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In recent years, artificial intelligence (AI), such as image recognition and fixed-point and digital scanning, has been increasingly applied in dental orthodontics. ChatGPT is an emerging artificial intelligence technology that has attracted a considerable amount of attention from people of all walks of life since its introduction. This paper discusses the application potential of ChatGPT in the field of orthodontics from two perspectives—education and clinical practice—and analyzes its limitations. Current reports show that ChatGPT can improve the efficiency of teaching in orthodontic education as well as assist users in completing medical mock exams training, writing papers and conducting academic research, etc. In the clinic, ChatGPT can be used to engage patients in medical dialog, simplify clinical procedures and improve diagnostic and treatment efficiency. However, because ChatGPT is still in the early stages of research and application, there are problems such as insufficient data, inaccurate answers, and poor academic ethics and privacy. In the future, additional studies, training and optimization are needed to ensure the safety, ethics and benefit of AI, laying the foundation for improving the use of AI in the field of orthodontics.

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 mediating its pathogenesis. The adhesion of Enterococcus faecalis to dentin involves non-specific adhesion and specific adhesion, and the latter is mediated by adhesion-related virulence factors, mainly including the adhesin of collagen from enterococci (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 various virulence factors, including ace and gelE, thus affecting the adhesion of Enterococcus faecalis. In addition, the mechanochemical 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 rational 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 Enterococcus faecalis to dentin and its influencing factors.

Successful treatment of endodontic and periapical diseases requires the elimination of bacteria and microbial biofilms from root canals. Currently, the most preferred irrigation method involves the delivery of sodium hypochlorite via the combination of a syringe and ultrasonic activation. Calcium hydroxide is the main choice for intracanal medicament between endodontic appointments and treatment. However, conventional chemical disinfection of root canals is controversial due to drug permeability and drug resistance. New small biomolecule formulations with high penetrability and bioremediatory capacity, including antimicrobial peptides such as M33D and LL-37, antisense RNA ASwalR/ASvicR and nanoparticles such as silver nanoparticles, mesoporous calcium-silicate nanoparticles and chitosan nanoparticles, have effective antibacterial and antibiofilm properties for use in root canal systems and dentinal tubules, thereby promoting the healing of apical lesions. However, the in vivo drug stability, biosafety, and clinical efficacy of small biomolecule formulations need further investigation. Future research will still focus on the improvement and combination of traditional drugs, as new small molecule formulations and ideal disinfectant drugs need to be developed. In the present paper, we reviewed the development of new antibacterial agents and application of small biomolecule formulations for chemical disinfection of infected root canals.

The standardized workflow of computer-aided static guided implant surgery includes preoperative examination, data acquisition, guide design, guide fabrication and surgery. Errors may occur at each step, leading to irreversible cumulative effects and thus impacting the accuracy of implant placement. However, clinicians tend to focus on factors causing errors in surgical operations, ignoring the possibility of irreversible errors in nonstandard guided surgery. Based on the clinical practice of domestic experts and research progress at home and abroad, this paper summarizes the sources of errors in guided implant surgery from the perspectives of preoperative inspection, data collection, guide designing and manufacturing and describes strategies to resolve errors so as to gain expert consensus. Consensus recommendation: 1. Preoperative considerations: the appropriate implant guide type should be selected according to the patient's oral condition before surgery, and a retaining screw-assisted support guide should be selected if necessary. 2. Data acquisition should be standardized as much as possible, including beam CT and extraoral scanning. CBCT performed with the patient’s head fixed and with a small field of view is recommended. For patients with metal prostheses inside the mouth, a registration marker guide should be used, and the ambient temperature and light of the external oral scanner should be reasonably controlled. 3. Optimization of computer-aided design: it is recommended to select a handle-guided planting system and a closed metal sleeve and to register images by overlapping markers. Properly designing the retaining screws, extending the support structure of the guide plate and increasing the length of the guide section are methods to feasibly reduce the incidence of surgical errors. 4. Improving computer-aided production: it is also crucial to set the best printing parameters according to different printing technologies and to choose the most appropriate postprocessing procedures.

Oral plaque biofilms are one of the bases for the survival and metabolism of different bacteria. With the emergence of drug-resistant bacteria due to antibiotic abuse, the prevention and treatment of plaque biofilm-associated oral diseases are becoming increasingly difficult. Although some research progress has been made in the field of biofilm formation and destruction, there is still a lack of effective clinical therapies for plaque biofilm-associated oral diseases. Metal nanoenzymes possess the physical properties of nanoparticles and exhibit catalytic activity similar to that of natural enzymes. The nanoscale size of metal nanoenzymes provides a greater specific surface area to help reactive oxygen species spread rapidly to active catalytic sites and improve the antioxidant properties of nanoenzymes. Additionally, metal nanoenzymes are easy to produce using different methods, such as electrochemical reduction, solvent thermal synthesis and microwave-assisted synthesis. Moreover, metal nanoenzymes can produce a high concentration of hydroxyl radicals, catalyze plaque biofilm degradation, lyse glucan and inhibit biofilm formation by oxidative stress reactions, as well as kill bacteria by releasing metal ions. Thus, metal nanoenzymes are expected to become a new option for the prevention and treatment of oral plaque biofilm-associated diseases. However, metal nanoenzymes can enter organisms through oral, intravenous and respiratory routes, triggering potential toxic effects such as pulmonary toxicity, hepatotoxicity and neurotoxicity. In a complex biological environment, the occurrence of metal nanoenzymes toxicity may involve multiple mechanisms, and the mechanism of action and safety need to be thoroughly investigated. In this paper, we intend to describe the research progress on metal nanoenzymes through an overview of their properties, antibacterial mechanisms, biotoxicity and applications in the prevention and treatment of oral plaque biofilm-related diseases, which may provide new ideas for the prevention and treatment of these diseases.

Through a review of the literature on surface treatment of superhydrophilic implants and its clinical application, this paper discusses the shortening of load time, the improvement of the planting success rate and its long-term effect. Additionally, attention should be paid to the nonindication of superhydrophilic implants and issues requiring attention. The literature review showed that healthy patients could carry out an early load 21 days after implantation of superhydrophilic implants, and the load could be completed as soon as 6 weeks after implantation with superhydrophilic short implants when the residual alveolar bone height of the posterior dental area was repaired. Even if the residual alveolar bone density of the patient is low, the application of superhydrophilic implants can shorten the healing period to 8 weeks. Notably, some studies have reported that superhydrophilic implants have no significant effect on patients with a history of radiotherapy and the use of anticoagulants. Because the adhesion of the superhydrophilic implant to the bacteria is also improved to some extent, it is very important to prevent the use of antibiotics when using the superhydrophilic implant. Finally, this paper discusses and anticipates the future research direction of superhydrophilic implants: longer periodic follow-up and more in-depth molecular mechanism studies.

