Table of Content

    20 February 2020, Volume 28 Issue 2
    Expert Forum
    Expert consensus on marsupialization of cystic lesions of the jaw
    TAO Qian,HE Yue,LIU Bing,HOU Jinsong,NAN Xinrong,ZHANG Bin,ZHANG Leitao,QIAO Bin
    2020, 28(2):  69-72.  DOI: 10.12016/j.issn.2096-1456.2020.02.001
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    Marsupialization is effective in the treatment of cystic lesions of the jaw. It is a simple operation that can result in minimal trauma, the reduction of postoperative recurrence, and maximum preservation of the surrounding tissue structure and function. However, there is a certain failure rate in clinical treatment due to the improper grasp of indications and nonstandard operation. The highest failure rate reported in the literature is 32.6%. To further standardize the clinical application of marsupialization and improve the success rate of treatment, we put forward an expert consensus of marsupialization in the treatment of jaw cystic lesions by reviewing the domestic and foreign literature and summarizing the experience in marsupialization from some famous domestic experts. In this consensus, we propose three elements of marsupialization: the establishment of the opening, the maintenance of cyst plugs and regular washing. The scope of application of marsupialization includes jaw cysts and cystic ameloblastomas. It is necessary to standardize the position of the opening, the size of the opening and the manufacture of the cyst plug, and a panoramic film or cone beam computed tomography(CBCT) should be used to observe the changes in the cystic cavity before and after operation. A second-stage operation should be performed when the lesion is significantly reduced by more than 50% or at least 5 mm from important structures; furthermore, the teeth of focus should be treated according to the relationship between the lesion and tooth and the type of tooth.

    Basic Study
    Biocompatibility of bone marrow mesenchymal cells on polyetheretherketone and titanium surfaces in vitro
    LIAN Keqian,ZHANG Xin,ZHOU Jieyu,LIAO Yanfen,SI Shanshan
    2020, 28(2):  73-78.  DOI: 10.12016/j.issn.2096-1456.2020.02.002
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    Objective To compare the in vitro biocompatibility of bone marrow mesenchymal cells on polyetheretherketone (PEEK) and titanium (Ti) surfaces. Methods PEEK and Ti foils with thicknesses of 1 mm and diameters of 10 mm were prepared. First, bone marrow mesenchymal cells were separated and purified by the whole bone marrow adherent culture method in vitro. Then, osteogenesis-induced bone marrow mesenchymal cells were cultivated on the surfaces of the PEEK and Ti foils. Scanning electron microscopy (SEM), the Alamar Blue test, an alkaline phosphatase (ALP) kit and Alizarin Red staining were used to analyze calcium nodules and compare the adhesion, proliferation and osteogenic differentiation ability of bone marrow mesenchymal cells on the surfaces of the PEEK and Ti foils. Results ① The morphology of the bone marrow mesenchymal cells cultured on the PEEK and Ti foils at 1 h, 4 h and 24 h showed no significant differences. ② In the 1 h, 3 h, 1 d and 3 d cultures of the bone marrow mesenchymal cells inoculated on the surfaces of the foils, the number of living cells in the PEEK group was greater than that in the Ti group (P < 0.05). ③ In the 7 d and 14 d osteogenesis-induced cultures of the inoculated bone marrow mesenchymal cells, the ALP activity of the PEEK group cells was significantly greater than that of the Ti group cells (P < 0.05). ④ Semiquantitative analysis after Alizarin Red staining showed that the mineralization degree of the bone marrow mesenchymal cells induced by osteoblasts was greater in the PEEK group than in the Ti group (P < 0.05). Conclusion PEEK has better in vitro biocompatibility than Ti and can better promote cell adhesion, proliferation and osteogenic differentiation compared with Ti, and so it is expected to become a new dental implant material.

