Objective To investigate the changes of the electromyography (EMG) of masseter muscle and excitability of trigeminal motor nucleus (Vmo) neurons induced by chronic restraint stress in mice, aiming to provide an experimental basis for exploring the central mechanism of the relationship between psychological factors and temporomandibular joint disorders (TMD). Methods Thirty-two male mice were randomly divided into control group and stress group. The mice in stress group were subjected to restraint stress for consecutive 14 d (4 h/d). The behavioral changes were evaluated by open-field test and elevated plus maze text. The EMG level of the masseter muscle was measured in the awake state. The electrophysiological properties of the neurons in the Vmo were observed using the whole-cell membrane clamp technique. And the expressions of vesicular glutamate transporter 1/2(VGLUT1/2) in Vmo were assessed by immunofluorescence staining. Results The time spent in center area (P=0.000 4) and distance moved (P=0.000 4) in center area of mice in the stress group were significantly shorter than those in the control group in the open field experiment. The percentage of open-arm entries (P=0.000 2) and the open-arm retention time (P=0.001 3) of the mice in the stress group were significantly lower than those in the control group in the elevated plus maze text, indicating a significant anxiety-like behavior. Before the experiment, there was no significant difference in the integral electromyography (iEMG) (P=0.877 9) and root mean square (RMS) (P>0.999 9) of the masseter muscle between the control and stress group. After the stress process, the iEMG (P=0.000 4) and RMS (P=0.000 1) of the masseter muscle was higher in the mice of the stress group than in the control group. In the control group, there was no difference in the iEMG (P=0.798 9) and RMS (P>0.999 9) of the masseter muscle before and after the stress process. In the stress group, the iEMG (P=0.001 1) and RMS (P=0.001 9) of the masseter muscle at the end of the stress process was significantly higher than the level before it. The electrophysiological results showed that increased spike numbers were elicited in Vmo neurons in stress group compared with control group when currents of 60, 80 and 100 pA (P<0.05) were applied in the current clamp mode. The frequency (P=0.003 0) and amplitude (P=0.000 2) of spontaneous excitatory postsynaptic currents in Vmo neurons in mice of the stress group were significantly higher than that in the control group in the voltage clamp mode. Immunofluorescence staining showed that the fluorescence intensity of VGLUT1 (P=0.001 0) and VGLUT2 (P=0.001 3) in the Vmo was significantly higher in the stress group than in the control group. Conclusion Chronic restraint stress can lead to anxiety-like behavior in mice with increased levels of electromyographic activity of masseter muscles. The elevated excitability of Vmo neurons in the brain and the increased glutamergic excitatory projections to them may be one of the central mechanisms leading to the hyperactivity of masseter muscles caused by chronic restraint stress.

Objective To evaluate the utility of Icon in preventing early enamel caries and provide a theoretical and laboratory research basis to cure early enamel caries in a safe, effective, easy and feasible way. Methods In the present study, 110 premolars of patients aged 10-25 who underwent orthodontic treatment were included. The artificial caries samples were established with an acid gel. The atomic absorption spectrophotometer was used to detect concentration of Ca²⁺in an acid solution and the anti-acid effect of enamel surface with Icon, fluoride protector and sodium fluoride was evaluated. The scanning electron microscope was used to observe ultrastructure of enamel surfaces and the longitudinal profile and then the blocking effect of demineralization zone with Icon was evaluated. Results The measurement results of Ca²⁺ concentration showed that the Ca²⁺ release levels in the Icon group, fluoride protector group, and sodium fluoride group were (6.432±1.867), (31.208±7.784), and (41.176±3.512)μg/mL, respectively. The Ca²⁺release in the resin infiltration group was significantly lower than that in the fluoride protector group and sodium fluoride group, with statistically significant difference (P<0.01). SEM observations revealed that the enamel surface in the Icon group exhibited a complete and relatively smooth material coverage. Icon formed a thin resin film on the enamel surface and penetrated well into the porous demineralized areas, forming a dense mesh-like network. Fluoride protector and sodium fluoride groups exhibited a fractured glass-like crystalline structure on the enamel surface, with significantly larger void diameters compared to the Icon group. Conclusion Icon can inhibit enamel demineralization effectively and enhance the acid resistance of enamel surface. It is better than fluoride protector and sodium fluoride.

