Equipped with characteristics of high precision, high quality and high efficiency, the development of digital technology provides a new alternative for the design and manufacture of removable partial denture / complete denture. In this paper, three key factors of digital impression, digital design and digital production were discussed.

Objective　 To probe into the protective effect of dexmedetomidine on ischemia-reperfusion injury of posterior intercostal artery perforator flap in rats. Methods　 24 SD rats were randomly divided into control group, Ischemia-reperfusion group (I/R group) and dexmedetomidine+Ischemia-reperfusion intervention group (DEX+I/R group). Rats in control group was prepared with the posterior intercostal artery perforator flap; rats in I/R group were prepared with vascular pedicle clipping for 6 hours after flap harvesting, and the DEX+I/R group was treated with dexmedetomidine 100μg/kg after ischemia process and repeated dosing 24 hours later. On day 7 after flap construction, survival rate of the flap was determined by gross observation; HE staining was used to observe the pathological condition of rat skin flap tissue; TUNEL fluorescence staining was used to detect the apoptosis of rat skin flap tissue; contents of SOD and MDA in rat plasma were determined by enzyme-linked immunosorbent assay. The expressions of apoptosis-related proteins (C-Caspase-3, Bcl-2) and PI3K/Akt pathway proteins (PI3K, pAkt/Akt) in rat skin flap tissues were detected by western blotting. Results　 Survival rate of the flap in control group, I/R group and DEX+I/R group was (94.15±2.28) %, (38.15±10.48) % and (57.71±10.22) %. Compared with control group, the flap survival rate in I/R group was significantly lower (P<0.001); compared with I/R group, the flap survival rate in DEX+I/R group was significantly higher (P=0.006). At the distance of 1cm from vascular pedicle, the apoptosis rate of skin flap tissue in I/R group was higher than that in control group (P< 0.001); the apoptosis rate of skin flap tissue in DEX+I/R group was lower than that in I/R group (P< 0.001). At the distance of 2cm from vascular pedicle, the apoptosis rate of skin flap tissue in I/R group was higher than that in control group (P<0.001); the apoptosis rate of flap tissue in DEX+I/R group was lower than that in I/R group (P=0.004). Compared with control group, SOD activity in serum of rats in I/R group was lower (P<0.001); compared with I/R group, SOD activity in serum of DEX+I/R group was increased (P<0.001). The serum MDA content in I/R group was higher than that in control group (P< 0.001); compared with I/R group, MDA content in serum of DEX+I/R group was decreased (P< 0.001). The expression of Bcl-2 (P=0.001), PI3K (P=0.003), AKT (P=0.023) and pAkt (P=0.002) in I/R group were lower compared with control group, while the expression of C-caspase-3 was significantly increased (P=0.002). The expression of Bcl-2（P=0.003), PI3K（P<0.001AKT)（P<0.001) and pAkt（P<0.001) in I/R group were increased compared with control group, while the expression of C-caspase-3 was significantly decreased (P<0.001). Conclusions　 Dexmedetomidine can alleviate ischemia-reperfusion injury of posterior intercostal artery perforator flap in rats.

Abstract:Objective:To reveal the function of DLX5(Distal-Less Homeobox 5) in migration and chemotaxis of DT-MSCs(Dental tissue-derived mesenchymal stem cells) by using the loss of function and gain of function studies. Methods:After constructing the plasmid of DLX5,we overexpressed and knocked down the expression of DLX5 by retrovirus transfection. real-time RT-PCR and Western Blot were used to detect the expression of DLX5.Scratch migration assays and transwell chemotaxis assays were used to examine the migration and chemotaxis capacity of SCAPs in vitro.The effect of DLX5-overexpressing conditioned medium on the migration and chemotaxis capacities of PDLSCs were tested by Scratch migration assays and transwell chemotaxis assays in vitro.Results:(1)After transferring the plasmid of DLX5 overexpression and knockdown with lentivirus ,the results of western blot and real-time RT-PCR showed that the overexpression and knockdown efficiency of DLX5 was significantly high.(2)The overexpression of DLX5 enhance the migration and chemotaxis capacity of SCAPs.(3)The knockdown of DLX5 inhibited the migration and chemotaxis capacity of SCAPs.(4)The conditioned medium of SCAPs overexpressed DLX5 promoted the migration and chemotaxis capacity of SCAPs.Conclusion: DLX5 significantly promoted the migration and chemotaxis capacities of SCAPs;The conditioned medium of SCAPs overexpressed DLX5 promoted the migration and chemotaxis capacity of PDLSCs . Key words:Distal-Less Homeobox 5;Dental tissue-derived mesenchymal stem cells,Migration;Chemotaxis;Conditioned medium.

