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Objective@#To evaluate the antiseptic effect of combined using of 5% sodium hypochlorite and calcium silicate-based root canal sealer against Enterococcus faecalis (Ef) biofilms in infected dentinal tubules in vitro.@*Methods@#Cells of Ef were inoculated into the dentinal tubules of single-rooted teeth (without caries, periapical lesions and malformations extracted due to periodontal disease or orthodontic reasons; collected from Department of Maxillofacial Surgery, The First Affiliated Hospital of Zhengzhou University) with centrifugation and incubated in brain-heart infusion (BHI) to form 3-week-old biofilms. The infected samples were subjected to sodium hypochlorite or sterile water bathing for 10 minutes followed by calcium silicate-based root canal sealer (iRoot SP) (calcium silicate-based group), Gutta-percha group and sterile water group placed on the root canal wall for 1, 4 and 12 weeks. There were two samples in each treatment at each point. The antiseptic effectiveness of combined use of sodium hypochlorite and calcium silicate-based root canal sealer was analyzed by laser scanning confocal microscope (LSCM), ANOVA and LSD-t test.@*Results@#After treatment with 5% sodium hypochlorite, in calcium silicate-based group for 4 and 12 weeks more Ef biofilm cells [(75.3±3.5)% and (74.8±3.8)%] were killed than in Gutta-percha group [(65.9±4.1)% and (63.0±3.7)%] and sterile water group [(63.9±4.0)% and (64.2±3.5)%] (P<0.05). After being treated with sterile water, the proportion of dead bacterial cells in calcium silicate-based group for 1, 4 and 12 weeks [(27.5±4.6)%, (43.0±4.4)% and (40.3±6.1)%] were more than those in Gutta-percha group and sterile water group (P<0.05). After being treated with 5% sodium hypochlorite or sterile water, more biofilm bacteria were killed in calcium silicate-based group for 4 and 12 weeks than in calcium silicate-based group for 1 week (P<0.05).@*Conclusions@#The combined use of sodium hypochlorite and calcium silicate-based root canal sealer kills more biofilm cells in infected dentinal tubules.
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Objective@#To investigate the stress corrosion and electrochemical corrosion resistance of titanium produced through laser rapid forming (LRF), and to provide a basis for their clinical application.@*Methods@#Forged commercial pure titanium (CP-Ti) was used as control group and LRF pure titanium was used as LRF group. All samples were placed in acidic artificial saliva containing fluorine (pH=7), and loaded with a stress of 1.2 × σ0.2 Pa (σ0.2 represents the yield strength of material). Stress corrosion resistance of specimens that have been soaked for 30 days was analyzed by naked eye observation, X-ray diffraction analysis and scanning electron microscopy. For samples placed in artificial saliva, neutral fluoride solution (pH=7) and acidic fluoride solution (pH=3) (4 test pieces in each corrosive medium), and their electrochemical corrosion resistance was evaluated by free corrosion potential (Ecorr) measurements, corrosion current (Icorr), electrochemical impedance spectroscopy (EIS), and anodic polarization curves.@*Results@#With the prolongation of immersion time, the corrosion products gradually increased. The stress corrosion of CP-Ti group was significantly more than that of LRF-Ti group, and the pit diameter was significantly larger than that of LRF-Ti group. The electrochemical corrosion results showed that the Ecorr (-469 mV) of LRF-Ti in artificial saliva was higher than that of CP-Ti (-555 mV), and the Ecorr (-925 mV) of LRF-Ti was higher than that of CP-Ti (-943 mV) in neutral fluoride solution. In acid fluoride solution, the Ecorr (-943 mV) of LRF-Ti was higher than that of CP-Ti (-956 mV). The Ecorr of the same metal was the highest in artificial saliva and the lowest in acid fluoride solution; the Icorr of the same metal was the lowest in artificial saliva and the highest in acid fluoride solution.@*Conclusions@#Under the same corrosion conditions, LRF Ti demonstrated better stress and electrochemical corrosion resistance than CP-Ti.
