Objective To investigate the change rules of oxygen level and bone metabolism after mandibular ramus osteotomy and try to figure out the effects of jaw surgery on bone remodeling. Methods Thirty healthy seven-week-old male rats were randomly divided into 6 groups. A set of 5 rats were sacrificed at pre-operation and 1d, 3d, 5d, 7d, 14d respectively. Operation groups were treated by bilateral mandibular ramus osteotomy. The area of alveolar bone between the roots of the first molar was examined as region of interest. Hypoxyprobe-1 combined immunofluorescence staining was used to detect changes of oxygen environment at molecular level. Tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) staining were utilized to observe the changes in bone metabolism. Results Obvious hypoxia occurred at 1d and was maintained at 3d postoperatively. The degree of hypoxic condition began to decline at 5d, but there was still a statistical difference compared to the preoperative period. The hypoxia status was relieved and returned to preoperative levels at 7d. Alveolar bone metabolism was active after surgery. The alveolar bone resorption activity was significantly enhanced at 1d, peaked at 7d and decreased to preoperative levels at 14d. Alveolar bone osteogenesis activity was not obvious from 1d to 5d after surgery. However, early osteogenic differentiation was significantly active at 7d and 14d. Conclusion Hypoxic microenvironment of the alveolar bone at an early stage after osteotomy promotes bone resorption. Osteogenesis is enhanced when hypoxic condition is relieved.

Abstract: Objective To investigate the effect of graphene oxide-silver nanocomposites（GO-Ag）on Streptococcus mutans（S.mutans）and its biofilm formation. Methods Colony forming units counting method, flow cytometry and live/dead staining method were used to detect the antibacterial effect of graphene oxide-silver nanocomposites on S.mutans. The biomass of GO-Ag-treated S.mutans biofilm was tested by crystal violet assay. The data were analyzed by One-Way ANOVA and Dunnett’s test. Results The results of antibacterial effect of GO-Ag tested by all these methods had significant difference with the control group（P<0.05）. Comparing with the control group, the biomass of GO-Ag-treated S.mutans biofilm was greatly reduced（P<0.05）. Conclusion Graphene oxide- silver nanocomposites（GO-Ag）exhibited great antibacterial effect and biofilm inhibition on S.mutans.

Objective　 To investigate the effects of different phosphoric acid etching time and conditioning with different phosphoric acid ester monomers on the surface roughness and micromorphology of enamel. Methods　 Enamel samples were prepared with 35% phosphoric acid etching for 3, 15, 30 and 60 seconds, respectively. A two-step self-etch adhesive Optibond Versa (OV) primer containing phosphoric acid ester monomer GPDM (glycerol phosphate dimethacrylate) and Tetric N Bond Universal (TNBU) containing phosphoric acid ester monomer 10-MDP (10-Methacryloyloxydecyl dihydrogen phosphate) were used to pretreat enamel surface for 20 seconds. The enamel surface roughness (Ra), were tested by a profilometer and compared with the untreated group (Ctr) and the surface morphology were observed by scanning electron microscope (SEM). Results　The surface roughness obtained by 35% phosphoric acid etching was the highest, followed by OV, TNBU and Ctr (P＜0.05). SEM showed that the enamel-prism dissolved slightly after phosphoric acid etching for 3 seconds, and the typical fish scale-like honeycomb structure was formed after phosphoric acid etching for 15 seconds. With the extension of phosphoric acid etching time, the gaps between the enamel-prisms became more obvious and the enamel-prism structure collapsed. The obvious enamel-prism contours can be observed on the enamel surface treated with OV primer. There was no obvious enamel-prism etching in TNBU, and the scratches were still clear. Conclusions　15 seconds phosphoric acid etching of enamel is recommended. Enamel surface roughness can be increased by phosphoric acid etching and GPDM-containing primer conditioning. GPDM-containing primer achieved higher demineralization depth than that of 10-MDP containing adhesive.

