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    28 December 2015, Volume 31 Issue 12 Previous Issue    Next Issue

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    Adhesion of Human Dental Pulp Stem Cells on Poly Lactic-co-glycolic Acid/hydroxylapatite (PLGA/HA) Composite Scaffolds with Different Proportions.
    WANG Ran-xu, PAN Shuang, HE Li-na, NIU Yu-mei. Department of Endodontics, Stomatology Hospital, Harbin Medical University. Harbin 150001, China
    2015, 31(12): 1171-1173. 
    Abstract ( 187 )   PDF (1116KB) ( 215 )  
    Objective: To prepare and evaluate the Poly (lactide-co-glycolide)/Hydroxylapatite (PLGA/HA) composite scaffold with different proportions. Methods: PLGA/HA composite scaffolds with different HA contents (10%, 20% and 30%) were fabricated by solvent casting/particulate leaching technology, while PLGA without HA was used as control group. The tensile strength and microstructure were detected by using electro-mechanical universal testing machines and scanning electron microscopy (SEM). Human dental pulp stem cells were isolated, cultured and identified. The cells were seeded in the PLGA/HA scaffolds with different proportions. The adhesion properties were measured by DAPI staining. Results: The tensile strength of 10% HA was higher than that of 20% HA, and both of them showed a higher tensile strength than the control group. However, that of 30% HA was lower than control group (P<0.05). Scaffolds with different proportions of PLGA/HA showed high porosity and pore connectivity and the pore size was 100-250 μm investigated by SEM. Cell attachment and number in PLGA/HA after the incubation of 2h, 6h and 12h were significantly higher than the control group (P<0.05), and the cell adhesion ability in 30% HA group was the highest (P<0.05). Conclusions: The present study shows that PLGA/HA composite scaffolds with HA contents may be suitable for tissue engineering. In addition, 10% HA shows a higher tensile strength, while the adhesion ability of hDPSCs in 30% HA is better.
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    Effects of Satellite Glia Cells Activation in Masseter Allodynia Induced by Restraint Stress in Rats.
    LIU Yang, MIAO Li, ZHAO Ya-juan, WANG Jian, ZHANG Min, ZHAO Rui-ni, CHEN Yong-jin, ZHAO Wen-feng.
    2015, 31(12): 1174-1178. 
    Abstract ( 211 )   PDF (2072KB) ( 163 )  
    Objective: To investigate the role of satellite glia cells (SGCs) activation and substance P (SP) expression in the trigeminal ganglion (TG) in the increased masseter mechanical sensitivity induced by psychological stress in rats. Methods: Forty male Sprague-Dawley rats were randomly divided into control group, 3-day, 7-day, and 14-day stress group (n=10). The rats were subjected to restraint stress 6 hours per day. The body weight gain and open field test were employed to evaluate the animals' stress condition. The electronic Von-Frey anesthesiometer were used to evaluate the masseter mechanical sensitivity. The expression of glial fibrillary acidic protein (GFAP) and SP was detected by immunofluorescent staining. Results: The rats in the stress group showed significant slower body weight increase, anxious and depressive behavior compared to control group. The masseter mechanical sensitivity of rats in the stress group was significantly elevated. The expression levels of GFAP and SP in TG were significantly up-regulated in the stress groups compared with control group. Conclusion: Chronic restraint stress could result in satellite glia cells activation and elevated SP expression in TG, indicating that the satellite glia cells activation may be involved in the increased masseter mechanical sensitivity induced by psychological stress in rats.
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    Effects of Recombinant Human Beta-defensin-3 on Inflammation Induced by Porphyromanas Gingivilis Lipopolysaccharide.
    LV Jing-lu, BIAN Tian-ying , LI Li-li, CUI Di, ZHANG Ting, LEI Lang, YAN Fu-hua.
    2015, 31(12): 1179-1183. 
