (PC): (200.9±25.7) MPa], the stresses of TrussAC [BC: (146.0±12.9) MPa, PC: (167.6±15.9) MPa] (t=9.01, P<0.001; t=4.59, P<0.001) and SMIAC [BC: (142.6±13.7) MPa, PC: (168.1±17.4) MPa] (t=9.64, P<0.001; t=3.76, P=0.004) significantly reduced the peak von Mises stress on the cervical area of the maxillary first premolars after root canal treatment. Under vertical loading conditions, SMIAC also reduced the central tendency of stresses on the occlusal surface, cervical area and root. In the case of oblique loading conditions, similar results were observed. Under both loading conditions, there was no significant difference in the peak von Mises stress on the cervical area of the maxillary first premolar between TrussAC and SMIAC groups. Conclusions: The design of SMIAC could preserve the mechanical properties of the maxillary first premolar following root canal treatment, which might have certain clinical feasibility.

Effect of csn2 gene deficiency on the starvation tolerance and the synthesis of extracellular polysaccharides in oligotrophic environment of Streptococcus mutans / 中华口腔医学杂志

Objective: To explore the effect of csn2 gene deficiency on starvation tolerance and extracellular polysaccharides (EPS) synthesis in an oligotrophic environment of Streptococcus mutans (Sm). Methods: The csn2 gene deletion strains and complementary strains of Sm were cultivated and then an oligotrophic growth environment for Sm growth by setting different concentration gradient media were created. Cell growth in oligotrophic environment was detected by growth curve. Biofilm volume was measured by crystalline violet staining. Scanning electron microscopy (SEM) and laser confocal microscope were performed to observe the biofilm structure of Sm. The synthesis of EPS was measured by the anthrone-sulfuric acid method. The expression of genes related to EPS synthesis was evaluated by quantitative real-time PCR (qRT-PCR). Results: The growth curve results showed that the deletion of csn2 gene inhibited the growth of Sm under starvation stress. Furthermore, the results of laser confocal microscope showed that the biofilm EPS/bacteria ratios produced by the wild-type strain, csn2 gene-deficient strain and complement strains under nutrient sufficient culture conditions were 0.44±0.07, 1.05±0.13 and 0.57±0.08 respectively, while the ratios of EPS/bacteria in an oligotrophic environment were 0.93±0.24, 3.05±0.21 and 1.32±0.46 respectively, indicating that the deletion of csn2 gene enhanced the ability of extracellular polysaccharide synthesis of Sm in the oligotrophic environment. The expression levels of EPS synthesis-related genes gtfB and gtfC were up-regulated by 2.5 fold and 1.8 fold respectively and the expression level of gtfD was down-regulated by two-thirds. Conclusions: The csn2 gene deficiency showed multiple effects on the physiological functions and virulence characteristics of Sm, including starvation tolerance and EPS synthesis. These changes might be related to the shift of the complex regulative network caused by csn2 gene deletion.

Regulation effect of lipopolysaccharide on the alternative splicing and function of sweet taste receptor T1R2 / 华西口腔医学杂志

OBJECTIVES@#To identify the alternative splicing isoform of mouse sweet taste receptor T1R2, and investigate the effect of lipopolysaccharide (LPS) local injection on T1R2 alternative splicing and the function of sweet taste receptor as one of the bacterial virulence factors.@*METHODS@#After mouse taste bud tissue isolation was conducted, RNA extraction and reverse transcription polymerase chain reaction (PCR) were performed to identify the splicing isoform of T1R2. Heterologous expression experiments @*RESULTS@#T1R2 splicing isoform T1R2_Δe3p formed sweet taste receptors with T1R3, which could not be activated by sweet taste stimuli and significantly downregulated the function of canonical T1R2/T1R3. Local LPS injection significantly increased the expression ratio of T1R2_Δe3p in mouse taste buds.@*CONCLUSIONS@#LPS stimulation affects the alternative splicing of mouse sweet taste receptor T1R2 and significantly upregulates the expression of non-functional isoform T1R2_Δe3p, suggesting that T1R2 alternative splicing regulation may be one of the mechanisms by which microbial infection affects host taste perception.

Research progress of Candida albicans on malignant transformation of oral mucosal diseases / 华西口腔医学杂志

Oral cancer is the most common malignant tumor in the head and neck, and is one of the world's top ten malignancies. Microbial infection is an important risk factor of oral cancer. Candida albicans is the most popular opportunistic fungal pathogen. Epidemiological studies have shown that Candida albicans is closely tied to oral malignancy. Animal experimentation have also proven that infection of Candida albicans can promote the development of oral epithelial carcinogenesis. The current studies have revealed several mechanisms involved in this process, including destroying the epithelial barrier, producing carcinogenic substances (nitrosamines, acetaldehyde), inducing chronic inflammation, activating immune response, etc. However, current researches on mechanisms are still inadequate, and some hypotheses remain controversial. Here, we review the findings related to Candida albicans' effect on the malignant transformation of oral mucosa, hoping to provide reference for deep research and controlling oral cancer clinically.