    Influence of two kinds of zirconia primers on the bonding effect of zirconia ceramics
    Chen WANG
    2020, 28(2):  79-83.  DOI: 10.12016/j.issn.2096-1456.2020.02.003
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    Objective To evaluate the effect of two commonly used zirconia primers on the bond strength and durability of zirconia ceramics. Methods Zirconia wafers with a diameter of 5 mm and a thickness of 2 mm were cut and prepared by CAD/CAM (51). After sintering, sandblasting, ultrasonic cleaning and drying, the zirconia wafers are divided into three groups according to the types of zirconia primer: group A, no primer group; group B, Z-Prime plus; and group C, Clearfil Ceramic Primer, with each set containing 17 samples. The surface morphology of zirconia was observed by scanning electron microscopy after applying the coating primer according to the operation specifications. Then, the microshear bonding specimens were made, and the bonding strength was tested after water storage for 3 days and 5 000 × thermocycling. Results The surface of zirconia ceramics was roughened by sandblasting. After Z-Prime plus coating, the primer did not completely cover the zirconia surface, which is island like. After coating with the Clearfil Ceramic Primer, the primer was completely covered on the surface of zirconia ceramics without exposure to zirconia. Energy spectrum analysis showed that the content of C, O, Si and P in the coating area was relatively high. After primer coating, the bonding strength between zirconia and resin cement was significantly higher than that of group A (20.6 ± 2.1)MPa, P < 0.05, while there was no significant difference in the immediate bonding strength between group B (33.2 ± 3.9)MPa and group C (30.7 ± 2.4)MPa (P > 0.05). After 5 000 × thermocycling, the bonding strength of group A was(4.1 ± 2.5)MPa, that of group B was (23.1 ± 2.3)MPa and that of group C was (28.9 ± 2.6)MPa. There were statistically significant differences among groups A, B and C. The aging adhesive strength of groups A and B was significantly reduced compared with the immediate adhesive strength (P < 0.05). Group C had the highest bonding strength after aging (28.9 ± 2.6) MPa, with no significant difference before and after aging (P > 0.05). After 5 000 × thermocycling aging, the percentage of bonding failure in the fracture mode of group A increased from 66% to 100% and that of group B increased from 16% to 53%. In group C, the percentage of bonding failure increased from 20% to 24%. Conclusion The zirconia primers on the surface of zirconia ceramics after sandblasting can enhance the bonding strength and durability of zirconia.

    Cinical Study
    Comparison of the clinical effect of a facial-submental artery island flap in reconstruction after resection of oral cavity and oropharyngeal squamous cell carcinoma
    YUAN Kaifang,CHEN Weiliang,ZHOU Bin,ZHANG Daming
    2020, 28(2):  84-87.  DOI: 10.12016/j.issn.2096-1456.2020.02.004
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    Objective To compare the clinical effect of the reconstruction of defects of the surgical area with the facial-submental artery island flap (FSAIF) after resection of oral cavity squamous cell carcinoma (OC-SCC) and oropharyngeal squamous cell carcinoma (OP-SCC). Methods A total of 203 cases of oral cavity squamous cell carcinoma and 72 cases of oropharyngeal squamous cell carcinoma were treated with the FSAIFs. The complications and success rate of the two groups were observed. The swallowing and voice functions of the two groups were evaluated and compared 6 months after the operation. The survival of the two groups was followed up. Results No significant differences were found in TNM stage, the skin paddle of the flap, the rate of flap failure, or local complications between the OC-SCC and OP-SCC groups (P > 0.05). Significant differences in swallowing and speech outcomes were observed between the groups (P < 0.05). No significant differences were found in survival outcome between the groups after 9-59 months of follow-up. Conclusion FSAIF can be used for reconstructing the defect in oral cavity or oropharynx, but the swallowing function of reconstructing the defect in oropharynx is poor.

