Table of Content

    20 March 2021, Volume 29 Issue 3
    Expert Forum
    Dental implant treatment for patients with chronic kidney disease
    YUAN Quan
    2021, 29(3):  145-150.  DOI: 10.12016/j.issn.2096-1456.2021.03.001
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    Chronic kidney disease is a global public health problem threatening human health and affects the function of multiple organ systems. The oral health of patients is often affected as the disease progresses. Dental implants have become the best way to repair tooth loss. It is necessary and challenging to provide safe and reliable dental implant treatment for patients with chronic kidney disease. Dental clinicians should evaluate the health of patients comprehensively, complete blood biochemistry, coagulation function, and imaging examinations, and provide feasible, reliable and personalized treatment plans. During the treatment phase, dental clinicians need to consider prophylactic antibiotics, painless minimally invasive surgery, infection control, and delayed restoration, and they must cooperate with other clinicians in multiple disciplines to reduce risks to provide personalized, safe, and effective oral implant treatment for patients with chronic kidney disease.

    Basic Study
    Effects of concentrated sulfuric acid etching durations on the shear bond strength between polyether-ketone-ketone and dentin
    WANG Chenwei,SUN Fangfang,YANG Chuncheng,DING Ling,CHEN Xi,ZHANG Jiaqi,WU Guofeng
    2021, 29(3):  151-156.  DOI: 10.12016/j.issn.2096-1456.2021.03.002
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    Objective To study the effects of different concentrated sulfuric acid etching durations on the shear bond strength between polyether-ketone-ketone (PEKK) and dentin, providing a scientific basis for the clinical bonding procedures of PEKK prosthesis. Methods Forty-four PEKK specimens were prepared and randomly divided into four groups: group A was the control group, which was only polished with abrasive papers, group B, group C and group D were experimental groups, which were etched by 98% concentrated sulfuric acid for 5 s, 30 s and 60 s, respectively. In addition, one sample was randomly selected from each group, and the profile was prepared by a slow cutting machine. The surface morphology of the profile was observed under SEM. After the four groups of specimens and dentin were bonded by resin, they were soaked in distilled water at 37 ℃ for 24 h. After the shear bonding strengths were measured, the fracture interfaces of the specimens were examined by the scanning electron microscopy and stereomicroscopy, and failure models of bonding were analyzed. Results After acid etching treatments, the cross-sectional images in group B presented uniform spongy shapes, while the cross-sectional images in group C and group D showed destructive pore structures. The shear bond strengths of group B (16.84 ± 1.84) MPa, group C (12.33 ± 1.22) MPa and group D (6.44 ± 1.18) MPa were higher than that of group A (3.99 ± 1.06) MPa (P < 0.05). The highest shear bond strength was observed in group B (16.84 ± 1.84) MPa. Conclusion The surface treatment of 98% sulfuric acid etching for 5 s manifested the best bond strength between PEKK and dentin.

    High-throughput sequencing analysis of the microbiota of subgingival plaque in patients with periodontitis
    YANG Wanjuan,XU Jie
    2021, 29(3):  157-165.  DOI: 10.12016/j.issn.2096-1456.2021.03.003
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    Objective To detect the composition of the subgingival microbiota in generalized aggressive periodontitis (GAgP) and severe chronic periodontitis (SCP) patients tested by high-throughput sequencing (HTS) technologies, analyze its diversity and function by using bioinformatics, and observe changes in the subgingival microbiota before and after periodontal initial therapy. Methods Eleven patients with GAgP and 14 patients with SCP who visited the Department of Periodontics in Stomatological Hospital of Kunming Medical University from September 2018 to May 2019 were recruited, and subgingival plaque samples were collected at baseline and 6 weeks after initial therapy. Then, the genomic DNA was distracted and sequenced by the Illumina MiSeq high-throughput sequencing platform. QIIME (quantitative insights in microbial ecology), Mothur, SPSS and other software were used to analyze community information. LEfSe difference analysis (linear discriminant analysis effect size), network analysis, and the KEGG PATHWAY database (https://www.kegg.jp/kegg/pathway.html) were used to predict community function. Results At baseline, the dominant microbiota of GAgP and SCP patients were similar, including Bacteroidetes, Porphyromonas and Porphyromonas endodontalis. Six weeks after initial therapy, as the periodontal pocket became shallower, the variation trend of the microbiota of GAgP and SCP patients was similar. The relative abundance of gram-negative bacteria, such as Bacteroidetes, Porphyromonas and Porphyromonas endodontalis, decreased, while the relative abundance of gram-positive bacteria, such as Proteobacteria, Actinomyces and Rothia aeria, increased. Actinobacteria were significantly increased biomarkers of the subgingival microbiota in GAgP after treatment. Streptococcus is an important genus that connects the microbiota related to periodontitis and the microbiota related to periodontal health. Community function prediction result showed that initial treatment can reduce the functions of amino acid metabolism, methane metabolism, and peptidase in GAgP and SCP patients. Conclusion The subgingival microbiota of GAgP and SCP patients are similar. Streptococcus, as an early colonizer, may play an important role in promoting plaque biofilm formation and maturation in the process of subgingival flora from health to imbalance. Initial therapy can change the composition and structure of the subgingival microbiota, reduce community diversity, and reduce the functions of amino acid metabolism, methane metabolism, and peptidase in GAgP and SCP patients.