Objective To explore the photodynamic treatment method and therapeutic effect of oral verrucous carcinoma and to provide a reference for the clinic. Methods This study follows the requirements of medical ethics. This paper summarized the photodynamic treatment of an oral verrucous carcinoma with a diameter of approximately 2.5 cm in the right buccal mucosa and retrospectively analyzed the characteristics and treatment of oral verrucous carcinoma and the photodynamic treatment of potential malignant lesions of the oral mucosa through a review of the literature. Results After four rounds of photodynamic therapy, the size of the right buccal lesion was significantly reduced. After 6 months of follow-up, the white verrucous hyperplasia of the right buccal mucosa had completely subsided, and there was no obvious scar formation. Three years after treatment, there was no recurrence of the lesion in the right buccal mucosa and no obvious scar formation in the treated area. The degree of mouth opening was 3 fingers, and there was no lymph node enlargement in the bilateral submandibular, submental or neck. The literature review shows that oral verrucous carcinoma is a rare subtype of squamous cell carcinoma with the characteristics and biological behaviors of slow growth, low malignancy, and rare metastasis. Surgery is the preferred treatment, but there are some limitations. Photodynamic therapy is a minimally invasive, repeatable treatment with mild adverse reactions. In recent years, photodynamic therapy has been gradually applied for the treatment of potential malignant disorders of the oral mucosa and early oral squamous cell carcinoma and has achieved positive results, but it has not been reported for the treatment of oral verrucous cancer. Conclusion Photodynamic therapy is a new option for nonsurgical resection of oral verrucous carcinoma.

Periodontal ligament stem cells (PDLSCs) have the potential for multidirectional differentiation and are the preferred seed cells for periodontal tissue regeneration. In recent years, a large number of studies have confirmed that PDLSCs also possess broad immunomodulatory properties. Therefore, in-depth exploration of their specific molecular mechanisms is of great significance for the treatment of periodontitis. The aim of this paper is to summarize the research progress on the regulation of PDLSCs on various immune cells and the effect of the inflammatory environment on the immune characteristics of PDLSCs to provide an important theoretical basis for the allotransplantation of PDLSCs and improve the therapeutic effect of periodontal tissue regeneration. Studies have shown that PDLSCs possess a certain degree of immunosuppressive effect on both innate and acquired immune cells, and inflammatory stimulation may lead to the impairment of the immunoregulatory properties of PDLSCs. However, current studies are mainly limited to in vitro cell tests and lack in-depth studies on the immunomodulatory effects of PDLSCs in vivo. In vivo studies based on cell lineage tracing and conditional gene knockout technology may become the main directions for future research.

With the increasing demand for beauty, the treatment of gingival recession has become a common request among patients. Clinically, gingival recession is mainly treated by surgery. The common surgical methods include free gingival grafting, pedicled flap technology and double flap technology (subepithelial connective tissue transplantation combined with coronally advanced flaps). If patients with indications are selected, satisfactory surgical results will be obtained. However, there are still some shortcomings in the above mentioned methods, such as the root coverage effect not being satisfactory. In recent years, researchers have put forward some improved schemes to minimize the shortcomings of the above methods to treat different degrees of gingival recession. A gingival unit graft containing gingival papilla and free gingiva can improve the blood supply of the recipient area and improve the effect of root coverage. It can obtain better root coverage for slight retraction, widening of the angular gingiva and deepening of the vestibular sulcus, but there may be issues with inconsistent color and shape of the gingiva after surgery, as well as poor aesthetic effects. Modified coronally advanced flaps, flaps prepared by the technique of half-thickness, full-thickness and half-thickness, and modified coronally advanced envelope flap technology are designed with the most serious retraction teeth as the center in the case of multiple gingival retractions, both of which can improve the effect of root covering. Tunnel technology and modified tunnel technology, without severing the gingival papilla and tunneling the gingival flap to accommodate the graft, can effectively reduce tissue damage and promote wound healing. This paper reviews the literature and summarizes the outcome of the modified surgery techniques in the treatment of gingival recession. These treatment options for gingival recession are proposed with the aim of improving clinical work, and some suggestions for the treatment of gingival recession to achieve a stable root coverage effect are put forward. In the future, the development direction of mucogingival surgery is to reduce trauma and have a stable curative effect.

Periodontitis is a widespread disease worldwide, with the primary cause of tissue loss being an immune inflammatory response mediated by bacteria. Increasing evidence has revealed a significant correlation between mitochondrial dysfunction and the occurrence and progression of periodontitis. This paper provides a review of current research on the role of mitochondrial dysfunction in the occurrence and development of periodontitis and related therapies from the perspectives of oxidative stress, inflammatory responses, and the regulation of mitochondrial homeostasis. Mitochondria are the main source and target of cellular reactive oxygen species. Mitochondrial dysfunction can generate large amounts of reactive oxygen species, exacerbating local oxidative stress in periodontal tissues and causing cell toxicity and tissue damage. Mitochondria are also the center of cellular inflammatory responses, and the positive feedback loop of inflammation induced by mitochondrial dysfunction may explain the persistent and unresolved nature of periodontitis. Biomaterials loaded with pharmacological agents show potential in restoring mitochondrial function, controlling the development of periodontitis, and promoting periodontal tissue regeneration. However, the key sites of mitochondrial dysfunction in the occurrence and development of periodontitis are not yet fully understood, and the improvement of mitochondrial function in periodontal therapy is still in the experimental stage. Future research efforts should focus on the effect of mitochondrial dysfunction on periodontal cells and explore its specific mechanism in the occurrence and progression of periodontitis in order to provide new insights into the treatment of periodontitis.

Caries is a chronic infectious disease that occurs in the hard tissues of teeth. The interaction of oral microorganisms, host, food and time leads to the occurrence and progression of caries. Free sugar is an important food factor in the occurrence of dental caries. This paper reviews the research progress on the relationship between free sugar and caries in recent years, providing a reference for further clarifying the mechanism of the occurrence and progression of caries caused by free sugar and exploring the methods of caries prevention. The cariogenic mechanism of free sugar is multifaceted. Free sugar can not only be used by oral microorganisms in dental plaque biofilms to produce acid and synthesize intracellular and extracellular polysaccharides but also cause an imbalance in oral microecology and enhance gene expression related to the cariogenic toxicity of oral microorganisms. Based on the correlation between free sugar and caries, it is important to limit the intake amount and frequency of free sugar to prevent caries. This can be achieved mainly by formulating public health policies for reducing sugar, creating a low-sugar family environment with good eating habits, using sugar substitutes and using fluoride. There are few studies on the relationship between free sugar and oral microecology. More research is needed to better understand the effect of free sugar on oral microecology and its mechanism and to validate the caries-preventing effect of various sugar reduction measures. We believe such studies would open up new avenues for the effective prevention of caries.

The Porphyromonas gingivalis type IX secretion system (T9SS) is a recently discovered protein secretion system that is widely distributed in Bacillus cereus. The T9SS is structurally complex and powerful. More than 20 T9SS components have been verified, and more than 30 virulence factors can be secreted by Porphyromonas gingivalis alone, which contributes significant to the pathogenicity of Porphyromonas gingivalis. T9SS is a large protein complex spanning the inner cell membrane, periplasm, and outer cell membrane. Through the structural and functional connections among its components, it forms a sophisticated functional complex that includes power provision, energy transduction, inner and outer membrane translocation, outer membrane modification, and regulatory systems to recognize, translocate, shear, and modify cargo proteins and translocate bacterial intracellular cargo proteins to the cell surface. In recent years, with advancements in X-ray diffraction and in situ cryoelectron microscopy, the exploration of T9SS has evolved from the functional study of single components to the in situ structural study of multiprotein complexes. Still, the structural resolution of the protein still has shortcomings such as low resolution and an inability to capture dynamic functional structures. Future research directions should focus more on exploring how T9SS interacts and functions with cargo proteins. In this paper, we review the research progress on Porphyromonas gingivalis T9SS on X-ray diffraction and cryoelectron microscopy structure resolution in order to gain a deeper understanding of the transport mechanism of T9SS.