    Cone-beam computed tomography study of C-shaped root canal of mandibular premolars
    KONG Qianying,LIANG Lizhong
    2020, 28(2):  88-92.  DOI: 10.12016/j.issn.2096-1456.2020.02.005
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    Objective To investigate the incidence and morphology of C-shaped root canals in mandibular premolars by cone-beam computed tomography (CBCT) imaging, which provides a reference for clinical diagnosis and treatment. Methods The CBCT scanning data of 964 mandibular first premolars and 907 mandibular second premolars in 508 cases were collected, and the root canal morphology, incidence of C-shaped root canals, bilateral symmetry and location of radicular grooves were analyzed. Results The incidence of C-shaped root canals in mandibular first premolars was 4.1% and that in mandibular second premolars was 0.6%. The incidence of C-shaped root canals of mandibular first premolars was significantly higher than that of mandibular second premolars (χ 2=25.775, P < 0.001). The symmetrical ratio of C-shaped root canals in the mandibular first premolars was 29%. There were no symmetrical C-shaped root canals in the mandibular second premolars. There were significant differences in the distribution of the C-shaped root canal configuration in the root canal (P < 0.001). The C-shaped configuration mainly existed in the middle axial and apical level of the mandibular premolars. The C2 type was more common. No C-shape was found in the coronal level of the mandibular premolars. Vertucci I single tube type was the most common type of root canal for the mandibular premolars included in this study; the incidences were 81.7% and 98.3% for the mandibular first and second premolars, respectively, and the difference was statistically significant (χ 2=140.544, P < 0.001). The other root canal types of mandibular first premolars were more than those of mandibular second premolars. The incidences of Vertucci Ⅱ, Ⅲ, Ⅳ, and Ⅴ and C-shaped root canals in mandibular first premolars were significantly higher than those in mandibular second premolars. C-shaped root canal mandibular premolars had radicular grooves, and most of them were located at the mesiolingual side. Conclusion The morphology of the C-shaped root canal in mandibular premolars was complicated. CBCT can provide direct and accurate imaging evidence for clinical diagnosis and treatment.

    Prevention and Treatment Practice
    Malformation of Wharton′s duct with multiple sialoliths: a case report and literature review
    LI Ruichun,JING Kaian,WANG Lina,MA Rui,JING Jie,MA Jian
    2020, 28(2):  93-96.  DOI: 10.12016/j.issn.2096-1456.2020.02.006
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    Objective To explore the diagnosis and treatment of ductal malformations of the submandibular gland with multiple stones. Methods A case of a malformation of Wharton′s duct with multiple sialoliths according to the clinical data, diagnosis and treatment of the patient was analyzed retrospectively. Results The patient′s physical examination and CBCT showed a tumor on the left floor of the mouth. In this case, it was found that the mass was a malformation of Wharton′s duct with multiple sialoliths according to operative exploration. The postoperative pathological examination showed (left submaxillary) salivation gland tissue, duct dilation and duct epithelia hyperplasia, duct calculus, and a large number of lymphocytes proliferating around the duct; 1 month after the follow-up, the patient had healed well. Through literature review and analysis, it was found that cases of submandibular ductal malformation with multiple stones were rare and should be carefully differentiated from arteriovenous malformation at the base of the mouth. Calculi of the submandibular gland can be removed by incision through the oral submandibular duct or by combined resection of the submandibular gland and ductal calculi, and some smaller calculi can also be treated by endoscopy of the salivary gland. Conclusion In cases of submandibular ductal malformation with multiple stones, intraoral and extraoral incisions should be performed simultaneously to remove the associated ductal stones.

