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18 February 2019, Volume 35 Issue 2 Previous Issue    Next Issue
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Research Progress of 3D Printing in Manufacturing Dental Ceramics MA Jian-feng, LIN Ting-ting, HUANG Sheng-bin. 2019, 35(2): 107-112.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.001 Abstract ( 543 )   PDF (2572KB) ( 683 )   Ceramic materials have been favored in oral prosthetics due to their excellent mechanical properties, aesthetic performance, biocompatibility, and other characteristics. However, the traditional dental ceramic restoration process is verbose and difficult to meet the growing dental market. 3D printing technology is an emerging material forming technology in industry in recent years, which can quickly produce objects with complicated shapes and has advantages over traditional processing methods and material reduction. This paper reviews the progress of the current 3D printing technology in the field of dental ceramic molding, and summarizes its process principle, application status, advantages, and disadvantages. At the same time, it discusses the future development trend of 3D printing technology in the field of dental ceramic molding. References | Related Articles | Metrics

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Research Progress of Porphyromonas Gingivalis Escaping from Defense of Innate Immune System. LI Yu-yang, MENG Wei-yan. 2019, 35(2): 113-115.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.002 Abstract ( 376 )   PDF (784KB) ( 302 )   Porphyromonas gingivalis (P. gingivalis) is one of the major pathogenic bacterium in periodontitis and its structure and virulence factors play key roles in destroying periodontal tissues. Researchers found that it could escape from the defense of the innate immune system by breaking through mucosal barriers, resisting phagocytosis, and destroying complement systems, resulting in periodontitis. The article reviewed P.gingivalis about its leading to the development of periodontitis and the mechanism for escaping from the defense of the innate immune system. References | Related Articles | Metrics

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A Review of Gingival Biotype in Anterior Tooth Area YAN Xue-dan, ZHANG Li-na, REN Xiu-yun. 2019, 35(2): 116-118.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.003 Abstract ( 442 )   PDF (764KB) ( 531 )   The gingival biotype is one of the indexes to reflect the individualized difference of periodontal tissues, and the gingival biotype in the anterior tooth area often involves the prognosis of the treatment in the smile aesthetic area. In recent years, clinicians pay attention to the gingival biotype in the anterior dentition, and the effects of different gingival biological patients on periodontal, orthodontic, and oral implantology treatment are different. This article reviews the classification of gingival biotype, the common clinical judgment methods and the clinical significance of the anterior dental region. References | Related Articles | Metrics

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Preparation of Fluorinated Graphene and Its Researches in Medical Field LIU Qing, CHEN Wen-yuan-feng, SONG Fu-xiang. 2019, 35(2): 119-121.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.004 Abstract ( 325 )   PDF (768KB) ( 522 )   In recent years, fluorinated graphene has gained extensive attention due to its outstanding properties, including good stability, corrosion, friction resistance, high mechanical strength, antibacterial properties, and good biocompatibility. It is reported that fluorinated graphene can be widely used in the fields of biosensors, tissue engineering, bioimaging, and medical diagnosis and treatment. However, the fluorination degree of graphene cannot be effectively controlled and the mass production is difficult to achieve, and the studies of fluorinated graphene in vivo are still needed, which limits its application to some extent. In this paper, the preparation of fluorinated graphene and its research status in the medical field are comprehensively analyzed, aiming to provide some theoretical data supports for its further application and development in medical field. References | Related Articles | Metrics

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Research Progress on Mechanical Principle of Retention and Cause of Loosening of Screws in Implant-supported Single Crown. ZHOU Qiang-qiang, LIAO Hong-bing. 2019, 35(2): 122-124.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.005 Abstract ( 310 )   PDF (773KB) ( 462 )   The problem of retentive screw loosening often occurs after clinical restoration. There are many factors that affect the screw retention, such as the screw preload,screw material and morphology, the degree of cohesion between the implant-abutment interface and its connection design, and occlusion force. This article intends to discuss the mechanical principles and causes for the loosening of fixing screws and the latest relevant research progress. References | Related Articles | Metrics

