Table of Content

20 July 2019, Volume 27 Issue 7

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Expert Forum

Difficulties and prevention and management of serious complications in surgical treatment of osteoradionecrosis of jaw

HOU Jinsong,ZHANG Yadong

2019, 27(7):  409-416.  DOI: 10.12016/j.issn.2096-1456.2019.07.001

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Osteoradionecrosis of the jaw (ORNJ) is a common complication after radiotherapy for head and neck malignant tumors. Surgery is the main treatment method for ORNJ with large lesions. In the case of serious maxillofacial and cervical soft and hard tissue damage caused by radiation, surgical treatment may have some difficulties and risks. In this paper, we discuss the main points for indication selection and treatment as well as surgical difficulties and their causes, including local inflammation and radiation injury during the operation, timing of bone defect reconstruction, condylar preservation, selection of recipient vessels, implant bed treatment, common complications of ORNJ operations (i.e., wound healing and nerve injury), severe complications (i.e., vascular crisis and tissue flap necrosis), pulmonary infection, cerebral pulmonary embolism, important vascular rupture, and severe psychological trauma, including its prevention and treatment. This information will enable clinicians to fully understand the various difficulties and risks that may be encountered during the ORNJ operation and will minimize serious complications, ensure the life, health and safety of the patients, and provide a reference for improvement of the clinical efficacy of ORNJ treatment.

Basic Study

Screening and identification of mitochondrial miRNAs related to chemotherapy resistance in tongue squamous cell carcinoma

Xinyu LIN,Weixiong CHEN,Xinyuan LEI,Zhanpeng OU,song FAN,Jinsong LI

2019, 27(7):  417-422.  DOI: 10.12016/j.issn.2096-1456.2019.07.002

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Objective To investigate the differential expression of mitochondrial microRNAs (mitomiRs) in tongue squamous cell carcinoma (TSCC) and to screen out mitomiRs related to chemotherapy resistance. Methods Mitochondrial, cytoplasmic, and total cellular RNAs were extracted from the squamous cell carcinoma cell line CAL-27 and the cisplatin-resistant cell line CAL-27-re. High-throughput miRNA microarrays were used to screen for differentially expressed mitomiRs between the drug-resistant and parental cells. The upregulated mitomiRs in the CAL-27 and CAL-27-re cells and in samples from chemoresistant and chemosensitive tongue squamous cell carcinoma patients were verified by qRT-PCR. Results The microarray detected 263 miRNAs in 6 components of the mitochondrial, cytoplasmic and total cellular RNAs from the CAL-27 and CAL-27-re cells, including 57 mitomiRs and 134 cytoplasmic microRNAs (cytomiRs). Compared with the total miRNAs, 35 mitomiRs were upregulated in the CAL-27-re cells, and 31 mitomiRs were upregulated in the CAL-27 cells (≥ 1.5-fold). Further comparative analysis of mitomiRs that were differentially expressed between the parental and drug-resistant cells identified 11 upregulated mitomiRs (miR-2392, miR-4462, miR-1290, miR-4449, miR-1268a, miR-1246, and miR-371a-5p, miR-3934-5p, miR-4271, miR-513p, and miR-664b-3p) and 5 downregulated mitomiRs (miR-188-5p, miR-1973, miR -3653, miR-4499, and miR-5787); the expression levels of the other 41 mitomiRs were almost identical in both cell lines. The qRT-PCR results were consistent with the miRNA microarray results. The 11 upregulated mitomiRs that were validated between the CAL-27 and CAL-27-re cells included miR-1268a, miR-2392, miR-4462, and miR-1290. Additionally, 5 mitomiRs, including miR-4449, were upregulated in the clinical chemotherapy-resistant tongue squamous cell carcinoma samples. Conclusion Differentially expressed mitomiRs were found between cisplatin-resistant and cisplatin-sensitive tongue squamous cell carcinoma cells. mitomiRs with high expression levels (miR-2392, miR-4462, miR-1290, miR-4449 and miR-1268a) may play important roles in the drug resistance of tongue squamous cell carcinoma.

