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Research Progress in Pathogenesis and Clinical Management of EGFR-TKIs-related Oral Mucositis. WANG Wenmei, DUAN Ning 2021, 37(10): 869-874.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.001 Abstract ( 276 )   PDF (1211KB) ( 258 )   Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are considered to be a landmark turning point in the treatment of lung cancer, which has substantially extended the survival time of patients. Oral mucositis (OM) is one of the common complications in the treatment of tumors with EGFR-TKIs, which is manifested as oral mucosal erythema, edema, erosion, and ulcers. The oral mucosa can be covered with pseudomembrane, oozed blood, and caused necrosis and pain, which seriously hindered food intake, reduced patients' nutrition and tolerance to treatment, and led to failure in patient's EGFR-TKIs treatment. The prevention and treatment of EGFR-TKIs-related oral mucositis is crucial to ensure the smooth progress of EGFR-TKIs treatment and improve the quality of life of patients. Based on the review of clinical manifestations and pathogenesis of EGFR-TKIs-related oral mucositis, this paper illustrates the prevention and management of EGFR-TKIs-related oral mucositis, and proposes the early discovery, early prevention, and full-process monitor of EGFR-TKIs-related oral mucositis in an effort to strengthen clinicians' awareness, thus facilitating the clinical application of EGFR-TKIs and other cancer-targeted drugs. References | Related Articles | Metrics

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Mechanisms of Malignant Transformation of Oral Submucous Fibrosis: An Update ZHU Jiayi, LU Rui 2021, 37(10): 875-878.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.002 Abstract ( 328 )   PDF (808KB) ( 405 )   Oral submucous fibrosis (OSF) is a chronic and progressive oral mucosal disease associated with betel nut chewing. The main manifestations include pale oral mucosa, burning sensation in oral cavity when eating spicy food, progressive limitation of mouth opening, and blisters in soft palate. OSF contains a malignant potential, with the malignant transformation rate ranging from 7% to 13%. As a result, it was included into the classification of oral potentially malignant disorders by the WHO. The mechanisms of malignant transformation of OSF comprise of various aspects, including genetic susceptibility, cell cycle changes, epithelial-related protein changes, hypoxia, angiogenesis, senescence, epithelial-mesenchymal transition, etc., which have not been fully revealed. In this review, we summarize the molecular mechanisms of the malignant transformation of OSF, aiming to provide references for understanding the mechanisms and early prevention of OSF malignant transformation. References | Related Articles | Metrics

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A Discussion of the Consensus Process for Immediate Implantation in the Esthetic Area MA Yue, SONG Ke 2021, 37(10): 879-882.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.003 Abstract ( 284 )   PDF (811KB) ( 380 )   Immediate implantation has been widely used in clinical practice due to its unique advantages. However, a highly complex operation accompanied with great aesthetic risks is included in the aesthetic zone by placing implant immediately. Higher requirements on indication, surgical operation and clinical skill of surgeon should be considered in immediate implant placement. In this review, the relevant references, consensus opinions, and recommended clinical programs for immediate implantation in the aesthetic zone under favorable and unfavorable conditions are searched, analyzed, summarized and discussed, to look forward to providing references for strategy, design and resolution of clinical cases. References | Related Articles | Metrics

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Research Progress on Improving Bonding Properties of Universal Adhesives to Dentin ZHU Xuanyan, ZHU Song 2021, 37(10): 883-885.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.004 Abstract ( 395 )   PDF (775KB) ( 872 )   Oral adhesive plays an important role in the treatment of dental restoration. Universal adhesive is gradually widely used in oral clinic. It can be applied to different bonding modes, bonding a variety of materials, simplifying the bonding process and improving the bonding efficiency. However, due to the high protein and high water content of dentin, there are still some defects in the bonding between universal adhesive and dentin. Many studies are performed to improve the bonding performance between universal adhesive and dentin. The purpose of this review is to review the methods to improve the bonding properties between universal adhesives and dentin. References | Related Articles | Metrics

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Research Progress on Biomimetic Mineralization of Dentin HE Ting, ZHANG Linglin 2021, 37(10): 886-889.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.005 Abstract ( 379 )   PDF (792KB) ( 571 )   Biomimetic mineralization of dentin is the focus of both oral medicine and biomaterial science. Biomimetic materials obtained by biomimetic mineralization, which are similar to natural dentin in terms of composition, structure, and function, are ideal materials for dentin repairg. In this paper, we summarize the research progress on biomimetic mineralization of dentin. References | Related Articles | Metrics