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Effect of Dicliptera Chinensis Polysaccharide on Expression and Significance of VEGF in Rat Parotid Gland after Radiation Injury. QIN Shan-shan, WANG Dai-you,SUI Bin, ZHANG Yan,SUN Zhe. 2019, 35(2): 125-128.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.006 Abstract ( 235 )   PDF (1163KB) ( 122 )   Objective : To explore the regulation and significance of Dicliptera Chinensis Polysaccharide(DCP) on VEGF in rat parotid gland after radiation injury. Methods: Ninty-six adult SPF healthy male SD rats (200g-220g) were randomly divided into normal group (non-irradiated with 0.9% sodium chloride solution), radiation group (18Gy 60Co γ-ray irradiation with 0.9% sodium chloride solution), normal treatment group (non-irradiated with 200 mg/kg Dicliptera Chinensis Polysaccharide solution), and radiotherapy group (18Gy 60Co γ-ray irradiation with 200 mg/kg Dicliptera Chinensis Polysaccharide solution). Each group had 24 rats. All rats were weighed once a week to monitor the general condition. Hematoxylin-eosin staining (HE) was used to observe the morphological changes of the parotid gland in rats. The expression of VEGF was detected by real-time fluorescent quantitative polymerase chain reaction,FQ-PCR and Western blotting. Results: The weight loss of rats was observed in the radia tion group and the radiotherapy group. HE staining results showed that the salivary gland cells and blood vessels in the radiation group were damaged heavier. And the radiotherapy group had less damage. The relative expression of VEGF gene detected by FQ-PCR in radiation group was lower than other groups (P＜0.05). The expression of VEGF protein detected by WB in the radioactive group was lower than other groups (P＜0.05). Conclusion: DCP can alleviate parotid damage and up-regulate VEGF expression. DCP may repair the radial damage of rat parotid gland. References | Related Articles | Metrics

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Correlation between Methyltransferase DNMT1 and TCDD-induced Cleft Palate in Mice LI Yong, ZHANG Wei, AN Li, SONG Hong-quan, ZHANG Xing-wei, GAO Yu-wei, ZANG Qi-guang, JIAO Xiao-hui. 2019, 35(2): 129-132.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.007 Abstract ( 243 )   PDF (1131KB) ( 156 )   Objective : To investigate the correlation between DNMT1 and TCDD-induced cleft palate in mice by detecting the expression of DNMT1 in TCDD-induced cleft palate mice. Methods: TCDD could cause fetus rats cleft palate by toxic effects on palatal medial edge epithelial cells. C57BL/6J pregnant mice were treated with TCDD (64 μg/kg) at day 10.5 (E10.5) to be the modeling. Oral tissues of E13.5, E14.5, E15.5, and E17.5 fetal rats were obtained, and HE staining was used to detect the occurrence of fetal cleft palate. Reverse transcription quantitative polymerase chain reaction was used to detect the changes of mRNA expression in DNMT1 of fetal rats. Western blot was used to detect the expression level of DNMT1 protein. Results: HE staining showed that the incidence of cleft palate in group TCDD was 56/57, and there was no cleft palate in control group. RT-qPCR results showed that DNMT1 mRNA in TCDD group was significantly higher than that in control group (P<0.01). Western blot results showed that compared with the control group, the expression level of DNMT1 protein in TCDD group was significantly higher (P<0.01). Conclusion: Methyltransferase DNMT1 plays an important role in the process of TCDD induced cleft palate formation in fetal rats. References | Related Articles | Metrics