Oxidative stress is closely associated with the development of oral diseases such as caries, periodontitis and endodontitis. The accompanying oxidative stress during inflammation could aggravate tissue damage. However, numerous studies have shown that some dental materials, such as composite resins, bleach, drugs for root canal irrigation and dental implants, can give rise to abundant free radicals, which have adverse effects on peripheral tissues. Therefore, it is essential to supplement with extra antioxidants against free radicals. Plant-derived natural antioxidants have attracted great attention in biomedicine because of their excellent biocompatibility and easy access. This paper focused on the redox imbalance in the oral cavity and the application of natural antioxidants to oral therapy and their modification of dental materials. Current research shows that by constructing polyphenol-based metal organic nanoenzymes or adding vitamins and polyphenols to bionic hydrogels, the safety and utilization rate of antioxidants can be significantly improved. However, these polymer delivery systems have problems such as poor degradability, hepatotoxicity and nephrotoxicity, and the research is still in its infancy. In terms of material modification, it is crucial to choose the type and ratio of natural antioxidants and raw materials, as well as appropriate modification methods. A strong chemical bond between the antioxidant and the raw material may lead to the failure of antioxidant release from the modified composite, lowering the antioxidant activity. At the same time, the selection of polyphenols rich in pyrogallol functional groups can retain more free phenolic hydroxyl groups after chemical modification, which is conducive to greater antioxidant activity by the implant materials. Although research on natural antioxidants in oral therapy has made progress, there is a lack of data supporting clinical trials and long-term application effects, and further research is still needed.

Recurrent aphthous ulcer (RAU) is one of the most common diseases of the oral mucosa. At present, no effective method is available for RAU treatment, especially for refractory RAU, which significantly affects patients’ oral health and quality of life. Research shows that combination with systemic diseases greatly increases the difficulty of curing refractory RAU, making conventional oral ulcer treatment harder to perform effectively. This is probably because dentists commonly only focus on handling oral ulcers but neglect to think about the etiology of oral ulcers from a holistic perspective. Thus, we summarized some conditions of refractory RAU accompanied by systemic diseases, including inflammatory bowel disease, iron deficiency anemia, diabetes mellitus, Behçet’s disease, Reiter’s syndrome, sprue syndrome, Sutton syndrome, and acquired immunodeficiency syndrome. We also outlined the treatment principles of these patients. To be specific, on the one hand, dentists should cooperate with the relevant specialists to treat the systemic diseases, while on the other hand they should take measures including topical/general use of medicine, local physical therapy, Traditional Chinese medicine treatment, and psychotherapy for RAU management. This paper aims to provide clinicians with a more comprehensive understanding of the diagnosis and treatment of refractory RAU, in order to make personalized treatment plans for patients and improve the clinical efficacy of refractory RAU.

Gingival recessions (GRs) result in root hypersensitivity, root surface caries, and esthetic problems. Various root coverage surgeries are being developed for periodontal plastic therapy. The tunnel technique (TUN) is one of the most widely applied surgeries due to its features of being minimally invasive, practical, excellent outcomes and long-term stability; however, there are still some limitations of this technique. The history and evolution from the envelope flap to TUN, including its efficiency when compared with coronally advanced flaps with a connective tissue graft (CTG), are reviewed in this paper. The limitations of TUN are discussed in consideration of our clinical experience; for example, there is high technique sensitivity when TUN is applied in GR>5 mm because of the great difficulty in covering the grafts. The advantages of surgical access, including vertical incisions in the vestibule, “W” type and pinhole access, are discussed for different situations. Mattress sutures and sling sutures in a single tooth or multiple teeth are applied in TUN. The different types of grafts, such as CTG, platelet-rich plasma, articular dermal matrix and xenogeneic collagen matrix, are described. Mechanical, chemical and biological conditioning of the root surface are recommended during surgery. Protecting the surgical area and taking antibiotics postoperatively are also very important. Finally, the modifications when TUN is applied with other kinds of techniques are discussed, including lateral closed TUN, laterally positioned flaps, double papilla flaps and frenuloplasty. Minimally invasive, esthetic, long-term stability and simplified techniques are the development trends of TUN in the future.

Facial symmetry evaluation has always been a hot topic of concern for doctors who engage in the study of facial beauty disciplines such as orthodontics, dentistry, and plastic surgery. Although scholars at home and abroad have carried out much research on the evaluation of facial symmetry with a variety of emerging technologies and methods, there is still a lack of unified standards for the evaluation of facial asymmetry due to the complexity of the content and methods and individual subjectivity. Facial asymmetry involves changes in the length, width and height of the face. It is a complex dental and maxillofacial malformation whose early identification and accurate evaluation are particularly important. Clinically, in addition to the necessary dental and maxillofacial examinations, it is also necessary to evaluate facial asymmetry with the help of corresponding auxiliary methods. This paper gives a summary of the commonly used three-dimensional evaluation methods. The evaluation methods of facial asymmetry can be divided into 5 categories: qualitative analysis, quantitative analysis, dynamic analysis, mathematical analysis, and artificial intelligence analysis. After the analysis and summarization of the characteristics, advantages and limitations of each method in clinical applications, it is found that although these methods vary in accuracy, evaluation scope, diagnosis nature and calculation method, etc., the three-dimensional evaluation methods are more objective, more accurate and more convenient and will become the mainstream evaluation method for facial asymmetry with further development of three-dimensional measurement technologies.

Proanthocyanidin (PA), as a kind of natural plant polyphenol, have a variety of biological functions, such as promoting remineralization, inducing collagen cross-linking, inhibiting protease activity and inhibiting bacteria. Therefore, PA could be broadly used in the clinical application of treatment and repair of deep caries in the future; for example, PA could promote dentin remineralization, improve resin-dentin bonding durability and improve the dentin acid erosion effect. This application potential of PA arises from several features, firstly, PA can not only promote dentin remineralization on its own or with other remineralizers but also exhibits antibacterial effects, which can inhibit acid production while reducing the formation of cariogenic pathogens and their biofilms. Based on the above features, PA can reduce the incidence of caries disease; thus, PA improves deep caries and long-term effects after treatment. In addition, PA added to adhesives or etch agents can improve the etching and bonding effect of dentin by inducing collagen cross-linking and inhibiting protease activity, thus achieving the ultimate goal of improving the bonding performance of deep caries. This paper summarizes recent progress of research on PA for the treatment and repair of deep caries, including the promotion of dentin remineralization and antibacterial activity as well as the improvement in dentin bonding and acid etching effect, to provide a more comprehensive reference for treating and restoring deep caries in clinical practice.

It is the key step of the occlusal reconstruction to determine the correct occlusal vertical dimension for edentulous patients. Although there are several methods in clinical practice, there is no ideal way. This paper summariz⁃ es the following methods: inter⁃occlusal distance, closest speaking space method, pre⁃extraction record, face proportion division method and facial appearance observation, cephalometric analysis, electromyography, swallowing, bite force de⁃ termination and self feeling method. In this paper, the current research status and the feasibility of each method are dis⁃ cussed.

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.