    Abstract ( 196 )   PDF (1405KB) ( 179 )  
    Objective: To investigate the effects of recombinant human beta-defensin-3 (rhBD3) on acute inflammation induced by Porphyromanas gingivilis lipopolysaccharide (P.g-LPS) in apolipoprotein E knockout (ApoE-/-) mice and murine RAW264.7 macrophages. Methods: Male ApoE-/- mice (20 weeks old) were randomly divided into PBS control group, P.g-LPS group and P.g-LPS+rhBD3 group, and were stimulated by intraperitoneal injection. Serum inflammation markers (MCP-1, TNF-α, IL-6, IL-1β and NO) secretion levels were measured 2 hours later. The effects of rhBD3 on inflammation induced by P.g-LPS in RAW264.7 cells were also evaluated by detecting the secretion levels and mRNA relative expression levels of inflammation markers in culture supernatant and cells, respectively. Results: Serum MCP-1, TNF-α, IL-6 and NO secretion levels in P.g-LPS group of ApoE-/- mice were significantly upregulated, while the levels of MCP-1, TNF-α and NO decreased significantly in P.g-LPS+rhBD3 group. The increased levels of TNF-α and NO in culture supernatant and mRNA relative expression levels of TNF-α and IL-6 in RWA264.7 cells stimulated by P.g-LPS could be downregulated by rhBD3. Conclusion: rhBD3 has suppressive effect on acute inflammation induced by P.g-LPS in vivo and in vitro. It may play a modulating role in the interaction between periodontitis and hyperlipidemia.
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    Preliminary Study of Demineralized Dentin Matrix- Platelet-rich Plasma Gel Applying to Scaffold Material of Periodontal Bone Tissue Engineering.
    HOU Zong-peng, GUO Liang-wei, ZHOU Jin, Sun Jin-huan.
    2015, 31(12): 1184-1187. 
    Abstract ( 192 )   PDF (1509KB) ( 258 )  
    Objective: To evaluate the effects of demineralized dentin matrix (DDM) to the platelet-rich plasma (PRP) gel delivery system for growth factors. Methods: After double centrifugation for preparation of PRP, the concentrations of platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β) in the whole blood gel (group C), PRP gel (group B), and PRP/DDM gel (group A) were measured in two weeks by enzyme-linked immunosorbent assay (ELISA). The structure of prepared PRP/DDM gel was observed by scanning electron microscopy (SEM). DDM was implanted into the pit of femoral muscles of SD rats and tissue sections were performed to study the toxicity reaction. Results: Compared with other two groups, PRP/DDM had a much longer time to continuously release the growth factors (P<0.05). Through SEM and tissue section, it was found that PRP and DDM combined with each other closely and orderly and DDM had a fine biocompatibility. Conclusion: The combination of PRP and DDM can better slower the release of growth factors.
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    Tooth-forming Potential of Rat Bone Marrow Mesenchymal Stem Cells in the Milieus of Diverse Growth-Factor Induction and Scaffold in Vivo.
    SHEN Yu-feng,HU Yang,ZHANG Yue, HE Yu-tong, LI Jing, LIU Jing, HE Hui-yu.
    2015, 31(12): 1188-1192. 
    Abstract ( 163 )   PDF (2206KB) ( 220 )  
    Objective: To investigate the tooth-forming potential of bone marrow mesenchymal stem cells (BMSCs) in the milieus of diverse growth-factor signaling inductions and scaffolds in vivo. Methods: BMSCs were inducted via either a single signaling mixed multi-signaling. The BMSCs were further co-cultured in GS or polyvinyl alcohol-double crystal ceramic powder (PVA-DCCP) scaffold constructed by a 3D printer. The re-implanted tissues were harvested and the RT-PCR of ameloblastin (AMBN), DMP1, Collagen-1, and DLX1 mRNA were performed at 1, 3, 7, 14 and 28 days after implantation to assess teeth-forming potential histologically and genetically. Results: With prolongation of culturing, the mRNA level increased in Collagen-1, whereas decreased in AMBN, DMP1 and DLX1 in the five groups; and the mRNA levels of four genes were significantly lower in group A-D than that in group E (P<0.05). Furthermore, the mRNA levels were significantly different among tissue samples with diverse scaffolds (P<0.001). Conclusion: BMSCs induced by mixed multi-signaling could proliferate more quickly and differentiate more profoundly, compared to the single signaling induced ones. Moreover, these BMSCs expressed more corresponding odontogenic genes which promoted the formation of tooth tissue when combined with diverse scaffolds.
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    In vivo Micro-CT Observation of Tooth Movement and Relapse in Rats.
    XU Xiao-lin, YANG Feng-xue, DAI Hong-wei, ZHOU Jian-ping.
    2015, 31(12): 1193-1196. 
