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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.

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.

Dental bonding technology and materials have been used widely in dentistry because of their excellent properties. The development of novel bonding technology and materials is constantly being performed to improve the effect of dental bonding restorations. Observation and analysis of the dental bonding interface is one of the most important methods for laboratory evaluation of bonding efficiency. This paper aims to review the methods of observation and analysis of dental bonding interfaces to provide a reference for the selection of evaluation methods in dental bonding research. The features of 6 methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), Raman spectroscopy (RS), optical coherence tomography (OCT) and atomic force microscopy (AFM), were described and summarized. Among these methods, SEM and TEM are used most often in the analysis of fine structures; CLSM and OCT are used for the acquisition of characteristic image signals, such as microleakage and exogenous and endogenous fluorescence; and RS and AFM can test chemical composition and mechanical properties.

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.

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.

Er: YAG laser bleaching is a new tooth bleaching method compared with traditional bleaching technology. The Er: YAG laser significantly improves the bleaching efficiency, has the advantages of high safety, short treatment time and excellent bleaching effect and is widely used in clinical operations. This paper summarizes the working principle and bleaching characteristics of Er: YAG laser bleaching technology and its effect on tooth structure. The existing literature suggests that the high absorption of water and hydroxyapatite by the Er: YAG laser makes it work well on water-bearing tissues and dental tissues. When it is absorbed by the bleaching agent on the tooth surface, it accelerates the catalytic oxidation-reduction reaction and selectively acts on the pigment particles deposited on the tooth, thereby achieving the effect of tooth bleaching. Er: YAG laser bleaching can be applied to most discolored teeth. The bleaching process is rapid and effective. During the bleaching process, for the dental pulp tissue, the temperature of the pulp cavity is lower than the critical value of 5.6 ℃, causing no pathological damage to the dental pulp tissue. For the hard tissues of the teeth, laser irradiation will cause changes in the chemical composition of calcium and phosphorus. The enamel presents a unique lava-like shape, and the bonding strength of the tooth increases after bleaching. Compared with other lasers, the Er: YAG laser has a wavelength close to the peak of water, and adding other ingredients to the bleaching agent is not required. Almost all the energy is used for the bleaching agent, with no damage to the surrounding tissues.

Currently, cell transplantation in combination with scaffold materials are one of the main strategies in periodontal bone tissue engineering. In periodontal bone tissues, the stiffness and spatial structure of tissues such as alveolar bone and cementum differ, and the difference in mechanical properties of scaffolds also has disparate effects on the proliferation and differentiation of stem cells. Accumulating evidence shows that mechanical stimulating factors such as matrix stiffness and scaffold topography modulate biological behaviors of various seeding cells, including adipose-derived stem cells and periodontal ligament stem cells. A hard matrix can promote cytoskeletal stretching of stem cells, leading to nuclear translocation of Yes-associated protein (YAP) and promoting osteogenic differentiation by upregulating alkaline phosphatase (ALP) and osteocalcin (OCN) via the Wnt/β-catenin pathway. The topologic structure of scaffolds can affect cell adhesion and cytoskeletal remodeling, increase the hardness of cells and promote the osteogenic differentiation of stem cells. In this paper, the effects of mechanical stimulation on the differentiation of stem cells in periodontal bone tissue engineering are reviewed.

In recent years, pulp regeneration has become a research hotspot in the field of stomatology. 3D printing can realize precise control of structure and shape of scaffolds, which provide basis for seed cell adhesion and growth factor release. The 3D printing "pulp complexes" constructed by 3D printing scaffolds for tissue engineering provides a new direction for pulp regeneration research. This paper reviews the applications of 3D printing technology in pulp regeneration. The results of literature review showed that the scaffold materials, seed cells and growth factors in the 3D printing "pulp complexes" all play an important role in the pulp regeneration research. Among them, the scaffold materials act as carriers to load seed cells and growth factors and provide a suitable microenvironment for them. The common seed cells such as dental pulp stem cells, stem cells from apical papilla and stem cells from the human pulp of exfoliated deciduous teeth can provide the cellular basis for pulp regeneration. Moreover, the introduction of growth factors can further support the differentiation of pulp tissue and the reconstruction of pulp vessels and promote pulp regeneration. At present, the 3D printing "pulp complexes" in the study of dental pulp regeneration has made some progress and can induce the formation of pulp-like tissues in the laboratory. However, preparing 3D-printing "pulp complex" with good biological activity, which integrates biomimetic blood vessels and nerves to supply oxygen and nutrients to the cells in the root canal, remains a huge challenge and still needs further exploration and research.

The development of materials science is of great significance to the treatment of dental pulp diseases. Poly lactic acid glycolic acid (PLGA) copolymer is an organic macromolecule compound that is widely used in the preparation of biomedical materials. In recent years, PLGA, as a drug/molecular loaded system and tissue regeneration scaffold, has shown prospects for application in the treatment of dental pulp diseases. This paper will review the application of PLGA in the treatment of dental pulp diseases and provide a basis for its further development and utilization. The results of the literature review show that PLGA is a drug/molecular delivery system that is mainly used in the improvement of pulp capping materials, root canal disinfectant and apexification materials. PLGA-improved pulp capping agents can prolong the action time of the drug and reduce toxicity. The modified root canal disinfectant can realize the sustained release of drug, make the drug penetrate deeper into the subtle structure, and contact more widely with the pathogenic bacteria. The modified apexification materials can provide more convenient administration methods for apexifixment. As a scaffold for tissue engineering, PLGA is mainly used in the study of pulp regeneration. The optimization of PLGA physical properties and action environment can provide a more suitable microenvironment for seed cells to proliferate and differentiate. How to utilize the advantages of PLGA to develop a more suitable material for endodontic application needs further study.

Objective To study the effects of different concentrated sulfuric acid etching durations on the shear bond strength between polyether-ketone-ketone (PEKK) and dentin, providing a scientific basis for the clinical bonding procedures of PEKK prosthesis. Methods Forty-four PEKK specimens were prepared and randomly divided into four groups: group A was the control group, which was only polished with abrasive papers, group B, group C and group D were experimental groups, which were etched by 98% concentrated sulfuric acid for 5 s, 30 s and 60 s, respectively. In addition, one sample was randomly selected from each group, and the profile was prepared by a slow cutting machine. The surface morphology of the profile was observed under SEM. After the four groups of specimens and dentin were bonded by resin, they were soaked in distilled water at 37 ℃ for 24 h. After the shear bonding strengths were measured, the fracture interfaces of the specimens were examined by the scanning electron microscopy and stereomicroscopy, and failure models of bonding were analyzed. Results After acid etching treatments, the cross-sectional images in group B presented uniform spongy shapes, while the cross-sectional images in group C and group D showed destructive pore structures. The shear bond strengths of group B (16.84 ± 1.84) MPa, group C (12.33 ± 1.22) MPa and group D (6.44 ± 1.18) MPa were higher than that of group A (3.99 ± 1.06) MPa (P < 0.05). The highest shear bond strength was observed in group B (16.84 ± 1.84) MPa. Conclusion The surface treatment of 98% sulfuric acid etching for 5 s manifested the best bond strength between PEKK and dentin.