Porphyromonas gingivalis (P. gingivalis) is closely related to the occurrence and development of periodontitis. It is considered to be one of the important pathogens leading to alveolar bone resorption. At present, research on P. gingivalis mostly adopts standard laboratory strains whose genetic characteristics have been confirmed, are guaranteed and are traceable, such as ATCC 33277. The virulence phenotypes (endotoxin, firmbria, etc.) of clinically extracted isolates are quite different from those of standard strains, and the pathogenic effects and ability of the host are also widely different. In addition, P. gingivalis is considered to have a significant correlation with a variety of systemic diseases, and the virulence characteristics and pathogenic ability of different strains will have different effects on systemic diseases. However, at present, there is a lack of research on clinical strains and standard strains, and there is a lack of systematic comparison between the two sources of bacteria. In this paper, the differences in the virulence phenotypes and pathogenic effects between clinical isolates and standard strains of P. gingivalis in the last 5-10 years are reviewed. The aim is to elucidate the important virulence gene loci in the P. gingivalis gene sequence, which will play an important role in improving therapeutic methods and the development of related drugs.

Traditional titanium implants do not completely meet the clinical requirements because they are bioinert. The surface of titanium implants, modified by strontium ions, can enhance osseointegration and reduce peri-implantitis. In this paper, the biological properties of titanium implant surfaces modified by strontium ions were reviewed. Strontium ions can be coated on the implant surface by hydrothermal treatment, electrochemical deposition, phosphate chemical conversion, flame-spraying, supramolecular self-assembly, magnetron sputtering, laser deposition and alkali etching. Implant surfaces modified by strontium ions can not only promote osteogenesis and early osseointegration but also inhibit bacterial growth and reduce postoperative infections. Even better osseointegration and antibacterial effects can be achieved when strontium ions are incorporated with other elements, such as silver, zinc, gallium, and calcium. However, most of the studies on the use of strontium ion-modified titanium implants are animal experiments and in vitro experiments, and the observation time is short compared with the actual service life of the implants. Thus, the conclusions obtained may be different from the actual clinical application, and the long-term effects need to be studied. In addition, the osteogenic effects of various modification methods also need to be compared. Future research can focus on the following points: ① to find efficient modification methods that can be widely used in the clinic; ②to study how to control the concentration of strontium ions near the implant to exert their biological function and reduce their toxic side effects; and ③ to conduct long-term follow-up clinical trials to observe their osteogenic and antibacterial effects.

Impacted teeth are a kind of complex malocclusion, and their incidence differs among different races, sexes and dental positions. The causes of impacted teeth include systemic factors and local factors, such as endocrine disorders, malnutrition, and acute and chronic infectious diseases. Local factors can cause abnormal tooth development or eruption during the process from tooth development to tooth eruption, such as damaged permanent tooth embryos caused by local inflammation or trauma, insufficient eruption space caused by premature loss of deciduous teeth, and eruption disorders caused by local lesions for example hyperplasia or odontoma. The clinical manifestation of impacted teeth is the absence of a permanent tooth in a normal position. We can use cone beam CT (CBCT) to locate the impacted teeth. Comprehensive orthodontic treatment includes surgical-assisted eruption, extraction of retained deciduous teeth or supernumerary teeth, removal of lesions such as odontomas and cysts, and expansion of the orthodontic space. When the dysfunctional local soft and hard tissues are removed during a surgical operation, the tooth still cannot sprout smoothly, and it needs to be assisted by orthodontic traction-guided eruption or extracted and autotransplantation. A clear diagnosis, evaluation of the difficulty of treatment and appropriate treatment are the keys to improving the success rate of treatment. In this paper, the epidemiology, etiology, diagnosis and corresponding treatment methods of impacted teeth will be reviewed, and the orthodontic treatment of impacted teeth will be comprehensively described to provide a reference for clinicians about the treatment of impacted teeth.

Gingival pigmentation is a nonplaque gum disease. Patients are often afraid to communicate with others because of gum color problems, which affect the social and mental health of patients. The commonly used treatment methods for gingival pigmentation include scalpel excision, gingival grinding, laser therapy, cryosurgery and electrosurgery. In this paper, the progress of gingival pigmentation treatment was reviewed in terms of bleeding, pain, tissue healing and recoloring. The results showed that the clinical effect of laser treatment was better. Among them, the semiconductor laser had more advantages in reducing bleeding, pain and the restaining rate, while the Er:Cr:YSSG/Er:YAG laser performed better for promoting tissue healing. Clinicians can choose the best kind of laser to use according to the actual situation. For patients with thin gingival biotypes, floating gingival transplantation or substitute materials can be selected to restore the gingival morphology. With the in-depth study of melanin regulation mechanisms, various drugs, such as ascorbic acid, natural peptides, synthetic peptides and derivatives, may be the main research direction for the treatment of gingival pigmentation in the future.

Metabolomics reflects the endogenous metabolite changes in organisms through qualitative and quantitative detection of small molecules in biological samples, revealing the metabolic changes during disease development. Metabolomic studies of periodontitis further elucidate the etiology, diagnosis and predictive markers of periodontitis at the levels of metabolites and metabolic pathways. In this paper, the concept and research methods of metabonomics were summarized, and the current status of the metabonomics of saliva and gingival crevicular fluid in the study of periodontitis was reviewed. Previous studies have shown that metabolites such as short-chain fatty acids and amino acids and metabolic pathways such as glutamic acid and pyrimidine metabolism might promote the occurrence of periodontitis, and it was suggested that lactic acid, γ-amino-butyrate, butyric acid and lysophosphatidic acid might be potential diagnostic markers of periodontitis. The metabolomics study of periodontitis still faces challenges such as high heterogeneity of results and fluctuation of metabolites. In the future, its study could be optimized through multicenter prospective studies to provide fresh approaches for the etiology and diagnosis of periodontitis.

In the process of enamel development, premature senescence and apoptosis of ameloblasts are important causes of hereditary enamel hypoplasia. Silence information regulator 2-related enzyme 1 (Sirt1) is a nicotinamide adenosine dinucleotide (NAD+)-dependent deacetylase that has been widely reported to be involved in the regulation of cell senescence. This paper reviews the research progress of Sirt1 regulating epithelial cell senescence, starting with the structural characteristics of Sirt1, and further expounds on the relationship between Sirt1 and senescence. When epithelial cells are stimulated, Sirt1 affects the senescence of epithelial cells in many ways, such as mitochondrial dysfunction. Sirt1 participates in regulating mitochondrial function and metabolic homeostasis, and telomere length is negatively related to senescence. Sirt1 regulates the expression of telomere reverse transcriptase needed for telomere extension, thus positively regulating telomere homeostasis. DNA damage will undergo damage repair, unrepaired DNA damage will cause cell senescence, and the Sirt1/p53 pathway can inhibit epithelial cell senescence by reducing DNA damage. Senescent cells are the source of chronic inflammation, and chronic inflammation can also promote aging in many ways. Sirt1 inhibits epithelial cell senescence by relieving inflammatory symptoms. In future research, we can focus on the effect of Sirt1 on ameloblast senescence and explore its specific mechanism of action on ameloblasts to find a breakthrough in the etiology and treatment of enamel hypoplasia.

Ectopic eruption of the first permanent molar is a common malocclusion in the early stage of mixed dentition. The incidence among children aged 6-10 years is 0.83%-8.7%, with an increasing trend. The main manifestation is mesial impaction of the first permanent molar during eruption, which is accompanied by the loss of root resorption and space loss of the second primary molar. Ectopic eruption of the first permanent molars can lead to underdevelopment of the dental arch and severe crowding of the posterior dentition. Prevention and early intervention are very important. The ectopic eruption of the first permanent molar is related to the disruption of the differential growth and developmental balance among the teeth, alveolar bone and jaw. In clinical practice, the diagnosis can be made according to the patient's medical history and clinical and imaging examinations, and the treatment can be performed by dividing the teeth, dividing the distal slices of the second primary molars, and distally moving the first permanent molars. This paper reviews the incidence, etiology, clinical manifestations, risks of ectopic eruption of the first permanent molar, diagnostic methods, and common treatment options to provide references for clinical treatment.