    Abstract ( 169 )   PDF (1243KB) ( 260 )  
    Objective: To explore the law of tooth movement and relapse induced by different orthodontic forces through in vivo Micro-CT dynamic observation. Methods: Fifteen 10-week-old rats were divided into three groups randomly. Force of 20g, 50g and 100g were delivered to the first molars of left maxillary for 14 days. The Micro-CT scan was taken at day 0, 3, 7,10,14,28 after the appliance was applied and day 3, 7,10,14,28,42 after the appliance was removed.Thedistance oftooth movement at different time points was measured. Results: At first 3 days, the first molars of all groups mesially moved significantly. From day 3 to day 10, the tooth movement became slower. The 20g and 100g groups moved rapidly after day 10.In the 20g groups, the tooth movement relapsed significantly during day 0 to day 3, the 50g and 100g groups relapsed significantly during day 0 to day 7. At day 28, all groups almost completely relapsed. Conclusion: The process of tooth movement showed the pattern of an instantaneous displacement, delay, and a fast moving. The light force induced more tooth movement. The distance relapsed dramatically in the initial stage after the appliance was removed, and the greater the movement distance, the faster the relapse occurred.
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    Study on the Fabrication and Biocompatibility of Hierarchical Titanium Surface.
    LIU Zi-chuan, LI Ya-jing, SUN Ya-jie, XIE Qi, DU Qing, XIE Wei-li.
    2015, 31(12): 1197-1200. 
    Abstract ( 147 )   PDF (1432KB) ( 191 )  
    Objective: To fabricate micro/nanostructures on titanium surface and analyze effects of hierarchical titanium surface on its biocompatibility. Methods: Mixed alkali treatment on the titanium surface was conducted after sandblast and acid etching, then scanning electronic microscope (SEM) and the X-ray energy dispersive spectrometer (EDS) were used to investigate microstructures of the titanium coatings. Survival rate of L-929 cells were detected by CCK-8 kit. The adherent cells of each group were stained by DAPI, while the proliferation of preosteoblast of each group was investigated further. Results: On the hierarchical structures of titanium surface, the scale of micro pit was about 3-5μm, while the nanostructure was about 100-200nm. Sodium and calcium were found on the new type surface. Cell toxicity was Class 0. Adhesion assay showed that the number of adherent cells both on MTi and NTi were bigger than that of STi, while cells on NTi were most at 1 hour or 2 hours. Proliferation test displayed that the proliferation activity on MTi was significantly lower than that on STi at day 1, 4, 7, while the proliferation activity on NTi was higher than that on STi at day 7. Conclusion: Hierarchical structure shows more biocompatible structure and better activity of adhesion and proliferation.
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    Clinical Effect of Pingyangmycin in the Treatment of Oral and Maxillofacial Hemangioma.
    LIANG Yun-feng, LI Guo-lin.
    2015, 31(12): 1201-1202. 
    Abstract ( 128 )   PDF (737KB) ( 275 )  
    Objective: To analyze the clinical effect of pingyangmycin in the treatment of oral and maxillofacial hemangioma. Methods: Eighty-six patients with oral and maxillofacial hemangioma (43 cases of pingyangmycin group and 43 cases of cod liver oil acid sodium group) were collected from March 2008 to July 2014, meanwhile the therapeutic effect and adverse reaction were observed. Results: The therapeutic effect of pingyangmycin group was significantly better than cod liver oil acid sodium group (P<0.05), and the incidence of adverse reactions in the pingyangmycin group was obviously lower than the cod liver oil acid sodium group (P<0.05). Conclusion: Pingyangmycin has good clinical efficacy in the treatment of oral and maxillofacial hemangioma.
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    Comparison of Sonicfill System and Layered Filling Technology in Microleakage of Composite Resin.
    PAN Yue-ping, XIA Wen-wei.
    2015, 31(12): 1203-1205. 
    Abstract ( 230 )   PDF (1134KB) ( 345 )  
    Objective: To compare the microleakage of composite resin restorations using a sonicfill system and a layered filling technology. Methords: Class-Ⅱcavities (3 mm×4 mm×5 mm) were prepared on 20 freshly extracted molar teeth. The teeth were randomly divided into 2 groups with 10 teeth each. Group A was restored with Sonicfill system. Group B was restored with the traditional way. After restoration, all teeth were stained with 2% methylene blue solution for 1 week. The depth of methylene penetration was measured under the scanning electron microscope. Results: There were no significant differences between group A and B. Conclusions: The new Sonicfill system was the same as the traditional layered filling technology in the microleakage of composite resin restoration.