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Expression of Serum Annexin A2 in Oral Squamous Cell Carcinoma and Its Relationship with Radiosensitivity. WANG Yu-mei, LIU Wei-wei, CHEN Li 2019, 35(2): 133-136.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.008 Abstract ( 255 )   PDF (786KB) ( 132 )   Objective : To investigate the expression level of serum annexin A2 in oral squamous cell carcinoma (OSCC) and its relationship with radiosensitivity. Methods: From 2015 to 2018, 77 cases of middle and advanced oral squamous cell carcinoma treated in our hospital were collected in the case group and 50 healthy persons were collected in the control group. Three-dimensional conformal radiation therapy before operation was applied in the case group. The level of serum annexin A2 was detected in the two groups, respectively. The difference of serum annexin A2 in patients with different radiosensitivity was analyzed. Receiver operating characteristic curve (ROC) was used to analyze the predictive value of serum annexin A2 level before radiotherapy in patients with oral squamous cell carcinoma. Results: In 77 cases of oral squamous cell carcinoma patients after the radiotherapy, 29 cases were completely relieved, 41 cases were partial remission, 7 cases were ineffective, and the total effective rate of radiotherapy was 90.91%. The serum annexin A2 level in case group before and after treatment was significantly higher than that in control group (P<0.05); the level of serum annexin A2 before treatment in the complete remission group was significantly lower than that in the partial remission group and the ineffective group (P<0.05); the serum annexin A2 level in the partial remission group was significantly lower than the ineffective group before the treatment (P<0.05); the serum annexin A2 level in the complete remission group and the partial remission group was significantly decreased (P<0.05); the serum annexin A2 level in the ineffective group was not statistically significant compared with that before treatment (P>0.05); serum membrane lipoprotein A2 was associated with tumor size and lymph node metastasis in oral squamous cell carcinoma (P<0.05); the area of ROC curve (AUC) was 0.755; the sensitivity was 71.40%; and the specificity was 75.70% for the prediction of radiosensitivity in patients with oral squamous cell carcinoma before radiotherapy. Conclusion: Serum annexin A2 is closely related to radiosensitivity in patients with oral squamous cell carcinoma, and can be used as a biomarker to predict the sensitivity of radiotherapy for patients. It has important guiding significance for the development of clinical treatment plan for oral squamous cell carcinoma. References | Related Articles | Metrics

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Effect of FMNL2 Gene on Invasion, Migration, and NF-κB Signal in Oral Squamous Cell Carcinoma. LI Yong-wei, QIU Xun-ding, GU Ming, DENG Yi, XIE Li-li 2019, 35(2): 137-141.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.009 Abstract ( 247 )   PDF (1752KB) ( 148 )   Objective : To investigate the effect of down-regulation of FMNL2 gene expression on invasion, migration, and NF-κB signal in oral squamous cell carcinoma (OSCC). Methods: FMNL2 specific siRNA (si-FMNL2) and negative control siRNA (NC) were transfected into human oral squamous cell carcinoma cells CAL-27. PDTC was set as NF-κB signal inhibitor. After the cells were treated for 48h, western blotting was used to detect FMNL2, E-cadherin, Vimentin, NF-κBp65, and IκBα protein expression. Results: Compared with the blank group, the cell invasion and migration ability in si-FMNL2 group and PDTC group decreased obviously, the expression of E-cadherin protein increased obviously, and the expression of Vimentin, NF-κBp65, and IκBα protein decreased significantly (P<0.05). Compared with the PDTC group, the cell invasion and migration ability in PDTC+si-FMNL2 group decreased obviously, the expression of E-cadherin protein increased obviously, and the expression of Vimentin protein decreased significantly (P<0.05). Conclusion: Downregulation of FMNL2 gene expression can reverse EMT by inhibiting NF-κB signaling pathway, thus inhibiting the invasion and migration of oral squamous cell carcinoma. References | Related Articles | Metrics