The evaluation of immune function plays an important role in the diagnosis, treatment and prognosis of many diseases. To date, immune function detection includes cellular immunity, humoral immunity, and inflammatory markers. In this paper, the application of immune function detection in the diagnosis, differential diagnosis and treatment monitoring of various diseases was discussed; then, the application value of immune function detection in the diagnosis and treatment of three common oral mucosa-related diseases, including recurrent aphthous ulcer (RAU), oral lichen planus (OLP), and oral squamous cell carcinoma (OSCC), were reviewed combined with the literature and our research. Our research found that RAU patients present abnormal humoral immune function and obvious inflammatory reactions, whereas OLP and OSCC patients present mild inflammatory reactions and more serious abnormal cellular and humoral immune function, so the combined detection of immune function has a certain guiding value for the diagnosis and treatment of these diseases. Moreover, in the future, it is necessary to carry out a study on large sample, multicenter and multiindex joint detection to better clarify the role of immune dysfunction in the pathogenesis of various diseases and its mechanism, to establish the corresponding diagnostic model and prognostic prediction model, to find more effective treatment methods.

Oral cancer is one of the most common cancers that occur in the head and neck and can seriously affect the life span and living standard of oral cancer patients. Candida albicans （C. albicans） is the most common opportunistic pathogenic fungus in the oral cavity, shows pathogenicity and easily causes Candida infection when the host′s immune function is low. Recent studies have shown that C. albicans infection is closely related to oral cancer. This paper reviews the epidemiology of C. albicans infection in oral cancer patients, the influence of C. albicans infection on the occurrence and development of oral cancer and research on its mechanism. Existing studies have shown an increased risk of C. albicans infection in oral cancer patients, while C. albicans infection may promote the occurrence and development of oral cancer through mechanisms such as damaging the oral epithelium; producing carcinogens, including nitrosamine and acetaldehyde; and inducing a chronic inflammatory response and T helper cell 17 immune response. However, these mechanisms are still relatively superficial and lack sufficient direct evidence. In the future, additional in-depth studies are still needed to further clarify the cancer-promoting mechanisms of C. albicans and provide new ideas for the prevention and treatment of oral cancer.

Mucositis is a common gastrointestinal complication in cancer patients undergoing chemoradiotherapy, including oral mucositis and gastrointestinal mucositis, with clinical manifestations of oral ulcers, vomiting, diarrhea and pain that seriously reduce the quality of life of patients and even affect anticancer therapy. Toll-like receptor (TLR) are important receptors involved in innate immunity and in the development of chemoradiation-induced mucositis by mediating the effect between microorganisms and the host. A comprehensive understanding of the role of TLR in mucositis is helpful to guide the prevention and treatment of mucositis. This paper reviews the available studies on TLR and mucositis. The results of the literature review indicate that different TLR have different roles in chemoradiation-induced mucositis: TLR2 is an important receptor in the inflammatory cascade of chemoradiation-induced mucositis; TLR4 activation can increase gastrointestinal mucosal inflammation and lead to oral epithelial ulceration; TLR5 agonists can reduce the degree of radiation-induced mucositis damage; and antagonizing or knocking out TLR9 can reduce chemoradiation-induced gastrointestinal mucositis. However, no TLR agonists or inhibitors have yet been applied in clinical practice, and additional studies are needed to explore the role of different TLR in mucositis in the future to provide a reference for the precise prevention and treatment of chemoradiation-induced mucositis.

Postoperative fistulae are one of the most significant complications of cleft palate repair. They usually has an adverse effect on patients’ oral hygiene, speech and even mental health. There has been a wide range of rates of fistula occurrence, from 0.8%-60%, with the classification and definition of fistulae differing from one author to the next. In this paper, the definition and classification of palatal fistulae and their reconstruction method are reviewed. At present, there is a lack of a consistent definition of palatal fistulae and a classification that can fully reflect the characteristics of palatal fistula. Adjacent flap is mainly used for repairing small fistulae with an adequate amount of surrounding tissue; anteriorly based dorsal tongue flaps are a safe and reliable method for large fistulae; free flap is beneficial for refractory and complicated palatal fistulae that are difficult to repair by the local and pedicle flap; and different synthetic materials are used in multilayer repair of fistulae; among them, composite polymer membrane is highly biocompatible, promoting cell attachment and proliferation in animal models, but its security in the human body needs further research.

Oropharyngeal carcinoma is a highly heterogeneous disease that is mainly caused by tobacco and alcohol abuse or high-risk human papillomavirus (HPV) infection. HPV-positive oropharyngeal carcinoma and HPV-negative oropharyngeal carcinoma have obvious differences in etiology, epidemiology and prognosis; therefore, different methods should be adopted for treatment. It is known that the TP53 gene is not mutated in HPV-positive oropharyngeal carcinoma, and radiation therapy can activate it and induce cell apoptosis via DNA damage. There are common repair pathways to DNA damage, such as nonhomologous end joining, and this pathway is more sensitive to radiotherapy under the inhibition of HPV oncoprotein. In addition, the further activation of the immune response under the effect of radiation also participates in the elimination of tumors. In this paper, we reviewed the research on the sensitivity of HPV-positive oropharyngeal cancer to radiotherapy to provide a scientific basis for targeted treatment for various pathogenic factors and clinical stages of oropharyngeal cancer in the future.