Research progress on the regulation of phenolic compounds of traditional Chinese herbs on oral microbes / 华西口腔医学杂志

Phenolic compounds are widely found in natural Chinese medicinal plants and have excellent pharmacological properties, such as antioxidation and anti-inflammation. They are the main pharmacological components of many medicinal Chinese herbs. Oral microbiota, especially its composition and metabolism, is highly related to the balance of oral microecology and plays a key role in the occurrence and development of oral diseases. Recent studies have shown that phenolic compounds of traditional Chinese herbs can prevent and treat oral diseases, such as caries, periodontal disease, and oral mucosal infection, by regulating the composition, metabolites, and virulence of oral microorganisms. This review will summarize and discuss the regulation of phenolic compounds on oral microbes.

A review of peri-implant microbiology / 华西口腔医学杂志

Dental implants represent the majority of treatment strategies used to replace missing teeth. However, peri-implant diseases caused by disturbance in peri-implant microbiological balance are among the reasons for implant failure. Since the 1980s, peri-implant microorganisms have been a hot research topic in dental microbiology. The bacterial ecology between the disease and health largely differs, which directly or indirectly increases the risk of peri-implant diseases. Accordingly, the determination of the 'core microbiome' of peri-implantitis and peri-implant mucositis is a key point of recent research.

Criteria for success in dental implants / 华西口腔医学杂志

With the comprehensive application and development of implant dentistry in recent years, multi-institutional data have supported a large number of clinical research findings. A consensus was gradually reached on the evaluation of the state and effect of implants and types of indicators that were selected after restoration. This study aims to examine the frequently used criteria to define treatment success in implant dentistry.

Potential application of human microbiomes in the diagnosis and treatment of type 2 diabetes mellitus / 华西口腔医学杂志

Human microbiome refers to the total microorganism genetic information of human body surface and internal, which is closely related to human health and disease. Oral and gut microbiomes are the most diverse microbial communities, which can interact and play a role in the development of the disease, and can reflect the health and disease state in real time. Type 2 diabetes mellitus is a metabolic disorder caused by both genetic and environmental factors. Recent research has shown a link between microbes and diabetes. This article reviewed the latest research on the changes of oral and gut microbiomes in type 2 diabetes mellitus patients, which expects to provide a reference for exploring the development of the disease model for prediction, diagnosis and prognosis of type 2 diabetes mellitus based on human microbiome characteristics.

Oral microbiota and inflammatory bowel disease / 华西口腔医学杂志

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract with a high incidence but a poor therapeutic outcome. However, IBD is generally caused by complicated interactions between environmental factors and gut microflora in genetically susceptible individuals. In view of a series of oral manifestations in patients with IBD and a high detection rate of oral bacteria among this population, oral microbiota may play an important role in the development of IBD. This article reviews the relationship between oral microbiota and IBD.

Role of autophagy in the pathogenesis of periodontitis / 华西口腔医学杂志

Periodontitis is a chronic inflammatory disease of periodontal tissues initiated by oral biofilm. Cellular autophagy is an effective weapon against bacterial infection. Recent studies have shown that autophagy not only promotes the removal of bacteria and toxins from infected cells, but also helps to suppress the inflammatory response to maintain the homeostasis of intracellular environment, which is closely related to the development of periodontitis. Here, we reviewed the relationship between autophagy and periodontitis from three aspects: the interactions between autophagy and periodontal pathogen infection, the regulation of autophagy and immune inflammatory responses, and the relationship between autophagy and alveolar bone metabolism. We aim to provide ideas for further study on the mechanisms of autophagy and periodontitis, and ultimately contribute to a better prevention and treatment of periodontitis.

Research progress on the relationship between periodontal disease and common malignancies / 华西口腔医学杂志

Periodontal disease is a common oral disease that can cause irreversible damage of periodontal support tissue. Studies on the relationship between periodontal disease and malignancies have also increased. In this review, the relationship between periodontal disease and gastrointestinal malignancies (e.g., stomach cancer, colorectal cancer, and pancreatic cancer), lung cancer, and breast cancer are discussed. The related mechanisms are summarized in terms of four aspects, namely, immu-nity, inflammation, gene, and microbiota and its products, to provide novel methods for the prevention and early diagnosis of malignancies.