    Finite element analysis of the stress distribution of dental implant crowns with different all-ceramic materials and thicknesses
    LI Jiesen,LIN Zhenxiang,WU Dong,ZHENG Zhiqiang,LIN Jie
    2021, 29(3):  166-170.  DOI: 10.12016/j.issn.2096-1456.2021.03.004
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    Objective To compare the stress distribution of different all-ceramic restoration materials and thicknesses in dental crown restorations using the finite element method and provide a reference for the selection and design of clinical crown restoration materials. Methods A finite element model of mandibular first molar implant crown restoration was created, and 6 crown thickness designs and 4 different crown restoration materials were evaluated, namely, resin-based ceramics (Lava Ultimate and Vita Enamic), lithium disilicate glass-ceramics (IPS e.max CAD), and zirconia ceramic (Cercon) designs. The mandibular first molars were loaded at 600 N, and the stress distribution was analyzed by using the finite element software ANSYS 10.0. Results The crown stress analysis showed that 156.05 MPa was the highest in 4 mm Cercon group and 18.85 MPa was the lowest in 1 mm Lava Ultimate group. The stress analysis of resin cement showed that 62.52 MPa was the highest in the 4 mm Lava Ultimate group and 16.74 MPa was the lowest in 1 mm IPS e.max CAD group. During the use of the finished platform, the stress concentration of the Lava Ultimate group in the crown prosthesis and resin cement was higher than that of the personalized platform with the same crown thickness. Conclusion With increasing crown thickness, the maximum principal stress concentration in crown restoration and resin cement increases. Personalized abutments are more conducive to reducing stress concentrations for resin-based ceramics.

    Clinical Study
    Clinical efficacy evaluation of minimally invasive periodontal therapy assisted by endoscopy
    XIA Jiaojiao,LI Houxuan
    2021, 29(3):  171-177.  DOI: 10.12016/j.issn.2096-1456.2021.03.005
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    Objective To investigate the clinical effect of periodontal endoscope-assisted scaling and root planing (SRP) in treating advanced periodontitis. Methods Nineteen cases of grade Ⅲ and Ⅳ periodontitis selected from June 2017 to January 2019 in the Nanjing Stomatological Hospital, Medical School of Nanjing University were divided into the periodontal endoscope and control groups. In the periodontal endoscope group, SRP was performed under a periodontal microscope in one treatment after initial supragingival scaling; in the control group, SRP was performed under regular conditions, and additional SRP was conducted in positive bleeding on probing sites twice every other week as needed. Periodontal status, including probing depth (PD), bleeding on probing (BOP) and attachment loss (AL), was recorded by a Florida probe. Results For sites of 4P < 0.05). There was no significant difference between the two groups at 6 months (P >0.05). There was no significant difference in the BOP positive rate or AL change between the two groups at 3 months and 6 months (P > 0.05). For sites with PD > 6 mm, at baseline, the positive rates of PD, BOP and AL in the endoscope group were more serious than those in the control group, and the differences were statistically significant. The PD- and BOP-positive rates and AL in the endoscope group and control group decreased significantly from baseline at 3 and 6 months. However, PD in the endoscope group became shallower than that in the control group (P < 0.05) after 3 and 6 months. There was no significant difference in the BOP positive rate or AL between the two groups (P>0.05). Conclusion When compared to regular SRP, periodontal microscope-assisted SRP achieves better improvement in PD and is more beneficial for reducing the BOP and AL of deeper sites.