Nonsyndromic cleft lip with/without cleft palate is a common congenital birth defect of the maxillofacial region. The pathogenic mechanism is related to the interaction of genes and environmental factors. At present, there are many studies on genes, and genome-wide association analysis has found that the new susceptibility gene v-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB) is associated with the development of nonsyndromic cleft lip with/without cleft palate. This paper reviews the research progress on the correlation between single nucletide polymorphism(SNPs) in MAFB and nonsyndromic cleft lip with/without cleft palate. The results of this review reveal how the MAFB gene is expressed and differentiated in various cell types and plays an important role in maintaining the development of various organs, such as the brain, pancreas, and parathyroid glands. The MAFB gene is significantly associated with the occurrence of nonsyndromic cleft lip with/without cleft palate in the Asian population. rs13041247, rs11696257, rs17820943 and other teratopoietic single nucleotide loci are the most commonly studied teratopoietic single nucleotide loci, and the research conclusions on the correlation between SNPs in MAFB genes are obviously different in different populations. The interaction between the MAFB gene and other susceptibility genes leads to the occurrence of nonsyndromic cleft lip with/without cleft palate; nevertheless, more in-depth research is needed on specific mechanisms and approaches based on the relationship between these two factors

Osteocytes, which develop from osteoblasts, are recognized as the main cells embedded in mature bone tissue. The traditional notion is that osteocytes exclusively play a structural role, however, with the development of related research in recent years, the role of osteocytes in bone metabolism has been explored. Periodontitis is a chronic inflammatory disease initiated by plaque biofilm, and is the main cause of adult tooth loss. Clinically, periodontitis primarily manifests as attachment loss, bleeding on probing and other symptoms. Alveolar bone resorption is the most characteristic pathological change. Current research demonstrated that osteocytes sense mechanical stress, participate in bone remodeling, regulate mineral balance, and participate in endocrine function. Thus, these cells play an important role in bone homeostasis and systemic metabolic balance. Osteocytes are actively involved in the development of periodontitis through the high expression of receptor activator of nuclear factor kappa B ligand (RANKL), secretion of sclerostin, and effect on apoptosis, senescence and autophagy. In the future, the detection of bone cell metabolism-related products will have certain application prospects for the clinical evaluation of periodontitis prevention and treatment. Therefore, this paper reviewed the role of osteocytes in bone homeostasis and the relationship between osteocytes and periodontitis, to provide new ideas for the prevention and treatment of periodontitis.

In recent years, many researchers have devoted themselves to the application of photodynamic therapy (PDT) in root canal disinfection, as conventional root canal disinfection methods have failed to achieve the optimal effect. Some clinicians have also applied PDT to root canal disinfection. PDT is expected to have a better effect than traditional root canal disinfection. This paper reviews the research progress on the mechanism, effect, influencing factors and limitations of PDT in root canal disinfection. Current research suggests that differences in the type and status of the bacteria, photosensitizers, light sources, operating environment and methods all affect the efficacy of root canal disinfection of PDT. Most of the research into PDT for root canal disinfection finds that it is effective, nontoxic, advantageous to dental pulp regeneration and comfortable for the patient, as well as lacking an excitant; however, its bactericidal effect is inferior to that of sodium hypochlorite. At present, it cannot replace traditional chemical washing but is a promising auxiliary method. The design of the photosensitizer, the energy dose of the light source and the optimal irradiation time need to be determined by further experiments, and more clinical verification is needed before its application in root canal therapy.

Complete avulsion of teeth are one of the most serious traumatic dental injuries. The preferred treatment is tooth replantation. When teeth usually cannot be treated in time, the periodontal membrane on the root surface becomes necrotic , and the success rate of replantation is greatly reduced. How to use seed cells, growth factors and scaffold materials to promote periodontal tissue regeneration, improve periodontal membrane healing of replanted teeth, and achieve successful replantation of completely dislocated teeth is an urgent problem. Periodontal ligament stem cells (PDLSCs) express stem cell markers, have the potential to undergo multicellular differentiation and have important application value in periodontal tissue regeneration and repair. Fibroblast growth factor-2 (FGF-2), basic fibroblast growth factor (bFGF), lysobisphosphatidic acids (LPA) and other related regulatory factors promote periodontal tissue regeneration. Seed cells combined with scaffold materials can promote periodontal tissue regeneration and repair periodontal tissue defects. At present, studies have shown that PDLSCs and other seed cells have the potential for periodontal tissue regeneration and have been widely studied in experimental animal models of periodontitis and bone defects. However, there are few reports on the application of replanted teeth after complete avulsion, and its mechanism is not clear. In this paper, the research progress of periodontal tissue regeneration after total dislocation replantation is reviewed. We expect to apply periodontal tissue regeneration research to the replantation of fully dislocated teeth to achieve periodontal membrane healing of fully dislocated replanted teeth to provide a theoretical basis for future clinical work.

Treponema denticola is an important pathogenic Treponema pathogen in the human oral cavity. Early studies have found that Treponema denticola is closely related to the occurrence and development of periodontal diseases. With the development of technical methods in recent years, many studies have shown that Treponema denticola not only can participate in periodontal diseases through a variety of mechanisms but also can play an important role in the development of various oral diseases. Treponema denticola is detected in high concentrations in peri-apical diseases and peri-implant diseases, and its surface protein is also prevalent in oral tumor samples. This paper reviews the research progress of Treponema denticola in periodontal diseases, pulp peri-apical diseases, peri-implant diseases and oral tumors, and summarizes the relevant mechanisms. For example, Treponema denticola can cause immune regulation disorder, destroy the epithelial barrier, induce bone absorption, promote the occurrence and development of inflammation through a variety of surface proteins, including chymotrypsin-like protease complex (CTLP), major outer sheath protein (Mosp), Td92, and LOS. It can also escape complement-mediated killing effects through surface FhbB lipoproteins and promote the occurrence and development of oral tumors by regulating the tumor microenvironment. These theories provide a theoretical basis for further understanding the development of oral diseases, controlling the infection of Treponema denticola, and exploring more effective treatment strategies.

Eye tracker is an instrument that can record the characteristics of eye movement when people process visual information. This instrument is important for basic psychological research. In the study of dental aesthetics, an eye tracker reflects the observer′s objective eye movement pattern and reveals the underlying aesthetic psychology. This paper summarizes the major research methods of dental aesthetics while focusing on eye-tracking studies in oral aesthetics. Eye tracking studies show that different population has different eye movement patterns when observing the same faces, while the same population can have different eye movement patterns when observing the faces of dental patients and normal people. This finding reveals that the personal characteristics and experience, the social environment and the featured facial structure of the observed individuals can influence eye movement patterns. This study also shows the factors that cause the aesthetic differences among different individuals and groups, as well as the psychological mechanisms.

The crown-root ratio (C/R) theory of natural teeth has been widely recognized in the field of stomatology,and has important clinical significance in predicting and assessing the prognosis of natural teeth as well as for abutment selection during denture restoration. In the past few decades, scholars have advocated for the implantation of implants as long in length as possible to improve the success rate according to the theory of crown-root ratio of natural teeth. However, with the application of short implants, our philosophy of implantation has changed, and the relationship between the crown-implant (C/I) ratio and complications has become one of the current research hotspots. In this paper, the concept of the crown-implant ratio, the research progress of the C/I ratio, the implant survival rate and clinical complications of implant restoration were reviewed and summarized, and the following suggestions were put forward: although most studies have shown no significant correlation between the C/I ratio and implant survival or marginal bone loss, this relationship may increase the risk of mechanical complications. A C/I < 3 and a crown length < 15 mm are recommended in implant restoration; when ultra-short implants are applied, the implant system can increase the bone-to-implant contact area, and splint prostheses such as crown or bridge are recommended.

