Table of Content

20 April 2019, Volume 27 Issue 4

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Expert Forum

Current status of dental implantation therapy for diabetic patients

SONG Yingliang,ZHANG Sijia

2019, 27(4):  205-211.  DOI: 10.12016/j.issn.2096-1456.2019.04.001

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In 2017, there were 451 million people (ages 18 to 99) with diabetes worldwide, and this number is expected to grow to 592 million by 2035. A series of complications in diabetic patients often leads to oral vascular and bone lesions. Therefore, dental implant doctors urgently need to understand the clinical characteristics of diabetes mellitus patients to provide the best treatment. For dental implant doctors, the following problems still exist in the treatment of diabetic patients with poor blood sugar control: ① alveolar fossa healing in diabetic patients is slow after extraction, and bone regeneration is often needed, which prolongs the treatment cycle and increases the pain of patients; ② the rate of new bone formation in diabetic patients after alveolar bone grafting is slow; ③ it takes a long time for the body to achieve effective bone bonding after dental implantation in diabetic patients, and the outcomes are poor; ④ the health of the tissue around dental implants is affected by blood sugar level, which is difficult to maintain in diabetic patients. Current studies suggest that the long-term success rate of implants is predictable in diabetic patients when blood sugar levels are well controlled (HbA1c < 6%). This article will review the current research status of dental implantation therapy for diabetic patients to provide a reference for clinical practice.

The applications of Nd：YAG laser and Er：YAG laser in endodontics

WEI Xi,LIU Hongyan,HAN Yuqing

2019, 27(4):  212-218.  DOI: 10.12016/j.issn.2096-1456.2019.04.002

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With the gradual maturity of laser technology, it has become widely considered a new method for disease treatment. Nd：YAG laser and Er：YAG laser are two representative solid-state lasers. These lasers are easy to use, comfortable and safe, and thus, they have recently become a research hotspot in dental treatment. Nd：YAG laser and Er：YAG laser have been used for the treatment of dentin hypersensitivity and dental caries, root canal therapy, pulp preservation and apical surgery. They are effective adjuvant methods for the treatment of dental pulp diseases and provide new avenues for clinical treatment. In this paper, the application of Nd：YAG laser and Er：YAG laser in the treatment of dental pulp disease is described to provide a reference for clinical treatment options.

Basic Study

Distribution of oral Streptococcus mutans and its correlation with dental caries in children of Bortala Mongolian Autonomous Prefecture

YANG Ting,ZHANG Wanting,LI Beibei,DONG Ying,CAO Hongfei,ZHAO Jin

2019, 27(4):  219-225.  DOI: 10.12016/j.issn.2096-1456.2019.04.003

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Objective To study the detection rate of Streptococcus mutans in oral cavities of 3-5-year-old Han, Uygur and Mongolian children in Bortala Mongolian Autonomous Prefecture, and the correlation between genotype and dental caries of preschool children.Methods Ninety children were randomly selected from the sample bank of children′s oral epidemiological survey data in the Bozhou area of Xinjiang. Forty-five children were included in the high caries group (more than 5 missing teeth), and 45 children were included in the noncaries group (0 missing teeth); each group comprised 15 children of each of the Han, Uygur and Mongolian nationalities. Plaque samples were collected and cultured with light saliva-bacillin agar medium and brain-heart infusion medium. Streptococcus mutans were cultured, and clinical isolates were further isolated and identified by Gram staining, biochemical identification and polymerase chain reaction. Genotype distribution was detected by random primer polymerase chain reaction.Results The detection rate of Streptococcus mutans in the 90 included children was 75.5%. The detection rate of Streptococcus mutans in the high caries group was 86.7%, which was significantly higher than that in the caries-free group (64.4%) (P=0.014). There was no significant difference in the distribution of Streptococcus mutans among Han, Uygur and Mongolian nationalities (P=0.457). A total of 549 clinical strains of Streptococcus mutans were obtained, and 113 different genotypes were found. In the high caries group, 61.5% carried more than one genotype of Streptococcus mutans, and 37.9% of the caries-free group had more than one genotype. The genetic polymorphism of Streptococcus mutans in the high caries group was significantly higher than that in the caries-free group (P=0.035). Spearman correlation analysis showed that there was a positive correlation between oral Streptococcus mutans gene polymorphism and caries sensitivity (r=0.258, P=0.034).Conclusion The distribution of Streptococcus mutans in children′s oral cavity in the Bozhou area was different between the high caries group and the caries-free group, but there was no difference among nationalities. Streptococcus mutans in the high caries group had more genotypes than those in the caries-free group. The genetic polymorphism of Streptococcus mutans might be related to the caries-causing ability of Streptococcus mutans.