Effect of arecoline on SD rat survival after buccal mucosal biopsy

Bo YANG,Mengfan FU,Zhangui TANG

2019, 27(7):  423-427.  DOI: 10.12016/j.issn.2096-1456.2019.07.003

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Objective To provide an experimental basis for predicting the sample size needed for animal experiments by studying the survival of SD rats after buccal mucosal biopsy with arecoline administered at different concentrations with different methods. Methods In all, 48 rats were divided into 8 groups, with 6 in each group, as follows: rats in groups A-D were treated with arecoline at different concentrations (0, 0.5, 2, 8 mg/mL); rats in groups E-H were treated with arecoline at different concentrations (0, 0.5, 2, 8 mg/mL), followed by stimulation of the buccal mucosa by mechanical rubbing. After 16 weeks, a 6-mm-diameter sample of the buccal mucosa was collected, and the wound was closed with interrupted sutures. The survival time of the rats was recorded, and the relationship between the survival time and the concentration of arecoline and mechanical stimulation was analyzed. Results No rats died during the first 16 weeks after treatment or after biopsy. The success rate of the arecoline stimulation model was 66.7%. The average observation time of all SD rats after biopsy was 42.5 days. Up to 120 days after biopsy, the cumulative survival rate in the eight groups was 50%, 33%, 17%, 0%, 33%, 17%, 0% and 0%, respectively (in alphabetical order). The cumulative survival rate in the groups administered 0 mg/mL (groups A and E), 0.5 mg/mL (groups B and F), 2 mg/mL (groups C and G), and 8 mg/mL (groups D and H) was 42%, 25%, 8% and 0%, respectively. Cox survival analysis showed that moderate and high concentrations of arecoline (2, 8 mg/mL) significantly affected the survival duration (P < 0.05), while mechanical stimulation had no significant effect on the survival duration (P > 0.05). The chi-squared test showed that the survival rate of rats showing wound healing (33.3%) was significantly higher than that of rats showing incomplete wound healing (0.0%) (P=0.003). Conclusion The success rate of the rat buccal submucosal fibrosis model was higher than moderate and high concentrations of arecoline, but the survival duration was significantly reduced after biopsy. Mechanical stimulation did not lead to a significant decrease in the survival duration, and impaired wound healing may be a cause of death in this model.

Expression of the receptor of advanced glycation end products in gingival tissue endothelial cells from type 2 diabetic rats with chronic periodontitis

Gang WANG,Peng SUN,Juan LI,Shiguang HUANG

2019, 27(7):  428-434.  DOI: 10.12016/j.issn.2096-1456.2019.07.004

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Objective To evaluate the expression of the receptor for advanced glycation end products (RAGE) in gingival tissue endothelial cells from type 2 diabetic rats with chronic periodontitis and to explore the role of RAGE in the pathogenesis of diabetes in cases with chronic periodontitis. Methods Sixty 7-week-old female Wistar diabetic obese rats were randomly divided into two groups. Periodontitis was induced in 30 rats by silk ligation, and the other 30 rats were used as the control group in which the periodontal tissues were not treated. One week after periodontal ligation and inoculation, the periodontitis and control group rats were randomly divided into two subgroups; the first subgroup was fed a high-fat diet, and the second group was fed a low-fat diet. Thus, 15 rats per group were included in the high-fat diet periodontitis (HF/P), low-fat diet periodontitis (LF/P), high-fat diet periodontal health (HF/C), and low-fat diet periodontal health (LF/C) groups. Glucose tolerance tests were performed weekly to measure the fasting insulin and blood glucose levels and the insulin resistance index to verify successful construction of the rat diabetes model. After successful modeling of chronic periodontitis, the rats were sacrificed at the 13th week after measurement of the serum necrosis factor-α (TNF-α), interleukin-6 (IL-6) and leptin levels. The tooth periodontal tissues were prepared and sectioned to observe histological changes. Immunofluorescence double staining was used to detect the density of RAGE-positive endothelial cells in the gingival tissues of the four groups. Results The serum fasting blood glucose and insulin levels and insulin resistance index were significantly higher in the HF/P and HF/C groups than in the LF/P and LF/C groups (P < 0.01). The serum TNF-α and IL-6 levels were significantly higher in the HF/P and LF/P groups than in the HF/C and LF/C groups (P < 0.01). The serum leptin levels were significantly higher in the HF/P group than in the other three groups. The density of RAGE-positive endothelial cells was significantly higher in the HF/P and HF/C groups than in the LF/P (P=0.001) and LF/C groups (P=0.040). The density of RAGE-positive endothelial cells in the HF/P group was higher than that in the HF/C group (P=0.027). Conclusion Endothelial cells in type 2 diabetic rats with periodontitis have increased gingival tissue RAGE and serum leptin levels.