Objective　To detect the expression of stem cell markers P75NTR and SOX2 in ameloblastoma (AM), and to investigate the correlation between tumor stem cells and their biological behavior. Methods 28 AM cases with different types were selected as subjects，and 5 cases of odontogenic cysts and 5 cases of keratocyst were taken as control group. Immunohistochemical staining was used to detect the expression of P75NTR and SOX2, and non-parametric rank-sum test was used to analyze the expression difference of P75NTR and SOX2 between solid AM and unicystic AM, as well as the expression difference between AM and dentigerous cyst and keratocyst. Results The expression intensity of P75NTR in solid AM was significantly higher than that in unicystic AM. The expression intensity of P75NTR in AM was significantly higher than that in dentigerous cyst and keratocyst (P<0.05). These differences showed a statistical meaning. There was no significant difference in SOX2 expression between solid AM and unicystic AM, AM and odontogenic cyst (P > 0.05), and there was difference between AM and keratocyst (P < 0.05). Conclusion The expression of the stem cell marker P75NTR in AM may be related to cell proliferation and stem cell characteristics, and may be involved in tumor invasiveness. SOX2 is less expressed in AM, and its role in AM remains to be further explored.

Objective　 To study the effect of different concentrations of cinnamaldehyde on the proliferation, migration, invasion, apoptosis and epithelial-mesenchymal transition of oral squamous cell carcinoma (OSCC) CAL27 cells in two dimensional conditions in vitro. Methods CCK8 test was performed to determine whether cinnamaldehyde can inhibit the proliferation of OSCC CAL27. Scratch test was conducted to determine whether cinnamaldehyde has an inhibitory effect on the migration of CAL27. Transwell test was used to test whether cinnamaldehyde can inhibit the invasion of CAL27. Flow cytometry was used to test whether cinnamaldehyde can promote the apoptosis of CAL27. Western blot was performed to determine whether cinnamaldehyde has an effect on the epithelial-mesenchymal transition of CAL27. Results The results of CCK8 showed that the experimental group treated with cinnamaldehyde had a time and drug concentration dependence effect on inhibiting the proliferation of CAL27. The results of scratch test and transwell test showed that the experimental group treated with cinnamaldehyde inhibited the cell migration ability and invasion ability in a dose-dependent manner. The results of flow cytometry showed that the experimental group treated with cinnamaldehyde promoted the apoptosis of CAL27 in a dose-dependent manner. The results of Western blot showed that the experimental group treated with cinnamaldehyde inhibited the expression of Vimentin and Snail and promoted the expression of E-cadherin in a dose-dependent manner. Conclusion The experimental group treated with cinnamaldehyde inhibits the proliferation, migration and invasion of OSCC CAL27 and promotes its apoptosis in a dose-dependent manner in two dimensional conditions in vitro. Cinnamaldehyde inhibits the migration of OSCC CAL27 by affecting the epithelial-mesenchymal transition process.

Objective To analyze the effect of different numbers and different angles of inclined implants on the stress distribution of implants and bone tissue by three-dimensional finite element analysis under the condition of constant static force loading. Methods Six models with different inclined-angle implants which were named No.1-5 from right to left in edentulous maxilla were designed. The implant placement sites were fixed. Through the reverse engineering modeling method, the 3D CaMega optical 3D scanning system was used to scan the Bego implant and abutment entities. Finally, the obtained reverse feature parameters were constructed using forward modeling tools to construct a solid model of the implant and abutment. Model Ⅰ: No.1-5 implant axial tilted 0 degree; Model Ⅱ: No.1 and No.5 implant were distal tilted 30 degrees, the rest of the implants axial tilted 0 degrees; Model Ⅲ: No.1, 2, 4and No.5 were distal tilted 15 degrees, and the rest of the implants axial tilted 0 degrees; Model Ⅳ: No.1 and No.5 were distal tilted 30 degrees, No.2 and No.4 were distal tilted 15 degrees, and the rest of the implants axial tilted 0 degrees. Model Ⅴ: No.1, 2, 4 and No.5 were distal titled 30 degrees. Model Ⅵ：No.1, 5 were distal titled 30 degrees. No.2, 4 were miso titled 15 degrees. The stress of the implant surface and bone tissue surface was analyzed by loading 300 N load on the 15 teeth. Results Models of maximum stress values on the surface of No.1 implant were Ⅰ＜Ⅳ＜Ⅴ＜Ⅱ＜Ⅲ＜Ⅵ, and models Ⅱ to Ⅵ increased by 28.17%, 45.70%, 7.90%, 22.33%, and 57.04%, respectively, compared with model I. The maximum stress value on the surface of implant No. 3 was the highest in model Ⅰ, which decreased by 29.19%, 43.62%, 23.48%, 20.46%, and 16.44%, respectively. Based on the maximum Mise stress value of the surface of bone tissue No. 1 in model I, the surface stress values of bone tissue No.1 in models Ⅱto Ⅵ decreased by 10.12%, 58.22%, and 18.35%, respectively, and those of models Ⅴand Ⅵ increased 57.59% and 12.65% respectively. Conclusion In maxillary toothless jaw fixed prosthesis, the asymmetry adds the angle of the distal inclined implant, which is conducive to obtaining better stress distribution. The symmetrical distal inclination of the implant in the anterior dental area will significantly reduce stress on the surface of the dental implant and bone tissue, and will also reduce the risk of bone resorption in the anterior dental area and fixed denture fracture.