Objective To determinethe mucosal irritant, acute systemic toxicity and antibacterial propertiesof novel magnesium alloys(Mg-3Sn-0.5Mn). Methods Through the mucosal stimulation experiment of golden gopher and the acute toxicity experiment of mice, the biocompatibility of the new magnesium alloy was tested. The bacterial state on the surface of the new magnesium alloy was observed by plate counting and scanning electron microscopy after the culture of magnesium alloy and bacterial liquid(Escherichia coli and Staphylococcus aureus) for 1 d and 3 d. Results Acute systemic toxicity experiment of mice showed that during the 72 h observation period, there was no acute toxicity reaction in the experimental group and the mice in the control group. Mucosal stimulation experiment showed that after 14 d, there was no obvious abnormality between the experimental group and the control group in the cheek mucosa HE staining and gross observation of the golden gopher. Antibacterial experiment revealed that compared with 316 stainless steel in the control group, the number of bacterial colonies on the surface of the petri dish was significantly smaller, and the antibacterial effect was obvious. According to scanning electron microscope observation,the number of Staphylococcus aureus on the surface of magnesium alloy was significantly less than that of the control group, and the shape was obviously wrinkled. Conclusion The new magnesium alloy(Mg-3Sn-0.5Mn)has good biocompatibility and antibacterial properties, which can initially meet the basic requirements of medical materials.

Objective Three-dimensional finite element analysis was used to compare the mechanical effects of double rectangular attachments on the molar mesial movement with clear aligner. Methods Four groups of the three-dimensional finite element model on the molar mesial movement with clear aligner was derived from a cone-beam CT(CBCT)scan data and then built in the software of Mimics, Geomagic Wrap, Unigraphics Nx and Ansys Workbench: Model A with a horizontal rectangular attachment of 5 mm long on mesiobuccal side, model B with double horizontal rectangular attachments of 3 mm long on mesiobuccal and mesiolingual side, model C with double horizontal rectangular attachment of 3 mm long on mesiobuccal and distobuccal side, model D with double vertical rectangular attachments of 3 mm long on mesiobuccal and distobuccal side. Four models were used to analyze the initial tooth displacement, tension-compression pattern at the periodontal ligament and Von Mises stress in mesial alveolar fossa. Results ①In the four models, the mandibular first molars achieved mesial tipping movement. The total displacement and inclination of mandibular first molars were as follows: Model B>model C>model D>model A. The retention force of the attachment and the displacement of the molars were proportional to the inclination of molars. The differences among the three groups of model A, C and D were small. ②The maximum values of periodontal ligament stress on the mesiodistal surface of the mandibular first molar and the maximum Von Mises stress on the mesial surface of the alveolar fossa were as follows: Model B>model C>model D>model A, which was confirmed by the displacement of mandibular first molars. Conclusion ①Only rectangular attachments have mesial tipping movement on the molar mesial movement with clear aligner; ②The attachment can increase the retention force of the molars in the clear aligner. The retention force of the attachment and the displacement of molars are proportional to the inclination of molars; ③The retention force of a horizontal rectangular attachment of 5 mm long on mesiobuccal side, double horizontal rectangular attachments of 3 mm long on mesiobuccal and distobuccal side and double vertical rectangular attachments of 3 mm long on mesiobuccal and distobuccal side are moderate, and the displacement and inclination of molars are moderate. The actual molar movement is more in line with the expected design of the clear aligner, and the aligner is less likely to fall off. It is suggested that when the molars move mesially in clear aligner, the above three attachments should be designed on the molars.

