Objective　To analyze the effect of 10-MDP-calcium salt formation on dentin bonding performance. Methods　Using the etch-and-rinse technique mode, the teeth were randomly divided into the following 4 groups(n=5) according to the treatment method of the dentin surface and the choice of the adhesive, and the dentin/resin bonding specimens were made：① in the control group, the single bond 2(SB2) was directly treated and bonded;② in the 10-MDP group, the dentin surface was pretreated with a self-prepared primer containing phosphate monomer 10-MDP before using SB2 treatment for bonding;③ in the CHX group, the dentin surface was pretreated with chlorhexidine(CHX) before bonding with SB2;④ in the SBU group, single bond universal(SBU), a MDP-containing universal adhesive, was directly used for bonding. The bonding strength was measured by micro-tensile bond strength(μTBS), and the dentin surface treated with self-prepared 10-MDP primer and two kinds of dentine adhesives was characterized by X-ray diffraction(XRD) and in situ zymography test to analyze the effect of 10-MDP-calcium salt formation on the dentin bonding performance. Results　The results of micro-tensile bond strength test showed that there was no significant statistical difference between the adhesive specimens treated with different methods after 24 h water-storage(P>0.1). After 6 months water-storage, compared with the 10-MDP group and the SBU group, the micro-tensile strength test of the control group was significantly reduced(P<0.05), while the micro-tensile strength test of the CHX group did not change significantly(P>0.05). The XRD results showed that the characteristic peaks of 10-MDP-calcium salt formation were detected in both the 10-MDP group and the SBU group, indicating the formation of 10-MDP-calcium salt. The results of in situ zymography showed that there was no significant difference between the 10-MDP group and the SBU group. The fluorescence intensity of the hybrid layers in the control group was significantly higher than that of the 10-MDP group and the SBU group, while the fluorescence intensity of the CHX group was lower than that of the 10-MDP group and the SBU group. Conclusion　The formation of 10-MDP-calcium salt can protect the exposed collagen fibers from contacting MMPs and avoid hydrolysis, thereby enhancing the dentin/resin bonding performance.

Objective　To investigate the effect and mechanism of estrogen combined with mechanical tension on human periodontal ligament fibroblasts. Methods　hPDLF cells were sorted and identified by magnetic beads. The hPDLF cells were divided into the control group, 17β-estradiol group, mechanical tension group and 17β-estradiol combined with mechanical tension group. Cell proliferation was measured; alizarin red staining was used to detect osteogenic differentiation of hPDLF cells. qRT-PCR was used to detect osteogenic gene mRNA expression, and Western blot was used to detect osteogenic protein, estrogen receptor expression, and activation of Akt signaling pathway. Results　It was identified that the extracted hPDLF cells conformed to its characteristics. The cell proliferation ability and OD-value of alizarin red staining in the 17β-estradiol and mechanical tension groups were significantly higher than those in the control group. The estrogen receptor ER-β and osteogenic genes RUNX2, OCN, OSX, OPN expression, Akt phosphorylation level were significantly higher than those of control group. Estrogen combined with mechanical tension cell proliferation ability, alizarin red staining OD value was significantly higher than the 17β-estradiol and mechanical tension group. The expression of estrogen receptor ER-β, osteogenic genes RUNX2, OCN, OSX, OPN, Akt phosphorylation level were significantly higher than those of 17β-estradiol and mechanical tension group. Conclusion　Estrogen combined with mechanical tension can promote osteogenic differentiation of hPDLF cells, and promote the expression of estrogen receptors and osteogenic genes, as well as the activation of Akt signaling pathway.

