Extracellular vesicles are nanoscale membranous vesicles secreted by cells and are an important mediator for intercellular communication. Tumor-derived extracellular vesicles not only affect tumorigenesis and progression, but also mediate tumor immune escape and therapeutic resistance through interaction with immune cells. Liquid biopsies based on extracellular vesicles and therapeutic strategies targeting extracellular vesicles have promising applications in tumor therapy. This paper describes the biological properties of extracellular vesicles and their role in immune regulation of oral tumors, and discusses therapeutic strategies for oral tumors based on extracellular vesicles, providing a theoretical basis for promoting the clinical translation of extracellular vesicles.

Objective To investigate the regulatory ability and mechanism of metformin on the activation of NOD-like receptor protein 3 (NLRP3) in human periodontal ligament cells (PDLCs) by constructing a model of diabetes and periodontitis in vitro, and to provide new insights for metformin in the treatment of patients with diabetes and periodontitis. Methods Methyl thiazolyl tetrazolium assay was used to detect the cytotoxicity of metformin on human PDLCs. Human PDLCs were divided into five groups. Group A was a normal glucose concentration group (8 mmol/L glucose). Group B was a hypertonic environment group (8 mmol/L glucose and 17 mmol/L mannitol). Group C was a high concentration glucose group (25 mmol/L glucose). Group D was a high glucose environment group treated with metformin (25 mmol/L glucose+40 mmol/L metformin). Group E was a high glucose environment group treated with metformin and the AMPK inhibitor (25 mmol/L glucose+40 mmol/L metformin+ 10 μmmol/L compound C). All A-E groups were exposed to Porphyromonas gingivalis LPS at the same time. The level of IL-1β and IL-18 were detected by ELISA. The changes of proteins NLRP3, Caspase-1, ASC, AMPK, and p-AMPK were detected by western blot. Changes of mitochondrial complex Ⅰ activity were also detected. Results Metformin with a concentration not exceeding 40 mmol/L had no significant cytotoxicity on human PDLCs. Metformin treatment could significantly inhibit the inflammatory response in high glucose environments, characterized by the decrease of IL-1β, IL-18, NLRP3 and Caspase-1, and also reducing the activity of mitochondrial complex Ⅰ, while increasing the expression of p-AMPK. However, the introduction of AMPK inhibitor reversed some of the changes. Conclusion In human PDLCs, metformin reduces the activation of NLRP3 inflammasome in high glucose environment by reducing the activity of mitochondrial complex Ⅰ and activating AMPKs pathway, which provides new evidence for metformin to prevent and treat diabetes patients with periodontitis.

Objective To evaluate the contributions of resveratrol to dentin biomimetic remineralization and resin-dentin bond durability. Methods The middle dentin slices cut by a low-speed diamond saw were etched with 35% phosphoric acid and divided into three groups, which were respectively immersed in distilled water(Ctr group), directly remineralized for 7 d (Pos group), and pretreated with resveratrol for 30 min and then remineralized for 7 d (Res group). The formation of minerals on the dentin surface was observed by scanning electron microscope(SEM), and the crystal characteristics were analyzed by X-ray diffraction(XRD)and attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR). Micro tensile strength was used to observe the resin-dentin bond durability. Results SEM showed that the dentin after remineralization could form crystals, and more crystals were formed on the resveratrol-pretreated dentin surface. XRD and ATR-FTIR analysis showed that the newly formed crystal was hydroxyapatite(HA). Pretreatment with resveratrol significantly increased the initial micro-tensile strength compared with the positive control group without primer conditioning. Micro-tensile strength decreased during aging, however, the decrease in resveratrol-pretreated samples was the least significant. Conclusion Resveratrol can promote the biomimetic remineralization of demineralized dentin and improve resin-dentin bond durability.

Objective To investigate the effect of different power of Er:YAG laser on bonding performance of tooth enamel. Methods One hundred and forty-four first molars were selected and randomly divided into three groups: A, B and C, with 48 in each group. Each group of A, B and C was divided into 6 subgroups (n=8), and the treated enamel surface was irradiated with 6 different power lasers, namely 0, 3, 4, 5, 6, and 7 W. Group A was calculated by three-point bending test for the large positive stress and the maximum shear stress; group B was measured by the Owens two-liquid method; group C was measured by the nano-indenter for the elastic modulus and hardness. Results The maximum normal stress and maximum shear stress of A4 (5 W) were the largest (P<0.05); there was no significant difference between A3 (4 W) and A4 (5 W) (P>0.05); B3 (4 W) had high surface energy value (P<0.05); the elastic modulus of C4 (5 W) was the highest (P<0.05), and there was no significant difference with C3 (4 W) (P>0.05); C3 (4 W) had the highest hardness value (P<0.05). Conclusion Two laser parameters of 4 W, 20 Hz, 200 mJ and 5 W, 20 Hz and 250 mJ show good bonding properties (total stress, table Energy, modulus of elasticity and hardness), and can be used to enhance the bonding effect of enamel surface treatment.