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Experimental Study on Nicotine Promoting Root Migration of Junctional Epithelium in Rats ZHONG Yueyue, MA Su, QIN Zegen, ZHOU Huiling, LIU Peihong, LI Yanwu 2021, 37(10): 890-893.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.006 Abstract ( 180 )   PDF (1727KB) ( 236 )   Objective: To investigate the effect of nicotine on root migration of junctional epithelium (JE) in rats. Methods: Twenty healthy male Wistar rats of six weeks of age were randomly divided into experimental group (intraperitoneal injection of nicotine 0.73mg/kg daily) and control group (intraperitoneal injection of the same amount of physiological saline daily). Each group was divided into two subgroups of 30 days and 90 days. After being killed according to the experimental design, the mesiodistal paraffin sections of tooth-periodontal joint tissue in the right mandibular molar area were routinely made and stained with Masson. The length of first molar enamel cementum boundary to the root apex of JE was measured. Results: On the 30th day, there was a slight root migration of JE in the experimental group compared with the control group without statistical significance (P>0.05). The collagen under the epithelium of both 30-day groups of rats was dense and neatly arranged. While the JE in the control and experimental groups had root migration at 90 days, the migration length of the experimental group was significantly longer than that of the control group (P<0.01), and the collagen under the epithelium of the experimental group was sparser and slender than the control group. In the different time points, the length of JE root migration in the experimental group at 90 days was significantly longer than that in the experimental group at 30 days (P<0.01). Conclusion: JE of rats migrated apically in a time-dependent manner, which could be enhanced by the intraperitoneal injection of nicotine. References | Related Articles | Metrics

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Differential Expression Profiles of miRNAs in Blood of Periodontitis Patients. ZHANG Zheng, ZHENG Youli, BIAN Xiaowei 2021, 37(10): 894-899.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.007 Abstract ( 223 )   PDF (3671KB) ( 170 )   Objective: To characterize the microRNA (miRNA) profiles in blood of periodontitis patients. Methods: One miRNA expression profile (GSE61741) was downloaded from the GEO database and analyzed using GEO2R. Logistic regression analysis was used to screen independent variables among differentially expressed miRNAs (DE-miRNAs). The diagnostic values of screened miRNAs were determined by the area under the receiver operating characteristic (ROC) curve (AUC). Results: A total of 232 DE-miRNAs, consisting of 109 upregulated DE-miRNAs and 123 downregulated DE-miRNA, were screened. Logistic regression analysis showed that there were three miRNAs related to periodontitis, namely hsa-mir-361-5p, hsa-mir-663, and hsa-mir-744. The AUC values of hsa-mir-361-5p, hsa-mir-663, hsa-mir-744, and their combination in the diagnosis of periodontitis were 0.871, 0.899, 0.925, and 0.981, respectively (P<0.01). Conclusion: MiRNAs are expressed differentially in periodontitis patients. hsa-mir-361-5p, hsa-mir-744, and hsa-mir-663 were associated with the risk of periodontitis and had potential value in the diagnosis of periodontitis. References | Related Articles | Metrics

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Effect of T-type Calcium Channel on Osteogenic Differentiation of Human Dental Follicle Cells YANG Jingjing, ZUO Dongchuan, XIE Yihang, CAI Xin, YUAN Xiaoping, ZENG Jin 2021, 37(10): 900-905.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.008 Abstract ( 208 )   PDF (5276KB) ( 263 )   Objective: To investigate the effect of Ca2+ on osteogenic differentiation of human dental follicle cells (hDFCs) and to explore its molecular mechanism. Methods: hDFCs were isolated and cultured. Its source was verified by flow cytometry and immunofluorescence staining. The gene expression of L-type calcium channel, T-type calcium channel, inositol triphosphate receptor, and ryanodine receptor of hDFCs and mRNA expression of osteogenic differentiation related gene were detected by reverse transcription polymerase chain reaction (RT-PCR). Alizarin red staining was used to evaluate the formation of calcium nodules after the removal of extracellular Ca2+, intracellular Ca2+, and the application of voltage-gated calcium channel specific blockers. Results: The osteogenic ability of hDFCs was significantly decreased after removal of extracellular Ca2+ or intracellular Ca2+. RT-PCR results showed that hDFCs expressed L-type calcium channel, T-type calcium channel, inositol triphosphate receptor, and ryanodine receptor. Nifedipine, an L-type calcium channel blocker, had no effect on the osteogenic mineralization of the cells, while amlioride, a T-type calcium channel blockers significantly inhibited the osteogenic mineralization of the cells. Elevation of extracellular Ca2+ concentration (5 mmol/L) significantly promoted osteogenic differentiation of hDFCs, and the effect was inhibited by application of KN-93 (10 μmol/L, a Ca2+/CaMK Ⅱ signaling pathway specific blocker). Conclusion: T-type calcium channel mediated calcium influx is involved in the osteogenic differentiation of hDFCs. References | Related Articles | Metrics