Objective To investigate the effect of titanium surface modified with zinc-containing nanowire on the behavior of vascular endothelial cells. Methods After polishing up, acid-etching and alkali-heat treatment, the titanium surface modified with nanowires (NW-Ti) and zinc-containing nanowires (Zn-NW-Ti) were prepared on the commercially pure titanium surfaces. The polished titanium surfaces (cp-Ti) were set as the control group, and two modified titanium surfaces were set as the experimental groups. Scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and contact angle meter were used to analyze the surface morphology, elemental compositions and hydrophily of three specimens. The concentration of zinc ions released from Zn-NW-Ti was tested by zinc ion releasing kit. Human umbilical vein endothelial cells (HUVECs) were seeded on different titanium surfaces to study the effects on angiogenesis properties by cell adhesion, proliferation, migration and real-time quantitative PCR assays. Results Trace zinc element was detected on Zn-NW-Ti, which presented a uniform topological structure of nanowires. The concentration of zinc ions released from Zn-NW-Ti was approximately 1 mg/L. Compared with the other two groups, Zn-NW-Ti could significantly promote the adhesion, proliferation, migration of human umbilical vein endothelial cells, and up-regulate mRNA levels of angiogenic factors: HIF-1α and VEGF-A. Conclusion The titanium surface modified with zinc-containing nanowires can promote the adhesion, proliferation, migration and angiogenic factors of vascular endothelial cells.

Abstract：　Objective　To prepare biomimetic mineralized nano-calcium phosphate and explore its sealing performance on dentinal tubules. Methods　The amorphous calcium phosphate (DACP) was prepared based on DMEM biomimetic mineralization strategy, and observed its physical and chemical characterization by the Transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectra and other tests. Selecting human oral keratinocytes cells (HOK) and dental pulp cells (DPC) to co-culture with the materials for 24 h, respectively, and the biocompatibility of the materials was evaluated by CCK-8. Demineralized dentin disks were prepared by collecting intact and caries-free teeth, and applied evenly by DACP material suspension. Set positive group with NovaMin and blank group. After treatment for 1 day and 7 days respectively, scanning electron microscope (SEM) was used to evaluate the surface and cross-sectional sealing effect of dentin disks on DACP group. Results　TEM showed that DACP was uniform amorphous spherical nanoparticles, and the particle size increased with the extension of mineralization time. CCK-8 results showed that the cell viability of HOK and DPC were good under 25 μg/mL, 50 μg/mL, 100 μg/mL and 200 μg/mL DACP, suggesting that the material has good biocompatibility. After treated for 1 day, most of the dentinal tubules of DACP group were closed. After treated for 7 days, all dentinal tubules surface of DACP group was completely closed and cross-sectional images showed that DACP could penetrate into the tubules. Conclusions　The nano-calcium phosphate prepared based on DMEM biomimetic mineralization strategy has good bio-compatibility and sealing effect of dentinal tubules, which is expected to be a desensitization material.

Objective: Biofilm and planktonic states are two major styles for C. albicans living. The aim of this study is compare the output, purity and integrity of total RNA of C. albicans in biofilm and planktonic states using modified Trizol method and modified hot phenol method, respectively. Method: The biofilms and planktonic C. albicans SC5314 were incubated for 24 h. Total RNA of C. albicans were extracted using modified Trizol method and modified hot phenol method, respectively. The difference of the output，purity and integrity of total RNA isolated by two methods were compared by ultraviolet spectrophotometer, and further confirmed using agarose gel electrophoresis and RT-PCR. Result: Modified Trizol method appeared more efficient than modified hot phenol method ( p<0.0005). The purity of the total RNA extracted by modified Trizol method was higher than that extracted by modified hot phenol method ( p<0.05). The result of electrophoresis showed that there were three clear bands- 28s rRNA, 18s rRNA and 5s rRNA respectively when isolating RNA by modified Trizol method and modified hot phenol method. The result of RT-PCR confirmed the purity and integrity of total RNA of C. albicans with the clear target bands. Conclusion: Modified Trizol method appeared higher output in extracting the total RNA of C.albicans in the form of planktonic than modified hot phenol method. Moreover, the modified Trizol method is rapid with easy operation and can be applied in experiments with efficiency in connection with C. albican.

