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Table of Content
01 June 2023, Volume 41 Issue 3
  • Special Review
    The infection control of post-and-core crown restoration
    Huang Cui, Zhu Jiakang, Wang Qian
    West China Journal of Stomatology. 2023, 41(3):  247-253.  doi:10.7518/hxkq.2023.2023030
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    Post-and-core crown is one of the most common forms of restoration of tooth after root canal therapy (RCT). Infection control is the core objective of RCT, which is usually well realized by endodontists. However, many prosthodontists often neglect the infection control of the tooth and the maintenance of the curative effect of RCT during the process of post-and-core crown, which may lead to the failure of the final restoration. The concept of integrated crown-root treatment advocated recently requires clinicians to consider the RCT and final restoration as a whole, rather than simply divided into two parts—endodontic treatment and restorative treatment. As the core content of integrated crown-root treatment, infection control should be taken seriously by clinicians and implemented throughout the whole treatment process, especially in the restorative treatment that is easily overlooked after RCT. Therefore, this article describes the infection control of post-and-core crown restoration, classifies the tooth requiring post-and-core crown restoration, and puts forward the measures of infection control before and during post-and-core crown restoration, in order to provide reference and guidance for clinical practice.

    Basic Research
    A comparative study based on the mandibular movement track and the movement parameters of the virtual articulator in simulating occlusal adjustment
    Ma Liya, Chao Jiarui, Liu Fei, Mei Jiansong, Shen Jiefei.
    West China Journal of Stomatology. 2023, 41(3):  254-259.  doi:10.7518/hxkq.2023.2022452
    Abstract ( 411 )   HTML ( 617 )   PDF(pc) (2687KB) ( 285 )   Save
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    Objective This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using the mandibular movement track and the movement parameters of a virtual articulator. Methods Twenty-two participants were recruited. Digital casts of the maxillary and mandibular arches were obtained using an intraoral scanner, and the jaw registration system was used to record the data of the mandibular movement track and the movement parameters of the articulator. Four kinds of restorations with 0.3 mm occlusal interferences were designed with dental design software. In particular, single crowns were designed for teeth 44 and 46, whereas three-unit bridges were designed for teeth 44-46 and 45-47, and the corresponding natural teeth were virtually extracted. Virtual adjustment of the restorations was performed using two dynamic occlusal recordings, namely, the mandibular movement track and the movement parameters of the virtual articulator. A reverse-engineering software was used to measure the root-mean-square of the three-dimensional deviation of the occlusal surfaces between natural teeth and the adjusted restorations. The differences between the two methods of virtual-occlusion adjustment were compared and analyzed. Results For the same group of restorations, the three-dimensional deviation of the mandibular movement track group were lower than those of the virtual articulator group, and the differences were statistically significant (P<0.05). For the four groups of restorations adjusted by the same method, the three-dimensional deviation of the 46-tooth single crown was the largest and the smallest three-dimensional deviation was that of the 44-tooth single crown. Statistical differences existed between the 44-tooth single crown and the other groups (P<0.05). Conclusion For the occlusal design of posterior single crown and three-unit bridge, the mandibular movement track could be a more effective approach to virtual occlusal adjustment than the movement parameters of the virtual articulator.

