Table of Content

20 June 2019, Volume 27 Issue 6

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Expert Forum

Gingival recession and minimally invasive tunnel technique

Fuhua YAN,Lingjun LI

2019, 27(6):  341-349.  DOI: 10.12016/j.issn.2096-1456.2019.06.001

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Gingival recession (GR) is characterized by exposure of the root surface into oral environment due to apical migration of the marginal gingiva to the cementoenamel junction (CEJ). A high prevalence of GR has been reported in several representative population samples. GR may result in a certain degree of functional and aesthetic alterations if left untreated for long periods. In severe cases, root-dentin hypersensitivity, abrasion, abfraction and root caries may also be involved in GR, which increases the challenge of plaque control. The etiology of GR is multifactorial, including periodontal disease, local anatomical variation, tooth malposition, improper tooth brushing, mechanical trauma and iatrogenic factors, of which periodontal disease is the most common cause. The treatments of GR consist of nonsurgical and surgical therapy, and the latter generally involves mucogingival surgery to restore the aesthetics and function of the local gingival recession. However, over the past 50 years, the periodontal plastic surgical technique has evolved from the traditional free gingival graft method into a more advanced, minimally invasive tunnel technique. For this technique, sulcular incisions instead of vertical relieving incisions are provided through each recession area, and full thickness mucoperiosteal flaps are created and extended beyond the mucogingival junction to facilitate coronal displacement. Each pedicle adjacent to the recession is gently undermined to create a tunnel at recipient site, where either autograft or allograft can be used. A minimally invasive tunnel technique is a better method for root coverage and reduced postoperative patient discomfort. This technique is characterized by both practical and aesthetic features.

Basic Study

Mitochondrial fission protein 1 determines mitochondrial fission and cisplatin sensitivity in tongue squamous cell carcinoma

Xinyuan LEI,Xinyu LIN,Zhanpeng OU,Yi RUAN,Jinsong LI

2019, 27(6):  350-354.  DOI: 10.12016/j.issn.2096-1456.2019.06.002

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Objective To investigate the effect of mitochondrial fission protein 1 (FIS1) on apoptosis and cisplatin resistance in tongue squamous cell carcinoma (TSCC) cells. Methods The squamous cell carcinoma cell lines SCC9 and CAL27 were used to detect the mRNA and protein levels of FIS1 after cisplatin treatment, the knockdown and overexpression of FIS1 of SCC9 and CAL27 with or without cisplatin treatment were accomplished through small interfering RNA (siRNA) and plasmid, respectively. The mitochondrial division state in cells was detected by mitochondrial staining, and the apoptosis state of cells was detected by TUNEL, flow cytometry and Caspase 3/7. Results FIS1 protein expression in tongue squamous carcinoma cells treated with cisplatin was increased, but the mRNA level did not change. Silencing of FIS1 expression reduced mitochondrial division and apoptosis in squamous cell carcinoma cells treated with cisplatin, whereas overexpression of FIS1 exhibited the opposite effects. The percentage of dividing mitochondria, the number of apoptotic cells and the activity of Caspase 3/7 in SCC9 and CAL27 cells were significantly different before and after modulation of FIS1 expression (P < 0.05). Conclusion FIS1 is involved in the regulation of cisplatin chemotherapy sensitivity in tongue squamous cell carcinoma and can be used as a new target for improving the sensitivity of cisplatin chemotherapy in oral squamous cell carcinoma.

The role of APOD in the proliferation and migration of human dental pulp cells

XU Shuaimei,ZENG Xiongqun,YUAN Peiyan,LIU Zhongjun,ZENG Shuguang

2019, 27(6):  355-359.  DOI: 10.12016/j.issn.2096-1456.2019.06.003

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Objective To explore the role of apoliprotein D (APOD) in the proliferation and migration of human dental pulp cells (DPCs) and to provide a basis for the use of APOD to promote pulp regeneration. Methods APOD expression in human dental pulp cells was inhibited by siRNA. The inhibition effect of APOD was confirmed by qPCR and Western blot. After APOD inhibition, colony formation experiments and CCK8 assays were employed to confirm the proliferation ability of dental pulp cells. Transwell assays were used to verify the cell migration ability after the inhibition of APOD expression. Results After inhibiting APOD expression, the colony formation rate in the si-apod group was reduced compared with the NC group, and the difference was statistically significant (t=7.624, P=0.002). The CCK8 experiment showed that the OD value in the si-apod group decreased at 3, 5 and 7 d compared with that in the NC group (P < 0.05). Transwell results showed that the number of cell divisions was 57.25 ± 4.03 in the si-apod group and 154.50 ± 8.39 in the NC group, and the difference was statistically significant (t=10.45, P < 0.001). Conclusion Inhibition of APOD expression in dental pulp cells inhibits their proliferation and migration ability.