Effect of laser-etched pure titanium surface on early proliferation of MG63 cells

Zehong GUO,Yingyuan NING,Shulan XU,Peijun ZHU,Xianglong DING,Yan GAO

2019, 27(7):  435-440.  DOI: 10.12016/j.issn.2096-1456.2019.07.005

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Objective To investigate the effect of a laser-etched pure titanium surface on proliferation of the human osteosarcoma cell line MG63 and to provide a basis for study of implant surface modification. Methods The pure titanium plate was cut into titanium pieces by a numerical control machine tool and divided into smooth surface and laser etching groups. The titanium surface of the laser etching group was etched with an Nd:YAG continuous wave laser using predetermined parameters, and the surfaces were observed by scanning electron microscopy (SEM). The surface micromorphology of each titanium sheet was evaluated. The relative element content of the titanium surface was measured by energy dispersive X-ray spectroscopy (EDS). The Ra value of each surface was determined using the Veeco roughness tester. MG63 cells were inoculated on 2 sets of titanium tablets. At 1, 3, and 6 h postinoculation, cell adhesion to the two groups of titanium sheets was observed under the microscope. At 24 h after inoculation, cellular F-actin was directly stained using immunofluorescence, and the morphology of the cytoskeleton was observed by laser confocal microscopy. Cell proliferation was examined at 1, 3, and 5 d using a MTS kit, and the data were analyzed with SAS 9.4. Results The surface of the smooth surface group was smooth and flat, the element composition was pure titanium, and the roughness Ra was 179.23 nm. The surface of the laser-etched group formed a regular and uniform pore structure. The composition was mainly Ti, O, C, etc, and the surface roughness Ra was 14.11 μm. A large number of cells were uniformly distributed on the two titanium sheets in the observations at 1, 3, and 6 h. At 24 h postinoculation, MG63 cells were completely stretched on the two sets of titanium sheets and had extended a large number of pseudopods and microfilaments to cross-link with peripheral cells; moreover, the cell division phase was observed. The cell proliferation of the two groups at 1, 3, and 5 d showed a significant increase with time, indicating that no cytotoxicity occurred on the surfaces of the two groups. However, the cell proliferation in the laser-etched group was superior to that in the mechanical smooth surface group. Conclusion The surface morphology of titanium can be controlled by laser etching, which is conductive to increase the microstructure of implants without cytotoxicity and promoting osteoblast proliferation in the early stage.

Comparison of polishing effects of three polishing systems on machinable composite resins

Yanan LIU,Likai WANG,Sisi LIU,Hui HUI,Haifeng WANG

2019, 27(7):  441-445.  DOI: 10.12016/j.issn.2096-1456.2019.07.006

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Objective To compare the polishing effects of three different polishing systems on machinable composite resins and to provide a basis for the rational selection of polishing systems in the clinic. Methods Block HC, Cerasmart, and Hyramic were fabricated into 90 test pieces. Then, 30 test pieces for each material were randomly divided into 3 groups with 10 pieces per group. The pieces were polished with the Vita Enamic ^? Polishing Set (Vita group), EVE RA341 composite polishing set (Eve group), and Toboo M elastic ceramic polishing set (Tob group). The surface roughness and gloss of each test piece after polishing were measured, and the surface morphology was observed using a scanning electron microscope. Results The surface roughness values of the Vita and Eve groups for the same composite material were significantly lower than those in the Tob group (P < 0.05). No significant difference was found between the Vita and Eve groups (P > 0.05). Lower roughness values could be achieved. The gloss values of the three composite resins in the same material group were in the order of Vita group > Eve group > Tob group, and the differences between the groups were statistically significant (P < 0.05). No significant differences in the surface roughness and gloss values were found among the different composite resins (P > 0.05). Scanning electron microscopy showed that the Vita group had fewer and lighter scratches on the surface and a more uniform texture. Conclusion The Vita Enamic ^?Polishing Set can be used to cut composite resin and yields the lowest roughness and highest gloss values with the best polishing effect. The same polishing system did not exhibit significant differences in the polishing effect for different machinable composite resins.