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    Clinical Comparison of 3M Flowable Resin and 3M Glass Ionomer Restoration in Primary Molars ClassⅡ Cavity.
    XIE Ni-na, SONG Wen-ting, WEI Lu-ming, LIU Zong-xiang.
    2015, 31(12): 1206-1208. 
    Abstract ( 199 )   PDF (756KB) ( 389 )  
    Objective: To explore the clinical effect of dental filling materials commonly used in pediatric dentistry on the restoration of mesial or distal occlusal surface cavities (class Ⅱ cavity) in primary molars. Methods: 266 primary molars with class Ⅱ cavities among 178 children aged 4-6 were randomly divided into two groups, namely, the 3M flowable resin group (experimental group) and 3M glass ionomer group (matched group). The clinical effect of two materials was compared after 1 and 2 years of treatment. Results: Treatment success rates of 3M flowable composite resin and 3M glass ionomer for class Ⅱ cavities were 96.00% and 87.80% respectively after 1 year. After 2 years, the rates were 95.76% and 86.61% respectively (P<0.05). Conclusions: For class Ⅱ cavity in primary molars, the clinical outcome of 3M flowable composite resin is better than that of 3M glass ionomer.
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    Ability of CarrisolvIII Combined with Low Concentration NaClO to Clean the Smear Layer of Root Canal.
    CHEN Ze-hua, YANG Qing-ling, WANG Zhi-qun, KONG Yu, LI Mei-na, ZHAO Yue, LI Bao-hua.
    2015, 31(12): 1209-1211. 
    Abstract ( 157 )   PDF (1670KB) ( 226 )  
    Objective: To investigate the effect of CarrisolvIII combined with 0.5%NaClO on removing the smear layer. Methods: Fifty maxillary incisors were randomly divided into 5 groups. During the process of preparation, five different fluids were used to irrigate the root canal. The amount of smear layer and erosion on the surface of the root canal walls were examined with the scanning election microscope. Results: The cleaning of root canal walls using CarrisolvIII combined with 0.5%NaClO was better than the CarrisolvIII or 0.5%NaClO alone, respectively. Conclusion: CarrisolvIII combined with 0.50%NaClO has a synergistic effect on the removal of the smear layer.
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    Analysis of Related Factors to the Dental Caries of 3-5-Year-Old Children in Baotou.
    MIAO Yu, WANG Xiao-chao, ZHANG Shuang-yang, WANG Zhao-jun.
    2015, 31(12): 1212-1215. 
    Abstract ( 154 )   PDF (777KB) ( 178 )  
    Objective: To analyze the related factors of the dental caries of 3-5-year-old children in Baotou. Methods: Four hundred and ninety-six 3-5-year-old children were randomly selected from 10 kindergartens in Baotou. 326 children who had caries were set as the case group and 170 children without caries as the control group by oral professional medical examination. 25 factors related to dental caries were investigated and recorded in two groups such as age, gender, daily snack times and daily brushing times, and so on. Then the related factors were analyzed with logistic multiple regression. Results: After excluding other factors involved in the model, per increase of daily snack time promoted the occurrence of dental caries 1.249 fold (OR was 1.249 and the 95% confidence interval did not contain 1, P<0.05). Weaning more than 1-year-old promoted the occurrence of dental caries 2.812 fold (OR was 2.812 and the 95% confidence interval did not contain 1, P<0.01). Risks to promote caries of not containing the bottle to sleep, not eating bedtime snack, and not drinking carbonated drinks were 0.194, 0.302, and 0.031 times of doing the above things (OR respectively was 0.194, 0.302, and 0.031, and all their 95% confidence interval did not contain 1, P<0.01). Conclusion: Increasing snack times and more than 1-year-old weaning are the dental caries risk factors of 3-5-year-old children of Baotou, while not containing the bottle to sleep, not eating bedtime snack, and not drinking carbonated drinks are the protective factors.
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    Assessment of Topographic Relationship between Maxillary Sinus Floors and Upper Molar Root Apices by Cone-beam Computed Tomography.
    TENG Yue-hui, HONG Yuan, LIN Zi-tong, YANG Zheng-yu, WANG Tie-mei.