Objective To investigate the correlation between the number of teeth lost and the degree of carotid atherosclerosis in hospitalized type 2 diabetes mellitus patients. Methods One hundred and seventy hospitalized type 2 diabetes mellitus patients in the Department of Endocrinology, the Second Hospital of Shanxi Medical University were selected. According to the number of missing teeth, the patients were divided into 0 missing tooth group (n=65), 1-8 missing tooth group (n=88), and ≥9 missing tooth group (n=17). The correlation between the missing tooth numbers and the incidence, number, Crouse score and plaque stability was analyzed, including laboratory examination indicators. Results ①In this study, the prevalence of carotid plaque was 74.7%, and patients with tooth loss was 61.8%. 55.9% had hypertension, 60.6% had hyperlipidemia, and 58.8% had a family history of diabetes. In terms of oral hygiene, less than 20% of the patients correctly used tooth-brushing method, dental floss or gap brush, and only 4.1% of the patients could adhere to regular oral examination. ②The missing tooth number was positively correlated with the occurrence of plaque (OR=1.277, 95%CI:1.080-1.509, P=0.004), the number of plaques (r=0.338, P<0.001), and the Crouse score of plaque (b=0.205, P<0.001). ③There was no significant correlation between the missing tooth numbers and unstable plaque, but the larger the number of missing teeth was, the higher the proportion of unstable plaque was (P>0.05). ④The level of plasma fibrinogen in the group with more than 9 missing teeth was higher than the groups with no missing teeth and 1-8 missing teeth (P<0.05). The number of missing teeth was not found to be associated with CHO, TG, HDL, LDL and HbA1c (P>0.05). Conclusion ①In this study, the level of glycosylated hemoglobin, the proportion of hypertension and hyperlipidemia, the overall detection rate of carotid plaque was high. The rate of missing teeth was high, and the oral hygiene habits and oral health awareness were poor. ②With the increase of the number of missing teeth, the incidence of carotid plaque increased, and the number of carotid plaque and plaque Crouse score also increased, suggesting that the missing tooth number may be an important risk indicator of carotid atherosclerosis and its severity. ③With the increase of the number of missing teeth, the proportion of unstable plaque increased. ④With the increase of the number of missing teeth, the plasma fibrinogen level also increased, suggesting that fibrinogen may be a systemic inflammatory indicator for the potential relationship between the degree of periodontal inflammation and CAS in T2DM patients.

Objective To investigate tooth movement characteristics of maxillary anterior teeth intrusion by three-dimensional finite element analysis with micro-implants implanted in different parts during the treatment of tooth extraction with clear aligners, so as to guide clinical practice. Methods A three-dimensional finite element model was established for the treatment of maxillary first premolar extraction with the clear aligner, and divided into four groups according to the implantation site of the micro-implant including working condition 1(control group without micro-implant), working condition 2(micro-implants implanted between maxillary central incisors), working condition 3(micro-implants implanted between maxillary central incisors and lateral incisors) and working condition 4(micro-implants implanted between maxillary lateral incisors and fangs). The traction force from the micro-implant to the cutting edge of the tongue side of the appliance was applied to analyze the tooth movement characteristics under different working conditions. Results In the first condition, the central incisor and lateral incisor showed oblique movement of the crown to the lingual side and the root to the lip side, while the second premolars to the second molars showed a small movement of the crown to the mesial root, and a small movement of the root to the distal root. In working condition 2 to working condition 4, the anterior tooth area showed depression accompanied by lip tilt movement, while the posterior tooth area showed midpoint crown inclination accompanied by a small amount of depression movement. The pressure of central incisor was in the order of working condition 2>working condition 3>working condition 4; the pressure of lateral incisor was in the order of working condition 3>working condition 4>working condition 2; the pressure of fangs and posterior teeth was in the order of working condition 4>working condition 3>working condition 2. Conclusion Elastic traction with micro-implants in the anterior tooth area can effectively increase the anterior tooth pressure. When the implant site moves back, the molar pressure increases significantly; the distal root movement of the posterior tooth increases, and the effect on anterior tooth lip inclination decreases.

