Objective To evaluate the remineralization effect of myricetin (MYR) on demineralized dentin matrix and its effect on dentin bonding strength. Methods The middle dentin slices were obtained and then were wet polished with 600 mesh silicon carbides and paper to simulate the smear layer. The dentin slices were etched with 35% phosphoric acid and divided into three groups, which were respectively immersed in distilled water, directly remineralized for 2 d and pretreated with MYR for 30 min and then remineralized for 2 d. Surface morphology of the dentin slices was observed with scanning electron microscope(SEM), and surface materials were analyzed with X-ray diffraction(XRD)and attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR). Micro tensile strength (μTBS)and nano-leakage experiments were used to observe the bonding effect. Results SEM showed that the dentin after remineralization could form crystals, while crystals formed by remineralized dentin after MYR pretreatment were the most obvious. XRD and ATR-FTIR analysis revealed that the newly formed crystal was hydroxyapatite(HA). μTBS and nanoleakage experiments showed that remineralization after MYR pretreatment could significantly increase bond strength and reduce nanoleakage. Conclusion MYR pretreatment can promote the remineralization process of demineralized dentin and improve the resin/dentin bonding strength.

Objective To screen key immune-related genes (IRGs) in oral squamous cell carcinoma (OSSC) and construct an immune-related prognostic model to predict the overall survival of patients with OSCC, so as to provide a basis for the planning of clinical treatment of oral squamous cell carcinoma. Methods Firstly, the OSCC gene expression data and corresponding clinical information were downloaded from The Cancer Genome Atlas (TCGA) database. Then the differentially expressed IRGs was determined. The immune-related prognostic model was established by univariate Cox regression analysis, Lasso-Cox regression analysis and multivariate Cox regression analysis, and the predictive performance of the model was verified. Results In this study, a prognostic model consisting of 6 IRGs was constructed. There was significant difference in total survival rate between low risk group and high risk group (P<0.05). The area under the curve (AUC) of the 1-, 3- and 5-year receiver operating characteristic(ROC) curves were 0.72, 0.73, 0.76 respectively, which indicated that the prognostic model had a good predictive effect. Subsequent univariate and multivariate Cox regression analysis showed that the risk score of the prognostic model was an independent prognostic factor (P<0.001). Conclusion In this study, 6 IRGs-based prognostic model is established to accurately predict the prognosis of patients with OSCC. This finding is helpful for clinicians to individualize treatment of patients with OSCC, and then improve the survival rate of these patients.

Objective To investigate the effect of chronic periodontitis on apoptosis of rat peritesticular adipocytes through protein kinase R-like ER kinase (PERK)-C/EBP homologous protein (CHOP) signal pathway. Methods Twenty male SD rats were randomly divided into experimental group and control group. Experimental group rat model of chronic periodontitis was established. The bilateral maxillary second molars were ligated with silk thread and injected with Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) into the gingival sulcus. The control group was injected with the same amount of PBS into the gingival sulcus. After 3 months of modeling, the rats were killed. The periodontal inflammation was evaluated by measuring the gingival bleeding index (GBI) and the probing pocket depth (PPD). The alveolar bone resorption of the second molar was analyzed by Micro-CT. The apoptosis of peritesticular adipocyte was observed by TUNEL staining. Western blot was used to detect the protein expression levels of PERK, p-PERK, CHOP, Caspase-12 and Cleaved-Caspase-3. Results GBI, PPD and CEJ-ABC in the experimental group were significantly higher than those in the control group (P<0.05), and the rat model of chronic periodontitis was successfully established. The apoptosis rate of peritesticular adipocytes in the experimental group increased significantly (P<0.05), and the expression levels of p-PERK, CHOP, Caspase-12 and Cleaved-Caspase-3 protein increased significantly (P<0.05). Conclusion Chronic periodontitis mediates apoptosis of peritesticular adipocyte in rats through the PERK-CHOP signaling pathway.

Objective To observe the influence of Piezo1 on the necroptosis markers receptor-interacting protein 3 (RIP3) and mixed lineage kinase domain-like protein (MLKL) in pressure-side periodontal tissue at various time points during tooth movement in rats. Methods Seventy-five male SD rats were randomly distributed into control group (group A), force group (group B) and force + inhibitor group (group C). The orthodontic model of the maxillary first molar was constructed in rats. The moving distance of the orthodontic tooth was measured with vernier calipers. Hematoxylin-eosin (HE) staining was used to observe changes of pressure-side periodontal tissue, and changes of RIP3 and MLKL were tested by immunohistochemical staining. Results Compared with group A, expression levels of RIP3 and MLKL in periodontal tissue in group B and C increased firstly and then fell (P<0.05), and the expression of RIP3 increased to the peak on the 5th day, MLKL on the 3rd day. Compared with group B, the expression of RIP3 and MLKL in periodontal tissue in group C were decreased as a whole (P<0.05), and the expression trend was consistent with group B. Conclusion Piezo1 channel may play a role in the mechanotransduction process of orthodontic tooth movement. Blocking the function of Piezo1 channel may reduce the expression of RIP3 and MLKL in pressure-side periodontal tissue, reduce the occurrence of necroptosis and the speed of orthodontic tooth movement.