The concept of “minimally invasive dentistry” aims to provide conservative treatment of cavities in which sound dentin is removed. Because the Er: YAG laser can selectively remove caries, the smear layer is removed, dentin tubules are exposed after the preparation of substrate conditioning, and its advantages of precision, safety and painlessness are deeply valued. At the same time, the bonding strength between the prepared dentin surface and the filling material is different due to the different parameters of the Er: YAG laser. In this paper, the principle of dentin bonding, the mechanism of Er: YAG laser action, after treatment of dentin with different parameters (power, energy density, pulse duration, and irradiation distance), whether there is thermal damage to pulp tissue, the ultramicro morphology of dentin surface, the bonding properties of different bonding systems and the filling materials between irradiated hard tissues were reviewed. An appropriate parameter range (power ≤ 10 Hz, energy density ≤ 60 mJ, and pulse duration ≤ 50 μs) combined with water spray cooling will not cause thermal damage to the pulp tissue, while the higher power, energy density and pulse duration of laser treatment for dentin will lead to melting, carbonization, cracks, narrowing of the gap between collagen fibers, etc., which will limit the penetration of adhesives and have a negative impact on bonding. However, whether the adhesive systems based on the smear layer are suitable for dentin after laser treatment needs to be further explored.

Bone tissue engineering, as an emerging method for the treatment of jaw defects caused by oral and maxillofacial trauma, inflammation, tumors and other diseases, has been a research hotspot due to its advantages of wide sources of materials, low risk of immune rejection and personalized treatment. However, due to functional activities such as chewing and expression in the oral and maxillofacial regions, the mechanical strength of scaffolds is highly required. A single component of scaffolds can not fully meet the requirements of oral and maxillofacial bone defect repair. In this paper, the methods of strengthening the mechanical strength of jaw bone tissue engineering scaffolds are summarized by summarizing the research on strengthening the mechanical strength of scaffolds in recent years. A review of the literature showed that, composite modification, crosslinking, coating, bionic scaffolding and other new processing methods have been used to enhance the mechanical strength of scaffolds. Among these studies, research on compound modification occurred the earliest. Although this process is simple, other substances have been introduced to increase the number of degradation products, and the compounding ratio needs to be adjusted. The crosslinking method has the risk of cytotoxicity due to the use of crosslinking agents; the coating method does not change the original structure and only changes the surface modification; however, it can be better utilized if the problem of stress concentration between interfaces is solved. Biomimetic scaffolds and microregulatory scaffolds are emerging technologies in recent years that can improve the internal molecular arrangement of materials, thus enhancing mechanical strength. Therefore, on the basis of perfecting the traditional method, future research will focus on new nanoscale materials, bionic scaffolds and new methods for the precise control of scaffold microstructure.

With the continuous development of maxillary sinus floor elevation technology, the osteogenesis mechanism of maxillary sinus floor elevation has always been a concern of scholars. The membrane of the maxillary sinus is an indispensable physiological structure in the process of space osteogenesis under the sinus floor after elevation of the sinus floor. In recent years, the role of the maxillary sinus floor mucosa in sinus floor space osteogenesis has been a research hotspot. Recent studies have found that the maxillary sinus floor membrane plays a role as a natural biological barrier membrane in the process of sinus floor space osteogenesis after maxillary sinus floor elevation; in addition, it has the ability to undergo osteogenesis. It has also been found that maxillary sinus membrane stem cells (MSMSCs) derived from the maxillary sinus floor membrane have characteristics of mesenchymal stem cells, which can differentiate into osteoblasts and participate in sinus floor space osteogenesis after maxillary sinus floor elevation. New studies have also found that small RNAs such as microRNAs, long noncoding RNAs and circular RNAs can regulate the osteogenic differentiation of MSMSCs, which may be important biological targets for promoting osteogenesis in the sinus floor space. In this paper, the relationship between the maxillary sinus floor mucosa and bone formation after maxillary sinus floor elevation, the barrier and osteogenic function of the maxillary sinus floor mucosa, the sources of osteoblasts involved in osteogenesis of the sinus floor space, and the molecular regulatory mechanisms of stem cells derived from maxillary sinus mucosa will be elucidated step by step.

At present, conventional periodontal treatment cannot achieve complete and effective periodontal tissue regeneration. Cell sheet technology (CST) is a kind of cell transplantation method without scaffold material that can maintain complete extracellular matrix, important ion channels of cells, growth factor receptors, etc., and ensure the interaction between cells and the extracellular matrix. In this paper, the application and research progress of the cell sheet in the field of periodontal tissue regeneration are reviewed. Different types of seed cells can be prepared into monolayer cell sheet, multilayer cell sheet, cell sheet fragments and cell sheet polymers. Among them, the monalayer cell sheet is easily damaged and requires high deoperator; the multilayer cell sheet shows improved mechanical properties, but its thickness needs to be controlled to avoid cell necrosis. The cell sheet fragment can be used in the narrow space between the alveolar bone and root cementum to reduce the difficulty of operation and improve the mechanical properties of the cell sheet. Cell sheet polymers are three-dimensional structures that can provide strong mechanical support and improve the stability of the cell sheet, but the stability of their biological activity needs to be further improved. In methods for construction of the cell sheet, the antifibrosis and antiangiogenesis properties of the amniotic sheet have shown that this structure is suitable as the matrix of cell culture; the method of using a temperature-sensitive culture dish is simple and easy; continuous induction with vitamin C can retain some important proteins on the cell surface; and the magnetic tissue engineering method can increase cell adhesion and easily form a stable cell sheet. The above methods have their own characteristics. In clinical applications, monolayer cell sheet is mainly used for direct transplantation to the receiving site to construct periodontal tissue; multilayer cell sheet of the same or different species overlap and are then transplanted to the receiving site; and multilayer cell sheet of the same kind are wrapped with scaffold material and then transplanted to the receiving site to construct a three-dimensional structure. Overall, cell sheet technology has shown good potential in periodontal tissue regeneration.