Objective To evaluate the clinical efficacy of asymmetric couple in uprighting the highly and mesially impacted mandibular second molar. Methods Eighteen adolescents with highly and mesially impacted mandibular second molars were selected. One miniscrew was implanted into the buccal shelf. The miniscrew and the posterior segment constituted the anchorage. The tube was bonded on the disto-buccal side of the second molar. After the NiTi segmental archwire was placed, the asymmetric couple was formed on both sides. After they were almost uprighted, the position of the buccal tube was adjusted to improve the occlusion. Graphpad prism 6.0 software package was used for paired t-test. Results All tilted molars were uprighted, and there was no occlusal interference during the treatment. The final local occlusion was good, and no obvious root resorption happened. The height of the distal alveolar bone of the adjacent first molar increased significantly, and the vertical distance from the mesial buccal cusp to the mandibular plane remained stable. Conclusion The asymmetric couple formed by miniscrew and NiTi segmental archwire can effectively erect the highly impacted mandibular second molar and control its vertical position at the same time.

Objective To investigate the effect of different conditions of the second molar on maxillary molardistalization through Modified C Palatal Plate(MCPP)and its biomechanical mechanism using three-dimensional finite element analysis. Methods Three groups of three-dimensional FE models of maxillary molardistalization with MCPP were established. Model 1(M1): The second molar erupted, with the archwire inserted into the buccal tube;Model 2(M2): The second molar erupted without buccal tube;Model 3(M3): The second molar did not erupt. In M1, 1.5 N traction forces were applied between the MCPP notches which were 1 mm(F1), 4 mm(F4), and 7 mm(F7)above the alveolar crest ridge and the palatal arch hooks respectively to find out the force direction that could distally move the first molar bodily. Then the same force was applied on M2 and M3 to observe the movement of tooth. Results The first molar moved distally in M1 and had a bodily movement in the M1-F4. Compared with M1, the distal displacement of the first molar slightly increased in M2, but there was more significant buccal displacement and mesial-in rotation. The second molar had more distal inclination, less buccal movement and mesial-out rotation of the crown. The first molar movement in M2 was similar with M3. Conclusion Bringing the second molar into archwire will decrease the buccal displacement and rotation of the first molar. The eruption of the second molar has no significant effect on the lateral movement of the first molar.

Objective To investigate the effect of root resorption of maxillary anterior teeth from adult patients with skeletal Class Ⅱ malocclusion before and after orthodontic treatment. Methods A total of 20 adult patients with bone protrusion who had undergone treatment in the orthodontic department were selected and all had CBCT taken before and after orthodontic treatment. The changes in the root surface of the anterior teeth of orthodontic patients were assessed by colour-coded maps using 3D reconstruction techniques. The root length and root volume of the upper incisors were measured and the amount of root resorption was calculated. Results Adult patients with bone protrusion had a significant reduction in root length and volume of each maxillary incisor after extraction (P<0.05), with women having significantly greater root length and volume resorption than men (P<0.05). The mesial incisors had greater root volume resorption than the lateral incisors (P<0.05), but there was no significant difference in length and volume between the maxillary incisors after treatment (P>0.05). Conclusion The length and volume of the roots of adult bone protrusions are reduced after fixed orthodontic treatment. Root resorption in the upper incisors is influenced by the degree of bone malformation and gender, with women experiencing a greater reduction in roots compared to men.

Objective To investigate the clinical application of Invisalign in treatment of Class Ⅱ malocclusion and evaluate its effect of anchorage control. Methods Thirty Class Ⅱ malocclusion patients were enrolled in the study, which was treated by Invisalign with premolar extraction. Terminal position in Clincheck was overcorrected based on CBCT. Cephalograms of pre-treatment and post-treatment were measured. The data were analyzed by SPSS 20.0. Results The overbite of all the 30 patients were back to normal and their lateral profile improved significantly after treatment. The skeletal analysis showed that only point A was significantly changed. SNA decreased by 1.63°±1.45°. The teeth analysis showed that upper and lower anterior teeth were retracted. After treatment, the distance of U1 to NA and L1 to NB reduced by (4.52±3.79) mm and (4.55±3.16) mm, respectively. The differences were statistically significant (P<0.05). The control of vertical direction were effective, while clockwise rotation occured on the occlusion plane. The maxillary first molar analysis showed that the distance of UMC to Ptm and UMA to Ptm increased by (1.51±1.42) mm and (0.99±1.59) mm. The differences were statistically significant (P<0.05). Conclusion Invisalign is an effective appliance for treating Angle Class Ⅱ case, and can control anchorage effectively.