Expression of NF-κB in oral squamous cell carcinoma and paracancerous tissues and its significance

GUI Xinwei,YAO Xiaowu,CHEN Shisheng,LU Zizheng,LIN Minxiao,PENG Yu

2019, 27(6):  360-364.  DOI: 10.12016/j.issn.2096-1456.2019.06.004

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Objective To investigate the expression and significance of NF-κB in oral squamous cell carcinoma and paracancerous tissues. Methods Cancerous and paracancerous tissues about 5 mm outside the tumor boundary were cut from 47 patients with OSCC. NF-κB expression in these tissues were detected by the immunohistochemical SP method and compared with that in 32 normal oral mucosa tissues. Results The average optical density (OD value) of immunohistochemical-positive cells in cancer tissues and paracancerous tissues was higher than that in normal tissues, and the difference was statistically significant (P < 0.001). There was no significant difference in the OD values between cancer tissues and paracancerous tissues (P=0.356). The rate of NF-κB positive expression in cancer tissue and paracancerous tissue was significantly higher than that in normal mucosa tissue, and the difference was statistically significant (P < 0.001). There was no significant difference in the rate of NF-κB positive expression between cancer tissues and paracancerous tissues (P=0.117), but the rate of moderate-to-strong positive expression in cancer tissues was significantly higher than that in paracancerous tissues (P < 0.001). Conclusion NF-κB may be involved in the development of OSCC.

Effects of Porphyromonas gingivalis infection with different fimA genotypes on the secretion of IL-1β, IL-6, and TNF-α by human umbilical vein endothelial cells

Shuyu CAI,Xiaoyue LIN,Jin LEI,Song GE

2019, 27(6):  364-369.  DOI: 10.12016/j.issn.2096-1456.2019.06.005

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Objective To study the effects of Porphyromonas gingivalis (P. g) infection with I, II and IV fimA genotypes on the expression of IL-1beta, IL-6 and TNF-alpha in human umbilical vein endothelial cells (HUVECs). Methods HUVECs infected with different fimA genotypes were divided into the fimA type I stimulation group, fimA type II stimulation group, fimA type IV stimulation group. In addition, a positive control group (E. coli LPS stimulation) and negative control group (cell culture medium only) were included. Cell proliferation was detected by MTT assay, and cell apoptosis was detected by flow cytometry. IL-1β, IL-6, TNF-α levels in the supernatant of HUVECs after P. g stimulation were assessed by ELISA at 2 h, 6 h and 24 h. Results HUVECs were infected by P. g with fimA type I,fimA type II and LPS for 24 h. Cell proliferation was inhibited compared with the negative control group (P < 0.05), but there was no significant difference in the apoptosis rate between P. g infection and the negative control group. IL-1β levels in cell culture supernatants were higher at 2th than 6 and 24 h after stimulation of HUVECs with different fimA genotypes, while the IL-6 levels were higher at 24 h than the other time, while the TNF-α levels were no significant difference at every time. After fimA type II and IV P. g infection, IL-1β, IL-6, and TNF-α levels were increased compared with fimA type I P. g (P < 0.05). Conclusion Different P. g fimA genotypes have different effects on stimulating HUVECs to induce dysfunction. Here, fimA type II and IV P. g exhibit a strong ability to upregulate the secretion of IL-1β, IL-6 and TNF-alpha.

Cinical Study

Clinical analysis of vitamin B₁₂ deficiency mainly manifested by recurrent aphthous ulcers

MENG Wenxia,FENG Lu,ZI Yunling,JIANG Liyi,LI Juxiong,ZHOU Zhen

2019, 27(6):  370-374.  DOI: 10.12016/j.issn.2096-1456.2019.06.006

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Objective To analyze the clinical characteristics and treatment experience of Vitamin B₁₂ (VB₁₂) deficient patients with recurrent aphthous ulcers (RAU) to improve the clinical efficacy. Methods A retrospective analysis was performed on 15 cases of recurrent oral ulcers from January 2016 to September 2018. The causes were analyzed according to the patients’ clinical characteristics. Results In total, 15 patients with RAU had no remission after routine immunotherapy. Further clinical examination suggested that vitamin B₁₂ levels were reduced. The erythrocyte mean corpuscular volume (MCV) was significantly increased, and the average number of red blood cells (RBC) and hemoglobin (Hb) levels were decreased. RAU disappeared after vitamin B₁₂ supplementation. Routine blood work showed that the MCV returned to the normal range, which was statistically significant compared with the pretreatment MCV (P < 0.001). Vitamin B₁₂ serum levels were significantly higher (P < 0.001) than those before treatment. Conclusion When the main manifestation of vitamin B₁₂ deficiency is recurrent oral ulcer symptoms, dentists should examine the lesions carefully, inquire about the medical history in detail, and perform further serological tests when necessary to avoid the overuse of immunosuppressive drugs for treatment.