objective: The aim of this study was to investigate the role of mammalian target of rapamycin (mTOR) in renal injury in rats with periodontitis. Methods: Twenty male Wistar rats were randomly divided into control group and periodontitis group, with 10 rats in each group. The animal model of periodontitis was established by 0.2mm orthodontic wire ligation, and the control group was not ligation. After 8 weeks, gingival bleeding index, probing depth and loosening degree of periodontal pocket were recorded. HE and PAS staining were used for histological analysis. qRT-PCR and Western Blot were used to detect the mRNA and protein expression of mTOR, phosphor-mTOR (p-mTOR) and BECN1 (Beclin-1) in kidney tissues of rats. Results: Compared with the control group, the gingival tissue in periodontitis group showed obvious swelling, color and texture changes; the glomerular Bowman’s capsular space was obviously dilated，basement membrane hyperplasia, renal tubule interstitial hyperemia was obvious, and brush margin was destroyed. The mRNA and protein expressions (p-mTOR /mTOR) of mTOR in periodontitis group were significantly higher than those in control group, and the mRNA and protein expressions of Beclin-1 were significantly lower than those in control group. Conclusion: mTOR plays a role in renal injury associated with periodontitis in rats.

Objective To investigate the correlation between the alveolar bone widths of maxillary lateral incisors and canine relationship, and evaluate the related factors influencing the alveolar bone morphology of sites for immediate implantation based on cone-beam CT (CBCT). Methods CBCT images of forty-nine patients (a total of 92 maxillary lateral incisors) were selected and canine relationships were determined(class I, class II and class III). The buccal and palatal bone width at both mid-root and apical level (mid-root buccal width/MBW; palatal/MPW; apical buccal width/ABW; palatal/APW) were determined. Then statistical analyses were performed to compare the differences of the alveolar bone widths and their width distribution in three different canine relationships. Results MBW (I: 2.94 ±1.20mm vs. III: 1.97 ±0.69mm), ABW (I: 1.60 ±0.55mm vs. III: 2.30 ±1.03mm), APW (I: 8.52 ±1.99mm vs. III: 5.78 ±1.56mm) along with their distributions in class III canine relationship and MBW (I: 2.94 ±1.20mm vs. 2.18 ±1.10mm), APW (I: 8.52 ±1.99mm vs. II: 6.53 ±2.34mm) and their distributions in class II canine relationship were statistically different from class I canine relationship (P<0.05). Conclusion Compared to class I canine relationship, the root and apex of maxillary lateral incisors with class III relationship were positioned and pointed more palatally, which makes the associated palatal alveolar bone relatively thinner and increases the risks of palatal perforation during immediate implantation, similar conclusions can be drawn from patients with class II canine relationship and proclined upper incisors. Therefore, class III canine relationship and tooth proclination can be the potential risk factors for immediate implantation at maxillary incisors.

Objective　To investigate clinical and pathological features of intra-parotid facial nerve schwannoma. Methods　A total of 5 cases of intra-parotid facial nerve schwannoma admitted to the Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Jiangsu University from 2015 to 2020 were collected and reviewed. Patients’ clinical data, imaging data, pathological data, preoperative diagnosis, treatment and postoperative nerve injury were analyzed. Results　All patients with intra-parotid facial nerve schwannoma were male (33-70 years old). Clinical manifestations were only painless parotid gland mass with clear boundary, without facial nerve paralysis and other symptoms. 2 cases were diagnosed as mixed tumor and 3 cases were diagnosed as Lymph gland adenoma before operation. The treatment method was tumor with involved facial nerve resection and anastomosis in which nerve was jointed end-to-end. Post-operative follow-up showed that the facial nerve function of 4 patients was basically normal, and only one patient had grade Ⅱ (House-Brackmann) facial nerve dysfunction. No recurrent cases and malignant changes were observed during follow-up for 10-72 months. Microscopically, tumor cells were long spindle-shaped and arranged in a braided pattern. Immunohistochemistry showed diffuse strong positive expression of S-100 protein in the nuclei and cytoplasm of 5 patients. Also Vimentin was strongly positive in cytoplasm in all 5 cases. Sox10 was positive in the nuclei of 4 cases. Focal expression of CK7 was found in 3 patients. The positive index of Ki-67, a marker of cell proliferation, was less than 3%, and AE1, EMA, P63 and SMA were negative in all cases. Conclusions　Clinical manifestations and auxiliary examination of intra-parotid facial nerve schwannoma are non-specific. Preoperative diagnosis is difficult and depends on tissue pathological diagnosis. S-100 and Vimentin could assist the diagnosis of intra-parotid facial nerve schwannoma.