    Hippo-YAP signaling pathway regulates autophagy of human periodontal ligament cells under cyclic tensile stress
    Wan Xiaofang, He Haiyan, Jialing Lü, Wu Yujie, Zhong Guannan, Xu Xiaomei
    West China Journal of Stomatology. 2023, 41(3):  260-268.  doi:10.7518/hxkq.2023.2022382
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    Objective This work aimed to investigate the molecular mechanism of cyclic tensile stress (CTS) stimulating autophagy in human periodontal ligament cells (hPDLCs). Methods hPDLCs were isolated and cultured from normal periodontal tissues. hPDLCs were loaded with tensile stress by force four-point bending extender to simulate the autophagy of hPDLCs induced by orthodontic force du-ring orthodontic tooth movement. XMU-MP-1 was used to inhibit the Hippo signaling pathway to explore the role of the Hippo-YAP signaling pathway in activating hPDLC autophagy by tensile stress. The expression levels of autophagy-related genes (Beclin-1, LC3, and p62) in hPDLCs were detected by real-time quantitative polymerase chain reaction. Western blot was used to detect the expression levels of autophagy-related proteins (Beclin-1, LC3-Ⅱ/LC3-Ⅰ, and p62) and Hippo-YAP pathway proteins (active-YAP and p-YAP) in hPDLCs. Immunofluorescence was used to locate autophagy-related proteins (LC3-Ⅱand p62) and Hippo-YAP pathway proteins (active-YAP) of hPDLCs. Results CTS-activated autophagy in hPDLCs and expression of autophagy-related proteins initially increased and then decreased; it began to increase at 30 min, peaked at 3 h, and decreased (P<0.05). CTS increased the expression of active-YAP protein and decreased the expression of p-YAP protein (P<0.05). When XMU-MP-1 inhibited the Hippo-YAP signaling pathway (P<0.05), active-YAP protein was promoted to enter the nucleus and autophagy expression was enhanced (P<0.05). Conclusion The Hippo-YAP signaling pathway is involved in the regulation of autophagy activation in hPDLCs under CTS.

    Effects of Foxp3 gene silencing on the expression of inflammatory cytokines and the proliferation and migration of human periodontal ligament fibroblasts in an inflammatory environment
    Lu Ting, Zhu Jiahao, Yang Shihe, Shen Zhe, Zhong Liangjun
    West China Journal of Stomatology. 2023, 41(3):  269-275.  doi:10.7518/hxkq.2023.2022409
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    Objective This study aimed to clarify the effects of Foxp3 silencing on the expression of inflammatory cytokines in human periodontal ligament cells (hPDLFs) in an inflammatory environment and on cell proliferation and invasiveness, as well as to explore the role of Foxp3 gene in the development of periodontitis. Methods An small interfering RNA (siRNA) construct specific for Foxp3 was transfected into hPDLFs. Foxp3 silencing efficiency was verified by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, and the siRNA with the optimum silencing effect of Foxp3 gene was screened. Using lipopolysaccharide to simulate an inflammatory environment in vitro, CCK-8 detected the effect of silencing Foxp3 on hPDLFs proliferation under inflammatory conditions. Wound-healing experiments and transwell assays were conducted to detect the effect of silencing Foxp3 on hPDLF migration under inflammatory conditions. The expression of the inflammatory cytokines interleukin (IL)-6 and IL-8 was detected by RT-PCR and Western blotting under inflammatory conditions. Results After siRNA transfection, RT-PCR and Western blotting analyses showed that the expression of Foxp3 mRNA in the Foxp3-si3 group decreased significantly (t=21.03, P<0.000 1), and the protein expression of Foxp3 also decreased significantly (t=12.8, P<0.001). In the inflammatory environment, Foxp3 gene silencing had no significant effect on hPDLFs proliferation (P>0.05), and Foxp3 gene silencing promoted hPDLFs migration (P<0.05). Moreover, the expression of IL-6 and IL-8 increased (P<0.05). Conclusion In an inflammatory environment, Foxp3 gene silencing promoted hPDLFs migration but had no significant effect on hPDLFs proliferation. The expression of inflammatory factors expressed in hPDLFs increased after Foxp3 gene silencing, indicating that Foxp3 gene inhibited inflammation in periodontitis.