It has been traditionally believed that a 1:1 cortical bone remodeling/tooth movement ratio has been preserved during orthodontic treatment for tooth movement, with the alveolar bone on the tension side growing and the alveolar bone on the pressure side resorbing to maintain the balance of the alveolar bone. However, recent studies have shown that alveolar bone loss has been found in patients who have undergone orthodontic treatment, suggesting that the alveolar bone does not change as the teeth change over time. Whether the morphology of the alveolar bone will change when the anterior teeth are moved has been the clinical focus. The changes of anterior alveolar bone in patients who have undergone tooth extraction after orthodontic treatment were summerized by literature review in this paper. The results of the review showed that the alveolar bone at the lingual/palatal root-cervical site of the anterior root is more prone to bone loss after extensive movement of the anterior teeth. With the development of imaging technology, CBCT is now more commonly used for analysis instead of two-dimensional images for measurement, as its results are more accurate. However, there are few multifactorial studies in which CBCT has been used to assess the morphological changes in the alveolar bone. The focus of future research is to compare the long-term changes in the anterior alveolar bone of patients of different ages based on three-dimensional imaging, and to study the correlation between different skeletal features, tooth movement patterns and alveolar bone remodeling.

Dental and craniofacial bone development is a highly coordinated process that is tightly controlled by genetics and influenced by complex environments. The abnormal regulation of many development-related signaling molecules may lead to abnormal tooth development, severe craniofacial bone formation disorders, and developmental deformities. Transforming growth factor-β (TGF-β) is widely expressed in vivo and participates in many cellular biological processes, showing complex regulatory roles in mammalian craniofacial bone growth and tooth development. In tooth development, abnormal TGF-β signaling can lead to the failure of tooth germ formation, and its deletion mutation can directly affect odontoblast differentiation and enamel formation defects. However, the current research on TGF-β mainly focuses on the early stage of tooth development, and a comprehensive and systematic study of TGF-β-related tooth development is lacking. TGF-β signal transduction mainly controls the development of teeth and craniofacial bone by regulating the expression of development-related molecules via the classical Smad-dependent signaling pathway. In addition, the nonclassical mitogen-activated protein kinase (MAPK) pathway also participates in this process. Abnormal TGF-β signaling may cause jaw development disorders, temporomandibular joint dysplasia and inflammation, and cleft palate. Because the specific regulatory mechanism of TGF-β in craniofacial bone development has not been fully elucidated, its specific application in the treatment of related diseases is also greatly limited. This paper describes the new research progress of TGF-β in the development of teeth, jaws, temporomandibular joints and palate as well as related diseases.

With the deepening of research in oral microbiomics, an important relationship between changes in the oral microbiome and orthodontic treatment has been found. Orthodontic treatment will have an impact on the oral and systemic microbiome. The presence of oral appliances can change the quantity and quality of the oral microbiometo and increase the risk of oral and even systemic diseases in patients undergoing orthodontic treatment. Compared with fixed orthodontic treatment, clear aligners will not have a harmful impact on the structure of the oral microbiome, which is more conducive to maintain oral health during the orthodontic treatment process. In addition, different bracket types and materials can lead to different changes in the oral microbiome, and the occurrence and development of orthodontic-related diseases, such as white spot lesions, dental caries, gingivitis and periodontitis, are also related to changes in the oral microbiome. At present, the role of the oral microbiome in the process of orthodontic treatment needs to be further studied. Whether a change in the oral microbiome caused by orthodontic treatment can be restored after orthodontic treatment is still uncertain and needs more research. This paper reviews the research progress on the application of microbiomics in orthodontics, including the impact of fixed appliances and clear aligners on the microbiome and the relationship between orthodontic-related diseases and the oral microbiome.

Polyetheretherketone (PEEK) is known as a high-grade engineering plastic with good mechanical properties, chemical stability and biocompatibility. Currently, PEEK materials have been widely used in prosthodontics, such as complete dentures and removable partial dentures. The relevant research shows that PEEK posts are superior to glass fiber posts, which have high tensile bond strength and bending strength. At present, few case reports of PEEK postcores have been published, and clinical case reports suggest that PEEK postcores have good oral prosthetic aesthetics and are ideal and reliable postcore crown materials. However, the preparation and surface treatment methods of PEEK require further refinement. A review of the related properties of PEEK and the prospects of its application in the field of postcore crown restoration will be presented in this paper.

Patients with impaired quality of life associated with xerostomia need long-term treatment, and a nerve stimulator has the advantage of providing natural saliva and long-term management for patients with xerostomia by electrically stimulating the relevant secretory nerves to promote saliva production. A number of clinical trials have preliminarily demonstrated the efficacy of nerve electrical stimulation in the treatment of xerostomia. However, electrical stimulation has not yet become the mainstream treatment for xerostomia. Large prospective randomized controlled clinical trials are still needed to confirm its long-term effectiveness and safety. In addition, the design of nerve stimulators is of great significance for clinical application. The large volume and inconvenient treatment associated with the extra oral nerve stimulator and the first generation intraoral nerve stimulator hinder their clinical application and popularization. The second- and third-generation intraoral nerve stimulator devices are small, convenient to use and have great application prospects. Research on electrical nerve stimulators for xerostomia treatment is mainly concentrated in European and American countries, while there is very little domestic research. It is urgent to master the core technology for the research and development of electrical nerve stimulators. The innovation of miniaturization, efficient power supply, data feedback and packaging will be the key issues of electrical nerve stimulators in the future. In this paper, the treatment and research of electrical nerve stimulation for xerostomia are reviewed to provide a reference for related basic research and the clinical application of electrical stimulators treating xerostomia in China.

With the arrival of the era of big data, increasing attention has been drawn to the application of artificial intelligence (AI) in the medical field. AI has many advantages, such as objectivity, accuracy, minimal invasiveness, time savings and high efficiency. Therefore, the combination of AI with dental diagnosis and treatment can help dentists improve work efficiency and save medical resources, offering potential significant benefits for dental application. At present, AI has been gradually integrated into prosthodontics, oral and maxillofacial surgery, orthodontics, endodontics and periodontics. The AI system can realize automatic tooth preparation, automatic tooth arrangement and implantology. Deep learning can be used to assist in diagnosing maxillary sinus inflammation, predicting the complications of tooth extraction and improving the accuracy of osteotomy. The AI system can also provide significant clues for the diagnosis, treatment and prognosis of oral and maxillofacial tumors. The breakthrough brought by AI in cephalometric and the assessment of facial attractiveness of patients has promoted the development of intelligent and personalized orthodontic treatment. Deep learning and analysis of medical images also promote the accuracy of root canal therapy as well as the diagnosis and treatment of periodontal diseases. AI technology has realized the leap from digitalization to automation and intelligence in oral diagnosis and treatment, and its application potential in the oral field should not be underestimated. Based on the concepts of AI, this paper will focus on the application of artificial intelligence in various oral clinical fields and briefly introduce its advantages, problems and future.