Abstract:　Objective　To investigate the effect of DZIP1 on the proliferation, migration and invasion of oral squamous cell carcinoma through the Wnt/β-catenin signaling pathway. Methods　Real-time quantitative PCR and Western blot were used to detect the mRNA and protein expression of genes related to DZIP1 and Wnt/β-catenin signaling pathway. Cell viability was detected by CCK-8. Oral squamous cell carcinoma(OSCC) was detected by clone formation to assay cell proliferation ability. Transwell assay was used to detect cell migration and invasion. Results　Compared with human oral keratinocytes(HOK), mRNA expression and protein expression of DZIP1 in human OSCC cell lines TSCCA, Tca8113 and SCC25 were significantly increased. Compared with the negative control(NC) group, knocking down DZIP1 significantly reduced the mRNA and protein expression of Wnt/β-catenin signaling pathway-related genes in SCC25 cells(P<0.05), and reduced cell viability(P<0.05), migration and invasion ability, inhibited cell proliferation(P<0.05). LiCl significantly increased the mRNA and protein expression of genes related to Wnt/β-catenin signaling pathway in SCC25 cells(P<0.05), increased cell viability(P<0.05), promoted cell proliferation(P<0.05), migration and invasion ability(P<0.05). Compared with the si-DZIP1 group, si-DZIP1 + LiCl significantly increased the mRNA and protein expression of genes related to the Wnt/β-catenin signaling pathway in SCC25 cells(P<0.05), and increased cell viability(P<0.05), promoted cell proliferation(P<0.05), migration and invasion capacity(P<0.05). Conclusion　DZIP1 promotes the proliferation, migration and invasion of oral squamous cell carcinoma by affecting the Wnt/β-catenin signaling pathway.

Abstract:　Objective　To investigate the effect of high glucose on the proliferation and oxidative stress of human dental pulp cells(HDPCs), and to explore the influencing mechanism of high glucose environment on dental pulp. Methods　Dental pulp cells were isolated and cultured, and the source of tissue was identified. The experiment was divided into four groups:low-glucose group(glucose 5.5 mmol/L), normal group(25 mmol/L), high-glucose group(50 mmol/L), and hyperosmolar group(osmotic pressure was equal to that of the 50mmol/L group and glucose concentration was equal to that of the 5.5 mmol/L group). CCK-8 kits were used to detect the proliferation level of HDPCs after 1 day, 3, and 5 days. DCFH-DA was used to detect intracellular ROS level after treatment with high glucose, the content of malondialdehyde(MDA) was measured by enzyme labeling method, and the activity of superoxide dismutase(SOD) was measured by Water-soluble tetrazolium method. Flow cytometry was used to analyze mitochondrial membrane potential in each group. Results　①Compared with the normal group, high glucose had significant inhibitory effect on the proliferation of HDPCs(P<0.05). ②The levels of reactive oxygen species(ROS) and malondialdehyde(MDA) increased significantly after exposure to 50 mM glucose for 72 h, and activity of superoxide dismutase(SOD) decreased. Compared with the normal group, there was a statistical difference(P<0.05).③ Flow cytometry detection of mitochondrial membrane potential showed that the fluorescence value of high glucose group was higher than that of normal group(P<0.05). Conclusion　High glucose can inhibit the proliferation of pulp cells, and lead to the decrease in mitochondrial membrane potential of HDPCs, induce oxidative stress, indicating that the high-glycemic environment reduces the vitality of dental pulp cells, which may also be a potential factor for the change of dental pulp tissues in diabetic patients.

Objective　To investigate the effect of human amniotic mesenchymal stem cells(hAMSCs) on osteoblast by paracrine manner. Methods　Primary hAMSCs were extracted by enzymatic digestion, and surface antigen markers were identified. Culture supernatant of hAMSCs after 24 h was collected and mixed with fresh medium by 1∶1, and was defined as condition medium(hAMSC-CM), while fresh medium was set as negative control. Their effects on the activities of MG63 were then detected. Cell proliferation was detected by MTT continuously for 4 days. The migrated cell number was estimated and counted after hematoxylin eosin staining by means of transwell system 2.5 h later. Alkaline phosphatase activity was measured after 5 days with p-Nitrophenyl Phosphate Disodium(pNPP). Results　hAMSCs showed the shape of fibroblast. Surface antigen markers were positive for CD29, CD105, CD49d, CD44， while negative for CD34, CD45, CD31, HLADR. hAMSC-CM promoted MG63 proliferation significantly during the first 3 days(P<0.05). Migration ability in hAMSC-CM group was enhanced prominently(P<0.05). ALP activity in cells cultured with hAMSC-CM exceeded control group markedly(P<0.05). Conclusion　hAMSCs are able to enhance the biological activity of osteoblast through CM mediated paracrine.