Objective To investigate the effect of berberine hydrochloride(BH)on inhibiting the proliferation of oral squamous cell carcinoma by regulating autophagy. Methods After different concentrations of BH (60, 90, 120, 240 μmol/L)acted on oral squamous cell carcinoma Cal-27 for 24 h, 48 h, 72 h, CCK-8 experiments detected the effect on Cal-27 cell viability. Colony formation detected the effect on the proliferation capacity of Cal-27 cell. Western Blot detected the effect of berberine hydrochloride on the expression of proliferation and autophagy protein of Cal-27 cell. The groups were set up: Control group (0), BH group (90 μmol/L BH), rapamycin (RAPA) group (50 nmol/L RAPA), and BH + RAPA cotreatment group (90 μmol/L BH+50 nmol/L RAPA). CCK8 experiments, colony formation experiments and Western Blot experiments were carried out in this group to detect the relationship between berberine hydrochloride inhibition of autophagy and inhibition of Cal-27 cell proliferation. Results CCK-8 results showed that the survival rate of berberine hydrochloride gradually decreased after it was applied to Cal-27 cells. The results of colony formation indicated that Cal-27 cells were significantly weakened after berberine hydrochloride treatment. The results of Western Blot demonstrated that with the increase of BH concentration, the expression of PCNA protein, which was a proliferation index, gradually decreased, and the expression of autophagy family protein Beclin-1 and LC3Ⅱ/Ⅰ also gradually decreased. Compared with the BH group, the cell activity and clonal formation ability of BH+RAPA group were enhanced, and the expression of PCNA protein, autophagy protein Beclin-1 and LC3Ⅱ/Ⅰ was upregulated. Conclusion BH inhibits the autophagy response of oral squamous cell carcinoma Cal-27 cell and further inhibits its proliferation by inhibiting autophagy.

Objective To report a novel approach to measuring the working force of twin-block like mandibular advancement appliance, measure the working force exerted by twin-block like clear aligner (A6, Angelalign) and explore its influencing factors. Methods Bilateral working force was measured by a portable pressure test system in patients with skeletal Class Ⅱ malocclusion treated with A6 appliance. Pearson correlation analysis was used to explore the influencing factors. Multiple linear regression was used to establish the prediction model of A6 working force. The prediction model was tested on a new sample of 8 patients who met the inclusion criteria. Results The working force exerted by the A6 appliance was (2.51±0.51)N unilaterally of 15 patients involved in this study, with sagittal advancement range from 2.6 to 7.4 mm. Pearson correlation analysis showed it was positively correlated with sagittal advancement (SA) and negatively correlated with vertical opening (VO). Multiple linear regression model for A6 working force was Y= 0.963+0.319X (X represents SA). The predicted working force was consistent with the real working force in 8 new participants (ICC=0.79). Conclusion This study for the first time established a novel method to measure the working force of twin-block like appliances, providing a tool for further research on the mechanobiology of twin-block like appliances and for orthodontists to record the force value in clinical work. The working force of A6 appliance and its influencing factors are preliminarily reported, and a prediction model is established, which paves the way for further research.

Objective Based on the HSB color model, the hue(H), saturation(S) and brightness(B) values of each region of the teeth were measured to explore the color change rule. Methods A total of 65 patients with 65 right maxillary central incisors were included in this study. The color of the cervical, middle and incisal regions of the right maxillary central incisors were measured using a color picker tool, avoiding reflective zones. The overall color parameters and the relative differences between each region and the overall tooth were calculated. Finally, results of the calculations were tallied to find rules of color change in three regions of the teeth. Results The results showed that in the same right maxillary central incisor, the cervical, middle and incisal regions differed in hue, saturation, and brightness compared to the overall color parameters of the teeth. In the same right maxillary central incisor, the differences between the hue of the middle region and the hue of the other two regions were statistically significant. Moreover, the differences in saturation between the cervical, middle and incisal regions were statistically significant. The difference in brightness between the cervical region and incisal region, and the difference in brightness between the middle region and the incisal region were also statistically significant. Conclusion There is variability in the color of three regions of the right maxillary central incisor. In the same right maxillary central incisor, the middle region has the most yellowish hue; the hue of the the cervical region and the incisal region are reddish. The cervical region is the most saturated; the middle region is the second most saturated, and the incisal region is the least saturated. The brightness of the incisal region is the lowest.