Abstract：Objective: Our study was aimed to investigate the morphological anomalies of atlas in patients with buccally or palatally maxillary impacted canines (BIC/PIC) using cone-beam computed tomography (CBCT), to assist predicting and early intervening maxillary impacted canines in clinic. Materials and methods: 196 CBCT images of patients with maxillary impacted canines were selected as the experimental group. And 196 CBCT images with normally erupted canines matched for sex, age and Angle classification were selected as control group. Lateral cephalometric and 3D images were reconstructed l in Dolphin to record the prevalence of ponticulus posticus and posterior atlas arch deficiency (including classification of posterior atlas arch and spondylolisthesis of posterior atlas arch). Statistics were analyzed using SPSS. Results: The prevalence of ponticulus posticus was 32.6% in the experimental group, significantly higher than 22.4% in the control group(P=0.024). The prevalence of ponticulus posticus in PIC group was significantly higher than that in the control group(P=0.005). There was no significant difference between BIC group and control group, so was between BIC and PIC group(P>0.05). The prevalence of posterior atlas arch deficiency showed no statistical difference between experimental group and control group(P>0.05). Conclusion: Ponticulus posticus occurred more often in patients with palatally maxillary impacted canines than people with normally erupted canines.

Linear regression analysis of the amount of maxillary central incisor retraction and arch space consumption GU Yuntong，WANG Lin，WANG Liang，WANG Yuhua，ZHAO Chunyang.( Jiangsu Key hiboratory o f Oral Disease ,Nanjing Medical University, Department o f Orthodontics ,Affiliated Hospital of Stomatology Nanjing Medical University ,Nanjing 210029 .China) Abstract：　Objective　To explore the relationship between the amount of maxillary central incisor retraction and the consumption of dental arch space. Methods　Two hundred and three adult orthodontic patients with overjet and extraction of the maxillary first premolars were selected .Three-dimensional reconstruction of the Cone-beam CT before and after the treatment were built.The amount of maxillary central incisor retraction (X1) ,intercanine width(X2) and the amount of distal movement of the canines were measured. The digital scanner was used to scan the maxillary plaster casts before treatment, and the crowding of the anterior segment of the maxillay arch was measured. The amount of the maxillary central incisor retraction, the change of intercanine width and the total amount of dental arch space consumption (Y) were analyzed using correlation analysis and linear regression analysis. Results　The amount of the maxillary central incisor showed strong poitive correlation with the consumption of the dental arch space(r=0.726,p<0.001),while the change of the maxillary canines width and the consumption of the dental arch space showed negative correlation(r=-0.337,p<0.001),the regression equation of maxillary central incisor retraction(X1), ,intercanine width(X2) and the total arch space consumption (Y) is Y=1.25X1-0.494X2-2.299. Conclusions　For every 1mm of maxillary central incisor retraction, the arch space required is 1.25mm, and for every 1mm reduction in the width between the canines, arch space required is 0.494mm.

Objective The purpose of this study was to compare the efficacy of subgingival scaling and root planning (SRP) combined Nd: YAP laser with SRP alone in the treatment of periodontitis and the influence of subgingival microorganisms. Methods　 Patients met inclusion criteria with generalized periodontitis were enrolled in this randomized controlled split-mouth clinical study. 1 week after supragingival scaling as the baseline. The test side was treated with SRP combined with Nd:YAP laser, while the control side with SRP. One periodontitis-affected site from homonymous single-root teeth in each group was selected for gingival crevicular fluid (GCF) and subgingival plaque sampling at baseline, 6 and 12 weeks after treatment. ELISA was used to detect the concentration of interleukin-6 (IL-6) in GCF. We analyzed and compared the microbial compositions of each sample by 16S rDNA high-throughput sequencing. Results　 The clinical indicators of the test and control sides were significantly improved compared with baseline, but there was no significant difference between the two groups. The IL-6 concentration in GCF in the two groups was significantly lower than that in the baseline. 6 weeks after treatment, the IL-6 concentration in the test side was significantly lower than that in the control group(P<0.05). α-diversity analysis showed that Shannon index was higher and Simpson index was lower on the test side at 6 weeks after treatment than at baseline. Sequencing results showed that, at 6 weeks after treatment, the relative abundance of Prevotella and Saccharibacteria_incertae_incerta_sedis in the test side decreased significantly compared with the baseline(P<0.05). The relative abundance of Treponema was lower, and the relative abundance of Capnocytophaga was higher than that of the control side(P<0.05). There was no significant difference at 12 weeks. Conclusions　 No additional advantage was achieved by using the Nd:YAP laser through the analysis of periodontal clinical data. However, it may be beneficial to the reduction of GCF IL-6 and the inhibition of certain periodontal pathogens in subgingival plaque in a short time.