Objective: To evaluate the effect of positive pressure irrigation on the clearance rate of bacterial infection during the root canal preparation using nickel titanium file, as well as pain rates after operation, to provide a new method for improving the effect of root canal treatment. Method: 80 cases of single root canal with chronic periapical periodontitis were collected and randomly divided into two groups according to with or without positive pressure irrigation during nickel titanium files preparation. The root canals were instrumental with M3 system using crown-down technique. Before and after root canal preparation, samples were taken and cultured under anaerobic condition for 48h to compare the number of colonies. The pain rates after operation were recorded. Results: Compared to the unprepared root canal, the number of bacterial colony was significantly decreased after root canal preparation (P < 0.05). The clearance rate of bacterial infection was significantly increased in the group with positive pressure irrigation compared to the group without positive pressure irrigation (P < 0.05). The 24h pain rate was statistically decreased in the group with positive pressure irrigation compared to the group without positive pressure irrigation (P < 0.05). Conclusions: Root canal preparation with positive pressure irrigation can reduce the bacterial infection in the root canal as well as pain rates after operation.

Objective To analyze the differentially expressed genes and long non-coding RNA (lncRNA) in gene expression microarray of ameloblastoma patients and normal person, and to explore the key lncRNA and its involved signaling pathways. Methods The gene expression omnibus (GEO) microchip data set GES38494 and GES132472 of ameloblastoma were downloaded to screen the differentially expressed genes and lncRNAs. The lncRNA-mRNA co-expression network was constructed and its involved GO and KEGG pathways were analyzed. The STRING database was used for protein interaction analysis and screening of core genes. Results A total of 801 differentially expressed genes were screened out by differential analysis, among which six were differentially expressed lncRNA and co-expressed with 283 mRNAs. The mRNA in the lncRNA-mRNA co-expression network was mainly involved in biological functions such as epithelial development, skin development, epidermal cell differentiation, keratinocyte differentiation and keratinization, as well as the pluripotent regulation pathway of stem cells, pancreatic secretion, retinol metabolism, axon guidance, extracellular matrix - receptor interaction, and adhesion signaling pathway of KEGG. In PPI analysis, IVL was the core gene with the highest degree of connectivity, and the expression of its co-expressed lncRNA MAGI2-AS3 was down-regulation, showing a negative correlation. Conclusion Through bioinformatics analysis, signaling pathways that related to ameloblastoma lncRNA-mRNA co-expression network genes and core genes of protein interaction are found out, which provides a theoretical basis for target selection in ameloblastoma treatment .

Abstract：Objective To use cone-beam computed tomography to measure the thickness of palatal masticatory mucosa in young people of Han nationality, analyze the change tendency and examine the associations of palatal masticatory mucosa with gender、palatal vault morphology and periodontal biotype. Methods 32 periodontally healthy youths of Han nationality (15 males, 17females) were included. The thickness of palatal masticatory mucosa, at five tooth positions from canine to second molar, were collected by CBCT from four different levels that 3, 6, 9 and 12mm away from the gingival margin. Futhermore, periodontal biotypes were determined according to transparency of periodontal probe through gingival margin in maxillary central incisor. Results The overall mean thickness of palatal masticatory mucosa was 3.66 1.15mm, 3.23 0.71mm in canine region, 3.53 0.75mm in the first premolar region, 4.87 0.58mm in the second premolar region, 3.21 0.90mm in the first molar region and 4.39 1.67mm in the second molar region. There were some differences in the thickness of palatal masticatory mucosa between the groups with high or low palatal vaults in some tooth positions. Conclusions The palatal masticatory mucosa thickness increased from canine to premolar region but decreased at the first molar region and increased again in the second molar region. And the palatal mucosa thickness also increased as the distance from the gingival margin increased. The association of palatal masticatory mucosa with palatal vault morphology was observed. The premolar region was recommended as the most appropriate donor site.