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Expression of Homo Sapiens Longevity Assurance Homologue 2 of Yeast LAG1 in Oral Squamous Cell Carcinoma and Its Effect on Cell Proliferation and Invasion. WANG Xiao-long, CAO Shun-shun, ZHANG Peng, SHU Chuan-ji, XIA Lin. 2019, 35(2): 142-146.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.010 Abstract ( 223 )   PDF (1370KB) ( 150 )   Objective : To investigate the expression of homo sapiens longevity assurance homologue 2 of yeast LAG1 (LASS2) in oral squamous cell carcinoma, and explore the effect of silencing LASS2 gene expression on proliferation and invasion of CAL27 cells. Methods: A total of 64 cases of patients with oral squamous cell carcinoma were selected. The expressions of LASS2 gene and protein in oral squamous cell carcinoma and adjacent tissues were detected by using real-time quantitative PCR and Western blot. CAL-27 cells were cultured and divided into siRNA-LASS2 group, negative control group, and blank group. The expression of LASS2 gene in cells was detected by using real-time quantitative PCR. The cell proliferation was detected by using MTT assay. The cell migration was detected by using scratch test. The cell invasive was detected by using Transwell chamber. Results: The relative expression levels of LASS2 mRNA and protein in the oral squamous cell carcinoma tissues were lower than those in the adjacent tissues (P<0.05). The relative expression levels of LASS2 mRNA and protein in oral squamous cell carcinoma tissues were related to TNM stage, differentiation degree, clinical stage, and lymph node metastasis (P<0.05). The relative expression level of LASS2 mRNA in the siRNA-LASS2 group was lower than those in the negative control group and the blank group (P<0.05). The absorbance A values at 1d, 2d, 3d, and 4d in the siRNA-LASS2 group were higher than those in the negative control group and the blank group (P<0.05). The cell migration rates at 24h and 48h in the siRNA-LASS2 group were higher than those in the negative control group and the blank group (P<0.05). The number of invasive cells in the siRNA-LASS2 group was higher than that in the negative control group and the blank group (P<0.05). Conclusion: LASS2 was lowly expressed in oral squamous cell carcinoma tissues. Specific inhibition of LASS2 expression in oral squamous cell carcinoma cells could promote cell proliferation and accelerate cell migration and invasion. References | Related Articles | Metrics

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A New Minimal Invasive Aesthetic Suture Technique for Anterior Teeth Crown Lengthening Surgery. ZHANG Hui-hui 2019, 35(2): 147-150.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.011 Abstract ( 347 )   PDF (2310KB) ( 290 )   After crown lengthening surgery for anterior teeth, surgical suture should be proceeded to close gingival flap. Suture and knots exposure on labial surface will affect the aesthetic outcome before suture removal. And dental biofilm and plaque will accumulate rapidly on sutures, then lead to infection and inflammation. We design a new minimal invasive aesthetic suture technique to hide labial suture by sub-epithelial suture and palatal knotted. Fifteen patients, who was performed with this suture technique after upper anterior teeth crown lengthening surgery, get satisfied aesthetic outcomes and feel little uncomfortable. References | Related Articles | Metrics

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Therapeutic Mechanism of Prunella Vulgaris Flavone Inhibiting Expression of Hypoxia-inducible Factor 1α in Rat Periodontitis. LI Kun-yang, LI Wei, ZUO Chun-ran, CAO Li-sha, WANG Shou-ru, CHEN Dong 2019, 35(2): 151-154.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.012 Abstract ( 235 )   PDF (1392KB) ( 281 )   Objective : To investigate the expression of hypoxia-inducible factor-1α (HIF-1α) in the treatment of rat periodontitis. Methods: Forty male Wistar rats with specific pathogen free (SPF) were randomly divided into 5 groups (n=8) according to random number table, i.e. normal control group, model group, and prunella vulgaris flavonoid groups (50, 100, and 200 mg/L). P.gingivalis impregnated silk ligation was used to construct a periodontitis model. The treatment continued for 8 weeks, during which the model group and the control group were treated with the same amount of normal saline. Gross specimens of rat periodontitis were examined by light microscopy. The gingival index was measured by L e and Silness method, and the loss of periodontal attachment was detected by periodontal probe. The expression of HIF-1α in gingival tissues and serum was detected by enzyme-linked immunosorbent assay. The expression level of HIF-1α in chondrocytes was detected by immunohistochemical staining. Results: In the model group, periodontal inflammation was typical, and the gums were atro-phied. The periodontal attachment was severely lost. The furcation was exposed and more visible. After treatment with prunella vulgarisflavonoids, the gingival edema gradually reduced, the periodontal pockets gradually became shallower, and the gingival recession and periodontal attachment loss also improved. Compared with the normal control group, the gingival in-dex, degree of periodontal attachment loss and HIF-1α expression in the model group all increased (P<0.01). Compared with the model group, the gingival index, periodontal attachment loss and HIF-1α of the prunella vulgaris flavonoid group showed a gradual decline with the increasing of the concentration (P<0.05). Compared with only a few cells in the normal control group, HIF-1α was weakly positively expressed, and the HIF-1α(+) cells in the model group significantly increased. However, the HIF-1α(+) cells in the various doses of prunella vulgaris decreased, and the HIF-1α(+) cell rate significantly decreased in each dose group (P<0.01). Conclusion: Prunella vulgaris flavonoids can relieve periodontitis by reducing the expression of HIF-1α. References | Related Articles | Metrics