Objective To evaluate the relationship between the root and alveolar ridge crest of the first and second maxillary molars and maxillary sinus floor by cone-beam computed tomography (CBCT), and to provide reliable reference for clinical diagnosis and treatment. Methods One hundred and eighty cases were selected from the CBCT database of the Affiliated Stomatological Hospital, School of Stomatology, Dalian Medical University, and divided into three groups (6-12 years old, 13-18 years old and 19-35 years old), with 60 cases in each group. CBCT was used to measure distance between each root apex of the first and second maxillary molars and maxillary sinus floor, distance between the alveolar ridge crest and the maxillary sinus floor. Comparison was conducted between different sides and genders respectively. Classification of the vertical relationship between each root of the first and second maxillary molars and the maxillary sinus floor was recorded and statistical analysis was carried out. Results In 6-12 age group, average distance between the mesiobuccal root of the first maxillary molar and the maxillary sinus floor ((1.21±3.09) mm) was the shortest among the maxillary roots. In 13-18 age group, the apices were all in the maxillary sinus. In 19-35 age group, the palatal root was ((0.41±2.73) mm). In 13-18 and 19-35 age groups, average distances between the mesiobuccal root of the second maxillary molar and the maxillary sinus floor (0.36±2.37) mm and (0.43±2.21) mm both were the shortest among the maxillary roots. The average distance between the alveolar ridge crest and the maxillary sinus floor decreased with ages (P<0.05). In the horizontal relationship, in all age groups, the maxillary sinus was most frequently observed at the level of root apices to root furcation in 13-18 age group and 19-35 age group. In the vertical relationship, in all age groups, the most common condition was that all three root apices were not in contact with the maxillary sinus floor of the first molar in 6-12 age group and 19-35 age group, and the second molar in 13-18 age group. Conclusion The first and second maxillary molars are closely related to maxillary sinus floor. It is suggested that CBCT should be applied before clinical treatment, which has positive significance for analyzing anatomical position of the posterior maxillary region and reducing incidence of maxillary sinus complications.

Objective To observe the effect of orthodontic extraction treatment of first premolar with strong anchorage on morphological changes of upper airway in adult patients with skeletal Class Ⅰ bimaxillary protrusion with different vertical skeletal patterns by Dolphin software and CBCT. Methods Fifty-six adult patients with bimaxillary protrusion treated from January 2016 to December 2021 were selected. All subjects extracted 4 first premolars and retracted the anterior teeth with strong anchorage. The patients were divided into high angle group, average angle group and low angle group according to SN-MP. The collected CBCT scans before and after treatment were reconstructed by using Dolphin software for measuring the airway volumes of velopharynx, glossopharynx, laryngopharynx and the minimum cross-sectional of oropharynx. Results Measurements of 56 adult patients showed that the minimum cross-sectional area of oropharynx in low angle group and high angle group was significantly smaller than that in average angle group. There was no significant difference in airway volume of velopharynx, glossopharynx and laryngopharynx among three groups. Furthermore, three-dimensional analysis of the upper airway showed that there was no significant difference in the airway volume before and after treatment in each group. The minimum cross-sectional area of oropharynx in low angle group and average angle group decreased significantly after treatment, but there was no significant difference in high angle group before and after treatment. Conclusion Based on CBCT evidence, for high angle adult patients with bimaxillary protrusion who will receive orthodontic extraction treatment, the orthodontist should pay attention to the control of vertical direction to prevent further reduction of the upper airway. For patients with low and average angle, when making the treatment plan, we should consider the patient′s face profile and morphology of upper airway.

Objective To explore root resorption of third molars after long-distance mesial movement through retrospective study on mandibular first molar extraction cases and to compare the effect of root development of the third molars on root resorption. Methods Thirty-two cases of mandibular first molar extraction were analyzed retrospectively, and 41 mandibular third molars were included in the study. According to root development of the third molars, they were divided into group A (root development completed) and group B (root development not completed). Length of the root was measured by direct digital panorama before and after treatment. Changes of the root at different development stages were studied after long-distance mesial movement. Results In group A, the mesial and distal roots absorbed (0.07±0.66) mm and (0.09±0.62) mm respectively, and the difference was not statistically significant (P>0.05). In group B, the third molars continued to develop and the length increased after correction,and the difference was statistically significant (P<0.05). The distance of mesial movement of mandibular molars in group B was greater than that in group A (P<0.05). There was no significant difference in the length of mesial roots between group A and group B (P>0.05) after treatment. The length of distal root in group B was longer than that in group A, and the difference was statistically significant (P<0.05). Conclusion The root resorption of mandibular third molars after long distance mesial movement is small and generally has no clinical significance. Root development has a certain impact on the distal root, suggesting that loss of mandibular first molars should be treated before the completion of root development of mandibular third molars.