    Maxillofacial Rosai-Dorfman′s disease: a case report and literature review
    CHEN Yi,XIE Hongliang,TANG Jianming,WENG Rulian,FENG Li,ZUO Min
    2020, 28(2):  97-101.  DOI: 10.12016/j.issn.2096-1456.2020.02.007
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    Objective To explore the clinical manifestations, histopathological features, diagnosis, treatment and prognosis of Rosai-Dorfman′s disease (RDD) in the maxillofacial region and to review the relevant literature in order to improve the understanding, diagnosis and treatment of oral and maxillofacial RDD. Methods The clinical manifestations, histopathological features, diagnosis, treatment, and prognosis of a patient with RDD in the maxillofacial region admitted to Shenzhen People′s Hospital were analyzed, and the literature was reviewed for analysis. Results The clinical manifestations were palpable masses of 3.5 cm × 2.0 cm × 1.0 cm in the right cheek and 3.0 cm × 2.0 cm × 1.0 cm in the right submaxillary area, with clear boundaries, good mobility, medium and hard textures, respectively, no tenderness, smooth surfaces, and no obvious nodules. On contrast-enhanced and plain CT scans of the maxilla and neck, a diffuse soft tissue shadow was seen in the right maxillofacial region with an unclear boundary and uniform density, and the contrast-enhanced scan also showed moderate and uniform enhancement. The primary diagnosis was right maxillofacial lesions. The tumor was resected surgically. The pathological report was right buccal and right submaxillary extranodal RDD. Under light microscopy, nodular lesions in the fibrous fat tissue were found, which were composed of light and deep staining areas. The light staining areas consisted of patchy, polygonal cells with large volumes and rich cytoplasm, in which lymphocytes and neutrophils could be seen stretching into the movement; the deep staining areas were composed of lymphocytes and plasma cells. IHC: S-100 (+), CD68 (+), CD163 (+), CD1a (-), CD21FDC (+), langerin (-), IgG (+), IgG4 (+). No recurrence was found 11 months after the operation. RDD is a rare, benign and self-limited tissue and cell disease and consists of multiple lesions in the maxillofacial region. Its imaging features are similar to those of lymphoma. Its pathological features are large volumes, rich cytoplasm and phagocytosis of lymphocytes and plasma cells. Generally, RDD only needs to be observed, and individuals with symptoms or the involvement of important organs need to be treated; the first choice for the extranodal type is drug treatment, with radiotherapy administered if the central nervous system is involved. Surgery is recommended if involvement of important organs and compression of the trachea are observed; chemotherapy should be used for diffuse RDD. Most patients with RDD experienced relapse or remission of the disease; a few patients died because of the involvement of important organs or complications. Conclusion The clinical manifestations of maxillofacial RDD vary and lack specific imaging features, and pathological immunohistochemistry is the gold standard for diagnosis. The etiology is not completely clear, the treatment methods are varied, and the prognosis is related to the involved range of the disease.

    Review Articles
    Research progress on factors affecting bacterial adhesion on the oral implant surface
    ZHOU Wen,PENG Xian,CHENG Lei
    2020, 28(2):  102-106.  DOI: 10.12016/j.issn.2096-1456.2020.02.008
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    Reducing the adhesion of microorganisms and the formation of biofilms on implant surfaces can prevent peri-implant inflammation and optimize the long-term prognosis of implanted dentures. To provide theoretical support for the development of new materials or the modification of existing materials and the improvement of the success rate of implant repair, a literature review was conducted, which shows that the factors influencing bacterial adhesion on dental implant surfaces included the type of implant material, material roughness, nonspecific physical and chemical properties, the type of antibacterial coating, the components of the acquired membrane on the implant surface, the structure of the bacterial cell wall, etc. The current research direction of implant materials aims to reduce bacterial adhesion and promote bone bonding. However, there is no consensus on the physical and chemical properties of implants that meet this requirement. At present, the development trend in implant materials is guided by research of the “core microbiome” of peri-implant inflammation, based on study of the factors related to the adhesion of pathogenic microorganisms to the implant surface, which is organically combined with a variety of modification methods to change the surface-related properties of the implant materials and even to endow the implant with antibacterial properties to reduce or inhibit the adhesion of pathogenic bacteria to the implant.