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Investigation and Analysis of Clinical Application of CBCT. YAN Hong-jing, LI Zhi-min, FENG Jing, SONG Zi-qi, WANG Bo, ZHANG Li, ZHANG Zu-yan. 2019, 35(2): 155-158.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.013 Abstract ( 283 )   PDF (921KB) ( 232 )   Objective : To obtain machine technique parameters for domestic production of CBCT. Methods: CBCT data in Department of Radiology of Stomatological Hospital of Jilin University between April 2016 to October 2017 were analyzed by machine field of view, department, voxel, and imaging purpose. The CBCT units include CS9300, Kodak 9500, and Planmeca ProMax 3D. Results: Large field of view (17×13) accounts for 7.5%, middle field of view (10×10, 8×8) examination accounts for 89.4%, and small field of view (5×5) accounts for 3.1%. Department of implant account for 47.1%, department of orthodontics account for 29.4%, department of endodontics account for 6.4%, department of maxillofacial surgery account for 5.5%, and other departments account for 11.6%. Conclusion: This article can provide referential data for domestic production of CBCT and for proper using CBCT by dentist. References | Related Articles | Metrics

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CBCT Evaluation of Root Diameter and Surrounding Bone Thickness of Maxillary Central Incisors. ZHU Yan-fei, MA Wei-cheng, GENG Jin-huan, LIU Qian, DING Yu-mei, LI Shu-e 2019, 35(2): 159-162.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.014 Abstract ( 272 )   PDF (937KB) ( 196 )   Objective : To measure root diameter and bone thickness overlying maxillary central incisors to offer more details for immediate implantation in esthetic area. Methods: 299 patients with CBCT image data were included. Labial-palatal and mesial-distal diameter, labial, palatal, mesial and distal bone thickness, 2mm below the cemento-enamel junction (CEJ) were measured. Gender and age difference were analyzed. Results: There were 9 and 14 fenestrations and dehiscences for female and male (P>0.05). Significance was found in different genders for labial-palatal and mesial-distal diameter (P<0.05). Female or group below 30 had more labial bone (P<0.05). Conclusion: CBCT can be applied for precise measurement. Both mesial-distal and labial-palatal root diameter, 2mm beneath the CEJ, had correlation with gender. Thicker bone was found below 30. References | Related Articles | Metrics

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Research on the Correction of Tilted Image in Forensic Identification of Palatal Rugae JIA Yu,JI Xin-xin,ZHANG Xiong,LI Bing,SHANGGUAN-hong 2019, 35(2): 163-167.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.015 Abstract ( 215 )   PDF (3241KB) ( 290 )   To correct the tilted image in the digital system for forensic identification of the palatal rugae and to evaluate its effect. Methods: Firstly, the criteria for standard palatal rugae image and the selection rules for feature points were set. Secondly, feature points according to the rules were characterized, and two lines were fitted and found their direction vector. Finally, to obtain the corrected images, the tilted images were rotated by the angle determined by the two direction vectors. Results: From the visual effect, the correction results were ideal, and the difference from the angle of the standard image could be ignored, and the stability of the algorithm was further demonstrated. Conclusion: The algorithm can correct the target image very well to get standard images and has strong robustness. References | Related Articles | Metrics