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Expression of RIP1, RIP3 and MLKL in Inflammatory Periodontal Tissue under Orthodontic Force ZHANG Minjie, ZHANG Miaomiao, JI Kaixin, CHEN Siyan 2021, 37(10): 906-909.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.009 Abstract ( 203 )   PDF (4033KB) ( 148 )   Objective: To study the expression of RIP1, RIP3, and MLKL in the pressure-side periodontal tissue during orthodontic tooth movement in rats and to explore its role in pressure-side periodontal tissue remodeling. Methods: Thirty healthy male SD rats were selected as the research object in this experiment and randomly divided into 6 groups: 0 d, 1 d, 3 d, 5 d, 7 d and 14 d groups, with 5 rats in each group. 0 d group was the blank control group. The two central incisors of the upper jaw were anchors, and the left first molar was pulled forward with a force value of 50 g by a nickel-titanium tension spring. After the rats were sacrificed at each time point, the first molar and the surrounding periodontal tissues were collected, and the expression levels of RIP1, RIP3, and MLKL on the pressure side were detected by immunohistochemistry. Results: Compared with the blank control group, the expression of RIP1, RIP3, and MLKL in the experimental group increased at first and then decreased, and the expression at each time point was higher than that in the blank control group. The expression increased significantly on the 7th day. Conclusion: There was necroptosis in the pressure side during the orthodontic tooth movement, and RIP1, RIP3 and MLKL were both involved in the periodontal tissue remodeling on the pressure side during orthodontic tooth movement. References | Related Articles | Metrics

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Study of Correlation between Soft Tissue Chin Morphology and Dento-maxillofacial Structure LU Yun, YU Shanshan, LAN Tingchao, ZHAO Bingjiao, MAO Yanmin, LIU Yuehua 2021, 37(10): 910-913.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.010 Abstract ( 236 )   PDF (1093KB) ( 447 )   Objective: To investigate the correlation between soft tissue chin morphology and dento-maxillofacial structure in skeletal class Ⅰ malocclusion without high angle. Methods: Forty patients with normal skeletal chin morphology were selected as the research objects, and the interferences of mandibular retrognathia and high angle were excluded (0<ANB<5°, SN-MP<40°). They were divided into normal chin morphology group and abnormal chin morphology group according to soft tissue chin morphology. Parameters related to sagittal and vertical pattern and dentition were measured respectively. Results: There was no significant difference in the parameters reflecting the sagittal pattern and mandibular morphology. Compared with the normal chin morphology group, the abnormal group exhibited decreased S-Go∶N-Me ratio (P<0.05), increased PP-MP and OP-MP (P<0.05) which negatively correlated with soft tissue chin morphology (d∶B’Mess) (P<0.05), and decreased SN-PP and L1-FH (P<0.05). Conclusion: The inclination of palatal plane is significantly related to soft tissue chin morphology. When the palatal plane shows a counterclockwise direction, the chin morphology worsens with increased dispersion of the maxilla and mandible. References | Related Articles | Metrics