Deep bite is a common clinical malocclusion that has a great impact on patients’ facial aesthetics and oral function. Bite opening is the key step in the treatment of deep bite, playing a decisive role in the development of mandible and the progress of orthodontic treatment. Torque and tip control during the correction of deep bites is a hot topic in orthodontics. The three-dimensional finite element method can accurately simulate clinical processes and conduct dynamic stress analysis, which provides the basis of the biomechanical mechanism. This paper reviewed the finite element analysis of various orthodontic systems for bite opening to provide a reference for clinical application. The emergence of mini-implants provided a new idea for anchorage control in bite opening. Finite element studies found that high-positioned mini-implants are beneficial for bodily tooth intrusion and proposed the ideal position for force application. For the finite element simulation of the reverse curve archwire, it was found that the intrusion and inclination of the anterior teeth increased with the curve depth of the archwire. The application of clear aligners has also been flourishing, but these forces are still difficult to effectively control. Finite element studies on their attachment design and corresponding tooth movement may be helpful to open the bite quickly and effectively. However, the existing studies still have modeling limitations. The structural simplification, linearization and nonstandard parameter definition of the model reduce model accuracy. Additionally, the existing research mostly focused on initial tooth movement, and studies on long-term tooth movement after bone remodeling are lacking. These studies are needed in the future.

Exosomes are phospholipid bilayer vesicles secreted by living cells that can carry a variety of signaling molecules, such as RNA, DNA, protein, and lipids. Exosomes play a role in the transmission of signaling molecules between cells, thus regulating many physiological and pathological processes. The methods of extracting exosomes include differential centrifugation, density gradient centrifugation, exclusion chromatography, ultrafiltration, coprecipitation, polymer immune affinity, microfluidic separation technology, etc. Each of these extraction technologies has advantages and disadvantages; however, there is no unified international standard. In addition, the expression of specific proteins and genetic material of exosomes from different cell sources are different; thus, their expression characteristics and functions are also distinctive. Based on this situation, research on exosomes is limited to preclinical studies, and difficulties and challenges still exist in clinical application. This paper summarizes the progress of research in the field of exosomes, to understand the characteristics, modification and application of exosomes from different cell sources, and to summarize their advantages and disadvantages as well as challenges, which can help researchers better understand and master the performance of exosomes. Furthermore, improvement of standard procedures in the extraction and manufacturing of exosomes is important, as it will provide a reference for researchers to carry out exosome-related translational clinical research.

With the growing maturity of implant technology, implant overdenture has gradually become a conventional repair method for edentulous patients to restore beauty and function, which improves the quality of life of edentulous patients. This paper reviews the effects of implant factors, attachment factors, occlusal factors and patients' own factors on residual alveolar ridge. Existing studies suggest that when designing denture, doctors first need to consider the oral mucosa and jaw conditions of patients before operation, and select the appropriate size of implant to ensure that sufficient bone remains around the implant; Secondly, when choosing the type of attachment, the number, location and A-P distance of implants should be fully considered, and the inclination of cusp should be properly reduced to avoid the harm of excessive lateral force to alveolar ridge; Finally, regular reexamination should be carried out after operation to maintain longer service time of denture and more sufficient bone mass of edentulous patients. However, there are many factors affecting jaw absorption. In the future, we should further explore many factors, such as patients' habit and frequency of wearing dentures, oral health and nutritional status, systemic diseases and medication.

In recent years, artificial intelligence technology has developed rapidly and has been gradually applied to the fields of clinical image data processing, auxiliary diagnosis and prognosis evaluation. Research has shown that it can simplify doctors’ clinical tasks, quickly provide analysis and processing results, and has high accuracy. In terms of orthodontic diagnosis and treatment, artificial intelligence can assist in the rapid fixation of two-dimensional and three-dimensional cephalometric measurements. In addition, it is also widely used in the efficient processing and analysis of three-dimensional dental molds data, and shows considerable advantages in determining deciding whether orthodontic treatment needs tooth extraction, thus assisting in judging the stage of growth and development, orthodontic prognosis and aesthetic evaluation. Although the application of artificial intelligence technology is limited by the quantity and quality of training data, combining it with orthodontic clinical diagnosis and treatment can provide faster and more effective analysis and diagnosis and support more accurate diagnosis and treatment decisions. This paper reviews the current application of artificial intelligence technology in orthodontic diagnosis and treatment in the hope that orthodontists can rationally treat and use artificial intelligence technology in the clinic, and make artificial intelligence better serve orthodontic clinical diagnosis and treatment, so as to promote the further development of intelligent orthodontic diagnosis and treatment processes.

The reconstruction effect of peri-implantitis bone defects depends on their morphological characteristics. This paper reviews the morphological classification and treatment of peri-implantitis bone defects. A literature review shows that the morphological classification of bone defects in peri-implantitis includes morphology classification and clinical classification. At present, the Renvert classification is more commonly used in the clinic and is divided into four-wall bone pockets, three-wall bone pockets, two-wall bone pockets, one-wall bone pocket and dehiscence according to the number of bone walls. This has guiding significance in the treatment plan of peri-implantitis. The treatment of peri-implantitis depends on the severity of peri-implant bone defects. Peri-implantitis with mild bone defects is treated by nonsurgical treatment, peri-implantitis with severe bone defects is recommended to remove the implant, and peri-implantitis with moderate bone defects is further judged according to the shape of the bone defects. Four-wall bone pockets, three-wall bone pockets and dehiscence are mostly treated by bone regenerative surgery. For shallow two-wall bone pockets, one-wall bone pockets and horizontal bone resorption, bone resection is often used. However, most peri-implantitis has a variety of bone defect forms at the same time, which need to be treated with bone regenerative surgery and bone resection surgery.

Optical illusion refers to the phenomenon in which the scene observed by the human eye is not completely consistent with the objectively presented scene. Optical illusions in stomatology, as well as their clinical application, are demonstrated in this paper in terms of shade, shape and aesthetic design. Shade is not only affected by the optical illusions with which it is associated, such as color metamerism, color constancy and the Chevreul illusion, but also influenced by the surroundings. It is suggested that the surrounding lighting during veneering should be the same as that during color matching in the clinic. As indicated by the Poggendorf illusion and the Leaning Tower illusion, the practice should be conducted and checked from multiple perspectives to compensate for the limitation of human eyes, such as intraoral scanning. Other digital technologies, including digital facial scanning and cephalometric measurement, could be used to reduce the subjective influence of observation. In terms of esthetic design, the interaction of the part and the whole, suggested by Ebbinghaus illusion, should be considered: an individual harmony smile should be designed considering the characteristics of the personality and the features of the face, lips, teeth and gingiva of the patient. Furthermore, personal information, such as gender and age, should be taken into consideration in beautification presentation. Further research should be focused on the influence of optical illusions in stomatology in more details. More communication among doctors, technicians and patients is needed. Clinicians should be aware of the impact of optical illusions to reduce subjective bias in clinical standardized operations and further take advantage of optical illusions to create beautification presentations of dental restorations and smiles.