Research on the inhibitory effect of Baicalin on the human tongue squamous cell carcinoma cell line SCC15

ZHONG Wende,LIU Rongjing,GUAN Hongbing,CHEN Guangsheng

2019, 27(4):  226-230.  DOI: 10.12016/j.issn.2096-1456.2019.04.004

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Objective To explore the inhibitory effect and possible mechanism of Baicalin on the human tongue squamous cell carcinoma cell line SCC15 and to provide a new idea and experimental basis for the clinical prevention and treatment of tongue squamous cell carcinoma.Methods SCC15 cells cultured in DMEM alone were used as the control group, and SCC15 cells cultured in 20 mg/mL baicalin solution were used as the baicalin group. Scratch tests and Transwell migration tests were performed to detect changes in cell migration ability, and flow cytometry was used to detect changes in the cell cycle. Western blotting was used to detect differences in the phosphorylation levels of signal transduction and transcription activator 3 (STAT3).Results Compared with the control group, the scratch test and the Transwell migration test showed that the cell migration ability of cells in the baicalin group was significantly decreased (t=4.927, P=0.008); flow cytometry showed that the number of cells of the baicalin group increased in the G0/G1 phase (t=9.893, P=0.001), decreased in the S phase (t=8.528, P=0.001), and decreased in the G2/M phase (t=3.550, P=0.024); Western blotting results showed that the STAT3 protein of SCC15 cells in the baicalin group decreased (t=3.550, P=0.024), and the phosphorylation level significantly decreased (t=8.262, P=0.001).Conclusion Baicalin inhibits the human tongue squamous cell carcinoma cell line SCC15, and its mechanism may be related to a decrease in STAT3 pathway phosphorylation activity.

Remineralization effect of nanohydroxyapatite on adjacent glazed surfaces

HU Beibei,BAI Hai,JIA Wanping,LIANG Yongqiang

2019, 27(4):  231-235.  DOI: 10.12016/j.issn.2096-1456.2019.04.005

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Objective To investigate the effect of a nanohydroxyapatite suspension with a 10% mass fraction on enamel demineralization after adjacent enamel removal and to provide a reference for the clinical use of nanohydroxyapatite to prevent enamel demineralization after adjacent enamel removal. Methods Forty fresh extracted premolars were incised from the coronal surface of the crown after glazing and polishing with sand strips. Each tooth was made into two specimens. Eighty teeth were randomly divided into four groups: a blank group, a dolofluoride group, a dental mousse group and a 10% nanohydroxyapatite group. After 30 days of pH cycling in vitro, a microhardness tester was used to detect the enamel surface elements before and after deglazing treatment. Scanning electron microscopy (SEM) and X-ray energy dispersive spectrometry (EDS) were used to analyze the enamel surface elements. Results After the experiment, the microhardness values of the adjacent glazed specimens of the four groups were (128.18 ± 6.89) kg/mm² in the blank group, (216.75 ±9.87) kg/mm² in the dolefluoride group, (198.88 ± 4.76) kg/mm² in the dental care group and (218.44 ± 7.88) kg/mm² in the 10% nanohydroxyapatite group, which were significantly different (F=189.14, P＜ 0.001). The LSD-t test showed that there was no significant difference between the dolefluoride group and the 10% nanohydroxyapatite group (P＜ 0.05), but the differences between the other groups were statistically significant (P > 0.05). There were significant differences in the Ca/P ratio among the blank group (1.39 ± 0.08), the dolefluoride group (1.70 ± 0.11), the dental care group (1.54 ± 0.12) and the 10% nanohydroxyapatite group (1.71 ± 0.14) (F=10.539, P＜ 0.001). There was no significant difference between the dolefluoride group and the nanohydroxyapatite group after the experiment (P > 0.05), but there were significant differences among the other groups (P＜ 0.05). Conclusion Dolerofluoride, dental protector and 10% nanohydroxyapatite can promote remineralization of enamel after enamel removal. The remineralization induced by 10% nanohydroxyapatite is similar to that induced by dolerofluoride.