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Retrospective Study of Submerged Implant Restoration after Ten Years HE Ping, FENG Yu, LI Ji-yin, WU Xiao-le, CHEN Xiao-dong 2019, 35(2): 168-171.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.016 Abstract ( 255 )   PDF (1122KB) ( 208 )   Objective : To evaluate the clinical effect and implant retention rate of submerged implant restoration, and to analyze and summarize the long-term clinical effects of various bone augmentation techniques and the reasons of the complications of the implant by retrospectively studying the submerged implantation cases. Methods: From January 2005 to January 2008, the Department of Implantology in our hospital was selected to study the submerged implants. According to the exclusion criteria, a total of 1776 implants were included in 893 patients. For patients who could not come to hospital, a telephone interview or X-ray film was sent for investigation. Results: A total of 865 implants in 467 patients were investigated through outpatient visits or telephone interviews, accounting for 48.7% of the total implants. According to the Wheeler implant retention rate standard, the retention rate for these implants was 96.65% for ten years. Conclusion: The overall satisfaction degree of submerged implant restorations after 10 years by clinical re-examination is high, with a retention rate of 96.65%. References | Related Articles | Metrics

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Effect of Insertion Angle on Stability of Loaded Titanium Microscrews WU Ye-ke,ZHAO Li-xing,GAO Ran-ran. 2019, 35(2): 172-175.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.017 Abstract ( 263 )   PDF (1562KB) ( 194 )   Objective : To evaluate the effect of insertion angle on stability of loaded titanium microscrews in beagle jaws. Methods: 48 microscrews were inserted at four different angles (30°,50°, 70°, and 90°) into intraradicular zones of the mandibular first molars and third premolars of 12 beagles and immediately loaded with 2 N for 8 weeks. Microcomputed tomography (micro-CT) and biomechanical pull-out tests were used to assess osseointegration of the interface. Results: All micro-CT parameters and maximum pull-out force (Fmax) of the microscrews were affected by insertion angles of microscrews. Higher micro-CT parameters and Fmax were seen for implants inserted at angles between 50°and 70°(P＜0.05). Excessive oblique and vertical insertion angles resulted in reduced stability (P＜0.05). Conclusion: An insertion angle of 50°to 70°is more favorable than excessive oblique or vertical angles to achieve stability of microscrews. References | Related Articles | Metrics

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Effects of D-Histidine on Streptococcus Mutans Biofilm. QUAN Xu, XU Tong-tong, ZHANG Hui-yan, WANG He-ling, WANG Chun-yang, CUI Yun-xia, FU Qi-yue, MENG Wei-yan. 2019, 35(2): 176-179.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.018 Abstract ( 266 )   PDF (1581KB) ( 223 )   Objective s: To evaluate the effects of D-Histidine on the Streptococcus mutans biofilm in vitro. Methods: Antimicrobial activity testing of D-Histidine was evaluated by determining the growth curve. Crystal violet biofilm biomass assay and polysaccharide measurement were performed to evaluate the potential activity of D-Histidine effectively inhibiting biofilm formation. SEM was used to observe the morphology and the structure of biofilm. Results: Growth curve showed that D-Histidine at concentration of 20% interfered with the viability of Streptococcus mutans in a dose-dependent manner. CV and EPS assays showed that D-Histidine at concentration of 40% effectively inhibited Streptococcus mutans biofilm formation and the polysaccharide level of Streptococcus mutans biofilm was greatly reduced. SEM results displayed that D-Histidine effectively inhibited Streptococcus mutans bioflim formation at concentration of 40% and bacterial aggregation amount declined with increasing concentrations of D-Histidine. Conclusion: D-Histidine effectively inhibits Streptococcus mutan biofilm formation in a dose-dependent manner and D-Histidine interferes with the viability of Streptococcus mutans. References | Related Articles | Metrics

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Tooth Movement Tendency with Different Micro Implant Heights in Lingual Straight Wire: A 3-dimensional Finite Element Analysis. LIU Hai-yan, JING Xuan, LI Bing, HEE-Moon Kyung, LI Shi-feng, WU Xiu-ping. 2019, 35(2): 180-184.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.019 Abstract ( 245 )   PDF (1495KB) ( 161 )   Objective : To establish the three-dimensional finite element models of micro-implants-lingual straight wire about anterior teeth retraction; and to analyze the teeth movement tendency with different micro-implant heights for providing the biomechanical reference for clinical application of lingual orthodontics. Methods: Three dimensional model of maxilla, teeth, and periodontal ligament was obtained by CBCT scan. The palatal micro-implants between first and second molars were set respectively with different heights (4 mm, 8 mm and 12 mm) from the alveolar crest. The obtained three-dimensional finite element models of micro-implants-lingual straight wire were used to analyze the teeth movement tendency and stress changes when labial intrusion force and lingual retraction force were applied. Results: All of the anterior teeth showed a degree of buccal root torque during the retraction. With the increase of palatal micro-implant height from the alveolar crest, the tendency of the buccal root torque of anterior teeth were significantly reduced, and the change of central incisors was the most obvious compared with the lateral incisors and canines. When the height of micro-implant was 8mm, the root and periodontal ligament stress was the minimum. Conclusion: It can effectively control the anterior teeth torque during the retraction in the lingual orthodontics treatment by choosing the right height of micro-implant and applying the labial intrusion force in anterior teeth. References | Related Articles | Metrics