    2015, 31(12): 1216-1219. 
    Abstract ( 251 )   PDF (906KB) ( 613 )  
    Objective: To evaluate the topographic relationship between maxillary sinus and upper molar root apices by Cone-beam Computed Tomography (CBCT) and to provide evidence for dental treatments that would get the upper molars involved. Methods: Included in this study were 98 sides of maxilla, left or right, in 53 non-sympotomatic subjects. The vertical distances from the root apices of maxillary molars to the floors of maxillary sinus were assessed by CBCT. The mean vertical distances were analyzed with interval estimation. Results: 98 sides could be classified into 4 categories according to the relationships between maxillary sinus and upper molar root apices. The distance for buccodistal root apex of first maxillary molar, the shortest one, was 0.44±0.61mm (confidence coefficient 95%). It was frequent that maxillary molars, particularly the second upper molar were close to the sinus floors. Conclusion: Maxillary molars were close to the maxillary sinus floor. The relationship could be and should be evaluated by CBCT before treatment when upper molars were involved so as to prevent an iatrogenic injury and an subsequent infection in the maxillary sinus.
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    Correlation between Periodontitis and Rheumatoid Arthritis through the Levels of TNF-α,IL-17,IL-23 in Serum.
    ZHU Jian-hua, YANG Yan-fei, LI Xiao-guang, LIU Ji-guang.
    2015, 31(12): 1220-1222. 
    Abstract ( 161 )   PDF (754KB) ( 233 )  
    Objective: To investigate the levels of the tumor necrosis factor (TNF-α), interleukin -17 (IL-17), interleukin -23 (IL-23) and their clinical significance in rheumatoid arthritis (RA) and chronic periodontitis. Methods: Twenty-eight rheumatoid arthritis (R) patients, 32 chronic periodontitis (P) patients, 22 rheumatoid arthritis and periodontitis (R+P) patients and 18 healthy persons (H) were selected according to the inclusion criteria. ELISA was used to detect the levels of TNF-α, IL-17, IL-23 in serum. Results: The levels of TNF-α, IL-17, IL-23 in groups P, H, and P+H were significantly higher than those of the control group (P<0.05); and the levels of TNF-α, IL-17, IL-23 in group P+H were significantly higher than those in group P and H (P<0.05). There was no significant difference between the group of P and H. Conclusion: TNF-α, IL-17 and IL-23 may be used as factors linking periodontal disease rheumatoid arthritis.
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    Efficacy of MTA versus Ca(OH)2 Applied for Immature Permanent Teeth Pulpotomy: A Systematic Review.
    ZHOU Hai-yan, PAN Yang-yang, XIA Ke-ke, MEI Li-qin.
    2015, 31(12): 1223-1227. 
    Abstract ( 173 )   PDF (1042KB) ( 440 )  
    Objective: To systematically review the efficacy of MTA versus Ca(OH)2 applied in pulpotomy for immature permanent teeth. Methods: The Cochrane Library, PubMed, EMbase, CBM, CNKI, VIP and WanFang Database, were searched up to March 20, 2015 to study the efficacy of MTA versus Ca(OH)2 applied for immature permanent teeth pulpotomy. Two reviewers independently screened literature according to the inclusion and exclusion criteria, extracted data and assessed the methodological quality of included studies. Then, Meta-analysis was performed by using RevMan 5.0 software. Results: A total of 13 studies involving 926 teeth were included. There were 458 teeth in the MTA group and 468 teeth in the Ca(OH)2 group. The results of Meta-analysis showed that compared with the Ca(OH)2 group, the MTA group was superior in the first year success rate [OR=4.43, 95%CI(2.38, 8.38)] and the second year success rate [OR=2.67, 95%CI(1.65, 4.32)]. Conclusion: Based on the current evidences, MTA is superior to Ca(OH)2 in pulpotomy for immature permanent teeth.
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    Correlation between Dental Care before and during Pregnancy and Preterm Low Birth Weight.
    YANG Xiu-qiao, DU Min-quan, WANG Jin-dong, LUO Wei, RUAN Li-ni, AN Zhi-guo, HUANG Xing-xing.
    2015, 31(12): 1228-1230. 