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Clinical Efficacy of Compound Chamomile and Lidocaine Hydrochloride Gel in Treatment of Wisdom Tooth Periodontitis LI Ning, SUN Xu, ZHANG Xiao, CHEN Ruixue 2021, 37(10): 914-918.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.011 Abstract ( 361 )   PDF (1028KB) ( 385 )   Objective: To explore the clinical effect of Compound Chamomile and Lidocaine Hydrochloride Gel in the treatment of wisdom tooth periodontitis. Methods: A total of 108 patients with wisdom tooth periodontitis treated in the Stomatological Hospital of Hebei Medical University from December 2019 to December 2020 were selected. Among them, 54 patients in the control group were treated with local irrigation plus Iodine glycerol in the blind bag. Fifty-four cases in the experimental group were treated with a local smear of Compound Chamomile and Lidocaine Hydrochloride Gel + local irrigation + the blind bag filled with Compound Chamomile and Lidocaine Hydrochloride Gel. Both groups were treated continuously and observed for 7 days. The clinical efficacy, degree of pain, sulcus bleeding index (SBI), gingival index (GI), and clinical symptom relief time of both groups were observed and compared. Results: The total effective rate of experimental group (96.67%) was significantly higher than that of control group (78.33%, P＜0.05). During the treatment, Wong-Baker facial expression score showed that 35.2% of the experimental group thought it was a little painful; 1.8% thought it was severe; 0 thought it was severe, and the number of patients in the experimental group was less than that in the control group, but there was no statistical difference (P>0.05). In the experimental group, 1.8% thought it was painless and 29.6% thought it was obvious. The number of patients in the experimental group was more than that in the control group, but there was no statistical difference (P>0.05). MCHEOPS score of the experimental group was lower than that of the control group, but there was no significant difference (P>0.05). After treatment, GI and SBI decreased in both groups (P<0.05), and periodontal index decreased significantly in the experimental group (P<0.05). The relief time of gingival swelling and pain, limited mouth opening, and disappearance time of gingival bleeding in the experimental group were significantly shorter than those in the control group (P＜0.05). Conclusion: Compound Chamomile and Lidocaine Hydrochloride Gel has a good therapeutic effect in the treatment of wisdom tooth periodontitis. It can obviously relieve inflammation, relieve pain, increase patient's comfort experience, shorten treatment time, and reduce the number of visits. References | Related Articles | Metrics

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Influence of Presurgical Nasoalveolar Molding on Postoperative Results of Unilateral Complete Cleft Lip LIU Xiaolin, ZHENG Qian, LI Chenghao, SHI Bing, YANG Chao 2021, 37(10): 919-923.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.012 Abstract ( 272 )   PDF (4365KB) ( 411 )   Objective: To evaluate the effect of presurgical nasoalveolar molding (PNAM) treatment on patients with one-stage unilateral complete cleft lip and palate. Methods: A total of 66 patients with one-stage unilateral complete cleft lip and palate, including 32 patients in PNAM group and 34 patients in control group, were taken photos immediately after operation, six months after operation, one year after operation, and more than one year after operation. The symmetry index of nose and lip was measured. Results: Immediately after operation, only the nasal tip symmetry index (P=0.015) and the nasal base symmetry index (P=0.016) had statistical differences. Half a year after operation, only the nasal tip symmetry index (P=0.011) had statistical difference. One year after operation, only the symmetry index of columella nasi (P=0.021) had statistical difference. For more than one year, there was no statistical difference in each index. Conclusion: PNAM treatment can improve the short-term effect of nose deformities in patients with one-stage unilateral complete cleft lip and palate after primary cheiloplasty, however, the nose tends to recur one year later. References | Related Articles | Metrics

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Clinical Analysis and Treatment Exploration of Mandibular Pycnodysostosis Complicated with Osteomyelitis LIU Hualian 2021, 37(10): 924-926.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.013 Abstract ( 222 )   PDF (2412KB) ( 275 )   Objective: To improve the level of clinical diagnosis and treatment by retrospective analyzing the case of osteomyelitis secondary to pycnodysostosis. Methods: A retrospective analysis was conducted on osteomyelitis secondary to pycnodysostosis in Nnazi Mmoja Hospital of Zanzibar from June 2013 to June 2015. The clinical data, imaging data, treatment methods, and follow-up data of patients were analyzed. Results: After treatment by antibiotics and sequestrum scraping or resection of dead bone, the normal values of ESR, CRP and blood routine were obtained. Four out of five patients were cured, while 1 patient showed recurrence within 12 to 24 months' follow-up. Conclusion: Pycnodysostosis is rare. Oral craniomaxillofacial characterization can be used as a key point for differential diagnosis of the pycnodysostosis. Antibiotic therapy and resection of dead bone in jaw lesions may be the preferred method for patients with pycnodysostosis secondary to osteomyelitis of jaw. References | Related Articles | Metrics

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Application of Round Collar Flap in Maxillary Completely Impacted Wisdom Tooth Extraction BAI Yunfei, LIU Ke, ZHOU Xiaocheng 2021, 37(10): 927-930.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.014 Abstract ( 251 )   PDF (2227KB) ( 769 )   Objective: To investigate the effects of "round collar flap" in the removal of completely impacted maxillary wisdom teeth. Methods: A total of 70 patients with maxillary impacted wisdom teeth were selected in the Department of Oral and Maxillofacial Surgery of Stomatological Hospital of Wuhan University from June 2020 to December 2020. According to random number table method, they were divided into observation group and control group, with 35 cases in each group. The observation group was treated with "round collar flap", while the control group was treated with traditional angular flap. The incision suture time and wound healing were compared between two groups. Results: There was no significant difference in the wound healing between both groups, however, the incision suturing time of observation group was significantly shorter than that of control group. Conclusion: Compared with traditional angle flap, wound of "round collar flap" is easier to suture, and the knot of "round collar flap" is easier to remove and is harder to omit. References | Related Articles | Metrics