Cinical Study

Clinical effect of titanium-zirconium small-diameter implants in the anterior esthetic zone

Dongsheng LIU,Yanmei WANG,Jiacai HE

2019, 27(7):  446-450.  DOI: 10.12016/j.issn.2096-1456.2019.07.007

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Objective To investigate the clinical effect of a titanium-zirconium small-diameter implant in anterior teeth with bone deficiencies in the esthetic area and to provide a basis for clinical application of this implant. Methods A retrospective analysis was performed using clinical data from 30 patients with a missing alveolar ridge width < 5.5 mm and a titanium-zirconium 3.3 mm diameter implant prosthesis in the anterior esthetic region. A total of 38 titanium-zirconium implants with a diameter of 3.3 mm were implanted in 30 patients. Clinical examination and CBCT were performed 12 and 24 months after implantation to evaluate the success rate and marginal bone resorption of the 3.3 mm small-diameter titanium-zirconium implants. The modified plaque index, improved gingival sulcus bleeding index, exploration depth, pink esthetic score (PES) and prosthetic complications were measured and recorded. Results The 24-month success rate of the implant was 100%. The average marginal bone resorption height was 0.51 ± 0.20 mm at 12 months after implant placement and 0.59 ± 0.18 mm at 24 months. The edge bone height did not change significantly (t=1.381, P=0.178). No significant differences were found in the modified plaque index around the implant, modified sulcus bleeding index and probing depth between 12 and 24 months (P > 0.05), and the gingival health was good. The PES value was 9.77 ± 1.48 at 12 months and 10.77 ± 1.50 at 24 months (t=0.426, P=0.672). The PES was increased at 24 months versus 12 months, but this difference was not significant (P > 0.05). The overall esthetic effect was good, and no complications occurred after repair. Conclusion Titanium-zirconium small-diameter implants can achieve good short-term clinical results in the esthetic area of the anterior teeth.

Apical sealability in extracted teeth by the root canal filling agents GuttaFlow and AH Plus: a systematic review

Xiyu YUAN,Zhaoxia CONG,Zeyu WU,Jin ZHAO

2019, 27(7):  451-456.  DOI: 10.12016/j.issn.2096-1456.2019.07.008

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Objective To compare the apical sealing effects of two root canal fillers, GuttaFlow and AH Plus, for clinical reference. Methods The Cochrane system evaluation method was used to search the Cochrane Library, Embase, CBM, PubMed, CNKI, Weipu, and Wanfang databases. Additionally, relevant journals and conference papers were manually retrieved, and relevant randomized controlled trials were collected. Two reviewers independently evaluated the quality of each study and extracted the data. A meta-analysis was performed using the RevMan5.3 software for homogenous studies, and a descriptive analysis was performed for studies with poor homogeneity. Results In total, 10 randomized controlled trials containing 398 isolated teeth were included. The meta-analysis results showed that the difference in apical microleakage was statistically significant at 1 week and 3 months [1 week: MD=-0.13, 95% CI (-0.22,-0.04), P=0.007; 3 months: MD=-1.27, 95% CI (-1.94,-0.60), P=0.000 2] but not at 6 months [MD=-0.10, 95% CI (-0.26, 0.06), P=0.23]. Conclusion Based on existing research results, GuttaFlow may achieve better results than AH Plus in the short term (≤ 1 week). Because it is subject to limitations of time, quality, and research methods, this conclusion requires more long-term, high-quality, large-sample, multimeasurement randomized controlled trials for further validation.

The oral health status of senile dementia patients: a systematic review

Peng ZHOU,Jianping TAN,Dan WANG,Ming TANG

2019, 27(7):  457-463.  DOI: 10.12016/j.issn.2096-1456.2019.07.009

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Objective To systematically evaluate the oral health status of senile dementia patients. Methods The CNKI, Wanfang, CBM, PubMed, Embase and Web of Science databases were searched online. Literature on the oral health status of Alzheimer′s patients published at home and abroad was collected. The search period extended to December 2018. Revman 5.3 software was used to perform the meta-analysis of homogeneous research. Results Ten studies satisfied the eligibility criteria. The meta-analysis revealed that older people with dementia had fewer remaining natural teeth [MD=-3.22 (95% CI -5.59, -0.85)] and more decayed missing filled teeth [MD=3.36 (95% CI 0.80, 5.92)] than the healthy control group (P < 0.05). The plaque index [MD=0.86 (95% CI 0.45, 1.28)], percentage bleeding on probing [MD=16.60 (95% CI 9.81, 23.39)], probing depth [MD=0.68 (95% CI 0.03, 1.34)], and clinical attachment loss [MD=1.13 (95% CI 0.38, 1.88)] were significantly higher in older people with dementia than in the healthy control group (P < 0.05). Conclusion The dental and periodontal health status of Alzheimer′s patients is worse than that of healthy controls. Thus, the former group needs special oral care and treatment.