    Research progress on trace elements-modified titanium implant surfaces
    CAO Zhiwei,YANG Yuqing,ZHOU Tao,WU Peiyao,XIE Liang
    2020, 28(2):  107-111.  DOI: 10.12016/j.issn.2096-1456.2020.02.009
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    Traditional titanium implants are bioinert, and some biological properties, such as osteogenic and antibacterial properties, can be obtained by adding different trace elements to their surfaces. These trace elements can help enhance implant-bone binding and effectively prevent peri-implantitis. Different trace elements have different advantages, and different modification methods can also affect the biological properties. In this paper, the biological properties of titanium implant surfaces modified by trace elements were reviewed. The results of a literature review show that implant surfaces modified by fluoride, silver, zinc, manganese, etc. can inhibit the growth of bacteria and reduce the negative impact on normal cells from bacteria. Other elements, such as strontium, tantalum and cobalt, can promote the differentiation of osteoblasts on the surface of titanium implants, improve the activity of alkaline phosphatase, and improve the expression of osteogenic genes, thus increasing the amount of bone formation and enhancing the strength of implant-bone integration. Most elements have multiple properties, and the combined application of two or more elements can yield more biological properties than a single element. Since there are many trace elements in the human body, there is still a wide research space available in the field of the surface modification of dental implants by trace elements.

    Influencing factors of functional orthopedic appliances on skeletal class Ⅱ malocclusion in adolescents
    WANG Huixia,LI Peilin,ZHAO Zhihe
    2020, 28(2):  112-117.  DOI: 10.12016/j.issn.2096-1456.2020.02.010
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    Functional orthodontics is one of the most important methods in the treatment of skeletal class II malocclusion in adolescents. A deep understanding of the many factors affecting the effect of functional orthopedics can improve the efficiency of correction and achieve good results. In this paper, from the two aspects of patients and appliances, we analyzed the factors that affect the curative effect of class II malocclusion functional orthopedics and deeply analyzed the therapeutic mechanism of functional appliances to guide clinical treatment. The results of the literature review show that the peak period of growth and development is the best period for the treatment of skeletal Class II malocclusion. For patients with a vertical growth type, it is recommended to use a high head cap traction appliance to prevent the lower jaw from rotating backward and downward, and functional appliances such as titanium plates or implant nail-assisted anchorage can effectively reduce the lip inclination of the lower anterior teeth. In addition, compared with the traditional functional appliance, digital and personalized transparent braces are not only more aesthetically pleasing, comfortable and beneficial to periodontal health but also have many orthopedic appliances advantages, such as two-stage fusion, better incisor torque and vertical control of the posterior teeth, and can solve the problems of anterior interference and lateral deficiency while leading. With the development of digital orthodontics, transparent appliances have become an important developmental direction for functional appliances, but there are few related studies, and more clinical studies are needed to confirm their efficacy.

    Application of Indocyanine green in visual treatment of oral cancer
    ZHANG Yu,JI Tong
    2020, 28(2):  118-122.  DOI: 10.12016/j.issn.2096-1456.2020.02.011
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    Indocyanine green (ICG) is a fluorescence indicator characterized by low trauma, a long effect time, low cytotoxicity, and high imaging resolution. It has been widely used in biomedical applications. However, ICG is not widely used in the treatment of oral cancer. This article reviews the application of ICG in the diagnosis and treatment of oral cancer. The results of a literature review showed that in the diagnosis and treatment of oral cancer, ICG mainly plays a role through the enhanced permeability and retention (EPR) effect of fluorescent substances and in coupling with various tumor-specific antibodies. For tumor visualization, ICG can focus on the primary tumor and lymph node metastasis by coupling the specific tumor antibodies and the EPR effect to guide the complete resection of the primary tumor and the determination of neck lymphadenectomy. In the reconstruction of the oral, head and neck regions, semi-quantitative measurement of ICG fluorescence intensity can be used to design a guide for a vascularized flap during the operation, for early detection of flap crisis after the operation, and to guide clinical flap exploration opportunities. In nonsurgical treatments of oral cancer, such as photothermal therapy and photodynamic therapy, ICG, as an important component of photosensitive nanomaterials, has attracted the attention of many scholars. ICG has good application prospects in the resection, reconstruction, visualization and nonsurgical treatment of oral cancer.