Objective To study the changes in levels of interleukin (IL)-6, IL-10, tumor necrosis factor-alpha (TNF-α), and alkaline phosphatase (ALP) in the gingival crevicular fluid (GCF) of patients with severe chronic periodontitis before and after nonsurgical periodontal therapy and to explore the relationship among the levels of these four biomarkers in GCF, their periodontal status and their clinical significance to evaluate the effect of nonsurgical periodontal therapy and periodontitis activity. Methods In total, 30 patients with severe chronic periodontitis were enrolled in a 1-year longitudinal pilot study (Chinese Clinical Trial Registry: ChiCTR-OCH-13004679). At baseline and 1, 3, 6, and 12 months after nonsurgical therapy, the periodontal clinical indicators plaque index (PLI), probing depth (PD), clinical attachment loss (CAL), sulcus bleeding index (SBI) were recorded. Filter paper strips were used to collect two deep-pocket (probing depth ≥ 6 mm) and two shallow-pocket (probing depth ≤ 4 mm) periodontal sites for each patient and weighed. The levels of interleukin IL-6, IL-10, TNF-α, and ALP in GCF were assessed using enzyme-linked immunosorbent assay. Meanwhile, 30 healthy sites of 15 subjects with healthy periodontium were used as the baseline controls for patients with severe chronic periodontitis. Results At the baseline, the TNF-α, ALP and IL-6 levels in GCF of the disease sites of patients with periodontitis were significantly higher than those in healthy periodontal sites of the control group (P < 0.001), and the levels of IL-10 were significantly lower than those in the control group (P < 0.001). In patients with severe chronic periodontitis, the levels of TNF-α, ALP and IL-6 in GCF at deep-pocket sites were significantly higher than those at shallow-pocket sites (P 0.05). 1, 3, 6, and 12 months after nonsurgical treatment, the periodontal clinical indicators were improved compared with the baseline. In addition, there was a significant correlation between the levels of these four biomarkers and the periodontal clinical parameters (P < 0.05). During the two follow-up visits after nonsurgical periodontal therapy, the sites with more than 2-mm increase in attachment loss had significant differences in the levels of the four biomarkers in the GCF compared with the previous visit time (P < 0.005). Conclusion The detection of the levels of these four biomarkers in GCF has strong clinical significance for assessing the severity of periodontitis and the efficacy of nonsurgical periodontal therapy. Increased levels of TNF-α, ALP, and IL-6 and decreased IL-10 levels in GCF may indicate periodontitis progression at this site.

Periodontitis is the inflammation of periodontal tissue caused by dental plaque, which absorbs the alveolar bone and cementum. The immune response triggered by CD4+T cells is the key factor for the aggravation of periodontitis. The activation of dendritic cells and the receptor activator of the NF-κB ligand (RANKL) pathway is an important link in the alveolar bone resorption of periodontal tissue. Pro-inflammatory factors such as interferon-γ (IFN-γ), tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β) also play important roles in the development of periodontitis. Interleukin-37(IL-37), which is a newly discovered cytokine in the IL-1 family, has five shear variants from a to e, among which the clover β-structure encoded by exon 4 plays an important role in the binding of cytokines and the corresponding receptors. IL-37 has strong anti-inflammatory and inhibition of autoimmunity, can enter the nucleus with the help of caspase-1 and bind with Smad proteins to regulate the transcription of pro-inflammatory genes. Extracellular IL-37 can bind to IL-18 binding protein and inhibit the production of pro-inflammatory factors. IL-37 can inhibit the progression of periodontitis by inhibiting the RANKL signaling pathway, inhibiting the proliferation and differentiation of dendritic cells and CD4+T cells, binding to Smad proteins, and releasing pro-inflammatory factors such as IFN-γ and TNF-α. The IL-37 concentration in periodontal tissue can indicate the progression of periodontitis. Few studies have described the interaction between the anti-inflammatory factor IL-37 and periodontitis. Thus, in this paper, the structure and function of IL-37 and the related factors between IL-37 and periodontitis will be reviewed.

Traumatic temporomandibular joint ankylosis refers to fibrous or bony fusion between the condyle and the glenoid fossa. It can cause problems with mouth-opening limitations, mastication difficulties, obstructive sleep apnea and hypopnea syndrome. When traumatic temporomandibular joint ankylosis occurs during childhood, it can cause facial asymmetry, micrognathia, and malocclusion, which significantly affect the physical and mental health. Once temporomandibular joint ankylosis occurs, it will be refractory and recurrent. The pathogenesis of temporomandibular joint ankylosis has not been completely elucidated and has always been a research hotspot in the oral and maxillofacial fields. In this paper, worldwide research was conducted, and the pathogenesis of traumatic temporomandibular joint ankylosis was clarified, such as “damage of condyle”,“disc displacement or rupture”,“damage to the glenoid fossa” and “lateral pterygoid muscle distraction”. The relative pathogenesis hypotheses were summarized, such as “hematoma organization” and “lateral pterygoid muscle distraction osteogenesis”. The related pathogenesis of traumatic temporomandibular joint ankylosis was discussed based on the latest cytology and molecular biology research.

Hemangiomas and vascular malformations are common clinical diseases. According to their clinical and imaging characterizations, the International Society for the Study of Vascular Anomalies (ISSVA) has systematically classified infantile hemangioma and vascular malformations, and the classification has been widely recognized and applied. To date, most vascular malformations involve the following important signaling pathways: PI3K/Akt/mTOR and RAS/MAPK/ERK. This discovery has major impacts on the diagnosis and treatment of vascular malformations including the following: the understanding of the biology of vascular malformations has been increased; the understanding of vascular malformations based on genotype has been refined; and the development of targeted drugs for the treatment of vascular malformations has been promoted. Despite facing many challenges, with the development of gene sequencing, molecular biology and imaging technology, the relevance of vascular malformation classification and the accuracy of diagnosis are improving, and this is accompanied by innovations in surgical treatment and sclerotherapy, interventional embolization, and continuous progress in targeted therapy. At present, investigations on vascular malformations are mostly retrospective clinical studies or low-level clinical trials. The purpose of this paper is to review the literature on the treatment of infantile hemangioma, lymphatic malformation, venous malformation and arteriovenous malformation and to review the research progress in evidence-based treatment of infantile hemangioma and vascular malformation.

Implant dentures have become the main method for the treatment of dentition defects or complete edentulism. However, due to the lack of periodontal ligament and periodontal ligament proprioceptors, implant dentures have very limited cushioning and sensing capabilities and are prone to occlusal overload. As a risk factor for peri-implantitis, occlusal overload seriously threatens the stability and success rate of implant dentures. This paper reviews the occlusal overload of implant dentures, the causal relationship between occlusal overload and plaque biofilms in peri-implantitis, the mechanism by which occlusal overload promotes peri-implantitis, and the effect of reasonable clinical occlusal adjustment on healing. This review shows that occlusal overload is closely related to the occurrence of peri-implantitis. Occlusal overload can promote the process of peri-implantitis by increasing the release of inflammatory factors and mechanical transduction mechanisms. The intervention of the patients’ bad bite habits and occlusal adjustment can promote the healing of peri-implantitis. At present, there is no uniform standard ideal experimental model for occlusal overload. The phenomenon and mechanism of bone resorption around the implant caused by overload force still need further observation and research, which will help determine the intensity, direction and timing of occlusal loading to guide clinical occlusal adjustment.

Dental resin materials have been widely used in the treatment of dental defects. However, the polymerization shrinkage of the resin materials tends to cause microleakage and accumulation of bacterial plaque, which leads to secondary dental caries. Endowing dental resin with antibacterial properties is an important way to solve this problem. Adding antibacterial agents to dental resin is the main method to give it antibacterial properties. Antimicrobial agents are mainly divided into three types: release type, non-release type and mixed type. In terms of antibacterial effects, the selection and addition of antibacterial agents will affect the antibacterial and mechanical properties of dental resin materials; and the long-term antibacterial effect of antimicrobial agents in the oral cavity remains to be verified; as antimicrobial agents or other environmental factors can lead to drug resistance and even dormant persistent bacteria. In recent years, researchers have been committed to improving the antibacterial effect by modifying antibacterial agents. The sustained release of antimicrobial agents via carriers is also the main research direction. This paper reviews the research progress on the antibacterial properties of dental resin materials.