    Effects of thermal cycling on bonding properties of novel low-shrinkage resin adhesive
    Wang Zonghua, Zhang Xiaoran, Yao Shuo, Zhao Jiaxin, Zhou Chuanjian, Wu Junling
    West China Journal of Stomatology. 2023, 41(3):  276-283.  doi:10.7518/hxkq.2023.2022459
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    Objective The current study aimed to investigate the bonding properties of a novel low-shrinkage resin adhesive containing expanding monomer and epoxy resin monomer after thermal cycling aging treatment. Methods Expanding monomer of 3,9-diethyl-3,9-dimethylol-1,5,7,11-tetraoxaspiro-[5,5] undecane (DDTU) as an anti-shrinkage additive and unsaturated epoxy monomer of diallyl bisphenol A diglycidyl ether (DBDE) as a coupling agent were synthesized. A blend of DDTU and DBDE at a mass ratio of 1∶1, referred to as “UE”, was added into the resin matrix at the mass fraction of 20% to prepare a novel low-shrinkage resin adhesive.Then, the methacrylate resin adhesive without UE was used as the blank control group, and a commercial resin adhesive system was selected as the commercial control group. Moreover, the resin-dentin bonding and micro-leakage testing specimens were prepared for the thermal cycling aging treatment. The bonding strength was tested, the fracture modes were calculated, the bonding fracture surface was observed by scanning electron microscope (SEM), and the dye penetration was used to evaluate the tooth-restoration marginal interface micro-leakage. All the data were analyzed statistically. Results After aging, the dentin bonding strength of the experimental group was (19.20±1.03) MPa without a significant decrease (P>0.05), that of the blank control group was (11.22±1.48) MPa with a significant decrease (P<0.05) and that of the commercial control group was (19.16±1.68) MPa without a significant decrease (P>0.05). The interface fracture was observed as the main fracture mode in each group after thermal cycling by SEM. The fractured bonding surfaces of the experimental group often occurred on the top of the hybrid layer, whereas those of the blank and commercial control groups mostly occurred on the bottom of the hybrid layer. Micro-leakage rating counts of specimens before and after thermal cycling were as follows: the experimental group was primarily 0 grade, thereby indicating that a relatively ideal marginal sealing effect could be achieved (P>0.05); meanwhile, the blank control group was primarily 1 grade, and the penetration depth of dye significantly increased after thermal cycling (P<0.05); the commercial control group was primarily 0 grade without statistical difference before and after thermal cycling (P>0.05), while a significant difference was observed between the commercial control group and experimental group after thermal cycling (P<0.05). Conclusion The novel low-shrinkage resin adhesive containing 20%UE exhibited excellent bonding properties even after thermal cycling aging treatment, thereby showing a promising prospect for dental application.

    Clinical Research
    Effectiveness of iliac cancellous bone grafting in alveolar cleft repair and analysis of factors affecting it
    Jing Bingshuai, Shi Bing, Zheng Qian, Li Chenghao.
    West China Journal of Stomatology. 2023, 41(3):  284-289.  doi:10.7518/hxkq.2023.2022446
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    Objective To review the effectiveness of secondary alveolar bone grafting using iliac cancellous bone in patients with unilateral complete alveolar cleft and to investigate the factors influencing it. Methods A retrospective study of 160 patients with unilateral complete alveolar clefts who underwent iliac cancellous bone graft repair at the Department of Cleft Lip and Palate Surgery, West China Hospital of Stomatology, Sichuan University, was conducted. Eighty patients in the young age group (6-12 years) and 80 in the old age group (≥13 years) were included. Bone bridge formation was determined using Mimics software, and the volume was measured to calculate the iliac implantation rate, residual bone filling rate, and resorption rate. The factors that affected bone grafting in both subgroups were investigated. Results Using bone bridge formation as the clinical success criterion, the success rate for the entire population was 71.25%, with a significant difference of 78.75% and 63.75% for the young and old age groups, respectively (P=0.036). The gap volume in the latter was significantly larger than that in the former (P<0.001). The factors that influenced bone grafting in the young group were the palatal bone wall (P=0.006) and history of cleft palate surgery (P=0.012), but only the palatal bone wall affected the outcome in the old age group (P=0.036). Conclusion The results of alveolar bone grafting for the old age group were worse than those for the young age group. The palatal bone wall was an important factor that affected alveolar bone grafting, and alveolar bone grafting in the young patients was influenced by the history of cleft palate surgery.