    Research progress on the relationship between enamel-related gene polymorphisms and caries susceptibility
    LIU Haotian,LI Huihui,LIU Shanshan
    2020, 28(2):  123-126.  DOI: 10.12016/j.issn.2096-1456.2020.02.012
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    Caries is a frequently occurring oral disease that is caused by chronic, progressive destruction of dental hard tissue. The enamel is the superficial layer of the tooth crown; enamel formation-related genes play an important role in the development of enamel, and enamel demineralization is a prerequisite for the occurrence of caries. Therefore, this paper reviewed the relationship between enamel-related gene polymorphisms and caries susceptibility and its possible mechanisms to provide new ideas for the prevention and treatment of caries. The results of a literature review showed that the gene polymorphisms related to enamel formation may increase or decrease susceptibility to caries by influencing the development and structure of enamel. For example, ENAM rs3796703 CT can increase the susceptibility to caries, and AMBN rs34538475 TT can reduce the susceptibility to caries. In the future, the detection and analysis of polymorphisms related to enamel formation that affect the structure or development of enamel may serve as a clinical method to evaluate the susceptibility of caries, which is of great significance for the early prevention and treatment of the disease.

    Application of dentin in bone tissue engineering
    XIAO Wenlan,HU Chen,RONG Shengan,ZHU Chenyou,WU Yingying
    2020, 28(2):  127-130.  DOI: 10.12016/j.issn.2096-1456.2020.02.013
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    Defects in oral hard tissue caused by various factors have a negative impact on the functional and aesthetic results of prosthetic treatment. In recent years, the usage of bone tissue engineering for bone reconstruction has drawn widespread attention. Bone tissue engineering exhibits significant advantages, including the abundance of building materials and few side effects. In this paper, the composition and structure of dentin and its application in bone tissue engineering are reviewed, providing a new way to further optimize its performance. The results of a literature review show that the structure of dentin is very similar to that of autogenous bone. The inorganic component is mainly hydroxyapatite (HA), while the organic component is mainly collagen I, noncollagenous proteins (NCPs) and growth factors. Because of its unique composition, dentin can act as a scaffold and/or growth factor source through different processing methods. The deproteinization process removes most of the organic substances and creates a HA-based scaffold material with high porosity, which allows for vascularization and cellular infiltration. Demineralization increases dentin porosity by reducing the crystallinity of the mineralized components, so that part of HA, collagen fibers and growth factors are preserved. Demineralized dentin possesses various regulation functions ranging from differentiation, adhesion and proliferation of primitive cells and bone forming cell lineage. Extracted NCPs, as bioactive molecules, have been proved to play important roles that control cell differentiation, crystal nucleation and mineralization in bone formation. NCPs could be combined with variety of scaffold materials and modify their properties.

    Progress in restorative treatments of primary incisor defects
    ZHANG Yunhan,DENG Xiaoyu,WANG Yan,ZOU Jing,ZHANG Qiong
    2020, 28(2):  131-136.  DOI: 10.12016/j.issn.2096-1456.2020.02.014
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    Dental caries and trauma are the most common oral diseases in children, which could result in defects of the teeth or detention. Maintenance of the primary dentition in a nonpathologic condition is important for oral health, craniofacial development, and the overall well-being of the children. In contemporary dentistry, primary anterior teeth defects are mainly treated with drugs, restorative treatments, or both. Restorative treatment is the most preferred method and includes direct restoration, full coronal restoration, post-and-core crowns, etc. This article reviews the available information regarding a variety of restorative treatments for primary incisor defects, including their backgrounds, clinical indications, clinical pathways, and related studies. The literature review shows that intraconal direct restoration is widely used on single surfaces. There are many kinds of full coronal restorations, and each has its own advantages. Pediatric resin-bonded strip crowns and zirconia crowns are the most popular and have excellent aesthetics. The use of post-and-core crowns for primary incisors is controversial. The absorbable post may be the next research hotspot. Therefore, treatment of severely destroyed primary incisors poses a challenge for pediatric dentists, as three important considerations must be kept in mind: children′s behavioral management, preservation of the tooth structure and parental satisfaction.