Objective　 Establish craniofacial model to analysis effects of different anterior traction directions and traction sites on the craniofacial complex during protraction combined with expansion. Methods　 Three-dimensional finite element model with 3 types (L1, L2, L3) maxillary palate skeletal protraction assisted expansion using reverse engineering method. When the palate is extended, a force of 500g is applied to the traction hook of the device, and the directions are 0 °, 15 °, 30 °, and 45 ° with the maxillary occlusal plane. The stress distribution and displacement trend of the craniofacial complex are analyzed. Results　 At the same traction angle, there is no statistical difference in the three-dimensional displacements of the three points of the N points (Nasion), IOB point (Infraorbital point), and A point (Subspinale) in L1, L2, and L3；L1, L2, and L3 groups have different stress values from the same bone suture；With the increase of the traction angle, the displacement values of the N, IOB, and A points in the Z direction decrease linearly；The same traction force produces different stresses in each bone suture, and the stress changes of each bone suture with the increase of the traction angle. Conclusions　 When maxillary palate skeletal protraction combined with expansion，the three device forms have little effect on the displacement trend of the craniofacial, which can cause the craniofacial to move forward with counterclockwise rotation, but L2 Relatively low stress on the same bone gap, with the increase of the traction angle, the counterclockwise rotation of the craniofacial decreases, and the stress of each bone suture changes differently. In the clinical application of the zygomatic bone support device for forward traction, a smaller traction angle can be selected for patients with deeper occlusion and deeper coverage, on the contrary, for patients with shallow occlusion and shallower coverage Large traction angle.

Objective: To explore the effect of micro-implant nail combined with self-efficacy intervention on the profile, facial shape and psychological status of adolescents with orthodontic treatment. Methods: From April 2016 to November 2018, 90 patients with gingiva in orthodontic Department of our hospital were recruited and randomly divided into three groups, 30 in each group. The routine group was treated with high J hook traction, the micro-needle group was treated with micro-implant nail, and the combined group was treated with self-efficacy intervention. The gingival exposure, profile, facial type and psychological status of the three groups were compared.Result: There was no significant difference in gingival exposure among the three groups before treatment (P > 0.05). After 2, 3 and 4 months of treatment, the gingival exposure in the microneedle group and the combined group was lower than that in the conventional group (P< 0.01), and the combined group had better effect (P< 0.01). After 4 months of treatment, the changes of side appearance and facial shape indexes in the micro-needle group and the combined group were better than those in the conventional group (P < 0.01), but there was no difference between the micro-needle group and the combined group (P > 0.05). There was no significant difference in SAS and SDS scores before and after treatment in the conventional group (P > 0.05). Compared with before treatment, SAS and SDS scores in the micro-needle group and the combined group were significantly lower after treatment (P < 0.01), and the combined group was better than the micro-needle group (P < 0.01). Compared with the conventional group, the satisfaction of micro-needle group and combined group was significantly improved (P > 0.01), the satisfaction of combined group was 93.3%, and that of micro-needle group was 70.0%. The difference between the two groups was significant (P > 0.01). Conclusion: Microimplant nail combined with self-efficacy intervention can significantly improve gingival exposure in patients with orthodontic treatment. It also has certain effect on patients'profile and facial shape, and can effectively alleviate negative emotions in the treatment process.

Abstract：Objective　Whether there is a relationship between the low angle malocclusion and cervical abnormalities was analyzed by the lateral cephalometric radiographs. The incidence of cervical vertebra abnormalities in low angle cases was statistically analyzed, and the relationship among cervical morphology, neck posture and craniofacial morphology was analyzed. Methods Sixty low angle cases of orthodontics in Harbin Medical University were selected as experimental groups in 2011-2019. Another 60 cases of average angle were randomly selected as the control group. All patients ranged in age from 16 to 40 years old. Based on data from the first 4 cervical fusions and posterior arch deficiency. The incidence of cervical anomalies was counted. And the correlation between the measurement of the craniofacial neck and cervical abnormalities was analyzed. Results The prevalence of cervical fusion in the low angle group was 56.7%, and the average angle group was 21.7%. Cervical fusion occurred mostly in the second and third cervical vertebrae. The difference between the two groups was statistically significant. There was no significant difference in the posterior arch deficiency. ML/OPT, ML/CVT, SNB, NSL/ML, FH/ML, NSL/NL, NL/ML, S-Go, N-Me, ANS-Me, S-Go/N-Me in the measurements of craniofacial was statistically significant between the two groups. Logistic regression analysis showed that the occurrence of cervical fusion was related to FH/ML. Conclusions　The incidence of cervical fusion in low angle patients is significantly increased, indicating that the occurrence of cervical fusion may be related to the vertical growth pattern of the face.