Minimal invasive microscopic tooth preparation based on endodontic, periodontal and functional health / 华西口腔医学杂志

Tooth preparation is the primary and core operation technique for dental esthetic restoration treatment, due to its effect of providing restoration space, bonding interfaces and marginal lines for dental rehabilitation after tooth tissue reduction. The concept of microscopic minimal invasive dentistry put forward the issue of conducting high-quality tooth preparation, conserve tooth-structure, protect vital pulp and periodontal tissue simultaneously. This study reviewed the concepts, physiology background, design and minimal invasive microscopic tooth preparation, and in the meantime, individualized strategies and the two core elements of tooth preparation (quantity and shape) are listed.

Dental-craniofacial manifestation and treatment of rare diseases in China / 华西口腔医学杂志

Rare diseases are genetic, chronic, and incurable disorders with relatively low prevalence. Thus, diagnosis and management strategies for such diseases are currently limited. This situation is exacerbated by insufficient medical sources for these diseases. The National Health and Health Committee of China recently first provided a clear definition of 121 rare diseases in the Chinese population. In this study, we summarize several dental-craniofacial manifestations associated with some rare diseases to provide a reference for dentists and oral maxillofacial surgeons aiming at fast-tracking diagnosis for the management of these rare diseases.

Advances in titanium dental implant surface modification / 华西口腔医学杂志

Titanium dental implants have wide clinical application due to their many advantages, including comfort, aesthetics, lack of damage to adjacent teeth, and significant clinical effects. However, the failure of osseointegration, bone resorption, and peri-implantitis limits their application. Physical-chemical and bioactive coatings on the surface of titanium implants could improve the successful rate of dental implants and meet the clinical application requirements. This paper reviews the characteristics of surface modification of titanium implants from the aspects of physics, chemistry, and biology. Results provide information for research and clinical application of dental implant materials.

Indirect pulp therapy for deciduous teeth with deep caries lesions / 华西口腔医学杂志

Deciduous teeth are the first dentition of humans and play an important role in children's physical and mental development. Dental caries are one of the most common oral diseases in children. According to the data of the World Health Organization, 60%-90% of school children worldwide develop dental caries. In China, dental caries of primary teeth feature high incidence and low rate of visits. Without timely treatment, the deep caries lesions of primary teeth can lead to teeth defect, pulpitis, apical periodontitis, and maxillofacial space infection. Moreover, the premature loss of deciduous teeth can cause malocclusion and eruption disorder of subsequent permanent teeth. These conditions all cause considerable effects on children's oral health and physical and mental development. Performing active and effective measures to treat deciduous teeth with deep caries lesions is important to maintain the integrity and normal physiological function of dentition and facilitate normal eruption of permanent teeth. The current situation of indirect pulp therapy in China was studied in this paper. Basic concepts, including indirect pulp capping, interim therapeutic restoration, partial caries removal, stepwise caries removal, and atraumatic restorative therapy, have been defined by consulting domestic and foreign literature. A theoretical basis for improving the clinical pathway of deciduous teeth with deep caries lesions is provided by explaining the technical connotation and therapeutic importance of indirect pulp therapy in primary teeth.

Dental care utilization of immigrants in Chengdu, China / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study considered Chengdu, Sichuan, China as an example to investigate the dental service utilization by foreigners and its influencing factors. Results of the study can be referred by dental practitioners to explore international development of dental services and can be provided for health policy makers to formulate oral health policies for immigrants.</p><p><b>METHODS</b>A simple random sampling method with a questionnaire was designed based on Anderson's health utilization model and "Oral Health Questionnaire for Adults" by the World Health Organization. Oral health condition, consciousness, and demographic data were collected. Binary Logistic regression and stratified analysis with SPSS 20.0 were performed.</p><p><b>RESULTS</b>A total of 654 immigrants repre-senting 75 countries participated in the study. Among all participants, 102 (15.6%) experienced dental problems while in residence in China but paid no visit to dentists. Female immigrants, who spent considerable time living in Chengdu, experienced oral problems in a year, used dental floss, and reported family members in Chengdu, were more likely to visit Chinese dentists. Participants who lived in Chengdu for at least 10.5 months were the threshold distinguishing differences in dental visits in the country.</p><p><b>CONCLUSIONS</b>The policymakers in Chengdu should consider creating a convenient and conducive dental care environment for immigrants. Additional information related to urgent oral and routine care should be provided to short- and long-term living immigrants in China. Dental practitioners in China should also contemplate on collaborating with foreign dental insurance companies to ensure better dental care access for immigrant patients.</p>

Endodontic infection management in root canal preparation: question and solution / 华西口腔医学杂志

The essence of pulp and periapical disease is bacterial infection. Thus, satisfactory infection control is the premise and foundation of healing, in which root canal preparation is a critical procedure. Root canal system anatomy, infection degree, physical cutting during root canal preparation, and certain cleaning measures affect the quality of infection control. Appropriate evaluation of the grades of infected root canals before treatment is necessary because different grades of root canal infection demand various disinfection schedules to facilitate tissue healing and guarantee the long-term success rate of endodontic treatment.