    Abstract ( 140 )   PDF (758KB) ( 304 )  
    Objective: To explore the relationship between oral intervention before and during pregnancy and preterm low birth weight (PLBW). Methods: 550 women in preparation for pregnancy were selected from antepartum clinic and marriage registry office between 2012 and 2014. In this study, oral questionnaire, oral examination, treatment recommendations and tracking pregnancy outcomes were performed. The data were estimated by χ2 and logistic regression. Results: There was no significant correlation between dental care before and during pregnancy and pregnant abnormalities in pregnant women with relatively better socioeconomic status and health awareness. Conclusion: There is a broad safety range for this group to accept oral intervention.
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    Relationship between Clinical Characteristics and Bacterial Flora in Periapical Lesions of Deciduous Teeth.
    CAI Shuang, ZHAO Huan-ying, ZHOU Yan, YANG Ning-yan, SHI Qing, SHANG Jia-jian.
    2015, 31(12): 1231-1235. 
    Abstract ( 151 )   PDF (808KB) ( 255 )  
    Objective: To detect the bacterial components in periapical lesions of deciduous teeth and analyze the relationship between the bacterial flora and clinical symptoms. Methods: 31 periradicular lesion samples of deciduous teeth diagnosed as periapical periodontitis were collected. DNA was extracted and analyzed using 16S rDNA cloning and sequencing for identification of bacteria. Chi-square was chosen to compare the detection rate of bacteria with different symptoms, including spontaneous pain, chewing pain and sinus. Results: 268 phylotypes from 2057 clones were identified belonging to nine phyla. The three most prevalent bacteria, Fusobacterium nucleatum (74.19%) , Dialister invisus (67.74%) and Campylobacter gracilis (64.52%)showed no relationship with any symptoms. Prevotella tannerae was detected to significantly increase in samples with spontaneous pain, so did Prevotella oris and Haemophilus parahaemolyticus in the group of chewing pain, and Prevotella nigrescens, Eubacterium brachy in samples with sinus. Two uncultured Veillonella sp. were significantly fewer in the samples of chewing pain. Conclusion: Periapical lesions in deciduous teeth contained polymicrobial. Prevotella, Eubacterium and Veillonella had certain relations with clinical symptoms.
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    Effects of Sequential Periodontal Treatment on Patients of Chronic Periodontitis with Mouth Breathing and Malocclusion Deformity.
    HAN Bing, SUN Jiang, YOU Li.
    2015, 31(12): 1236-1239. 
    Abstract ( 167 )   PDF (1357KB) ( 204 )  
    Objective: To study the clinical effect of sequential periodontal treatment on chronic periodontitis patients with mouth breathing and malocclusion deformity in anterior tooth region. Methods: Ten chronic periodontitis patients with mouth breathing and malocclusion deformity in anterior tooth region were selected in the Department of Periodontology and Oral Mucosa, Stomatological Hospital of Dalian from September 2007 to September 2008.These patients received sequential periodontal treatment for more than 5 years, including periodontal initial therapy, periodontal surgical therapy, orthodontic treatment, and periodontal supportive therapy. Clinical parameters of probing depth (PD), clinical attachment level (CAL), tooth mobility (TM) and bleeding on probing (BOP) were recorded by Florida electronic probe in anterior tooth region at baseline and 1-3 years after orthodontic treatment, and then analysis was carried out.Panoramic tomogram intraoral radiography was detected at baseline and 1-3 years after orthodontic treatment. Results: PD and CAL were decreased 1-3 years after orthodontic treatment, the positive sites of BOP were reduced, and the statistical differences were detected (P<0.01). TM was improved, however, not significant. Conclusion: For chronic periodontitis patients with mouth breathing and malocclusion deformity in anterior tooth region, the more than 5 years clinical treatment of sequential periodontal is effective and stable.
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    Study of Characteristics of Occlusal Contacts in Postorthodontic Extraction-treatment Patients.
    YUN PARK,QIAN Yu-fen.
    2015, 31(12): 1240-1243. 