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Three-dimensional Evaluation of Mandibular Stability during Intermaxillary Fixation after Bilateral Sagittal Split Ramus Osteotomy Surgery JIAO Xingqi, LI Yang, YI Biao 2021, 37(10): 931-935.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.015 Abstract ( 160 )   PDF (2353KB) ( 196 )   Objective: To analyze the short-term relapse tendency of mandible after bilateral sagittal split ramus osteotomy (BSSRO) surgery with three-dimension measurement. Methods: CBCT images of forty-nine patients seeking for orthognathic surgery were collected in the study. The collection time was four days preoperatively (T0), four days postoperatively (T1), four to six weeks postoperatively (T2), and three months postoperatively (T3). A three-dimensional analytic method to measure mandible was set up with Pro Plan software. The study measured and analyzed the indicators and angles to describe the mandibular position and orientation. Results: For mandibular advancement patients, the measurements showed a significant difference in B and Pg in horizontal axis during short term (T1-T2). The mandibular plane tended to have a clockwise rotation. For mandibular setback patients, the measurements showed a significant difference in B in horizontal axis and Pg in horizontal and vertical axis. Conclusion: There was a three-dimensional relapse tendency of mandible in short-term after BSSRO,however, in the acceptable region. References | Related Articles | Metrics

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Effect of Silane Coupling Agent Combined with Different Adhesive Systems on Adhesive Strength and Microleakage of Aging Composite Resin LIU Xiaoxue, LI Yanping, HE Lina, LI Ji, DAI Xinrui, NIU Yumei 2021, 37(10): 936-939.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.016 Abstract ( 217 )   PDF (930KB) ( 278 )   Objective: To investigate the effects of different bonding systems or combined silane coupling agents on the bonding strength and microleakage of aged composite resins. Methods: Nano-type composite resin was used to prepare resin blocks and stored in distilled water at (37±1) ℃ for 2 months. The surface was polished by carborundum bur and divided into five groups according to different surface treatment Methods: A, control group (without chemical treatment); B, two-step self-etching bonding system (Clearfil SE Bond, CSE group); C, silane coupling agent pretreatment and two-step self-etching bonding system (silane + CSE group); D, universal bonding system (Single Bond Universal, SBU group); and E, silane coupling agent pretreatment and general bonding system (silane+ SBU group). After treatment, the fresh resin was used for filling and curing, respectively. The samples were sliced longitudinally along two vertical directions using a low-speed diamond cutting machine, and 10 specimens with cross-sectional area of 1.0mm2 were prepared in each group. The microtensile test was carried out and all the fractures were observed under stereoscopic microscope. After the bonding was completed, the microleakage of the bonding interface was observed by methylene blue staining. Results: The microtensile bonding strength of the experimental group was significantly higher than that of the control group (P<0.05). Silane could increase the bonding strength between fresh and aged resin, and the microtensile bonding strength of silane SBU group was the largest (P<0.05). Under the stereoscopic microscope, the fracture modes of the samples in the experimental group were mainly cohesive fracture, while those in the control group were mainly adhesive interface fracture. The microleakage between fresh and aged resins in the experimental group was significantly less than that in the control group (P<0.05), but there was no significant difference among four experimental groups (P>0.05). Conclusion: The surface application of adhesive or combined silane coupling agent can significantly improve the bonding strength and reduce the microleakage between aged resin and fresh resin, and the repair effect of silane coupling agent combined with universal adhesive has better repair effect. References | Related Articles | Metrics