Objective　To investigate the effect of different gingival types of fixed bridge on the stress distribution of the abutment and periodontium via the method of three-dimensional finite element analysis. Methods　A fixed bridge with the mandibular second premolar and the second molar acting as the abutment to restore the missing first molar was established using three-dimensional modeling software based on original cone beam computed tomography(CBCT) data of healthy adult dentition. Three different types of bridge gingival ends were simulated, namely modified saddle type, modified crest type and bottom type. After vertical loadings were exerted on three kinds of finite element models respectively, the stress distributions of dentin and periodontal membrane of the fixed bridge abutment were analyzed using ANSYS 17.0 software. Results　①The second premolar teeth always suffered higher stress compared with the first molar teeth under the same loading condition. ②The stress distribution of a single teeth showed no significant difference among three different gingival types of fixed bridge, while the bottom type of prosthesis showed smaller stress in the second premolar teeth and bigger stress in the first molar teeth. ③The stress distribution of the periodontal membrane of the three groups of bridge abutment teeth was as follows: modified saddle type<modified crest type<bottom type. However, the stress in the three groups did not exceed the periodontal reserve of the abutment, and the periodontal reserve of the abutment increased with the decrease of the bridge gingival end volume. Conclusion　①Molars are ideal abutment. The periodontal supporting force of the first molar teeth should be first considered in the restoration. ②The bottom gingival type is more favorable to protect the single root teeth and improves the stress distribution of the fixed bridge. ③All the three kinds of gingival types can afford the daily bite force and have no effect on the health of the periodontal membrane.

Objective　To evaluate the effects of three kinds of rapid maxillary expansion with protraction appliances on maxilla and teeth using three-dimensional finite element method, and provide reference for clinical treatment. Methods　The three-dimensional finite element model of Hyrax with tooth-borne protraction appliance, MSE(Maxillary Skeletal Expander) with tooth-borne protraction appliance, MSE with bone-borne protraction appliance and cranial-maxillary complex was established. The expander screw was activated by 0.25 mm and the traction force of 500 g per side was applied to the traction site of the appliance. The direction of the force was 30°downward and forward to the occlusion plane. The displacement trend and stress distribution of maxilla and teeth under the three kinds of appliances were evaluated. Results　The stress distribution and the displacement trend of the three types of appliances were similar, but the lateral displacement of the maxilla under the two kinds of MSE with protraction appliance was 2.7 times as much as that of the Hyrax’s, and 2.6 times in sagittal displacement, and its stress value was much higher than that of the Hyrax’s. The tooth displacement trend of the three models was similar, but the tooth stress distribution pattern was different. MSE with bone-borne protraction appliance still affected the anchored molar. Conclusion　①MSE with protraction appliance is a better choice for adults or patients who need a large amount of maxilla movement.②MSE with protraction appliance needs to be improved.