Cinical Study

Study on the correlation between common diseases of oral mucosa and psychological factors

LIN Lin,DUAN Ning,WANG Xiang,SONG Yuefeng,WANG Wenmei

2019, 27(4):  236-240.  DOI: 10.12016/j.issn.2096-1456.2019.04.006

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Objective To explore the relationship between psychological factors and recurrent aphthous ulcer (RAU), oral lichen planus (OLP), and burning mouth syndrome (BMS) and to provide a reference for clinical diagnosis and treatment of the disease.Methods From July to October 2018, 50 patients with common RAU, refractory RAU, OLP and BMS were selected as the observation group, and 50 healthy participants without major systemic diseases and oral mucosal diseases matched for age and sex served as the control group. The psychological status of the subjects in each group was investigated by questionnaires, including the generalized anxiety disorder 7-item scale(GAD-7) and the patient health questionnaire-9 (PHQ-9).Results Compared with the control group, the PHQ-9 scores in the refractory RAU, common RAU, OLP and BMS groups were higher than those in the control group (P < 0.05), and the GAD-7 scores in the refractory RAU, OLP and BMS groups were higher than those in the control group (P < 0.05). In the RAU group, the GAD-7 score of intractable RAU was higher than that of common RAU (P < 0.05), and there was no significant difference in the PHQ-9 score (P > 0.05).Conclusion RAU, OLP and BMS are common psychosomatic diseases presented by patients in the Department of Oral Mucosal Diseases. Their occurrence and development are related to the psychological status of patients. A tendency toward anxiety is significantly more common among refractory RAU patients than common RAU patients.

Establishment and stress analysis of buccal-occlusal-lingual inlay finite element model of mandibular first molar

CHEN Jingping,WU Buling

2019, 27(4):  241-245.  DOI: 10.12016/j.issn.2096-1456.2019.04.007

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Objective To observe the stress distribution according to a model of the bucco-occluso-lingual (BOL) inlay of mandibular first molar after restoration to provide a basis for the clinical treatment of cracked tooth with BOL inlay.Methods A three-dimensional finite element model of mandibular first molar was established by combining micro-CT scanning technology with Mimics, UG, Ansys and Midas-FEA software. Based on this model, a BOL inlay restoration model was established. The material parameter of inlay IPS e.max CAD was given, and a Von-mises stress distribution nephogram under the same loading condition was obtained. The results of the stress distribution in each model were compared.Results The stress of intact teeth is mainly concentrated in the central fissure of the occlusal surface at the crown. The stress of the cavity after BOL inlay restoration is mainly concentrated in the mesial and distal walls of the cavity, the axial-pulpal line angle and the gingival wall. The stress of the inlay is mainly distributed at the bottom of the inlay, axial wall and the gingival wall.Conclusion BOL inlay restoration change the stress distribution in the complete dental model, which relieves the stress concentration in the fossa and groove of the occlusal surface and can play an active role in the treatment of cracked tooth.

Prevention and Treatment Practice

Comparison of the formation ability of two types of machine-made nickel-titanium instruments in simulated curved root canals

LI Tingting,JIANG Wei,PAN Yueping

2019, 27(4):  246-249.  DOI: 10.12016/j.issn.2096-1456.2019.04.008

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Objective To compare ProTaper Universal (PU) and M3-L instruments in preparing curved root canals and to provide a reference for clinical applications.Methods Twenty resin-simulated curved single root canals were randomly divided into two groups. Root canal preparation was performed with a PU nickel-titanium file or an M3-L nickel-titanium file. Root canal preparation time, root canal length before and after preparation and root canal deviation were recorded.Results In the M3-L group, the displacement measured at the 4th to 7th sites was less than that in the PU group (P < 0.05), but there was no significant difference between the other two groups (P > 0.05); The length of the root canal before and after root canal preparation in the M3-L group was （14.90 ± 1.92）mm and （14.57 ± 1.13）mm, respectively, and the difference between the two groups was not statistically significant (t=3.18, P=0.058). The root canal length before and after root canal preparation in the PU group was（14.53 ± 1.53）mm and （14.28 ± 1.39）mm, respectively. The difference between the two groups was not statistically significant（t=2.12,P=0.124）; The average preparation time of the M3-L group [（110.15 ± 10.43）s] was less than that in the PU group [（330.48 ± 12.62）s] (P < 0.05).Conclusion The M3-L nickel-titanium file has better central positioning ability and is less time-consuming than the PU nickel-titanium file in root canal bending preparation.