Epigallocatechin-3-gallate (EGCG) has antibacterial, anti-inflammatory, antitumor, and other functions. EGCG and its anticancer mechanism are hot research topics in the prevention and treatment of oral cancer. In this paper, the prevention and treatment effects of EGCG on oral cancer and its anticancer mechanism are reviewed. The results show that EGCG can regulate multiple cell metabolic signaling pathways, such as the G protein coupled receptor signaling pathway, mitogen-activated protein kinase (MAPK), and the Wnt signaling pathway, and it can regulate DNA methylation and act on RNA of oral cancer cells directly or indirectly through the oral cancer cell signal transduction network to inhibit the development of oral precancerous lesions and oral cancer. EGCG combined with 5-fluorouracil can enhance the curative effect and reduce adverse effects and is expected to be a new drug for the prevention and treatment of oral cancer.

The loss of jaw position relationship will seriously affect the face and masticatory function of patients, and accurate restoration of vertical dimension of occlusion (OVD) is the key to occlusal reconstruction in edentulous patients. There are many methods to measure OVD in edentulous patients. In this paper, the working principle, scope of application, advantages and disadvantages, measurement methods and operation points of OVD recording method are reviewed in order to provide some reference for clinical treatment. The results show that the pre- extraction recording method is more objective and accurate, but the diagnosis model before extraction is required to accurately reflect the patients′ original OVD; the rest and stop jaw reference method is easily affected by subjective factors, and the edentulous patients with unstable jaw relationship are forbidden; the swallowing method is more subjective, especially suitable for patients with emotional tension and poor coordination; The facial landmark measurement method is more objective, but it is also affected by some subjective measurement factors. The patients with maxillofacial malformation are forbidden; the subjectivity of speech method is strong, and the accuracy of measurement results is closely related to the clinical experience of doctors, and the patients with aphasia and deafness are forbidden. X-ray cephalometric method and finger measurement method have strong objectivity. They are new measurement methods in recent years and have a bright future. Among them, finger measurement method is especially suitable for patients with maxillofacial deformity or postoperative deformity of tumor.

Patients seeking implantation often have several systemic diseases, which will introduce complications to treatment. This paper reviews the risk assessments and prevention of systemic diseases in patients with oral implant therapy with the relevant literature. The patients with cardiovascular diseases are prone to stroke and cardiac arrest, and anticoagulants and antihypertensive drugs will complicate cases. The potential risks of endocrine system diseases are infections and crises caused by unstable hormone levels. The risks of respiratory diseases are dyspnea and swallowing devices. The difficulty of treating patients with neuropsychiatric diseases is attributable to poor cooperation and adverse effects of the drugs. Bone and joint system diseases may decrease the success of implantation. Hematological system, digestive system and kidney diseases may lead to hemorrhage. By inquiring about detailed medical and medication history, evaluating vital signs and detecting important objective indicators, performing targeted measures, discussing with specialists, and observing patients closely, clinicians can avoid the abovementioned risks.

In the stomatognathic system, a stable jaw position is influenced by occlusion, the temporomandibular joint and neuromuscular stability. The condylar position in the glenoid fossa is closely related to the jaw position, while no consensus has been reached on the optimum jaw position and its corresponding condylar position in oral therapy. This paper summarizes the controversial opinions regarding the selection of jaw position and the corresponding condylar position in prosthetics and orthodontics, including antero-superior, antero-inferior, and therapeutic positions. Their indications, theoretical bases and clinical applications are also included. The literature review results suggest that, the antero-superior position, in other words, centric relation, should be chosen when the patient has a stable jaw position without TMD. In cases where finding an ideal antero-superior position is difficult due to hyperplasia or deformation or disarrangement of the articular disc, the antero-inferior position is recommended to alleviate symptoms and facilitate reconstruction of the TMJ to obtain good stability. Moreover, for high-angle patients with Class Ⅱ malocclusion or for patients with mild skeletal malocclusion, camouflaged orthodontic treatment combined with antero-inferior jaw repositioning through the potential of condyle remodeling can be an alternative to orthognathic surgery and can simplify the treatment plan. While the therapeutic position is specifically proposed for coping with complicated situations related to cranio-mandibular dysfunction, such as maximal intercuspal position abnormalities or deflection, muscle and TMJ dysfunction, unstable jaw position, in which changes in the original occlusion or abnormal TMJ guidance are induced, and a new intercuspal position can be established and stabilized on the basis of occlusal support and modified guidance. The therapeutic position put aside the debate regarding condylar position, however, the specific position of the condyle has not been reported in this case. This review suggests that different jaw positions and condylar positions have different scopes of application, and their clinical selection should be based on based on whether the patient′s joints have organic changes and the stability of the jaw positions should be comprehensively considered. However, the long-term effects of oral therapy based on different jaw positions need to be further verified by controlled clinical trials in the future.

The oral microbiome has been identified as one of the most diverse microbial communities in the human body, and the ecological imbalance of the oral microbiome can not only induce a variety of oral diseases, such as dental caries, pulpitis, apical periodontitis, and periodontal diseases, but also is closely related to cardiovascular diseases, diabetes and other systemic diseases. The structure of the oral microbiome is affected by multiple factors. This paper reviews and summarizes the effects of genetics, the environment, diet and systemic diseases. Literature reviews have shown that environmental factors play an important role in the structure of the oral microbiome, while the influence of genetic and dietary factors is still controversial. In addition, systemic diseases may also affect the oral microbial community. High-throughput sequencing studies have identified some “core microbiota”, and “core microbiota” in different environments and in different genetic backgrounds will be the next research direction.

In recent years, due to precise control of the amorphous mineral precursor in the demineralization of dentine collagen fibers in orderly deposition, forming apatite crystals similar to the natural mineralized dentin, the bottom-up remineralization approach which does not depend on the existence of seed crystallites, dentin biomimetic mineralization techniques gradually become a hotspot in the research field of restoration of demineralized dentin caused by dental caries. This paper reviews the changing concepts and practices of the remineralization of demineralized dentin, emphasizing biomimetic remineralization studies. The results of the literature review show that the traditional dentin remineralization method is usually a disordered mixture of demineralized dentin and minerals, so mineralized dentin is not comparable to natural mineralized dentin in terms of the morphological characteristics and mechanical properties. With its gradual increase in recent years, dentine biomimetic mineralization technology perfectly resembles the minerals in the dentin overlapping sequence arranged with the dentine collagen fiber structure characteristics, leading to greatly improved microstructural, physical and chemical properties. As a result, dentine biomimetic mineralization technology is expected to achieve new breakthroughs in the fields of resin-dentin bonding mixing layers and the decay of dentin. At present, the technical obstacles that need to be overcome in the clinical application of the biomimetic remineralization of dentin are how to continuously supplement all the active ingredients needed for mineralization in the process of remineralization and how to keep the mechanical properties of the parent material unchanged while slowly releasing all ingredients. Researchers have successively proposed three-step transportation of the biomimetic remineralization of raw materials, as well as the preparation of mineralization precursors stabilized by polymers in advance and the reuse of mesoporous silicon nanomaterials for the transportation of the mineralized ingredient system. The concept described above provides the preliminary in vitro experimental basis for the transformation of the biomimetic remineralization strategy of dentin in clinical applications.