Objective　To compare the effect of different attachments and positions on the left maxillary canine tooth torsion in clear aligner by three-dimensional finite element analysis. Methods　The finite element models of the clear aligner-attachment-maxillary canine-periodontal ligament-spongy bone-cortical bone (attachment groups) and (non attachment group) were established according to the scanning data of in vitro maxillary canine. The models with attachments were divided into three groups based on different kind of attachment, namely vertical rectangular attachment、vertical wedge-shaped attachment、optimized torsion attachment groups. The placement positions were divided into buccal middle 1/3, distal 1/3 and buccal-lingual middle 1/3. 2°clockwise rotation of the tooth long axis was applied to the clear aligner. The action of the appliance and the canine were simulated and calculated by MSC.Marc.Mentat software. Then, the nephograms of stress and displacement, and the maximum stress and displacement values were collected. Results　①The distribution trend of the displacement of the canine and the stress of periodontal ligament is similar with or without attachments, but the displacement value of the canine and the stress value of periodontal ligament in the attachment group are higher than that in the non-attachment group.② When the same attachment was selected, the stress value and maximum initial displacement value were the highest in the buccal middle 1/3, the stress and displacement expression were more efficient in buccal-lingual middle 1/3, and the effect of the distal 1/3 was relatively bad. Conclusions　①There was no significant difference in the stress value and the maximum initial displacement between the buccal middle 1/3 and the buccal-lingual middle 1/3, but the buccal-lingual middle 1/3 was more efficient, eliminating unnecessary tipping movement and requiring less retention.②The orthodontic effect of vertical rectangular and vertical wedge-shaped attachments in “one tooth” model is significantly better than that of optimized torsion attachments. The actual effect needs further clinical verification.

The purpose of orthodontic treatment is to correct malocclusion, achieving a harmony, stable and aesthetic treatment effect, reducing or avoiding the adverse effects of orthodontic treatment on patients' periodontal health. Compared with the traditional fixed appliance, clear aligner has the advantages of comfortable, beautiful, removable and easy to clean. It has been widely used clinically for the correction of malocclusion. This article will review the impact of clear aligner on the periodontal health of orthodontic patients, and conduct research and analysis from three aspects: mechanical properties, periodontal clinical indicators and periodontal inflammation microenvironment, to provide advices on clear aligner in clinical application.

Adequate bone volume is a key factor for the success of implant restoration. However, insufficient bone volume in the implant area is common in clinical practice, making it difficult to obtain ideal implant orientation. Therefore, in order to ensure the success and stability of implant restoration, restoration and reconstruction of the alveolar ridge has important clinical significance. With the development of bone augmentation techniques, tenting screw technique based on basic principles of guided bone regeneration has achieved remarkable results in clinical practice, which allows the restoration and reconstruction of alveolar ridge defects with minimal or no use of autogenous bone. This article reviews the development of tenting screw technique and summarizes principles and conditions of application, clinical efficacy, associated complications, operational essentials and points for attention.

This article reviewed the latest research progress of Er:YAG laser activated root canal irrigation technology，including Photon initiated Photoacoustic Streaming (PIPS) technology and Shock wave enhanced emission photoacoustic streaming (SWEEPS) technology. Discus the progress of the principle, advantages of Er:YAG laser post space pretreatment and its’ influence on the bonding strength of fiber post .In order to provide new ideas for selecting appropriate methods of post space pretreatment in clinical practice.

Surgery-first approach (SFA) refers to patients bypassing the preoperative orthodontic process before orthognathic surgery, or performing only a short and simple preoperative orthodontic, and then directly performing orthognathic surgery, in order to avoid temporary face deterioration of orthodontics, shorten the course of treatment, improve patient satisfaction. Compared with the conventional orthognathic surgery, SFA has more stringent selection of indications and contraindications, surgical design and operation difficulties, clinical effects and long-term stability after treatment related research is also less. SFA, as an alternative to conventional orthognathic surgery, is one of the hot research topics in recent years, and this review will focus on the concept, advantages and disadvantages, indications and contraindications, surgical design and so on.

Obtaining the ideal pink aesthetic effect is one of the important conditions for successful implantation therapy in aesthetic areas. In clinical practice, the soft tissue can be guided to shape by temporary prosthesis to achieve the ideal aesthetic effect. The shape and size of the restorative emergence profile will have a significant impact on the aesthetics, health and stability of the hard and soft tissue surrounding the implant due to the obvious difference between the implant and the natural periodontal tissue. When improperly designed, the gingival profile endangers the blood supply in the area and the implementation of disease detection and professional maintenance measures, leading to loss of tissue volume around the implant and occurrence of disease. A thorough understanding of biological characteristics of these tissues as well as design principles of prosthesis emergence profile will help the prosthodontist to achieve the aesthetic, function, health and stability of peri-implant tissues through predictable management and shaping of the soft tissue.