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 manufacturing were discussed.

Objective To probe into the protective effect of dexmedetomidine on ischemia-reperfusion injury of posterior intercostal artery perforator flap in rats. Methods Twenty-four 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 100 μg/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 2 cm 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＜0.001), Akt(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). Conclusion Dexmedetomidine can alleviate ischemia-reperfusion injury of posterior intercostal artery perforator flap in rats.

Objective To reveal the function of Distal-Less Homeobox 5 (DLX5) in migration and chemotaxis of dental tissue-derived mesenchymal stem cells (DT-MSCs). Methods Retrovirus was used to transfect stem cells from apical papilla (SCAPs). After constructing the plasmid of DLX5, we overexpressed and knocked down the expression of DLX5. 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 effects 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 ①After transferring the plasmid of DLX5 overexpression and knockdown with retrovirus, results of western blot and Real-time RT-PCR showed that the overexpression and knockdown efficiency of DLX5 was significantly high. ②The overexpression of DLX5 enhanced migration and chemotaxis capacities of SCAPs. ③The knockdown of DLX5 inhibited migration and chemotaxis capacities of SCAPs. ④The DLX5-overexpressing conditioned medium of SCAPs promoted migration and chemotaxis capacities of PDLSCs. Conclusion DLX5 significantly promotes migration and chemotaxis capacities of SCAPs. The DLX5-overexpressing conditioned medium of SCAPs promotes migration and chemotaxis capacities of PDLSCs.

Objective To investigate the effects 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(cp-Ti) surfaces. The cp-Ti were set as the control group, and two modified titanium surfaces were set as the experimental groups. Scanning electron microscopy(SEM), X-ray photoelectron spectroscopy (XPS) and contact angle meter were used to analyze the surface morphology, elemental compositions and hydrophi licity 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 HUVECs, 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 gene expression of vascular endothelial cells.

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 its physical and chemical characterization was observed by the transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectra and other tests. Human oral keratinocytes cells (HOK) and dental pulp cells (DPC) were selected 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. Positive group with NovaMin and blank group were prepared. 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 tubules. Conclusions The nano-calcium phosphate prepared based on DMEM biomimetic mineralization strategy has good biocompatibility and sealing effect on dentinal tubules, which is expected to be a new desensitization material.

Objective To provide an effective method to obtain total RNA of Candida albicans(C.albicans) in biofilm and planktonic states by comparing different extraction approaches. Methods 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 in output, purity and integrity of total RNA extracted by two methods were compared by ultraviolet spectrophotometer, and further confirmed using agarose gel electrophoresis and RT-PCR. Results Modified Trizol method appeared more efficient than modified hot phenol method with less operation time (P＜0.000 5). The purity of the total RNA extracted by modified Trizol method was higher than that 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 in total RNA extracted by both 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 clear target bands. Conclusion Modified Trizol method contributes to more stable purity of the total RNA of C.albicans extracted 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.

Objective 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 group was established by 0.2 mm orthodontic wire ligation, and ligation was not conducted in the control group. After 8 weeks, gingival bleeding index, probing depth of periodontal pocket were, and loosening degree recorded and alveolar bone resorption was analyzed by Micro-CT. 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, and the gingival bleeding index, the probing depth of periodontal pocket and the degree of loosening were significantly increased and alveolar bone resorption was obvious. The glomerular Bowman's capsular space was obviously dilated; basement membrane hyperplasia, renal tubule interstitial hyperemia was obvious, and brush margin was destroyed; there was no significant difference in renal function.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 may play a role in periodontitis-related renal injury in rats by inhibiting autophagy.

Objective To investigate the correlation between the alveolar bone widths of maxillary lateral incisors and canine relationship, and evaluate 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) was measured. Then statistical analyses were performed to compare differences of alveolar bone width and their width distribution in three different canine relationships. Results MBW (Ⅰ: (2.94±1.20mm) vs. Ⅲ: (1.97±0.69)mm), ABW (Ⅰ: (1.60±0.55)mm vs. Ⅲ: (2.30±1.03)mm), APW (Ⅰ: (8.52±1.99)mm vs. Ⅲ: (5.78±1.56)mm) along with their distribution in Class Ⅲ canine relationship and MBW (Ⅰ: (2.94±1.20)mm vs. (2.18±1.10)mm), APW (Ⅰ: (8.52±1.99)mm vs. Ⅱ: (6.53±2.34)mm) and their distribution 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 are positioned and pointed more towards palatal, which makes the associated palatal alveolar bone relatively thinner and increases the risk 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 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. Two cases were diagnosed as mixed tumor and 3 cases were diagnosed as adenolymphoma 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. Conclusion 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.