    Research on the accuracy of dynamic real-time navigation and digital guide navigation implanting techniques
    ZHAO Yaqin,LIU Aipeng,CEN Feng,YANG Kaiwen,LI Yanfang,DENG Wenzheng
    2021, 29(3):  178-183.  DOI: 10.12016/j.issn.2096-1456.2021.03.006
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    Objective To compare the accuracies of implants with dynamic real-time navigation versus digital guide navigation to provide a reference for clinical precision dental implants. Methods Forty-six cases (seventy teeth) with missing teeth admitted to the Department of Stomatology, Wuzhou Red Cross Hospital from April 2018 to December 2019 were randomly divided into two groups (thirty-five teeth in each group) for dynamic real-time navigation and digital guide navigation implantation techniques. To compare the entry point, apex point, depth and angle deviation of the preoperative and postoperative position of implants in the two groups. SPSS 21.0 software was used for statistical analysis. Results Dental implants were successfully placed in both groups. The deviations of apex point, depth and angle in the dynamic real-time navigation group were all smaller than those in the digital guide navigation group, and the differences were statistically significant (P < 0.05). There was no statistically significant deviation in the entry point between the two groups (P > 0.05). Conclusion In this study, both techniques had good clinical effects. The accuracy of dynamic real-time navigation was higher than that of digital guidance.

    Review Articles
    Research progress on Streptococcus mutans phages in the prevention of dental caries
    LI Yuhan,LI Jiaxin,ZHANG Shiming,ZHANG Yaohua,LI Yuqing,ZENG Jumei
    2021, 29(3):  184-188.  DOI: 10.12016/j.issn.2096-1456.2021.03.007
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    The Streptococcus mutans (S. mutans) phage, as one of the principal pathogenic bacteria of dental caries, is a main cause of the formation and development of dental caries due to its overproliferation in dental plaque biofilms. Bacterial viruses, also known as bacteriophages, have the capability of specifically infecting bacteria and effectively degrading bacterial biofilms. S. mutans phages, therefore, may prevent and control caries. Therapy based on phages has been applied in many fields, but the application of S. mutans phages in caries remains exploratory. This article will review the research progress of S. mutans phages in clinical caries prevention, aiming to provide a new idea for the clinical prevention of caries. The results of the literature review show that the living bacteriophage system has the advantages of high specificity, high affinity and good safety. However, due to its unstable structure, it can be processed into a more stable formulation by freeze-drying, spray drying, adding stability enhancers, or incorporating bacteriophages into ointments, biodegradable polymer matrices or particles to a certain extent to improve stability. The lysozyme produced by phages can digest the bacterial cell wall and release the assembled phage particles, which effectively cleave biofilms. In addition, the antigen binding fragment library for cariogenic pathogens was screened by phage display technology, and the purpose of caries prevention and treatment was achieved by passive immunization of antigen binding fragments. However, the host range of bacteriophages is narrow, so this kind of problem can be overcome by phage combined with traditional therapy or other drug use or cocktail therapy with multiple phages in clinical caries prevention and control.

    The interaction between Cyclophilin A and CD147 and its clinical significance in periodontal diseases
    YANG Ting,HUANG Shiguang
    2021, 29(3):  189-193.  DOI: 10.12016/j.issn.2096-1456.2021.03.008
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    Cyclophilin A (CypA) is the first foldable enzyme in human cells that has peptidyl proliferase-trans isomerase activity and has a strong proinflammatory effect. CD147 can act as the signal receptor of CypA. The interaction of the two through cell-surface heparin binding activates extracellular regulated protein kinases (ERK1/2) and nuclear factor kappa-B (NF-κB) signaling pathways in macrophages and increases the expression of MMPs and other inflammatory factors. The CypA/CD147 interaction regulates inflammation, promotes the inflammatory response and bone resorption and is involved in the pathological processes of a variety of systemic diseases. CypA and CD147 may take part in the chemotaxis of inflammatory cells, increase white blood cell infiltration in tissues, and increase CypA and CD147 expression in periodontitis gum tissue and gingival groove liquid with inflammation, prompting their interaction to promote the progression of periodontitis. However, the specific function of the signaling pathways in the periodontitis mechanism still requires further elucidation.