Prevention and Treatment Practice

White sponge nevus: a case report and literature review

Pengyu HONG,Jiaxiong GAO,Dianri WANG,Zhangui TANG

2019, 27(7):  464-467.  DOI: 10.12016/j.issn.2096-1456.2019.07.010

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Objective To explore the etiology, clinical manifestation, diagnosis and treatment of white spongy spot nevus, so as to provide reference for clinical diagnosis and treatment. Methods The clinical data and related literature of a case of white cavernous nevus in oral cavity were retrospectively analyzed. Results White spongy nevus is a rare autosomal dominant hereditary disease with a family history. The mutations of keratin gene K4 and K13 in patients with white spongy nevus are considered to be the main causes. The disease usually starts in children and adolescents and tends to be stable in adulthood. It is characterized by extensive white water-wave folds on the mucosa, soft texture, and affects the bilateral buccal mucosa. Pathological examination usually shows excessive keratosis of epithelial cells, edema and vacuolation in spinous cells, while basal cells are generally normal. In clinic, it should be differentiated from oral leukoplakia, oral lichen planus and oral candidiasis. At present, there is no specific treatment method. Retinoic acid is often applied locally and gargle is used to keep oral hygiene and cleanliness. Patients can not be treated without conscious symptoms. The prognosis of the disease is good and there is no tendency of malignancy. Conclusion White spongy nevus is very rare and easily missed by clinicians. Diagnosis mainly depends on medical history, clinical manifestations and pathological examination. Future research directions should be devoted to finding more effective treatment.

IgG4-related Mikulicz disease: a case report and literature review

Hao LUO,Jian MENG

2019, 27(7):  468-471.  DOI: 10.12016/j.issn.2096-1456.2019.07.011

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Objective To explore the etiology, clinical manifestations, diagnosis and treatment of IgG4-related Mikulicz disease and to provide a reference for clinical diagnosis and treatment. Methods Case data from a patient with IgG4-related Mikulicz disease occurring in the submandibular gland and the literature were retrospectively analyzed. Results IgG4-related Mikulicz disease is a rare autoimmune disease. Its typical features include lacrimal gland and salivary gland swelling, a significant increase in the serum IgG4 level (> 1.35 g/L), and IgG4-positive plasma cell infiltration into a large number of pathological tissues. The disease can easily recur. Treatment is mainly symptomatic, including surgical resection and administration of glucocorticoid and other drug treatment. Long-term follow-up is required after the operation. Conclusion IgG4-related Mikulicz disease has no specific clinical features. The diagnosis relies mainly on pathological examination and serum IgG4 examination. The main treatment methods are surgery and the use of glucocorticoids, which require long-term follow-up.

Review Articles

Research progress in laser treatment of dentin hypersensitivity

XIONG Kaixin,ZOU Ling

2019, 27(7):  472-476.  DOI: 10.12016/j.issn.2096-1456.2019.07.012

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Dentin hypersensitivity is mainly associated with abrasion, wear, acid etching, cracking, wedge-shaped defects, enamel hypoplasia, caries, a lack of neck enamel, and cementum coverage accompanied by gingival recession, resulting in direct exposure of dentin tubules to the oral environment. Dentin hypersensitivity is mainly treated by sealing the exposed dentin tubules and reducing the excitability of the pulpal nerves. Laser therapy, as a safe, fast and convenient treatment measure, has achieved good results both alone and in combination with other medicines and has attracted increasing attention. This paper reviews the research progress in the treatment of dentin hypersensitivity using several common laser therapy mechanisms with parameter selections in various scopes of application. A review of the literature shows that the Nd:YAG laser has a strong penetrating power and a large thermal effect and can denature and coagulate proteins in dentin tubules in a very short time; while the CO₂ laser causes little damage to the dental pulp and has an obvious immediate curative effect by high absorption of water molecules in hydroxyapatite and the dentin surface is melted and recrystallized; the Er:YAG laser has high water absorption and a large thermal effect and can block the tubules by evaporating the fluid in the tubules and depositing salts; Er, Cr:YSGG laser energy can be fully absorbed by hydroxyapatite and water and result in desensitization by cutting hard tissues and melting periodontal dentin of the tube simultaneously; The Ga-Al-As semiconductor laser and He:Ne laser are low energy. The laser dosage mainly changes the permeability of nerve fibers to potassium and sodium ions and depolarizes the nerve fibers, producing an analgesic effect. The combination of a laser with a desensitizer can improve the clinical efficacy of treating dentin hypersensitivity.