Study on soft tissue changes of angle class Ⅱ division Ⅰ mandibular retraction patients during mixed dental period with MRC functional correction

You HUANG,Dongping YAO,Shijun LU,Yongchu PAN,Lin WANG

2019, 27(6):  375-380.  DOI: 10.12016/j.issn.2096-1456.2019.06.007

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Objective To observe the changes of soft tissue in patients with Angle class Ⅱ division Ⅰ malocclusion during mixed dentition treated with MRC functional appliance. Methods Twenty patients with Class Ⅱ division Ⅰ malocclusion of Angle were treated with functional MRC. The facial features before and after treatment were measured by software and the results were analyzed statistically. Results The patients′soft tissue profiles were improved significantly before and after treatment, The OE-Prn-Pos angle, OE-N′-B′ angle, OE-N′-Pos angle, OE-Prn-N′angle, Cm-Sn-UL angle, and N′-Sn-Pos angle increased significantly (P < 0.05). The OE-Sn-UL angle, and Sn-N′-B′ angle decreased significantly (P < 0.05); the distance between the lateral soft tissue line and the middle Sn-H line, UL-E line and LL-E line were significantly different (P < 0.05). The distances were all reduced, and the difference was statistically significant (P < 0.05). Conclusion The application of an MRC functional appliance can improve the relationship among nasolabial soft tissue, upper and lower lip soft tissue, and chin-lip soft tissue, thus improving the protrusion profile of patients.

Prevention and Treatment Practice

CBCT study on root and root canal morphology of maxillary second permanent molars in the Guangfu population in the Lingnan area

Qi LI,Shaohong HUANG

2019, 27(6):  381-386.  DOI: 10.12016/j.issn.2096-1456.2019.06.008

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Objective To research the root and root canal morphology of maxillary second permanent molars in the Guangfu population of the Lingnan area. Methods A total of 1220 maxillary second permanent molars were collected from the 723 CBCT images of the Guangfu population. The root and root canal configurations were observed and counted, and the morphological characteristics and changes were compared and analyzed. Results The maxillary second permanent molars included 709 three-root molars, 417 double root molars, 68 single root molars and 26 four-root molars. The difference in the detection rate of each root type in different sex and age groups was not statistically significant (P > 0.05). Root canal morphdogy of maxillary second permanent molars: type Ⅷ (3-3) was the most common type of root canals in single root molars, accounting for 63.25%. Significant differences in the detection rates of canal configurations were noted among the three subtypes of fused root canals in double root molars (P < 0.01). Root canal morphology of the mesiobuccal root of the three-root molars was mainly typeⅠ (1-1), significantly accounting for 78.84%. Significant sex and age differences were noted in the detection rate of type Ⅰ and Ⅳ root canals (P < 0.01). In addition, 75.86% of maxillary second permanent molars had symmetrical roots, and 73.64% of the bilateral teeth had symmetrical roots and canals. Conclusion The root and root canal morphology of maxillary second permanent molars in the Guangfu population in the Lingnan area are different compared with other areas at home and abroad.

Study on the application of cone-beam CT in root canal morphology of first deciduous molars

MA Xiangyu,LI Jianhua,PENG Hongda,MA Keyuan,ZOU Jing,WANG Yan

2019, 27(6):  387-390.  DOI: 10.12016/j.issn.2096-1456.2019.06.009

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Objective To analyze the number, distribution of root canals in children's first deciduous teeth through a retrospective study of cone-beam computed tomography (CBCT). Methods A total of 185 first deciduous molars were selected from 91 children aged 4 to 8 years old in the Stomatology Department of Mianyang Hospital of Traditional Chinese Medicine. The number, distribution of root canals were analyzed. Results All 46 maxillary first deciduous molars had three roots; 139 mandibular first deciduous molars had two roots (77.70%) and three roots (22.30%). The root canals of all maxillary first deciduous molars are type Ⅰ, while the main root canal type of mandibular first deciduous molars is type Ⅳ. Of 51 children with bilateral mandibular first deciduous molars, 48 (94.12%) had symmetrical root and canal distributions. Conclusion The first deciduous molars usually have 2 to 3 roots. Root canals are mainly type I and IV. The distribution of root canals is symmetrical.