    Research progress on the role of T helper cells 17 and interleukin 17 in oral mucosal diseases
    WANG Ziying,CHEN Xiaotao
    2021, 29(3):  194-197.  DOI: 10.12016/j.issn.2096-1456.2021.03.009
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    T helper 17 (Th17) cells are a new type of CD4+ T helper cell. They participate in the immune and inflammatory response by secreting specific interleukin-17 (IL-17). In oral mucosal diseases, oral lichen planus (OLP), recurrent aphthous ulcer (RAU) and Behcet′s disease (BD) are associated with Th17 cells and IL-17. There were 17 kinds of proteins in the saliva of patients with OLP that could upregulate the expression of Th17 cells and induce the secretion of IL-17. IL-17 can stimulate epithelial cells, endothelial cells and fibroblasts to produce a variety of cytokines, such as IL-6, IL-8, granulocyte macrophage colony-stimulating factor and cell adhesion molecule-1, leading to the production and aggravation of inflammation. Th17/Tc17 cell-targeted therapy can significantly improve the clinical symptoms of OLP patients′ mucosa and skin. IL-17 can stimulate oral keratinocytes through the IL-17RA or IL-17RE receptor and produce proinflammatory effects in RAU. Th17 cells in the peripheral blood of BD patients are significantly increased, while Treg cells are significantly decreased.

    The mechanism of chloroquine/hydroxychloroquine and its application in stomatological diseases
    LIN Lin,WU Kaihui,WANG Wenmei
    2021, 29(3):  198-201.  DOI: 10.12016/j.issn.2096-1456.2021.03.010
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    Chloroquine and hydroxychloroquine are both classic 4-aminoquinoline antimalarial drugs with similar chemical structures and mechanisms of action. As the toxicity and side effects of hydroxychloroquine are lower than those of chloroquine, hydroxychloroquine is the main clinical application at present, with good efficacy and safety. Chloroquine and hydroxychloroquine are widely used in the clinic because of their immunosuppressive, anti-inflammatory, antiviral, antitumor and photoprotective effects. The main mechanisms by which chloroquine/hydroxychloroquine inhibits immunity include inhibiting lysosome activity, autophagy, immune response signaling pathways production of proinflammatory cytokines. Chloroquine stabilizes the lysosomal membrane and reduces the release of lysosomal enzymes. As a prostaglandin antagonist, chloroquine can reduce the production of prostaglandins and leukotrienes, thus playing an anti-inflammatory role. Chloroquine/hydroxychloroquine can inhibit virus proliferation in the early stage of virus replication by inhibiting the glycosylation of the angiotensin converting enzyme 2 receptor. At present, hydroxychloroquine has been found to have significant efficacy in discoid lupus erythematosus, oral lichen planus, chronic cheilitis, pemphigus foliaceus, Sj?gren’s syndrome and other stomatological diseases. However, eye damage is the most important adverse reaction of hydroxychloroquine, and its occurrence is related to the cumulative dose of drugs.