Objective　To compare the forces on the upper and lower central incisors of bases made of different materials, self-curing resin materials and the thermoplastic materials, under the action of buccal multiple spring, hoping to choose proper materials to replace the bases made of self-curing resin and to solve the problem of anterior teeth inclination in patients treated with buccal multiloop appliance during the process of correcting Class Ⅲ malocclusion. Methods　According to voltage-force value relation, the voltage value could be converted into force value. The voltage on the incisors was measured by a thin film pressure sensor miniature force system when the buccal multiloop was opened for 2 mm, 4 mm, 6 mm, 8 mm, 10 mm respectively in the simulated closed position in vitro. Force values on the labial and lingual surfaces of the upper central incisors under the orthodontic force of different lengths of buccal multiloop springs were calculated and compared. Then the results were statistically analyzed. Results　With the increase of the length of buccal multiloop, the force values produced by the two kinds of bases on the labial surface of maxillary central incisors and the lingual surface of mandibular central incisors increased. When the buccal multiloop was opened to the same length, the labial force values of the thermoplastic material base on maxillary central incisors and the lingual force values of mandibular central incisors of that were less than those of the self-curing resin base(P<0.05). Conclusion　Compared with self-curing resin, the force value of the base made of the thermoplastic material on maxillary and mandibular central incisors is smaller, which can reduce the inclination of maxillary and mandibular central incisors and relieve the tooth effect.

Objective　To determine the changes after maxillary skeletal expansion(MSE) in adults with narrow upper arch by cone-beam CT(CBCT). Methods　This study included 13 patients(6 males, 7 females; range 18-24 years old, mean age 20.7) with narrow upper arch treated with MSE. CBCT images were taken before， after expansion. The following items were compared and measured:upper arch width, the midpalatal suture width, maxillary basal bone width, nasal cavity width, and other measurements. Statistical analyses were performed using paired t-test. Results　Except for 1 patient who failed because of the infection, all the other 12 patients obtained good effects. The CBCT measurements were as follows:① upper arch width was obviously expanded(P<0.05）; ② the midpalatal suture width, maxillary basal bone width and nasal cavity width were expanded respectively with significant statistical difference(P<0.05）; ③ the inclination of upper first molar was slightly increased with no significant statistical difference(P>0.05）. Conclusion　MSE is an effective method for maxillary expansion in adult patients with narrow upper arch.

Objective　To investigate the effect of gender on the evaluation of soft tissue profile in patients with skeletal Class Ⅲ malocclusion, and to provide reference for orthodontic clinic. Methods　The silhouette data of 30 orthodontic patients(15 male and 15 female respectively) were collected before treatment. Photoshop software was used to conceal their hair and neck which exposed gender features.54 junior undergraduate students(27 male and 27 female respectively) were selected to score the processed images on a numerical rating scale(NRS), and then a complete silhouette score was assigned 40 minutes later. The order was adjusted randomly.SPSS 17.0 software was used for data statistical analysis. Results　There was no significant difference between the silhouette score without gender characteristics and the silhouette score with gender characteristics in female and male patients(P>0.05). Conclusion　Gender of patients with skeletal Class Ⅲ malocclusion has no significant effect on the evaluation of soft tissue profile.It is suggested that in the process of orthodontic design and treatment, attention should be paid to the aesthetic analysis of the profile and the postoperative improvement rather than gender difference.

Objective　To investigate the regularities of caries distribution in the primary dentition of children in Nanjing, China. Methods　449 children of 2 to 6 years old in Nanjing were selected for oral examination. Regularities of caries distribution on different tooth surfaces were analyzed. Results　The distribution of caries was bilateral symmetrical. The caries concentrated on the mesial surface of the maxillary primary central incisor, followed by the proximal and occlusal surface of the primary molar, and the labial and proximal surface of the maxillary primary anterior teeth. The risk of caries in primary anterior tooth surface increased towards midline; in primary molars, caries risk was higher in mandible than that in maxilla. There was higher risk of occlusal caries surface in second primary molars, and higher risk of proximal caries surface in first primary molars than that in second primary molars. Conclusion　The primary tooth caries distribution has specificity in tooth surface. The caries risk of tooth surface with similar appearance and adjacent position may be different. Prevention and treatment should be strengthened on the tooth surface with high caries risks.

Objective　To explore a more convenient and reliable method for the treatment of fresh sagittal maxillary fractures. Methods　The fractured fragments were medially transversal distracted and reduced by palatal implants which were located in both sides of fr-acture line.Then a min-plate was contoured to the palatal vault and fixed to the palate as external fixator via transmucosa method.After that,palatal implants were removed. The mini-plate stayed in situ for a month to maintain the stability of fractured fragments and was then removed. Results　This method was efficient for the treatment of fresh sagittal maxillary fractures and made it possible to maintain good oral hygiene and function. Conclusion　This method is simple,reliable,comfortable and worthy of clinical promotion. It is suitable for relatively simple sagittal maxillary fractures.