There are many kinds of medical facial protective equipment with different functions. However, due to the lack of recognition of the hazards of facial occupational exposure, an incomplete understanding of the functions and effects of protective equipment and a lack of awareness, the proportion of staff that wear protective equipment in the Department of Stomatology is low. In this paper, the harmful and protective effects of face occupational exposure of dental staff were reviewed. A literature review showed that with the increasing prevalence of infection with AIDS, hepatitis B, hepatitis C and multidrug resistant bacteria in recent years, the occupational infection rate of medical staff in the Department of Stomatology has increased. The noise generated during oral treatment and the light from photosensitive curing lamps and treatment or surgical lasers can also cause occupational damage to hearing and vision. Face protection measures lack comprehensive functioning, and there is a lack of products that can be easily worn, indicating that the functions of face protection products need to be improved and strengthened. To minimize occupational infection and injury, we should not only improve the existing protective equipment but also improve personal protection awareness through advertising and education and comprehensively explore effective measures to improve occupational safety to ultimately achieve safe and high-quality medical services.

The postoperative evaluation of cleft lip is an important means to improve the operation method and the effect of the restoration. In recent years, the methods of cleft lip repair, such as Chinese western rotary propulsion, reconstruction of labial and nasal muscle tension band+trefoil flap, etc., have been developed. However, at present, there are still many secondary deformities, such as obvious scars and alar collapse. In this paper, in a review of the previous literature, the existing methods, advantages and disadvantages, and the application of the evaluation of the postoperative effect of cleft lip were reviewed. To date, there are many methods that can be used to evaluate the effect of cleft lip surgery. These research methods can be divided into subjective evaluation and objective evaluation, such as subjective evaluation, direct measurement, photo measurement, and three-dimensional scanning measurement. Among them, the subjective evaluation is simple, but the reliability is poor, and this method is suitable for all patients with cleft lip. The direct measurement has a low cost and is only suitable for one-dimensional information measurement, but the accuracy is poor, so it is difficult to determine the endpoints. The time of the photo measurement method is short, which can avoid tissue deformation, but it is easy to produce errors; this method is suitable for patients with cleft lip who can cooperate. The three-dimensional scanning measurement has a high accuracy, is time consuming and is a simple method but has a high cost and is suitable for areas with appropriate equipment conditions. Overall, the evaluation of the postoperative effect of cleft lip surgery should combine subjective evaluation with objective evaluation, dynamic evaluation with static evaluation, and utilize long-term follow-up to obtain comprehensive and accurate information and provide a reference for clinicians to carry out cleft lip surgery.

Corona Virus Disease 2019 (COVID-19) has broke out in 29 countries and regions in the world in a short period since December 2019. Various measures of prevention and control have been taken all over China. At present, the epidemic situation shows a positive trend, however, there are still a few new comfirmed cases in some area of China. So the job and thinking of epidemic prevention still cannot be relaxed. As an important specialty of stomatology, the risk of cross infection is high in oral medicine. Establishing an effective system of pre-inspection and triage and adopting strict measures of prevention and control are essential. According to the prevention and control situation of COVID-19, the characteristics of hospital infection, pre examination, protective measures, the home management strategies of oral mucosal diseases during the epidemic period and the differential diagnosis between COVID-19 and common oral mucosal diseases with fever were summarized and recommended in this paper.

Esophageal cancer is one of the most lethal digestive system cancers, and its pathogenic factors have always been the focus of research. Recently, it has been found that microorganisms and their metabolites in the esophagus may also represent one of the pathogenic factors. Because of their continuity in anatomical structure, the oral cavity and esophagus have a certain correlation in terms of the composition of flora. In recent years, many scholars have studied the relationship between oral microorganisms and esophageal cancer to monitor changes in oral microorganisms as well as to diagnose and treat esophageal cancer more effectively. In this paper, the research status of oral microorganisms and esophageal cancer was reviewed. The Results of the literature review show that the diversity of bacteria in the esophagus is affected by oral flora in terms of the occurrence and development of esophageal cancer. Among these bacteria, the periodontal red complex, which includes Porphyromonas gingivalis, forsythia and Treponema dentata, as well as common oral microorganisms, such as Streptococcus viridis and Fusobacterium nucleatum, are all related to the occurrence and development of esophageal cancer to a certain extent. At present, there are few studies on the mechanism of microorganisms and esophageal cancer, but scholars have found that lipopolysaccharides and endotoxins, the products of Gram-negative bacteria in the esophagus, may participate in the innate immune response of the host, and the relevant mechanism of action needs further study in order to find new targets for monitoring and treatment.

Functional orthodontics is one of the most important methods in the treatment of skeletal class II malocclusion in adolescents. A deep understanding of the many factors affecting the effect of functional orthopedics can improve the efficiency of correction and achieve good results. In this paper, from the two aspects of patients and appliances, we analyzed the factors that affect the curative effect of class II malocclusion functional orthopedics and deeply analyzed the therapeutic mechanism of functional appliances to guide clinical treatment. The results of the literature review show that the peak period of growth and development is the best period for the treatment of skeletal Class II malocclusion. For patients with a vertical growth type, it is recommended to use a high head cap traction appliance to prevent the lower jaw from rotating backward and downward, and functional appliances such as titanium plates or implant nail-assisted anchorage can effectively reduce the lip inclination of the lower anterior teeth. In addition, compared with the traditional functional appliance, digital and personalized transparent braces are not only more aesthetically pleasing, comfortable and beneficial to periodontal health but also have many orthopedic appliances advantages, such as two-stage fusion, better incisor torque and vertical control of the posterior teeth, and can solve the problems of anterior interference and lateral deficiency while leading. With the development of digital orthodontics, transparent appliances have become an important developmental direction for functional appliances, but there are few related studies, and more clinical studies are needed to confirm their efficacy.

Traditional titanium implants are bioinert, and some biological properties, such as osteogenic and antibacterial properties, can be obtained by adding different trace elements to their surfaces. These trace elements can help enhance implant-bone binding and effectively prevent peri-implantitis. Different trace elements have different advantages, and different modification methods can also affect the biological properties. In this paper, the biological properties of titanium implant surfaces modified by trace elements were reviewed. The results of a literature review show that implant surfaces modified by fluoride, silver, zinc, manganese, etc. can inhibit the growth of bacteria and reduce the negative impact on normal cells from bacteria. Other elements, such as strontium, tantalum and cobalt, can promote the differentiation of osteoblasts on the surface of titanium implants, improve the activity of alkaline phosphatase, and improve the expression of osteogenic genes, thus increasing the amount of bone formation and enhancing the strength of implant-bone integration. Most elements have multiple properties, and the combined application of two or more elements can yield more biological properties than a single element. Since there are many trace elements in the human body, there is still a wide research space available in the field of the surface modification of dental implants by trace elements.