    Application of poly(lactic-co-glycolic acid) in the treatment of pulp diseases
    ZHOU Fangjie,HE Libang,LI Jiyao
    2021, 29(3):  202-205.  DOI: 10.12016/j.issn.2096-1456.2021.03.011
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    The development of materials science is of great significance to the treatment of dental pulp diseases. Poly lactic acid glycolic acid (PLGA) copolymer is an organic macromolecule compound that is widely used in the preparation of biomedical materials. In recent years, PLGA, as a drug/molecular loaded system and tissue regeneration scaffold, has shown prospects for application in the treatment of dental pulp diseases. This paper will review the application of PLGA in the treatment of dental pulp diseases and provide a basis for its further development and utilization. The results of the literature review show that PLGA is a drug/molecular delivery system that is mainly used in the improvement of pulp capping materials, root canal disinfectant and apexification materials. PLGA-improved pulp capping agents can prolong the action time of the drug and reduce toxicity. The modified root canal disinfectant can realize the sustained release of drug, make the drug penetrate deeper into the subtle structure, and contact more widely with the pathogenic bacteria. The modified apexification materials can provide more convenient administration methods for apexifixment. As a scaffold for tissue engineering, PLGA is mainly used in the study of pulp regeneration. The optimization of PLGA physical properties and action environment can provide a more suitable microenvironment for seed cells to proliferate and differentiate. How to utilize the advantages of PLGA to develop a more suitable material for endodontic application needs further study.

    Research progress on microRNAs connected with oral lichen planus
    PAN Yingxiao,GUO Dawei,LI Xin,LU Shulai
    2021, 29(3):  206-210.  DOI: 10.12016/j.issn.2096-1456.2021.03.012
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    Oral lichen planus (OLP) is a common chronic inflammatory disease with unclear etiology, in which disorder of the cell-mediated local immune response plays an important role. MicroRNAs (miRNAs) have been found to play an important role in the occurrence and development of inflammatory responses and autoimmune diseases. In recent years, many studies have reported that miRNAs may be related to OLP. According to a literature review, high expression of miRNA-19a and low expression of miRNA-122, miRNA-199, miRNA-138, miRNA-635 and miRNA-578 may be related to the occurrence of OLP by regulating cytokines such as interleukin, interferon and tumor necrosis factor. The low expression of miRNA-125a and the high expression of miRNA-132, miRNA-146a and miRNA-155 may be related to the severity of OLP by influencing the differentiation of CD4+ T cells in the Th1/Th2 subgroup. High expression of miRNA-26a, miRNA-29a and miRNA-31 and low expression of miRNA-27b, miRNA-200a and miRNA-137 may be associated with malignant risk of OLP through functionally related genomes, transcription factors and miRNA coregulatory networks. Some deficiencies remain in current studies. For example, many studies using microarrays to screen differentially expressed miRNAs have not been further grouped according to the type of OLP or cancer risk.

    Research progress on microRNA-21 in regulating osteoclast and osteogenic differentiation in orthodontic treatment
    CHEN Zece,LONG Qian,GUAN Xiaoyan,LIU Jianguo
    2021, 29(3):  211-216.  DOI: 10.12016/j.issn.2096-1456.2021.03.013
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    In the process of orthodontic treatment, the balance between the modeling of alveolar bone and the mechanical stress exerted by the appliance is key to the effective movement of orthodontic teeth. Alveolar bone modeling involves many regulatory factors, and microRNAs (miRNAs), as posttranscriptional regulatory factors, play an important role in the occurrence of bone modeling. As an important member of the miRNA family, miRNA-21 promotes the differentiation of periodontal ligament stem cells into osteoblasts and plays an important role in maintaining bone balance and preventing bone resorption as a regulator of osteoclast formation and a promoter of osteoclast differentiation. A literature review showed that miRNA-21 can regulate osteoclast function and promote bone resorption through programmed cell death 4 (PDCD4), phosphate and tension homology deleted on chromosome ten (PTEN), receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG). MiRNA-21 is highly sensitive to external mechanical stress in the process of orthodontic tooth movement. After orthodontic force is applied, miRNA-21 can promote osteoclast formation and accelerate orthodontic movement; through targeted regulation of periodontal ligament associated protein-1 (PLAP-1), it can regulate periodontal ligament remodeling in the late stage of tooth movement and improve the potential of tooth movement. In addition, miRNA-21 mediates orthodontic tooth movement (OTM) and alveolar bone remodeling in the periodontal inflammatory microenvironment. miRNA-21 can upregulate the expression of hypoxia-inducible factor-1α (HIF-1α) in periodontal ligament stem cells in a hypoxic environment. It can promote the expression of osteogenic markers, such as osteopontin (OPN), osteocalcin (OCN), alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2), and promote osteogenic differentiation during orthodontic tooth movement.