    Modified tragus edge incision and transmasseteric anteroparotid approach to condyle reconstruction
    Tang Hui, Wang Lang, Wang Lei, Rao Pengcheng, Luo Daowen, Fu Guangxin, Xiao Jingang
    West China Journal of Stomatology. 2023, 41(3):  290-296.  doi:10.7518/hxkq.2023.2022496
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    Objective This study aimed to analyze the application value of a modified tragus edge incision and transmasseteric anteroparotid approach to condyle reconstruction. Methods Condyle reconstruction was performed in 16 patients (9 females and 7 males) with modified tragus edge incision and transmasseteric anteroparotid approach. After regular follow-up, the function of condyle reconstruction was evaluated by clinical indicators, such as parotid salivary fistula, facial nerve function, mouth opening, occlusal relationship, and facial scar. The morphology of rib graft rib cartilage was evaluated by imaging indicators, such as panoramic radiography, CT, and three-dimensional CT image reconstruction. Results At 6-36 months postoperative follow-up, all patients had good recovery of facial appearance, concealed incisional scar, no parotid salivary fistula, good mouth opening, and occlusion. One case had temporary facial paralysis and recovered after treatment. Radiographic evaluation further showed that costochondral graft survived in normal anatomic locations. Conclusion The modified tragus edge incision and transmasseteric anteroparotid approach can effectively reduce parotid salivary fistula and facial nerve injury in condylar reconstruction. The surgical field was clearly exposed, and the incision scar was concealed without increasing the incidence of other complications. Thus, this approach is worthy of clinical promotion.

    Imaging study on the relationship between anterior and posterior occlusal planes and temporomandibular osteoarthrosis
    Zhong Jiawei, Fan Peidi, Hu Shoushan, Gao Xinlin, Li Yijun, Wang Jun, Xiong Xin.
    West China Journal of Stomatology. 2023, 41(3):  297-304.  doi:10.7518/hxkq.2023.2023032
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    Objective The aim of this study was to compare the anterior and posterior occlusal plane characteristics of patients with different temporomandibular joint osseous statuses. Methods A total of 306 patients with initial cone beam CT (CBCT) and cephalograms were included. They were divided into three groups on the basis of their temporomandibular joint osseous status: bilateral normal (BN) group, indeterminate for osteoarthrosis (I) group, and osteoarthrosis (OA) group. The anterior and posterior occlusal planes (AOP and POP) of the different groups were compared. Then, the regression equation was established after adjusting for confounding factors, and a correlation analysis between the occlusion planes and other parameters was performed. Results SNA, SNB, FMA, SN-MP, Ar-Go, and S-Go were correlated with the occlusal planes. Relative to the BN and I groups, the FH-OP of the OA group increased by 1.67° on the average, FH-POP increased by 1.42° on the average, and FH-AOP increased by 2.05° on the average. Conclusion The occlusal planes were steeper in the patients with temporomandibular osteoarthrosis than in the patients without it, and the mandible rotated downward and backward. The height of the mandibular ramus, the mandibular body length, and the posterior face height were small. In clinical practice, attention should be given to the potential risk of temporomandibular joint osteoarthrosis in such patients. In addition, SNB, FMA, SN-MP, Ar-Go, S-Go, and occlusal planes had moderate correlations.

    Mandibular advancement with clear aligners and functional appliances in the treatment of skeletal ClassⅡmalocclusion: a systematic review and meta-analysis
    Yu Lei, Li Ziwei, Kang Fujia, Wang Songqing, Xie Zunxuan, Zhu Xianchun.
    West China Journal of Stomatology. 2023, 41(3):  305-314.  doi:10.7518/hxkq.2023.2022453
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    Objective This study aimed to conduct a meta-analysis of the efficacy of mandibular advance clear alig-ners with traditional functional appliances as the control group. Methods PubMed, Web of Science, Embase, Cochrane Library, China Biomedical Abstracts Database, China Knowledge Network Database, Wanfang Database, and Weipu Database were used in this study. The two groups of researchers screened the literature and extracted data based on the inclusion and exclusion criteria established by PICOS entries, and used the ROBINS-I scale for quality evaluation. Revman 5.4 and Stata 17.0 software were used for meta-analysis. Results Nine clinical controlled trials were included in this study with a total sample size of 283 cases. No significant difference was found in SNA, SNB, ANB, Go-Pog, U1-SN, Overjet, and other aspects between the invisible group and the traditional group in the treatment of skeletal class Ⅱ ma-locclusion patients; there was a 0.90° difference in mandibular plane angle between the two groups; the growth of the mandibular ramus (Co-Go) in the traditional group was 1.10 mm more than that in the invisible group; the lip inclination of the lower teeth in the invisible group was better controlled, 1.94° less than that in the control group. Conclusion The invisible group can better control the lip inclination of the mandibular anterior teeth when guiding the mandible. Furthermore, the mandibular plane angle (MP-SN) can remain unchanged, but the growth of the mandibular ramus is not as good as the traditional group, and auxiliary measures should be taken to improve it in clinical practice.