    Abstract ( 146 )   PDF (781KB) ( 187 )  
    Objective: To understand the differences between occlusal contact features in different populations and investigate the influence of orthodontic treatment on occlusion contact features. Methods: Selected 20 individuals with normal occlusion(group A), 20 individuals with malocclusion(group B), 30 individuals of post orthodontic treatment(group C), evenly distributed between male and female. Tee-Test occlusion analysis system was used to detect the full occlusal contact area, total of force(TOF), force per unit area, asymmetry of force (AOF), center of force(COF), the percentages of the single teeth in dentition. Results: TCA,TOF value were significantly higher in group A (P<0.05). Group C showed lower value of the force per unit area and higher value of COF, AOF than group A, and group B showed significantly difference between two groups(P<0.05). The maximum bite force area was distributed in the second molar area in group A and B, but changed to first molar area in group C(P<0.05). The gender differences in occlusion contact features showed no significant difference in three groups. Conclusion: The function and stable of occlusion after orthodontic treatment showed better results compared to malocclusion but the results were not as positive as the individual normal occlusion.
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    Combination of Cone-beam CT and Micro Power System to Extract Type Ⅲ Impacted Supernumerary Teeth for Children.
    ZHANG Zhi-yong, ZHANG Xiao, MENG Tian, GAO Wei, CHEN Quan, LIU Wen-shu, CHEN Yu-huan.
    2015, 31(12): 1244-1246. 
    Abstract ( 168 )   PDF (1495KB) ( 341 )  
    Objective: To investigate the clinical outcomes of combined application of Cone-beam CT (CBCT) and micro power system for extraction of type Ⅲ impacted supernumerary teeth for children. Methods: Children with type Ⅲ impacted supernumerary teeth who accepted the tooth extraction by CBCT and micro power system (implantology surgical unit) were collected. The accordance between CBCT and operation finding was analysed. The average operation time, post-operation pain and the complications of extraction were recorded. Results: The accordance was 100% between CBCT and operation finding. The average operation time was (27.5±6.1) min. Average Wong-Baker score for post-operative pain was (3.9±1.2) immediately after extraction and (1.3±1.1) 7 days after extraction. All wounds healed well without any complications. Conclusion: Combined application of CBCT and micro power system can reduce operation time to extract type Ⅲ impacted supernumerary teeth for children and reduce complications
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    Cephalometric Analysis for Skeletal Angle Class Ⅲ Malocclusion Patients in Retruded Contact Position.
    YANG Yi-ming, CHEN Lin-ling, ZHANG Zhe-chen, Liao Qian.
    2015, 31(12): 1247-1250. 
    Abstract ( 186 )   PDF (991KB) ( 380 )  
    Objective: To investigate the difference of cephalometric analysis between intercuspal position (ICP) and retruded contact position (RCP) in skeletal Class Ⅲ malocclusion patients. Methods: Included in this study were 16 skeletal Class Ⅲ malocclusion patients with functional mandibular displacement. Lateral cephalograms in both ICP and RCP positions were taken and analyzed. Results: The analysis of skeletal indices showed that SNB angle, Angle of convenxity, FMA angle, MP-SN angle, Y axis angle, distance from N-per to Pog, ANB angle, Wits, APDI, Cross overjet and ODI were significantly different between two positions (P<0.001). The analysis of dental indices showed that U1-L1 angle and FMA angle were statistically different (P<0.01 and P<0.001, respectively). The analysis of soft tissue indices showed that the distance from O-M to Pog' and Z angle were statistically different (P<0.001 and P<0.01, respectively). Conclusion: It is important to take and analyze lateral cephalogram in retruded contact position for diagnosing and treating skeletal Angle Class Ⅲ patients with functional mandibular displacement.
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    Association of Helicobacter Pylori Infection and Periodontal Disease Risk in Nonsmoking Chinese Han Population: a Case-control Study.
    LI Jing, SHI Jun.
    2015, 31(12): 1251-1253. 
    Abstract ( 146 )   PDF (764KB) ( 246 )  
    Objective: To explore the association of Helicobacter pylori (HP) infection with periodontal disease (PD) risk in nonsmoking Chinese Han population. Methods: Eighty-five PD patients and 95 healthy controls from June 2013 to March 2015 were included in this study. Urease Activity Assay Kit was used to detect the positive rate of HP infection in all of the participants. Differences of basic features and the association of HP infection and PD risk were calculated by SPSS19.0. Age, gender, drinking, and diabetes history were used as confounding factors to adjust the results. Results: Basic features were significantly different between case and control groups. Association analysis showed that high HP positive rate could increase the PD risk by approximately 3.23 folds (OR=3.23,95%CI=1.63-6.41). After adjusted by age, gender, drinking and diabetes history, the association was also statistically significant (OR=2.47, 95%CI=1.35-4.52). Conclusion: PD was significantly associated with the HP infection. HP might act as an independent and significant marker for PD.