Objective Canalis sinuosus(CS) is a bony canal that extends from the infraorbital nerve canal to the anterior part of the maxilla and contains prealveolar neurovascular bundles. The anatomical variations of CS in the anterior part of the maxilla are called accessory canals (ACs). Accurate identification of CS and ACs can reduce the possibility of neurovascular complications during anterior maxillary surgery and improve the prognosis. The aim of this study was to evaluate the main morphological and morphometric features of CS and its ACs in order to provide anatomical guidance for implant surgery. Methods Cone-beam computed tomography (CBCT) data of 336 patients who visited the Department of Stomatology, the First Hospital of Shanxi Medical University from June 2021 to June 2022 were collected. Software of NNT viewer was used to measure the morphometric characteristics of CS and its ACs. Statistical analysis was performed according to gender, age and nasopalatine canal (NPC) type. Results CBCT measurement analysis showed that the incidence of ACs was 46.73%. Most of the ACs were distributed bilaterally and vertically. The palatal side of lateral incisors (51.77%) and central incisors (22.70%) were the main areas of ACs distribution. There was a significant linear correlation between the distance from CS to the root apex of central incisor and age (R²=0.353, P< 0.001). The CS diameter of cylindrical-type NPC patients was significantly larger than that of banana-type (P<0.05), hourglass-type (P<0.01) and funnel-type (P<0.01) NPC patients. There was significant difference between hourglass-type and banana-type patients in the distance between CS and the root apex of central incisor (P<0.05). Conclusion Results of this study indicate that ACs has a high incidence in the anterior maxilla of the Shanxi population and that NPC types have a significant impact on the morphometric characteristics of CS and its ACs. Based on the results of this study, simultaneous evaluation of CS with its ACs and NPC is reasonable and helpful in preventing complications during implant surgery. Clinicians should assess risks more carefully before surgery and take appropriate preventive measures.

Objective To investigate the efficacy of digital guide plate guided concentrated growth factor(CGF)combined with Bio-Oss bone powder for filling bone cavity after jaw cyst surgery. Methods Sixty patients who attended the Department of Oral and Maxillofacial Surgery of the Affiliated Stomatological Hospital of Xuzhou Medical University from September 2021 to September 2022 for jaw cyst removal were randomly divided into experimental group, control group 1 and control group 2. In the experimental group, a digital guide was made intraoperatively to locate the cyst and CGF combined with Bio-Oss bone powder was filled into the bone cavity. In the control group 1, a digital guide was made intraoperatively to locate the cyst and Bio-Oss bone powder was filled into the bone cavity, and in the control group 2, Bio-Oss bone powder was filled into bone cavity during the conventional surgery. Preoperative, 24 h and 72 h postoperative blood CRP and WBC levels and the time of surgery were measured. Postoperative pain level was assessed and postoperative bone mineral density values were measured 3 and 6 months after surgery. Results The postoperative CRP and WBC of the three groups were significantly higher than those before surgery. The postoperative inflammatory reaction, operation time and pain level of the experimental group and control group 1 were lower than those of control group 2, and postoperative inflammatory reaction was significantly lower in the experimental group than in control group 1. The bone density of bone defect area of the three groups 3 and 6 months after surgerywas higher than that before surgery, and the experimental group was significantly higher than the other two groups. Conclusion Digital guide plate guided CGF combined with Bio-Oss bone powder to fill the bone defect area after jaw bone cyst removal can shorten operation time, reduce postoperative inflammatory reaction and pain and discomfort, promote bone healing, improve osteogenesis speed and quality, and restore jaw bone morphology faster, which is worth being promoted in clinical application.

Objective To investigate a case of dental treatment under general anaesthesia using a digital model to assist in the surgery of severe low grade childhood caries. Methods Preoperatively, the patient’s mouth was scanned using a digital oral scanner, and the electronic jaw frame was used to determine the orthodontic occlusal relationship and then a digital resin model was created by 3D printing. The preformed crown was trimmed on the model, and the trimmed preformed crown was worn directly after the intraoperative dental treatment. Results The use of digital model shortened the treatment time, restored the shape and occlusal relationship of the child’s teeth and resulted in no postoperative occlusal discomfort. Conclusion The use of digital models can improve the outcome of dental treatment for children with S-ECC under general anesthesia.

In temporomandibular disorders (TMD), anterior mandibular repositioning therapy guides the jaw into a therapeutic anterior position to re-establish a physiological disc-condyle-fossa relationship. Anterior repositioning splint (ARS) has been widely used to reduce symptoms and promote structural remodeling of the temporomandibular joint. Recently, various removable/fixed functional appliances have been gradually applied in the mandibular anterior repositioning therapy of TMD, but their effects remain controversial. This paper reviews the current status of different appliances used in TMD and summarizes implications for the restoration of the disc-articular relationship.