    Audit to assess the quality of 916 prosthetic prescriptions of removable partial dentures
    Zhang Na, Mao Bochun, Dai Yunhan, Chen Shengkai, You Ziying, Zhang Junjing, Chen Xin, Dong Haoyue, Yue Li, Yu Haiyang
    West China Journal of Stomatology. 2023, 41(3):  315-322.  doi:10.7518/hxkq.2023.2021565
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    Objective The objectives of this study were to assess the quality of prosthetic prescriptions of removable partial dentures (RPDs) and to analyze the current situation of the communication and information delivery between clinicians and technicians. Methods All RPD prosthetic prescriptions received by a major dental laboratory in 4 weeks were involved in a quality audit, and the prescriptions were divided into three groups in accordance with the grades of clients. The filling of prosthetic prescriptions was recorded. The items in the prescriptions for audit included the general information of the patient, the general information of the clinician, the design diagram information, other detailed information, and the return date. The prescriptions were categorized into four levels on the basis of their quality by two quality inspectors who have been working for more than 10 years. Results A total of 916 prescriptions were collected and assessed. The names in the general information of the patient and the clinician were filled out best, both at the rate of 97.6% (n=894). The return date was filled out worst, only at the rate of 6.4% (n=59). Of those prescriptions, 86.8% (n=795) exhibited inadequate design diagram information. The results of the quality assessment demonstrated that 74.2% of prescriptions were assessed as noncompliant ones and failed to meet the acceptable clinical quality standard. Conclusion At present, the overall quality of RPD prosthetic prescriptions is poor. The responsibilities of clinicians and technicians are unclear, and the communication between them is not ideal.

    Cognition about emergency management of avulsed incisor in children among dentists in Guangdong province
    Zhang Li, Xie Jing, Chen Ying, Deng Shuman, Chen Luyi, Gao Qi
    West China Journal of Stomatology. 2023, 41(3):  323-332.  doi:10.7518/hxkq.2023.2022473
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    Objective This study aimed to evaluate and analyze the current situation of dentists in Guangdong pro-vince regarding the management of avulsed incisors, thereby providing a reference for making treatment strategies for avulsed incisors in the future. Methods A total of 712 dentists with different educational backgrounds and working conditions in Guangdong province were randomly selected to conduct an online questionnaire survey on the cognition of children with avulsed incisors from April 2022 to May 2022. The data were recorded by Excel software and statistics were analyzed on Stata/SE 15.1. Results A total of 712 dentists were investigated and 701 questionnaires were collected (98.46%). In addition, 65.9% of investigators came from the Department of Stomatology in a First-class Hospital or Stomatological Hospital. The results showed that the average number of avulsed teeth consulted by dentists was less than 20 per year. Although 99.7% of respondents considered normal saline as a suitable storage medium, 3.1% and 23.8% of them had a misunderstanding that the tap/alcohol could be used for root cleaning. Moreover, 93.4% was the correct selection rate of the treatment plan for processing on root surfaces before replanting by investigators. The correct selection rate of the duration using elastic fixation was only 10.7%. Meanwhile, 42.9% of investigators refused to inoculate tetanus immunoglobulin after teeth replanting. Emergency management of dental avulsion (EM) and clinical management of dental avulsion (CM) answered correctly with average scores of 14.60±11.85 and 14.48±2.67, respectively. Multivariate linear regression analysis revealed that working years were negatively correlated with EM and CM scores (P<0.05). There was a positive correlation between CM and EM scores with the number of avulsion cases treated by physicians each year (P<0.05). In terms of the EM score of dentists’ learning attitude, investigators who had received enough knowledge were higher than those who had not and insufficient knowledge reserved, and the difference was statistically significant (P<0.05). The scores of investigators who thought they had a certain degree of knowledge about dental trauma were higher than those who thought they “did not understand”, and the difference was statistically significant (P<0.05). In terms of CM scores, investigators who thought the knowledge of dental trauma was “very helpful” had higher scores than those who thought it was “not helpful”, and the difference was statistically significant (P<0.05). The scores of the investigators who thought they had “relatively sufficient knowledge” of dental trauma were higher than those who thought they had “no knowledge” or “insufficient know-ledge”, and the difference was statistically significant (P<0.05). Conclusion The overall accuracy of the management of avulsed incisors among dentists was low in Guangdong province. Dentists were more likely to have a higher rate of accuracy choice in treatment options for luxation injury and avulsion to enhance the prognosis of replanted teeth.