Objective To explore the effect of three-dimensional virtual dental patients on the aesthetic restoration of anterior teeth. Methods Thirty patients requiring porcelain veneers or all-ceramic crowns on anterior teeth were selected and divided into three groups:Group 1 established three-dimensional virtual dental patients for restoration design; Group 2 combined with two-dimensional facial photographs for design; Group 3 was designed based on CAD/CAM morphological database without personalized information of patients. Three clinicians were invited to rate postoperative aesthetic outcome on a dental aesthetic evaluation scale. Satisfaction with the aesthetic outcome of restoration was evaluated by patients with visual analogue scales (VAS) in all groups. Results The digital model of three-dimensional virtual dental patient was established successfully. A dental aesthetic evaluation scale incorporating aesthetic elements of the face was developed. The total score of three groups were (82.53±2.70), (80.30±1.77), (72.90±3.39) points; score of Group 3 was significantly lower than that of Group 1 and Group 2 (P＜0.05). The facial outcome score of three groups were (27.97±1.39), (24.43±2.21), (22.33±2.25) points; score of Group 1 was significantly higher than that of Group 2 and Group 3 (P＜0.05). The VAS score of three groups were (8.70±0.71), (7.30±0.67), (6.60±0.84) points; score of Group 1 was higher than that of Group 2 and Group 3 (P＜0.05). Conclusion The establishment of three-dimensional virtual dental patients improves the predictability of aesthetic restoration in anterior teeth and reduces the risk of aesthetic restorations in the anterior zone. The harmony, balance and aesthetics of restoration are improved, which has clinical application value.

Objective To investigate glenoid fossa roof thickness of normal temporomandibular joint(TMJ) in Chinese young people by CBCT in order to provide theoretical guidance for fossa arthroplasty in computer aided navigation surgery of temporomandibular joint ankylosis. Methods One hundred and thirty-two volunteers (264 normal temporomandibular joints) were selected and underwent large field of view CBCT scans. After 3D reconstruction with image processing software, roof thickness at the thinnest part of mandibular glenoid fossa was identified and measured in both coronal and sagittal views and results were statistically analyzed according to gender, joint side and age. Results In the coronal view, measurements of volunteers were 0.940 (0.748,1.311) mm, 1.040 (0.731,1.675) mm for males, and 0.883 (0.753,1.199) mm for females. In the sagittal view, measurements of volunteers were 0.903 (0.720,1.331) mm, 1.073 (0.755,1.585) mm for males, and 0.865 (0.706,1.090) mm for females. Four sets of measurements of roof thickness of glenoid fossa were obtained from each individual. Comparison was conducted between males and females. In the right joint (P<0.05), roof thickness of glenoid fossa in both coronal and sagittal views was greater in males than females, and the difference was statistically significant; no significant difference found in the left joint (P>0.05). There were significant differences was found between two sides in coronal view in all individuals (P<0.05). Thickness of the left glenoid fossa roof was greater than the right, no difference between two sides in sagittal view (P>0.05). No significant difference was found between different age groups in both male and female samples (P>0.05). Conclusion In preoperative planning for temporomandibular joint ankylosis surgery using navigation system, measuring roof thickness of normal temporomandibular glenoid fossa for unilateral TMJ ankylosis is a significant reference in clinical practice.

Objective To compare and evaluate clinical efficacy of calcium silicate based bio-ceramic materials iRoot BP Plus and MTA as root-end filling materials and to determine prognostic factors affecting the outcome of endodontic microsurgery (EMS). Methods A clinical database was searched for EMS cases from 2016 to 2018. The nearest neighbor matching method was used to match age, gender, lesion location, root canal treatment type and whether the lesion complicated with periodontal desease of patients undergoing EMS using iRoot BP Plus or MTA as root-end filling materials with 1∶1 propensity score. Multifactor binary Logistics regression analysis was used to evaluate interfering factors of EMS and the forest plot was drawn. Results A total of 179 teeth were included. The absolute normalized differences of all co-variables were <0.1. One-year success rate of microapical surgery was 91.2% in iRoot BP Plus group and 89.7% in MTA group (P=0.771). Multivariate binary Logistic regression analysis after PSM showed that age, lesion location and whether the lesion complicated with periodontal desease had statistically significant effects on clinical efficacy and prognosis of microscopic apical surgery. Conclusion Microapical surgery has good clinical efficacy, and there is no significant difference in the success rate of microapical surgery with MTA or iRoot BP Plus as backfilling materials. Age, lesion location and whether the lesion complicated with periodontal desease are significant factors influencing the clinical effect of microapical surgery.