3D printing technology meets the needs of personalization and high precision and complex structure in orthodontics. It has received great attention in recent years and has become a research hotspot in this field. This paper briefly introduces the 3D printing technology commonly used in orthodontics, and reviews the progress of its application and research in the past years. Dental models, mini-implant surgical guides, occlusal splints, mandibular advancement devices and palatal expansion devices can be made by digital process combined with 3D printing, and unique and significant advantages are shown. With the advent of the new material, clear aligners may also be made with thermoplastic appliances by 3D printing. However, the accuracy of placing brackets in mouth using 3D printing indirect bonding trays needs to be verified and ensured by more clinical trials.

Temporomandibular joint disorders(TMD)are relatively common today and a detailed understanding of the spatial anatomy of temporomandibular joint(TMJ) in its physiological and pathological state can help clinicians diagnose and develop treatment plans. Magnetic resonance imaging(MRI) has the advantage of clear visualization of soft tissues such as the joint disc, but is usually limited to the two-dimensional plane. Three-dimensional reconstruction of TMJ based on MRI can better show the spatial structure through three-dimensional models. However, the current MRI 3D reconstruction technology is not fully mature; the methods are different, and there is no uniform evaluation standard. Therefore, this review summarizes the research on 3D model reconstruction of TMJ based on MRI and is expected to help clinical treatment of TMD.

Nitric oxide is a small-molecule free radical with a short half-life, which can penetrate the cell membrane and play the role of intercellular signaling. It has been found that nitric oxide plays a dual role in periodontal tissues. Under physiological conditions, it promotes vasodilation, stimulates cytokine expression, regulate bone homeostasis and platelet aggregation; under pathological conditions, it can cause connective tissue destruction and alveolar bone resorption. This article reviews the mechanism of nitric oxide in periodontitis and related application, hoping to providing reference for the future treatment of periodontal diseases.

Diabetic retinopathy(DR), as one of the common complications of diabetes, is the main cause of blindness in related patients. Diabetes is an important influencing factor for periodontitis, and in recent years, literature has shown that there is a correlation between periodontitis and DR. This article reviews epidemiological studies,common influencing factors and mechanism between periodontitis and DR, in order to provide research ideas for clinical prevention and treatment of periodontitis and DR.

All ceramic restorations are widely used in dental clinical practice, especially in implant repair. However, it is difficult to remove the cement-retained implant crowns in clinical treatment. Traditional removal methods such as grinding and knocking not only increase the time and cost of clinical diagnosis and treatment, but also bring fear and anxiety to patients. In recent years, some scholars have begun to study the use of Er:YAG laser as a new method to replace the traditional mechanical removal of implant all-ceramic restorations. But various factors, such as the material and thickness of the all-ceramic restoration, the type of cement, and the setting of laser parameters, have influence on the removal results. This article reviews the application and research progress of Er:YAG laser in removing implant all-ceramic crown restorations and provides relevant reference for doctors’ clinical operation.

Electrospinning technique is a method of preparing nanometer diameter fibers from soluble or fusible polymers under the action of high-voltage electrostatic field. These nanofibers have the advantages of large specific surface area, high matching with extracellular matrix and easy surface functionalization. Meanwhile, during the electrospinning process, nanofibers can be modified by different modification methods or adding inorganic particles, antibacterial agents, enzymes and other additives to address different clinical needs. This article reviews the application of electrospun nanofibers in oral implantology.

During the combined orthodontic-orthognathic treatment of orthopaedic Class Ⅲ patients, attention needs to be paid to the impact of receding mandible on the airway during orthognathic surgery, thus reducing the probability of medically induced obstructive sleep apnoea syndrome. Effective preoperative prediction of airway changes and selection of the correct procedure are essential in the overall treatment plan. This article reviews structural characteristics of the upper airway in patients with skeletal Class Ⅲ malocclusion, advantages and disadvantages of commonly used methods for measuring the upper airway, changes in the airway after orthognathic surgery and available methods for airway prediction.