    Analysis of dental clinic and dental chair distribution in Sichuan
    Zheng Yan, Yan Liuqing, Hua Chengge, Liang Xinhua, Yang Zheng.
    West China Journal of Stomatology. 2023, 41(3):  333-340.  doi:10.7518/hxkq.2023.2022454
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    Objective To thoroughly understand the current dental chair equipment status of dental clinics in Sichuan Province and provide a reference for administrative departments. Methods Data were collected from a health administrative department and a regional social development yearbook. The number of existing dental clinics and dental chairs in Sichuan Province was investigated. Results In Sichuan Province, 7 103 dental clinics were determined to be equipped with 21 760 dental chairs. The Gini coefficients of per capita dental clinics in the province were 0.50, 0.22, and 0.06, and the Gini coefficients of per capita dental chairs were 0.68, 0.31, and 0.15; these coefficients had the same distribution as that reflected by the Lorenz curve. In consideration of geographic distribution, the Theil index for the distribution of dental clinics and dental chairs among cities and states were 0.690 7 and 0.822 3, respectively. The overall Theil index va-lues for the distribution of dental clinics and dental chairs in the province were 0.902 4 and 1.079 4, respectively. The difference in the distribution of dental clinics and dental chairs among cities and states in the province contributed 0.765 4 and 0.761 8 to the total difference, respectively. Conclusion The allocation of oral health resources in Sichuan Pro-vince is relatively equitable in terms of population and economic distribution but uneven in geographical distribution.

    Implantology
    Clinical efficacy of simple taper retentive implants in immediate posterior dental implantation for 5-7 years
    Ren Bihui, Guo Shuigen, Xu Yehao, Dai Jieting, Wei Hongwu.
    West China Journal of Stomatology. 2023, 41(3):  341-349.  doi:10.7518/hxkq.2023.2022439
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    Objective This study aimed to evaluate the long-term clinical efficacy of simple taper retentive implants in the posterior dental area after immediate implantation for 5-7 years. Methods Selected from January 2015 to December 2017 in the Fourth Affiliated Hospital of Nanchang University dental clinic line tooth area immediately after the implant prosthesis, a total of 38 patients, 53 implants, were deep into (bone under 2 mm or higher) and the upper structure was repaired. In addition, after the completion of tracking observation of 60-90 months, the implant surrounding bone health was recorded and analyzed. Results After 5-7 years of follow-up, 1 of the 53 implants failed to fall out, and the implant retention rate was 98.1%. The amount of bone resorption in the proximal and distal margins 5-7 years after implant restoration was (0.16±0.94) mm and (-0.01±1.29) mm, respectively, and the difference in bone height between the proximal and distal margins of the implant and the immediate post-restoration period was not statistically significant (P>0.05). No statistically significant differences were found in the effects of periodontitis, implant site inflammation, and smoking on peri-implant marginal bone resorption (P>0.05). Conclusion The single taper-retained implant broadens the indications for immediate implant placement in the posterior region, and its deep sub-osseous placement (≥2 mm below the bone) avoids to a certain extent the disturbance of the implant by external stimuli and the exposure of the cervical abutment of the implant, with the good long-term stability of the marginal bone around the implant.