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Investigation and Analysis on Related Factors of Children’s Dental Fear. LIU Wan-ying,DAI Li-na 2019, 35(2): 185-188.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.020 Abstract ( 362 )   PDF (785KB) ( 231 )   Objective : To investigate and analyze the related factors of children’s dental fear with a view to providing some help for the prevention and treatment of children’s dental fear. Methods: One hundred and ten children aged 1-12 years old who went to Stomatological Hospital of Chongqing Medical University during February 2018 to April 2018 were randomly sampled by using clinical rating of anxiety and behavior comparative evaluation system. The data about dental fear gathered from 110 valid questionaires was analyzed with chi-square test. Results: The incidence rate of children’s dental fear in this survey was 58.2%. The result of chi-square test showed that age and bad dental experience were statistically different compared with DF and NDF. Conclusion: The occurrence of children’s dental fear is mainly related to age and bad dental experience. References | Related Articles | Metrics

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Analysis of Projects and SCI Papers as Projects Output in Stomatology Funded by NSFC from 2008 to 2012. SONG Fang, ZHANG Lin-kun, ZHANG Zhong-fang 2019, 35(2): 189-193.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.021 Abstract ( 239 )   PDF (893KB) ( 214 )   Based on the project data and SCI output data of projects supported by National Natural Science Foundation in stomatology, the paper was focused on the distribution of fund projects and analyzed from the literature external features. Based on the study findings, the authors tried to give some useful information for the NSFC researchers, as well as research management. References | Related Articles | Metrics

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A Case Report of Right Maxillary Second Molar with Five Canals. ZHAO Xiao-e, LI Ting-ting, LIAO Xiao-zhu, ZHANG Yun, CHEN Zhi 2019, 35(2): 194-196.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.022 Abstract ( 315 )   PDF (1782KB) ( 306 )   The root canals of the maxillary second molar have more variation in quantity and complexity in configuration, easily leading to treatment failure once omitted. To achieve perfect root canal treatment, it depends on the familiarity with the anatomical variation of the root canals, the root canal microscope, and other diagnostic tools. At the same time, the careful exploration and adequate liquidation of root canals, and the heat gutta-percha vertical condensation technique are also essential. The article reports a case of right maxillary second molar with five canals exhibiting double proximal buccal canals and two palatal canals. References | Related Articles | Metrics

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Autogenous Dentin Matrix for Immediate Implantation in Periodontal Postextraction Site-A Case Report. LI Peng,ZHU Hui-cong,PAN Ting,HUANG Zhan-hong,HUANG Da-hong 2019, 35(2): 197-198.  DOI: 10.13701/j.cnki.kqyxyj.2019.02.023 Abstract ( 293 )   PDF (1831KB) ( 229 )   Objective : To investigate the clinical efficacy of autologous dentin matrix granule in the immediate implantation in patients with severe periodontitis. Methods: One mandibular molar caused by periodontitis was pulled out and prepared into dentin matrix (DM). Dental implantation was performed immediately after the surgery. Autologous DM was used for guided bone regeneration. The stability of implant was detected. The panoramic radiograph and restoration were performed six months after surgery. Results: The ISQ value of implant was 52.7. The X-ray and clinical examination showed the bone integration half a year after surgery, and the function of implant was good at one-year follow-up. Conclusion: DM granule can be applied for the filling of bone defect in implantation, even in periodontitis case. But its long-term effect remains to be further observed. References | Related Articles | Metrics