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Effect of Er:YAG Laser on Interface of Dentin and Universal Adhesive LI Zhenjie, ZHOU Boyang, HAO Pengjie 2021, 37(10): 940-944.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.017 Abstract ( 163 )   PDF (2682KB) ( 309 )   Objective: To observe the characteristics of resin/dentin interface between dentine pretreated by Er:YAG laser and universal adhesive with self-etching or etch-and-rinse mode, and to explore the differences between two bonding mechanisms through comparing with traditional treated dentine bonding interface. Methods: Thirty-six intact human third molars were selected and randomly divided into four groups (group A: control + self-etching; group B: control + 35% phosphoric acid etching; group C: Er:YAG laser + self-etching; group D: Er:YAG laser+ 35% phosphoric acid etching). Nine teeth in each group were divided into three groups, which were prepared dentin disk in the thickness of 3mm and longitudinal cross-section of resin-dentin interface and resin-dentin transparent grinding plates in the thickness of 2mm. The interface observation and mass fraction analysis of calcium (Ca) and phosphorus (P) on dentine surface were carried out by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The length and number of resin tags were observed by laser confocal scanning microscope (CLSM). Results: SEM and EDX analysis showed that the surface of dentine was changed by Er:YAG laser pretreatment, and the mass fraction of Ca was increased. The bonding interface of group C showed a high density hybrid layer with similar thickness to that of group B and D. High density layer could be seen at the bonding interface of group A, B, and D. The length and number of resin tags in group C were higher than those in group A. Conclusion: In the self-etching mode, the dentine pretreated by Er:YAG laser and the universal adhesive formed a special hybrid layer with high density, which increased the length and number of resin tags. References | Related Articles | Metrics

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Influence of Dentin Shoulder Collar Shape on Fracture Strength of Mandibular Incisors LI Yang, WANG Shiyue, QI Lin 2021, 37(10): 945-950.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.018 Abstract ( 176 )   PDF (3368KB) ( 228 )   Objective: To study the effect of dentin shoulders on fracture strength of post-core crown restorated mandibular incisors by using the method of in vitro mechanical test and finite element analysis. Methods: Five groups of dentin shoulder collars with different shapes were designed for mandibular incisors. After post-core crown restoration, the bending test was performed on an electronic universal testing machine to study the effect of dentin shoulder collar position on the bending strength of the tooth. The mandibular incisors were scanned by CBCT to obtain the three-dimensional CT scanning data. The post-core crown restoration models of mandibular incisors with different dentinal shoulder collar shapes were established by Mimics, Geomagic, Ansys, and other software. The occlusion loading was simulated to analyze the von Mises stress distribution. Results: The fracture strength of buccal dentin shoulder collar and 2.0 mm intact dentin shoulder collar was the highest, followed by that of tongue dentin shoulder collar and near-middle dentin shoulder collar, and the fracture strength of tooth without dentin shoulder collar was the smallest. When 2.0 mm intact dentin collar was retained, the stress distribution of remaining tooth tissue was close to those of buccal dentin collar and lingual dentin collar. The stress distribution was uniform and the stress was relatively small. However, when retaining the near-middle dentin shoulder collar and the non-dentin shoulder collar, there was different degrees of stress concentration at the tongue side of tooth neck, and the stress was relatively large. Conclusion: Preserving 2.0 mm intact dentin shoulder collar can effectively improve the fracture strength of affected teeth. Retaining buccal tooth tissue as much as possible is helpful to enhance the fracture strength of the restored mandibular incisors. References | Related Articles | Metrics

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Periodontal Endoscope-assisted Treatment of Stage Ⅲ Grade B Periodontitis with Malocclusion: A Case Report HUO Xiaoyan, LI jia, QI Yali, GUO Jing, HU Yongqing, HUANG Xianghe, LI Shujuan 2021, 37(10): 951-953.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.019 Abstract ( 219 )   PDF (3558KB) ( 215 )   Periodontal endoscope is a minimally visual non-surgical adjunctive method for periodontal treatment. The use of periodontal endoscope can improve clinical results in contrast to traditional scaling and root planning (SRP) alone. In this paper, a patient with stage Ⅲ grade B periodontitis and malocclusion (Angle Class Ⅱ) who had deep residual periodontal pockets (PD≥5 mm) after traditional SRP obtained significantly improved periodontal results after adjunctive use of periodontal endoscopic. References | Related Articles | Metrics

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Successful Coverage of Soft-tissue Defect after Epulis Resection with Palatal Pedicled Transposition Flap: One Case Report LIU Rubing, YANG Dong, LIU Min, LIU Yusan 2021, 37(10): 954-954.  DOI: 10.13701/j.cnki.kqyxyj.2021.10.020 Abstract ( 183 )   PDF (3698KB) ( 328 )   Epulis with large size can extend from the buccal to the palatal embrasures. Traditional surgical excision of epulis can lead to soft tissue defects and root surface exposure. This case report showed successful treatment of residual soft tissue wound after epulis resection with palatal pedicled transposition flap. References | Related Articles | Metrics