There is a close relationship between the skeletal system and the immune system. As an important part of the immune system, B lymphocytes regulate bone homeostasis through the RANKL/RANK/OPG axis and the production of cytokines and antibodies, which play a key role in the occurrence and development of bone destructive diseases. This review will discuss the interaction between B lymphocytes and bone homeostasis and the role of B lymphocytes in bone destructive diseases, hoping to provide new ideas for research and treatment of bone destructive diseases.

Gingival melanin pigmentation (GMP) is a common clinical manifestation, characterized by black, brown or gray spots on gums. It often occurs in the attached gingiva of anterior teeth. GMP causes aesthetic problems for patients, especially those with bare-gummed smile. In addition, it may be a manifestation of some malignant tumors, genetic and systemic diseases in the oral cavity. In recent years, laser has been considered as an effective method to remove gingival melanin. This paper compares treatment time, pain, bleeding, healing speed, and recurrence of different wavelength lasers in the treatment of GMP to provide reference for clinicians.

Periodontitis is a chronic inflammatory disease caused by periodontal pathogen infection, which is more likely to occur in pregnant women. Adverse pregnancy outcome is an important cause for perinatal death of newborn, which is affected by systemic inflammation. This paper expounds the correlation between periodontitis and adverse pregnancy outcomes, further explores its mechanism from aspects of vaginal infection, bacteremia, immune inflammation, and intestinal flora, and briefly describes host′s susceptibility to periodontitis and adverse pregnancy outcomes in genetic background, in order to provide theoretical guidance for the prevention of periodontal diseases in pregnancy and adverse pregnancy outcomes in clinical practice.

Anti-seizure medication, calcium channel blocker and immune suppressor can cause gingival fibrosis and volume increase. In the past two decades, studies have explored the mechanism of drug-induced gingival overgrowth from aspects of epidemiology, clinical experiments and cytology. Subject to patient number and ethics, further investigation of mechanism and treatment relies on the establishment of animal model. This article reviews the research progress of animal model, relevant mechanism and influencing factors, in order to provide a reference for researchers to establish reliable animal models.

Temporomandibular joint anterior disc displacement is a common type of temporomandibular disorder, which is mainly manifested as pain, joint click and mandibular dysfunction, and in severe cases it can negatively impact patients’ daily lives. However, there has not yet been a consensus on the etiology because of its complexity, and there is still a lack of clear and comprehensive understanding of its pathogenesis. This article reviewed the etiology and pathogenesis of temporomandibular joint anterior disc displacement.

Oral squamous cell carcinoma (OSCC) is a malignant tumor of oral epithelial origin with a high incidence, and its pathogenesis has not been completely defined. OSCC is prone to early cervical lymph node metastasis, with poor prognosis and special anatomical location, which is an important factor leading to recurrence. Curcumin is an active ingredient extracted from rhizome of zingiberaceae. It has antioxidant, anti-inflammatory, anticoagulant, anti-cancer and other pharmacological effects, with rare adverse reactions, so it has an application prospect in medicine. A number of studies have proved that curcumin can induce the apoptosis of malignant tumor cells, inhibit proliferation and invasion of tumor cells, regulate cell cycle of tumor cells, alleviate tumor drug resistance and improve sensitivity of anticancer drugs by regulating specific effector factors in a variety of signaling pathways. In recent years, curcumin has been increasingly applied in various branches of stomatology, such as periodontitis, temporomandibular arthritis, mucosal precancerous lesions and so on. This article reviews the mechanism and research progress of curcumin alone and in combination with other natural drugs in prevention and treatment of OSCC in recent years, in order to provide reference for further research.

In recent years, clear aligner technique has developed rapidly and has been widely used in the treatment of various malformations. However, the function of its orthodontic force is complex and its biomechanical mechanism is still unclear. Construction of the mechanical model of clear aligner and precise study on dynamic orthodontic process are hotspots and difficulties of the current research on clear aligner technique. Therefore, this paper reviews the biomechanical research progress of clear aligner technique.

Zirconia has gradually become an ideal material in prosthodontics because of its excellent properties. With developing application scope and form, zirconia has been applied to implant, abutment, crown and complete dental arch restoration in clinical practice so far. Its long-term clinical results attract extensive attention and long-term clinical research is constantly emerging. This article reviews published research on clinical effects of zirconia on oral implant restoration. Conclusions are made based on published research with follow-up for at least one year. Emphases are put on the biological, mechanical and esthetic properties of zirconia prosthesis. Merits and shortcomings between zirconia and traditional materials are presented to provide a reference for clinical use of zirconia prosthesis.