Review Articles

Research progress on the influencing factors of dental fluorosis

Jiaxin DENG,Yuan CHEN,Zhuohui FU,Yan WANG

2019, 27(6):  391-395.  DOI: 10.12016/j.issn.2096-1456.2019.06.010

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Dental fluorosis is a kind of enamel hypoplasia caused by excessive fluorine intake during tooth development, leading to the formation of enamel with a lower mineral content and increased porosity, which can affect dental function and patients′ appearance. The prevalence of dental fluorosis remains high on a global level, and its occurrence is affected by many factors. Excessive fluorine intake is a major risk factor for dental fluorosis. The ways of fluorine intake mainly includes the application of fluorides, daily diet and air. Since fluorides have been widely used in the prevention of caries in recent decades and the methods of exposure to fluorine have been increasing, increasing numbers of studies have been conducted to explore how fluoride can achieve a balance between the effective prevention of caries and the prevention of dental fluorosis. In addition, exposure to fluorine at earlier ages can also increase the risk of dental fluorosis, while the improvement of nutritional structure can affect dental fluorosis prevention. Genetic susceptibility, socioeconomic status and parental awareness may influence dental fluorosis. This article aimed to review the latest research progress on the factors influencing dental fluorosis and provide a reference for the prevention and treatment of dental fluorosis.

The effects of the Sp and Wnt genes on abnormalities in embryonic developmental and cleft lip and palate

Zhongwei CHENG,Qinggao SONG

2019, 27(6):  396-399.  DOI: 10.12016/j.issn.2096-1456.2019.06.011

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Normal embryonic development is regulated by different genes and related signaling pathways. In recent years, the association between different genes and genes, genes and signaling pathways in the same organization has been widely concerned by scholars at home and abroad. Sp and Wnt gene deletion or mutation can lead to abnormal embryonic development. The results of this review indicate that abnormal embryonic development is due to Sp gene deletion/mutation The zinc finger protein superfamily member Sp1-9 is involved in the development of various tissues and organs , such as the hematopoietic system, respiratory system and skeletal system, and its deletion or mutation can lead to developmental abnormalities in embryonic tissues. In addition, the Sp8 gene is associated with the occurrence of cleft palate. By summarizing the observations about the relationship between the Wnt gene and cleft lip and palate in recent years, we can understand the abnormal expression of Wnt3, Wnt3A, Wnt5A, Wnt9B, Wnt10A and Wnt11 in humans. The occurrence of cleft lip and palate is closely related; Sp5/8 is a key downstream effector of the Wnt signaling pathway during embryonic development and participates in the Wnt signaling pathway. Sp5/8 and the Wnt signaling pathway are involved in the regulation of normal neural crest development and the self-renewal of embryonic stem cells in embryonic mice. In summary, this paper proposes that the Sp and Wnt genes may be involved in the regulation of the formation and occurrence of embryonic cleft palate and provides a reference for further study of the associated mechanisms between the two genes in the cleft palate model.

Advances in epigenetic changes induced by pathogenic factors of oral diseases

Yushu REN,Xiaoping LIN

2019, 27(6):  400-403.  DOI: 10.12016/j.issn.2096-1456.2019.06.012

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The oral cavity is a complex and complete ecosystem. In addition to the microbial community, anatomical structure, temperature, humidity, pH, nutrient sources, proteases, and external factors all influence the ecosystem. Under normal circumstances, this ecosystem maintains a dynamic balance with the host. However, due to the large number of influencing factors, this dynamic balance is fragile. Abnormal changes in a certain factor can disrupt this balance and cause oral cavity disease. Increasing studies have confirmed the role of genetic factors in the etiology of oral diseases. With the understanding of the pathogenesis of oral diseases, the pathogenic factors induced by oral diseases have attracted more attention. This article reviews the key role of epigenetic changes induced by pathogenic factors, such as bacteria, viruses, and cytokines, in the pathogenesis of oral diseases and contributes to the development and application of related drugs.

Effect of root canal irrigants on the bond strength between resin sealants and dentin

Chang LIU,Yali LIU,Xia LI

2019, 27(6):  404-408.  DOI: 10.12016/j.issn.2096-1456.2019.06.013

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When the root canal is filled, the use of the adhesive resin-based sealant to form a strong bond with the dentin reduces microleakage of the apex, enhances the bending resistance of the tooth, and resists the mechanical damage of the pile preparation, thus improving the success rate of root canal treatment. However, during root canal treatment, the use of a rinsing agent may change the tissue structure of the dentin and the wettability of the dentin, thereby affecting the bonding strength between the resin sealing agent and the dentin. In this paper, the effects of a traditional root canal irrigant and several new rinsing agents on the bonding strength of resin sealant and dentin are reviewed. The results show that the traditional root canal rinsing agent NaClO is reduced as the final rinsing agent. The bonding strength of resin sealant to dentin; EDTA affects the biomechanical properties of root dentin, and the removal efficiency is low, which will affect the bond strength between the resin sealant and dentin. EDTA combined with NaClO as a final rinsing agent can improve the bonding strength. Chlorhexidine can also increase the bonding strength between the blocking agent and dentin and can be used as the final rinsing agent. The new rinsing agent MTAD has a negative impact on the resin sealing agent and dentin bond strength. QMix and maleic acid remove smear efficiency with dentin bond strengths greater than or equal to EDTA and can replace EDTA as the final rinse.