Defects in oral hard tissue caused by various factors have a negative impact on the functional and aesthetic results of prosthetic treatment. In recent years, the usage of bone tissue engineering for bone reconstruction has drawn widespread attention. Bone tissue engineering exhibits significant advantages, including the abundance of building materials and few side effects. In this paper, the composition and structure of dentin and its application in bone tissue engineering are reviewed, providing a new way to further optimize its performance. The results of a literature review show that the structure of dentin is very similar to that of autogenous bone. The inorganic component is mainly hydroxyapatite (HA), while the organic component is mainly collagen I, noncollagenous proteins (NCPs) and growth factors. Because of its unique composition, dentin can act as a scaffold and/or growth factor source through different processing methods. The deproteinization process removes most of the organic substances and creates a HA-based scaffold material with high porosity, which allows for vascularization and cellular infiltration. Demineralization increases dentin porosity by reducing the crystallinity of the mineralized components, so that part of HA, collagen fibers and growth factors are preserved. Demineralized dentin possesses various regulation functions ranging from differentiation, adhesion and proliferation of primitive cells and bone forming cell lineage. Extracted NCPs, as bioactive molecules, have been proved to play important roles that control cell differentiation, crystal nucleation and mineralization in bone formation. NCPs could be combined with variety of scaffold materials and modify their properties.

Erbium，chromium：yttrium scandium gallium garnet（Er，Cr：YSGG）laser is mainly used for root canal treatment，periodontal disease，tooth decay，dentin hypersensitivity，pulp amputation，etc in the field of dentistry. This paper mainly describes the research progress of Er，Cr：YSGG laser in root canal therapy from following four as⁃ pects：root canal sealing，sterilization，cavitation effect and the effect on periapical tissue. The experimental results showed that when the operation parameters of Er，Cr：YSGG were 2 ~ 4 w and 20 Hz，it could effectively remove the stained layer of dentin tubules and improve the tightness between materials and dentin. The thermal effect produced by Er，Cr：YSGG energy has a sterilizing effect，while the optical conductivity of the tooth enables the rinse solution to enter deeper tissues，further improving the sterilizing effect. Er，Cr：YSGG also has a cavitation effect，which destroys the surface tension of the deep solution，removing the stain layer and bacteria in the deep layer. However，with the same operation parameters，if Er，Cr：YSGG is not used properly，the thermal effect of Er，Cr：YSGG will cause some damage to the periapical tissues. Therefore，reasonable use time of Er，Cr：YSGG and water cooling conditions are important.

Stem cells are a class of undifferentiated cells with high self-renewal and rapid proliferative capabilities. Undercertain conditions, stem cells can induce differentiation into other tissue cells of the human body, such as skeletal muscle cells, cardiomyocytes, osteoblasts, and nerve-like cells. In recent years, with the development of tissue engineering and regenerative medicine, stem cells have been extensively used in various fields of regenerative medicine as optimal seeded cells; however, there are still some problems, such as the decreased cell survival rate and regenerative capacity after transplantation, immune rejection, and ethical supervision. Therefore, it is difficult to universally and safely use stem cell banks for regeneration applications. The paracrine effect of stem cells has been extensively studied since its discovery. Increasing evidence supports the view that stem cells act in paracrine manner, and the secretion of exosomes plays a vital role in their biological functions. Exosomes are nanoscale extracellular vesicles containing biologically active molecules such as RNA and proteins; they possess similar functions to stem cells and play important roles in cell communication, immune response, and repair of tissue damage. At present, clinical studies on stem cell exosomes in tissue engineering and regenerative medicine have also been carried out in the fields of bone and cartilage repair, nerve tissue regeneration, liver tissue regeneration, skeletal muscle tissue engineering, vascular regeneration, taste bud repair, tooth regeneration, etc. In this paper, the composition, formation, release and identification of exosomes are introduced in detail. The research status of exosomes from different stem cell sources in tissue engineering and regenerative medicine is described, and their broad application prospects are discussed.

Crown pulp regeneration is a method to replace the pulp-capping agent with stem cells and scaffold structures, which are placed on the section of healthy root pulp tissue after pulpotomy to regenerate the pulp-dentin complex in the crown. This paper reviews the significance, physiological basis, application and challenges of crown pulp regeneration to provide new ideas for the study of pulp regeneration. The results of a literature review show that the combination of traditional pulpotomy, stem cell biology and tissue engineering, as well as the regeneration of crowns and pulp by using the tissue repair potential of healthy root pulp can effectively promote the regeneration of dentin and parts of pulp. In recent years, with the development of research on pulp regeneration, many challenges have been gradually revealed. It is necessary not only to select the treatment methods that can promote the proliferation and differentiation of dental pulp stem cells safely and effectively but also to continue to explore the scaffold materials suitable for the structural and functional diversity of the pulp chamber.

Periodontitis is a chronic infectious disease of periodontal tissue caused by plaque biofilm. Osteoporosis is a systemic skeletal disease characterized by low bone density and the microarchitectural deterioration of bone tissues, which leads to increased bone fragility and risk of fracture. Recent studies have indicated that there is a certain relationship between periodontitis and osteoporosis. This paper reviews the epidemiology, shared risk factors, and potential mechanisms of mutual impact between the two diseases. A literature review shows that periodontitis and osteoporosis can affect each other, and the RANKL-RANK-OPG pathway as well as a variety of cytokines and hormones involved in bone remodeling and inflammation are involved in both diseases. Common risk factors for periodontitis and osteoporosis include aging, vitamin D and calcium deficiency, and smoking, but further research is needed to determine the specific mechanism of interaction between periodontitis and osteoporosis.

Parotid obstructions can cause repeated swelling of the glands. Previously, duct stones were thought to be the main cause of obstructions, but salivary gland endoscopy examinations have revealed the absence of stones or foreign bodies in the duct system of the parotid glands with obstructive symptoms. Diseases of the parotid gland with obstructive symptoms include chronic recurrent parotitis, non-stone chronic obstructive parotitis, Sjögren′s syndrome, IgG4-related parotitis and radiation-induced parotitis. The mechanism of obstructions is unknown, and the disease course is prolonged. In this paper, based on a brief analysis of duct stenosis, distortion and mucus emboli, which may lead to parotid obstructions, a new perspective is emphasized: the duct system of the parotid and flowing saliva constitute a microflow field. Based on the principle of fluid mechanics, the flow of saliva in the flow field can be affected by the confluence, diameter changes, and twist of the ducts. This outcome results in changes in the low velocity zone, backflow, counterflow and turbulence; affects saliva flow and normal discharge; and causes symptoms of parotid obstruction. An analysis of the possible mechanisms of parotid obstruction using two variables, duct anatomy and saliva traits, helps explain the causes of nonstone parotid obstructions.