【Abstract】Objective To understand the oral condition, attitude, knowledge and behavior of 12-year-old teenagers in suzhou, and provide basis for dental prevention. Methods Five districts and one city of suzhou city were selected by multi-stage, stratified and random sampling method. The oral examination with CPI probe and questionnaire were made according to the fourth oral epidemiology method. Results 32.7% of 1666 children aged 12 years with caries experience and their DMFT was 0.62.About 19.3% of deciduous teeth was filled. The prevalence rates of gingival bleeding and dental calculus were 87.1% and 82.3% . 92.4% of the surveyed population had a positive attitude towards oral health.The survey of dietary habits showed that 71.9% of the population ate sugary food once or more per day.63.6% of the 97.6% population brushed their teeth twice or more every day.1.6 per cent and 1.3 per cent of the population flossed weekly and daily. 66.1% of them had dental treatment experience, among which 45.4% had the last dental visit time <12 months. Conclusion Oral health education and publicity should be strengthened to promote oral health in suzhou.

In vital teeth, pulpal pressure causes the continuous outward flow of intrinsic water through the dentinal tubules to the bonding interface,which damages the integrity of the adhesive-dentin bonding interface, and then reduces the bonding strength and affects the durability of adhesive repair.This article contains a brief review of the effects of the outward flow of intrinsic water through the dentinal tubules on the bonding interface, nano-microleakage and bonding strength of different bonding systems.Moreover, this article discusses the measures to reduce the detrimental effects of outward flow of intrinsic water through the dentinal tubules on the bonding interface.

Curved root canals are common in the clinic, and the complexity and variety of the curvatures make it difficult to maintain the original shape of the root canal and perform ideal canal preparation. Recently, with the continuous development of new thermomechanical-treated nickel-titanium instrument, the performance of the instruments has been improved to better prepare the curved canals. In this paper, the effect of new thermomechanical-treated nickel-titanium instruments on the shaping ability of curved canals is reviewed.

Oral microorganisms play an important role in the occurrence and development of caries. In addition to bacterial caries, evidence supports oral fungi involve in the caries process and interact with bacteria. At the same time, there is also evidence that fungi can inhibit the cariogenic process by bacteria inhibition. By analyzing recent evidences, this paper analyzes the mechanism of fungal caries and puts forward the remained questions on fungal research.

With the development of precision medicine, cone-beam CT (CBCT) has been widely used in dental clinic and scientific research due to its quantitative measurement function. In the clinical application of alveolar surgery imaging, precise positioning is needed in cases, in order to formulate more precise treatment plan. CBCT provides the possibility of accurate diagnosis and treatment for alveolar surgery diseases with its powerful line measurement function. In this paper, the application and accuracy of quantitative measurement of CBCT in alveolar surgery will be reviewed.

Smart hydrogels, also known as environmental responsive hydrogels, have the ability to sense certain signals and stimuli in the external environment, including temperature, pH value, biomolecules, electricity, light and pressure.The special physical and chemical properties of these materials make them have great potential in the application of controlled release of drugs in vivo.In this artical, the structure and properties of different response types of intelligent hydrogels and their applications in drug controlled release systems are reviewed.

Photobiomodulation (PBM) therapy is the application of light to stimulate cell responses aimed at alleviating pain, reducing inflammation, and promoting tissue regeneration. In recent years, a large number of basic experiments have found that PBM can regulate the inflammatory process and slow down the pain response. Several clinical trials have also proved the efficiency of PBM in temporomandibular disorders (TMD). This article aims to present a contemporary and comprehensive review on the role of PBM therapy in the treatment of TMD.