Guided bone regeneration technology applied in alveolar bone defect regeneration is based on the barrier function and space maintenance of the barrier membrane. Therefore, traditional development strategies for barrier membranes focus on their physical barrier function, degradation characteristics and biocompatibility to avoid immunogenicity. However, not only does the barrier membrane passively block connective tissue, it is recognized as a “foreign body”that triggers a persistent host immune response, known as a foreign body reaction. The theories of osteoimmunology reveal a close relationship between the immune system and bone system and emphasize the role of immune cells in bone tissue-related pathophysiological processes. Based on these findings, we propose a novel development strategy for barrier membranes based on immune microenvironment regulation: by manipulating mechanical properties, surface properties and physiochemical properties, barrier membranes are endowed with an improved immunomodulation ability, which helps to regulate immune cell reactions to induce a favorable local immune microenvironment, thus coordinating osteogenesis and osteoclastogenesis as well as barrier membrane degradation to increase the efficiency of barrier membranes in GBR applications. In this paper, we review the development of barrier membranes and their close relationship to the immune microenvironment concerning bone regeneration and membrane degradation. Additionally, the outcomes of research on barrier membranes based on the regulation of the immune microenvironment have been summarized to improve the osteogenesis efficiency of barrier membranes and solve the problem of the regeneration and repair of bone defects, especially alveolar bone defects.

Mucositis is the most common side effect of radiotherapy and chemotherapy. It is an inflammatory disease with an unclear pathogenesis, diverse clinical manifestations and no effective treatment. It often manifests as local mucosal burning and stinging pain in the oral cavity and nausea, vomiting and diarrhea in the gastrointestinal tract. At present, it has been found that local microflora imbalance promotes the occurrence and development of chemoradiotherapy mucositis, and probiotics can be used as an emerging approach to prevent and treat mucositis. This paper reviews the research progress of probiotics in the prevention and treatment of oral and gastrointestinal chemoradiotherapy mucositis, focusing on the influence of microorganisms on the pathogenesis and treatment of gastrointestinal mucositis. Literature review results showed that the occurrence and development of mucositis may be related to changes in the composition and function of local microflora, and probiotics can play a preventive role by regulating local microecology and host immunity. At present, the main probiotics used in the prevention and treatment of mucositis are Lactobacillus and Bifidobacterium. Most clinical trials have confirmed that probiotics have a positive effect in the prevention and treatment of mucositis. However, due to the variety of probiotics and different tumor treatment regimens, prevention and treatment effects may not be observed in some studies. Therefore, the selection of probiotics with high efficacy and safety and the design of the best combination of probiotics and intervention programs are current research hotspots.

Vital pulp therapy aims to maintain healthy pulp tissue as much as possible to improve the long-term survival of teeth. It has limited indications and uncertain curative effects. The pathological changes in inflamed pulp are the histological basis for the determination of treatment strategies and the treatment outcome; however, pulp sensitivity testing cannot reflect the actual histological status of the pulp. With the development of basic and clinical research on vital pulp therapy, the innovation of modern diagnostic and therapeutic technology and capping material, vital pulp therapy can be used as a treatment of teeth on which it was previously thought pulpectomy was necessary. Based on the evidence-based literature, this paper analyzes and summarizes the pathological changes of pulpitis and clinical research on the treatment of pulpitis. Vital pulp therapy can be a treatment for mature teeth with carious exposure and symptoms of irreversible pulpitis if comprehensive applications, including laser Doppler flowmetry, tissue oxygen monitoring, magnetic resonance imaging and microscopy, are used to determine the degree of pulp retention and if infection control and the use of biocompatible capping material are emphasized. In the future, it will be necessary to improve the success rate of vital pulp therapy for the treatment of pulpitis through research on the mechanism of pulp repair and regeneration, the precise diagnosis of pulpitis, and the development of pulp capping materials.

Chronic periodontitis is an infectious disease caused by plaque as the initiating factor. Clinically, it manifests as irreversible loss of hard tissue, leading to the destruction of surrounding periodontal tissue, including the deep periodontal pocket, loss of attachment, and finally, tooth loss. Interleukin-18 (IL-18) can promote inflammation and regulate immune function and plays an important role in mediating the host immune response and inflammatory response. An increase in IL-18 in vivo can induce the production of interferon and inflammatory factors, such as interleukin, tumor necrosis factor and matrix metalloproteinase, thus mediating the dual reaction of immunity and inflammation. These inflammatory factors are involved in the occurrence and development of chronic periodontitis. Many clinical studies have shown that the levels of IL-18 in serum, saliva, gingival crevicular fluid and gingival tissue samples of patients with chronic periodontitis may be positively correlated with the severity of periodontitis; however, as a candidate gene, IL-18 is involved in the susceptibility polymorphism of periodontitis. Understanding how to quantify the level of IL-18 in clinical studies and apply it to diagnostic tools and new sites identified by new methods (genome-wide association studies and omics research) will also deepen our understanding of the pathogenesis of IL-18 in chronic periodontitis and provide new ideas for future precision medicine and the formulation of personalized programs. In this paper, the structure, biological function and association between IL-18 and periodontitis are reviewed.

Most salivary gland stones involve the submandibular gland, which often cause recurrent swelling and pain of the glands after meals, and used to be the main reasons for the gland removals. With the trend of minimally invasive treatment, gland preservation and functional recovery in the diagnosis and the treatment of submandibular lithiasis have been paid more and more attention. New equipment and technologies such as CBCT and sialendoscopy, which are widely used in clinical practice, have contributed a lot to the accurate orientation and minimally invasive treatment of stones, and enriched the managements of submandibular lithiasis. Based on our experience and the review of relevant literature, this paper attempts to summarize the treatment strategies for submandibular stones distributed in different parts of the duct: ① emphasizing on the integrity and functions of the organ; ② endoscopy and minimal invasiveness come first; ③ scientific classifications and personal managements. Appropriate treatment options should be selected according to the features of the stones: endoscopic lithotomy helps a lot in removing those located in the anterior or middle part of the duct; endoscopic lithotomy or/and sialolithotomy are needed according to the features of hilar stones; the regular follow-up is required for the intraglandular stones. Meanwhile, the evaluation of the gland function is also important. After the removals of sunmandibular stones, the functions of the glands should be promoted to restore as far as possible.

Orthodontic tooth movement is a complex physiological process based on periodontal tissue remodeling. Numerous factors, such as the anatomical characteristics of oral and maxillofacial complications, occlusal interference, mechanical factors and systematic factors, may play critical roles in orthodontic tooth movement, leading to tooth movement difficulty. In recent years, many scholars have focused on factors related to tooth movement difficulty, but current research mostly involves animal experiments and retrospective studies. Clinical trials of high-quality and evidence-based medicine studies are required. Although no sound theory system is available that is universally recognized and the mechanism of many factors remains debatable, alveolar bone defects, the maxillary sinus, the gingiva, tooth ankylosis, bone islands and friction may cause orthodontic tooth movement. Understanding the factors related to the difficulty of orthodontic tooth movement is advantageous to develop a more comprehensive personalized treatment plan for patients and achieve more efficient and safer tooth movement. In this paper, the current factors related to orthodontic tooth movement are reviewed to provide references for clinical orthodontic treatment.