Objective　To compare the implant failure rates and peri-implant marginal bone loss(MBL) of tilted implants and axial implants in All-on-4 treatment concept after over 3-year follow-up. Methods　An electronic search was undertaken in PubMed, Web of Science and Cochrane Library with the searching time from the establishment of the database to August 2019. An additional manual search of the related reviews was also undertaken. After study selection and data extraction, a meta-analysis was conducted. The primary outcome was implant failure rates and the secondary outcome was MBL. Results　Twelve studies meeting the criteria were included. There was no significant difference in implant failure rates(RR=1.24, 95% CI:［0.85, 1.83］, P=0.27) between tilted implants and axial implants in All-on-4 treatment concept. In terms of MBL, meta-analysis showed that no significant difference was found between tilted implants and axial implants(MD=-0.02, 95% CI:［-0.07, 0.03］, P=0.47). Conclusion　After over 3-year follow-up, tilted implants and axial implants in All-on-4 treatment concept might have similar implant failure rates and peri-implant marginal bone loss. More high-quality studies with larger sample size and longer follow-up are needed to support our findings in the future.

In the big data era, digital technologies are becoming more and more popular in diagnosis and treatment of orthodontics. This article aims to review the progress of digital techniques in orthodontic diagnosis and treatment from the aspects of teeth, jaw bone and soft tissue. The development of 3D printing, artificial intelligence, virtual reality, and 5G technology in orthodontics were summarized and discussed, in order to the application of digital technology in orthodontics.

Sitagliptin is a highly selective dipeptidyl peptidase-4(DPP-4) inhibitor. As the first drug of its kind approved for the treatment of type 2 diabetes, it has the advantages of good efficacy, tolerance, and a low occurrence rate of hypoglycemia and weight gain. In recent years, with more and more studies on sitagliptin conducted, more effects of the drug in different situations have been discovered. In addition to the role of lowering blood sugar, sitagliptin also has the effects of anti-inflammation, anti-tumor, potential renal protection, cardiovascular protection, and tissue regeneration. This article reviews the roles of sitagliptin in various fields, which will provide a reference for the diagnosis and treatment of related diseases and tissue regeneration.

The paired related homeobox gene Prx1 is highly expressed during embryonic lib formation and craniofacial development. Postnatal Prx1+cells located in periosteum, bone marrow or calvarial sutures display the characteristics of mesenchymal stem cells(MSCs) or skeletal stem cells(SSCs). Recent research has shown that Prx1+SSCs participate in fracture healing and respond to mechanical forces in bone. At the same time, Prx1+cells in the periodontal ligament are noticed for its contribution to the normal development and defect repair of periodontal tissues. This paper reviews the characteristics and function of Prx1 gene and Prx1+cells and gives a summary of the role Prx1+SSCs play in bone remodeling and repair, which is helpful for the further studies of SSCs in regulating orchestrate craniofacial growth and promoting the regeneration of alveolar bones.

Obstructive sleep apnea-hypopnea syndrome(OSAHS) is a kind of sleep respiratory disease, whose pathogenesis is complex and can affect the sleep and life quality of patients. This paper will review the influence of various treatment methods on sleep quality of OSAHS patients and have clinical significance for the treatment on OSAHS.

Currently, occlusal dysesthesia(OD) is considered as a derivative form of somatoform disorder. Its symptoms are mainly manifested in the oral area, mostly due to the undetermined occlusal discomfort, which may be triggered by previous dental treatment. In order to diagnose and treat such patients in clinical practice as early as possible, this article will review occlusal dysesthesia from the aspects of epidemiology, etiology, diagnostic criteria, treatment and prognosis.