Mucoepidermoid carcinoma arising in Warthin’s tumor of the upper lip: a case report and review

ZHANG Ning,HU Yue,QIAO Chunyan,JI Xin,HAN Ruyu,SUN Lanfang,LI Minghe,HAN Chengmin

2019, 27(4):  250-254.  DOI: 10.12016/j.issn.2096-1456.2019.04.009

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Objective To provide a reference for the diagnosis and treatment of mucoepidermoid carcinoma arising in Warthin’s tumor of the lip by investigating the diagnosis, treatment and prognosis of the disease.Methods A case of mucoepidermoid carcinoma arising in Warthin’s tumor of lip was reported, including the clinical manifestation, treatment, pathological characteristics and prognosis. The related literature was also reviewed and analyzed.Results A painless mass on the left lip lasting more than one month was found. Resection of the left lip was performed. Pathological examination showed that the tumor was a hybridoma composed of mucoepidermoid carcinoma and Warthin’s tumor. There was no recurrence or distant metastasis after 34 months. To date, this type of disease has been rarely reported. After thorough resection, the prognosis and survival rate are promising in most cases, with no recurrence or metastasis.Conclusion Mucoepidermoid carcinoma in Warthin’s tumor of the lip is rare. Clinical manifestations, imaging features and histological examination are useful when diagnosing the disease. Thorough resection will reduce the risk of disease recurrence.

Review Articles

Research progress on the mechanism of radiocaries formation

WANG Zheng,CHENG Lei,ZHOU Xuedong,REN Biao

2019, 27(4):  255-259.  DOI: 10.12016/j.issn.2096-1456.2019.04.010

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Radioactive caries is the most common complication of head and neck cancer after radiotherapy. It is a rapidly progressing and widespread destructive disease of tooth tissue after radiotherapy. It is currently believed that salivary gland dysfunction and direct damage to teeth by radiation are the main pathogenic factors of radiation caries. In this paper, the pathogenesis of radiation caries, especially the effect of radiotherapy on oral caries-related microorganisms, are reviewed, and future research directions are proposed. Existing research has revealed that the structures of oral microorganisms change significantly after radiotherapy. The number and proportion of some dental caries-related microorganisms such as Streptococcus mutans, Lactobacillus lactis and Candida albicans increased, and their virulence increased. This indicated that the changes in oral microorganisms caused by radiotherapy played an important role in radioactive caries.

Research progress on early childhood caries

LI Zhenzhen,LIU Shanshan,ZHANG Kai

2019, 27(4):  260-263.  DOI: 10.12016/j.issn.2096-1456.2019.04.011

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Caries is a multifactor dynamic infectious disease with bacteria as the main factor and can affect the development of both deciduous teeth and permanent teeth. According to the fourth national oral health epidemiological survey, the prevalence rate of early childhood caries (ECC) in 5-year-old children reached 70.9%, showing an upward trend. Understanding the etiology and epidemiological characteristics of ECC is of great significance in preventing the occurrence and development of ECC. This article reviews the epidemic status, etiology and related factors of ECC. The results of a literature review show that the prevalence of ECC in China is high and regional differences are large. The main related factors include biological factors, behavioral habits factors, social and economic factors, etc.

Research progress on the function and metabolism of d-alanine in bacteria

GUO Xiao,DU Xinmei,CHENG Lei,ZHOU Xuedong,LI Mingyun

2019, 27(4):  264-267.  DOI: 10.12016/j.issn.2096-1456.2019.04.012

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D-alanine is a chiral molecule of L-alanine that participates in the formation and regulation of cell wall peptidoglycans, phosphoteichoic acid, spore germination and respiratory metabolism in individual bacteria. D-alanine participates in the formation and regulation of biofilm in bacterial communities. The function and metabolism of D-alanine in bacteria are specific, and the enzymes and genes in its metabolic pathway can be used as drug targeting sites. In this paper, the synthesis, metabolism and function of D-alanine in bacteria were reviewed, and the relationship between D-alanine and pathogenicity of Streptococcus mutans was discussed to provide a theoretical basis for candidate targeting sites of anti-caries drugs. According to existing research results, the enzymes and related genes involved in D-alanine metabolism play important roles in the growth and biofilm formation of Streptococcus mutans, and D-alanine is expected to be a target for the design of anti-caries drugs.

Research progress on the factors influencing the biological characteristics of dental pulp stem cells

HU Huiting,YU Fenglin,ZHAO Yueping

2019, 27(4):  268-272.  DOI: 10.12016/j.issn.2096-1456.2019.04.013

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Dental pulp stem cells (DPSCs) are mesenchymal stem cells derived from dental pulp tissue with self-renewal, high proliferative capacity and multidirectional differentiation potential. Under appropriate induction conditions, DPSCs can be differentiated into various types of cells, such as osteoblasts, odontoblasts, chondrocytes, adipocytes, and neuronal cells. DPSCs have been gradually applied to clinical trials and preclinical studies and are important seed cells in the field of periodontal tissue engineering and regenerative medicine. In this paper, the factors affecting the biological characteristics of DPSCs are reviewed together with a review of recent literature published worldwide. The results of the literature review show that the biological characteristics of DPSCs can be influenced by many factors, such as tissue source, culture method, environment and induction conditions, which has guiding significance for research and applications of DPSCs.