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    Clinical Research of Temporomandibular Disorders in the Elderly and College Students of Cantonese.
    LIU Ya-rui, ZHANG Qing-bin, FENG Zi-jun, ZHANG Yin, CAO Wei, LI Xing-yang, CUI Shi-man.
    2015, 31(12): 1254-1257. 
    Abstract ( 231 )   PDF (780KB) ( 481 )  
    Objective: To compare the features of temporomandibular disorders (TMD) between the elderly and college students of Cantonese. Methods: A total of 368 elderlies and 681 college students were included in this study. Subjects with positive symptoms were chosen as experimental group, while the others without any symptoms as control group. The factors were analyzed by unconditional Logistic regression and Chi-square test. Results: In the elderly group, the incidence of TMD was 64.9%. Pain, mandibular movement impairment and joint noises in diminishing order were the three leading common symptoms. In the college group, 42.0% of the students were found with positive symptoms. Joint noises, mandibular movement impairment, pain in diminishing order were the three leading common symptoms. Male and female showed significant differences. The unconditional Logistic regression showed that the loss of posterior teeth, unbalanced chewing and occlusal trauma were the major influencing factors in the elderly group. Meanwhile, the non-conditional Logistic regression showed that psychological factors, occlusal disorders/impaction of mandibular third molar, unbalanced chewing were the major influencing factors in the college student group. Conclusion: The incidence of TMD in the elderly was higher than that of college students in Guangdong. The leading etiological factor and the most common symptom of TMD for the elderly were different from those of college students.
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    Research Progress on Relationship between MicroRNA-7 and Tumor and Prospect of Its Application in Oral Malignant Tumors.
    GUO Shuan-long, ZHANG Bin, LI Ying.
    2015, 31(12): 1261-1263. 
    Abstract ( 145 )   PDF (773KB) ( 261 )  
    MicroRNAs are small and noncoding RNAs with regulatory functions, about 21 to 25 nucleotides, which play an important role in many human diseases, including cancer. Recent studies indicate that abnormal expression of MicroRNA-7 exists in a wide variety of tumor cells, and the cell proliferation, invasion and metastasis ability changed after introducing manual MicroRNA-7 into tumor cells. In this paper, advances in the research of MicroRNA-7 in tumors are summarized, and reasonable prospect is presented on its application in oral and maxillofacial malignant tumor.
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    Research Progress on the Oral Medical Applications of Biodegradable Shape Memory Polymers.
    WEN Chao-jv, ZHOU Yan-min, ZHAO Jing-hui, ZHANG Yi-di, MA Shan-shan.
    2015, 31(12): 1264-1266. 
    Abstract ( 184 )   PDF (774KB) ( 416 )  
    Shape memory polymers have the ability to switch from a temporary status to permanent status or transfer original shape triggered by heating, light irradiation, electrical stimulation, magnetic exposure or immersion in water. Among them, the heat-induced shape memory polymer is the most typical representative, which can change through a transition temperature. On the medical area, the relevant considerations, such as biocompatibility, mechanical property and biodegradability, are important factors. Depending on shape memory effect, biodegradable shape memory polymers have emerged as an extensive and potential alternative to other materials. In this article, the shape memory principle of shape memory polymers is discussed. The classification and oral medical applications of biodegradable shape memory polymers are introduced.
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    Progress in the Development of New Nickel-titanium Instrument Hyflex CM.
    LI Zong-li, XU Dong-dong, PENG Bing.
    2015, 31(12): 1267-1269. 
    Abstract ( 310 )   PDF (805KB) ( 616 )  
    Hyflex CM, developed in recent years, is a new type of nickel-titanium rotary root canal preparation equipment. Its characteristics include: Hyflex CM is made of a new type of NiTi wire, named the controlled memory wires (CM-wires); it has a lower percent in weight of nickel compared with other traditional NiTi alloy; after a special thermomechanical process, Hyflex CM has excellent flexibility and the ability of cyclic fatigue resistance improves significantly; a sterilization cycle can make the deformed Hyflex CM files regain their original shape and be able to regenerate. These properties may give rise to a reduce risk of transportation, ledging or instrument fracture, and so on. This study discusses research progress on the characteristics, physical properties, and application method of Hyflex CM
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