Objective To analyze pit and fissure sealing spatial heterogeneity and related influencing factors in Shanxi Province. Methods In 2016, 937 children aged 7 to 9 years were randomly selected from primary schools for pit and fissure sealing, and the effect of pit and fissure sealing was evaluated in 2017,2018 and 2021. The q-statistic was used to analyze the spatial heterogeneity of retention rate and influencing factors. Results The GeoDetector model was used to study the influence of eight influencing factors, including socioeconomic, medical resources and natural environment, one year,two and five years after pit and fissure sealing. Five years after pit and fissure sealing, the degree of spatial stratification and heterogeneity of the postoperative sealant retention rate was the largest, and the trend of increasing from north to south was the most obvious. The highest q value was observed at 1 year after surgery (q=0.52, P<0.05), indicating that water fluoride content was an important environmental factor determining the spatial heterogeneity of sealer retention at 1 year after surgery, followed by mean annual precipitation. The highest q values were observed for the proportion of health technicians at 2 and 5 years after surgery (q=0.70,P<0.05; q=0.69, P<0.05), indicating that the proportion of health technicians was an important environmental factor determining the spatial heterogeneity of sealant retention rates at 2 and 5 years after surgery. Conclusion In Shanxi Province, the total retention rate of sealant after one year was 95.06%, two years, 89.30%, and five years, 64.55%. There is spatial heterogeneity in the retention rate after fissure sealing, which increases from north to south. The proportion of health technicians and water fluoride content are the main factors influencing the spatial heterogeneity of fissure closure retention rate.

Dental pulp calcification can lead to root canal stenosis or obliteration which brings challenge to root canal therapy. Dynamic navigation technology provides a new idea and method for the treatment of pulp calcification, and reduces complications. In this case, the dynamic navigation technology was utilized which allowed for the successful location of the mesiobuccal and mesiolingual calcified root canals of mandibular second molar. This case can provide dentists with reference for the diagnosis and treatment of pulp calcification.

Cryotherapy is a surgical technique that employs freezing to destroy undesirable tissue. Major advantages of oral cryotherapy include safety, convenience and less side effects. It has been widely used in the treatment of many cutaneous diseases. Because oral mucosa is similar to skin, many diseases occurring in oral mucosa, such as vascular anomalies, mucosal pigmentation, oral ulcer, sialocele, oral lichen planus, oral leukoplakia, are appropriate for this technology. This article mainly discusses the principle, method and application of cryotherapy in the treatment of oral mucosal diseases. Due to its numerousadvantages, including small damage to surrounding tissues, no bleeding, no scar, light pain after treatment, low incidence of secondary infection and simple operation, cryotherapy has the potential to be the first choice or alternative in the treatment of many oral mucosal diseases.

Mesenchymal stem cells have been widely used in regenerative medicine due to their ability of self-renewal, differentiation and immunomodulation. However, the therapeutic effect is limited because of the low survival rate after transplantation and the potential tumorigenicity. Recently many studies have confirmed that the biological function of mesenchymal stem cells is achieved through the release of exosomes and the cell-free therapies based on exosomes have aroused great attention. Furthermore, hypoxia preconditioning can mimic the physiological environment of mesenchymal stem cells, enabling the secreted exosomes to have better bone regeneration capacity. In this review, research advances in the role of exosomes derived from hypoxia preconditioned mesenchymal stem cells in bone regeneration are investigated, and the related mechanisms are discussed. Finally, some problems that need to be noted before clinical application are presented.

In recent years, clear aligners have been widely employed in clinical treatment because of its esthetics and comfort. However, due to the complexity and unpredictability of tooth movement, the preset displacement cannot be fully achieved. And the efficiency varies with types of movement. Hence overcorrection is applied in clear aligners to enhance the efficiency. This article reviews the application of overcorrection design in arch expansion, intrusion, derotation, and extraction cases with clear aligners and provides reference for clinical practice.

Pemphigus is a group of autoimmune bullous diseases that can affect skin and mucosa. The etiology mainly includes genetic susceptibility and environmental factors. As one of the critical environmental factors, virus infection is considered to be closely related to the occurrence of pemphigus. Herpes simplex virus, hepatitis virus, and other viral infections may all trigger pemphigus. The potential mechanism involves molecular mimicry, continuous formation of antigen-antibody immune complexes, and abnormal differentiation and function of T cell subsets. Pemphigus patients with viral infection may benefit from combining conventional glucocorticoid or immunosuppressive therapy and antiviral therapy. This article reviews the relationship between viral infection and pemphigus, the potential pathogenic mechanism, and the selection of clinical treatment options for viral infection-related pemphigus.

Temporomandibular joint disorder(TMD)is a common oral disease, and its etiology is complex. Rheumatoid arthritis(RA), one of the autoimmune factors, may be an important pathogenic factor. Rheumatoid arthritis is an inflammatory disease that mainly affects joints. It is mediated by systemic immunity and its pathogenesis is unknown. Temporomandibular disorders and rheumatoid arthritis are often accompanied, but the pathogenesis and interaction between them need to be further studied. In this paper, we expound the correlation between temporomandibular disorder and rheumatoid arthritis, analyze the etiology combined with the results of epidemiological investigation, and further summarize the current situation of its treatment and prognosis. We hope to provide a new way of diagnosis and treatment for clinicians.