Posttreatment disease is a difficult clinical problem. Periradicular surgery is an important and effective method for cases that cannot be resolved by root canal therapy. In recent years, with the application of microscope for oral surgery and the development of microsurgical instruments, microsurgery in endodontics has reduced treatment trauma compared to traditional periradicular surgery and further improved the success rate of clinical treatment. However, as an invasive surgical method, the indications and timing of microsurgery in endodontics should be strictly defined for clinical applications. This paper reviews the literature on this important issue and discusses it with regard to the clinical experience of the author′s team. Explaining the effective root canal retreatment and good coronary closure are the primary considerations when posttreatment disease occurs. When root canal retreatment fails or cannot be completed after the initial treatment, the anatomical factors, lesion extent and periodontal lesion combination should be fully considered, and the microsurgery treatment strategy should be carefully formulated.

Dens invaginatus is a congenital tooth developmental malformation with substantial differences in anatomical morphology. Clinically it can be divided into malformed lingual fossa, root groove deformity, lingual cusp deformity and dens in dente. Most scholars believe that dens invaginatus is caused by the folding of the nipple during tooth development. Because of the complex anatomical shape, this condition often causes periodontal pulp joint lesions, which increases the difficulty of treatment. Therefore, this paper reviews the classification, morbidity, histopathology, clinical manifestations, imaging features and treatment methods of Oehlers crown indentation type III and malformation of the root groove to provide a reference and basis for clinical treatment. The literature review results show that the use of CBCT contributes to the diagnosis, treatment and prognosis of dens invaginatus. A personalized treatment plan should be developed based on different conditions by combining periodontal pulp therapy, pulp microsurgery, pulp revascularization, intentional replantation and other treatment techniques to preserve the teeth and improve the cure and preservation rates of teeth.

Among many factors affecting dental caries, bacteria are its initiating factor. From the perspective of ecological plaque hypothesis, the application of modern molecular biology methods enable scholars to deeply explore the relationship between the microbial population distribution, biodiversity, microbial community changes of dental plaque biofilm and the occurrence of dental caries in children. The decrease in microflora diversity is closely related to the occurrence of dental caries, which can be detected as early as 6 months before the occurrence of dental caries, providing an important basis for caries monitoring and caries risk assessment. Differential bacteria such as Lactobacillus and Veillonella may be used as biomarkers of caries in children to judge the risk of caries in children. However, current studies have shown that the dominant bacteria in the microbial community structure vary in different processes of caries occurrence and development, that the interaction between different flora is still not clear, and that the specific cariogenic mechanism of the oral plaque microbial community in the process of caries occurrence and development has not been clarified. Further research is still needed to explore the changes in plaque microbial diversity and composition during the development of dental caries and to screen specific dental caries biomarkers. This paper also summarizes the related research findings.

Fluoride is an important trace element in the human body and has active chemical properties, but its safety range is narrow. Excessive intake of fluoride can easily lead to fluorosis and various metabolic disorders, mainly manifested as dental fluorosis and skeletal fluorosis. In recent years, an increasing number of scholars have studied traditional Chinese medicine (TCM) because of its long history, few side effects, convenient oral administration and abundant resources. This paper reviews the current research. The results of the literature review show that traditional Chinese medicine, such as asparagus, cistanche deserticola and quercetin, can effectively prevent and treat fluorosis diseases that affected soft and hard tissues of the body due to is antioxidant properties. Moreover, the protective effect of TCM on fluoride-excreting organs of the body can further restore the fluoride-excreting ability of the body and reduce the damage caused by excessive fluoride on tissues as well as reduce fluoride in tissues by combining with excessive fluoride in the body. TCM can effectively improve the pain and joint dysfunction caused by skeletal fluorosis. Traditional Chinese medicine has important value in the prevention and treatment of fluorosis by enhancing immunity, promoting metabolism, eliminating fluoride in vivo, and improving the self-regulation mechanism to prevent fluoride toxic damage in the body.

Caries is an important public health problem that affect the quality of life of residents, and microorganisms is the most important factor in its incidence. Probiotics are types of microorganisms that are beneficial to the human body and can regulate the microecological balance; thus, they have great potential for caries prevention. This paper reviews the caries prevention mechanism of probiotics, the research progress of probiotics of different genera, and the early colonization of probiotics and their safety. The literature review showed that probiotics aimed at caries prevention could colonize the oral cavity and played a role in caries prevention by inhibiting the growth of cariogenic bacteria and regulating host immunity. At present, probiotics used to prevent dental caries include probiotic Lactobacillus, Bifidobacterium and Streptococcus. The positive effect of probiotics on dental caries has been confirmed in most clinical trials. Because probiotics include a variety of strains with strain-specific functions, different strains may be the reason for the lack of caries prevention in some clinical trials. The potential probiotic strains with a strong colonization ability and caries prevention effect in the oral cavity are the research hotspots for caries prevention probiotics.

Oral infectious diseases include caries, periodontal disease, halitosis, candidiasis albicans and so on. Over the past few decades, probiotics have mainly been studied in the field of the gastrointestinal tract. In recent years, probiotics have begun to be used in the prevention and treatment of various oral diseases and have become a new field in the research of oral disease prevention and control technology. This paper reviews the research progress of probiotics applied in the prevention and treatment of various oral infectious diseases. A review of the literature shows that probiotics can prevent and cure dental caries by inhibiting the growth of Streptococcus mutans and competing with them for nutrition and attachment sites. Probiotics not only inhibit periodontal pathogens and reduce the production of sulfide, they also regulate the body’s immune function to alleviate halitosis and periodontal inflammation. Probiotics can inhibit periodontal caries by inhibiting them. Probiotics can inhibit them mycelial growth of Candida albicans and interfere with its adherence, thus playing a role in the prevention and treatment of oral candidiasis. Current studies have shown that probiotics play an auxiliary role in the treatment of caries, periodontitis, halitosis and oral candidiasis. However, the mechanism of probiotics in the prevention and treatment of oral infectious diseases is still unclear, and the safety of probiotics remains to be further studied. In the future, oral probiotics should be studied with reference to intestinal probiotics to better work to prevent and treat oral diseases.