    In vitro research of oral microscope-assisted implant surface decontamination
    Su Wenqi, Li Jingwen, Jiang Lishan, Cui Wenjie, Zhao Yang, Li Houxuan.
    West China Journal of Stomatology. 2023, 41(3):  350-355.  doi:10.7518/hxkq.2023.2022509
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    Objective To investigate the effect of oral microscope-assisted surface decontamination on implants in vitro. Methods Twelve implants that fell off because of severe peri-implantitis were collected, and decontamination was carried out on the surfaces of implants through curetting, ultrasound, titanium brushing, and sandblasting at 1×, 8×, or 12.8× magnifications. The number and sizes of residues on the implants’ surfaces after decontamination were determined, and the decontamination effect was analyzed according to the thread spacing in the different parts of the thread. Results 1) The 8× and 12.8× groups scored lower for implant surface residues than the 1× group (P<0.000 1), and the 12.8× group scored lower than the 8× group (P<0.001); 2) no difference in residue score was found between the wide and narrow thread pitch (P>0.05), and the 8× and 12.8× groups had lower scores than the 1× group (P<0.001); 3) the lowest number of contaminants was observed at the tip of the thread, whereas the highest was observed below the thread, and the difference was significant (P<0.001). However, the thread pitch had no effect on the number of contaminants in different areas (P>0.05); 4) the residue scores of the 8× and 12.8× groups were lower than those of the 1× group at the thread tip and above, sag, and below the thread of the implants (P<0.05). Conclusion Residues on the surfaces of contaminated implants can be effectively removed by using an oral microscope. After decontamination, the residues of pollutants were mainly concentrated below the thread of the implants, and the thread pitch of the implants had no significant effect on the residues.

    Case Report
    Diagnosis and treatment of apical cyst of deciduous teeth with infection: a case report
    Zhang Yue, Liu Xiaowen, Yang Ran
    West China Journal of Stomatology. 2023, 41(3):  356-360.  doi:10.7518/hxkq.2023.2022428
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    There is a high incidence of chronic periapical periodontitis of deciduous teeth, however, there is a low incidence of the apical cyst. This paper reports a 7-year-old child with deciduous periodontitis caused by chronic periapical periodontitis of deciduous teeth. Through literature review, the etiology, imaging characteristics, diagnosis, differential diagnosis, and treatment methods were discussed to provide the basis for clinical diagnosis and treatment.

    Malignant peripheral nerve sheath tumor of tongue: a case report
    Liu Yibo, Wu Di, Lun Xiaohan, Dai Wei.
    West China Journal of Stomatology. 2023, 41(3):  361-364.  doi:10.7518/hxkq.2023.2022402
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    Malignant peripheral nerve sheath tumor (MPNST) is a rare neurogenic malignant tumor. MPNST has aty-pical clinical symptoms and imaging presentations, difficult diagnosis, a high degree of malignancy, and poor prognosis. It usually occurs in the trunk, approximately 20% in the head and neck, and rarely in the mouth. This paper reports a case of MPNST of the tongue. A summary of the clinical features, diagnosis, and treatment of MPNST is presented in combination with a literature review to provide a reference for the diagnosis and treatment of this disease.

    Anesthesia management for patient with bipolar disorder complicated with hypothyroidism during oral surgery: a case report
    Li Yue, Ji Yang, Luo Qiang.
    West China Journal of Stomatology. 2023, 41(3):  365-368.  doi:10.7518/hxkq.2023.2022448
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    Bipolar disorder is a major mental illness that is difficult to treat and has a high degree of recurrence. This article reports general anesthesia for oral surgery in a patient with bipolar disorder complicated with hypothyroidism. It also discusses the rational application of antipsychotic drugs and anesthetics with reference to the literature to improve the understanding of the disease and help patients with mental disorders complete the surgical treatment quietly and smoothly.