Objective To investigate morphological anomalies of atlas in patients with buccally or palatally maxillary impacted canines (BIC/PIC) using cone-beam computed tomography (CBCT), and to contribute to predicting and early intervening maxillary impacted canines in clinic. Methods A total of 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 gender, age and Angle classification were selected as control group. CBCT images of all samples were imported, and lateral cephalometric and 3D images were reconstructed 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, and so was there 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 occurrs more often in patients with palatally maxillary impacted canines than people with normally erupted canines.

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 treatment was established. The amount of maxillary central incisor retraction (X₁), intercanine width (X₂) and the amount of distal movement of 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 maxillary 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 maxillary central incisor showed strong positive correlation with the consumption of dental arch space (r=0.726,P＜0.001), while the change of maxillary canines width and the consumption of dental arch space showed negative correlation (r=-0.317,P＜0.001). The regression equation of maxillary central incisor retraction(X₁), intercanine width (X₂) and the total arch space consumption (Y) was Y=1.25X₁-0.494X₂-2.299. Conclusion For every 1 mm of maxillary central incisor retraction, the arch space required is 1.250 mm, and for every 1 mm reduction in the width between canines, arch space required is 0.494 mm.

Objective To compare the efficacy of subgingival scaling and root planning (SRP) combined with Nd: YAP laser and SRP alone in the treatment of periodontitis and the influence on subgingival micro-organisms. Methods Patients met inclusion criteria with generalized periodontitis were enrolled in this randomized controlled split-mouth clinical study, one week after supragingival scaling as the baseline. The test side was treated with SRP combined with Nd:YAP laser, while the control side was treated with SRP alone. Periodontitis-affected sites from the homonymous single root teeth in a homomaxillary pair in each patient were selected for gingival crevicular fluid (GCF) and subgingival plaque sampling. The probing depth (PD) and bleeding on probing (BOP)were detected, while GCF and subgingival plaque samples were collected at baseline, 6 weeks and 12 weeks after treatment. ELISA was used to detect the concentration of interleukin-6 (IL-6) in GCF. We analyzed and compared microbial compositions of each sample by 16S rDNA high-throughput sequencing. Results 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 two groups was significantly lower than that in the baseline. Six 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 control side at both 6 weeks and 12 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. Conclusion Nd: YAP laser combined with SRP and SRP alone both have significant effect on treating periodontitis. There was no significant difference in clinical indicators between these two therapeutic methods. However, Nd: YAP laser may be beneficial to the reduction of GCF IL-6 concentration 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 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 kinds of attachments, 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. Two degrees clockwise rotation of the tooth long axis was applied to the clear aligner. Actions of the appliance and the canine were simulated and calculated by MSC.Marc.Mentat software. Then, nephograms of stress and displacement, and the maximum stress and displacement values were collected. Results ① The distribution trend of the displacement of canine and the stress of periodontal ligament was similar with or without attachments, but the displacement value of canine and the stress value of periodontal ligament in the attachment group were 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. Conclusion ① There is 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 is more efficient, eliminating unnecessary tipping movement and requiring less retention. ② The 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, achieve a harmonious, stable and aesthetic treatment effect, and reduce or avoid adverse effects of orthodontic treatment on patients' periodontal health. Compared with traditional fixed appliance, clear aligner has advantages of being comfortable, beautiful, removable and easy to clean. It has been widely used clinically for malocclusion correction. 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 advice for clinical application of clear aligner.

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 great 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. The principle and advantages of Er:YAG laser post space pretreatment and its′ influence on the bonding strength of fiber post were discussed, 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 and improve patient satisfaction. Compared with conventional orthognathic surgery, SFA has more stringent selection of indications and contraindications. Surgical design and operation are more difficult, while related research on clinical effects and long-term stability after treatment is less. SFA, as an alternative to conventional orthognathic surgery, is one of the hot research topics in recent years. This review will focus on the concept, its 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.