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Objective@#To evaluate the antimicrobial activity of nonequilibrium plasma against Enterococcus faecalis (Ef) biofilms in vitro and to obtain novel evidence of root canal disinfection with nonequilibrium plasma.@*Methods@#Sterile cover slips and single-rooted canals were filled with Ef and incubated to form 1-week-old and 3-week-old biofilms, respectively. The infected samples were subjected to nonequilibrium plasma, 2% chlorhexidine digluconate (CHX) and saline for 3, 10 and 30 minutes, respectively. After treatment, the killing effectiveness of nonequilibrium plasma was analyzed by using laser scanning confocal microscopy (LSCM) and colony forming unit (CFU) counting.@*Results@#The 3-dimentional reconstruction LSCM images showed that about 48.3%-79.8% of 1-week-old Ef biofilm cells and 40.0%-67.4% of 3-week-old biofilm cells were killed by nonequilibrium plasma and 2% CHX compared to saline (P<0.05). The proportion of killing activity was lower after 3 minutes (40.0%-50.9% killing) than after 10 minutes (65.3%-77.8% killing) and 30 minutes (66.4%-79.8% killing) (P<0.05). And the killing of biofilm bacteria was fastest during the first 3 minutes (13.3%-17.0% killing per minute) and slow down greatly after 10 minutes. Remarkably more bacteria were killed in 1-week-old Ef biofilms (48.3%-79.8% killing) than in 3-week-old biofilms (P<0.05).@*Conclusions@#The nonequilibrium plasma killed more Ef biofilm cells in infected root canals showed promotional as an additional approach against bacterial biofilms during root canal disinfection.
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Objective To investigate labial and lingual alveolar bone plate thickness of the mandibular anterior teeth by using cone-beam computed tomography (CBCT),in order to provide a reference for immediate implantation.Methods 132 individuals with normal occlusion were examined with CBCT,and their mandibular anterior teeth were analyzed.The labial and lingual alveolar bone plate thickness at the level of the apical,1/4 of the apical,1/2 of the middle and 1/4 of the cervical were measured.The differences of the thickness were compared among the side and gender.Results There were no significant differences between the left and right sides. Except on the 1/4 of the cervical,the thickness of lingual bone plate was thicker than that of labial bone plate.The frequency of the thickness of the labial bone larger than 2 mm on the 1/4 of the cervical of the center incisor,lateral incisor,and canine were 0,0 and 1.5 1%,respectively,and on 1/4 of the middle were 0.76%,1.44% and 3.79%,respectively.The lingual bone plate thickness showed significant difference between genders.Conclusion Reference values of alveolar bone plate thickness in anterior teeth of normal occlusion were established by using CBCT,which can provide clinical instruction for immediate implant.
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Objective This study was conducted to measure the mandibular incisive canal (MIC) by cone beam computed tomography(CBCT)and to assess 3?dimensional structure, course and adjacent structure of the MIC , in order to ensure safe region for surgery of the mandibular interforaminal area. Methods A total of the CBCT images from 83 patients were studied and measured. The detection rates of MIC were calculated The diameter of the MIC and the distances from MIC to the labial and lingual cortices and the inferior border of the mandible and tooth tips were measured at canines and lateral incisors. Results MIC was found in 67.8%of the patients. In the position of canine, the diameter of MIC, the mean distance of the MIC to the tips of the teeth, to the buccal border of the mandible , to the lingual border of the mandible and the inferior border of the mandible were (1.3±0.4), (8.9±2.9), (4.3±0.9), (5.2±1.1) and (8.6± 1.5) mm, respectively. In the position of the incisor, the distance of MIC, the mean distance of the MIC to the tips of the teeth, to the buccal border of the mandible , to the lingual border of the mandible and the inferior border of the mandible were (1.0 ± 0.3), (13.3 ± 4.0), (4.2 ± 0.9), (5.9 ± 0.9) and (8.9 ± 1.8) mm, respectively. Conclusion CBCT clearly show three dimensional structure, course and adjacent structure of the MIC. Preoperative CBCT can provide vital information for surgery of the mandibular interforaminal area.
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Objective:To study the expressions of vascular endothelial growth factor(VEGF), and thrombospondin (TSP) in oral submucous fibrosis(OSF), and to determine the relationship between VEGF and TSP, so as to investigate their roles in the pathogenesis of OSF. Methods:30 patients with OSF, including early (10 cases), middle (10 cases), late stage (10 cases) were studied. 5 healthy volunteers were chosen as control group. Buccal mucosa biopsies were taken in all samples. Expressions of VEGF and TSP were detected by immunohistochemistry. Results:The expression of VEGF increased in early stage compared with normal oral mucous, and decreased in middle and late stage. The expression of VEGF in early stage had statistical difference compared with control group, middle stage and late stage respectively(P<0.05).The expression of TSP upregulated in early and middle, and downregulated in late stage. There were no statistical significant differences among groups(P>0.05). The expressions of VEGF and TSP had negative correlation(r=-0.620,P<0.05). Conclusions: The abnormal expressions of VEGF and TSP may be a pathogenesis factor of OSF.
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0.05).Conclusions:Laser welding joint gap at 0.00~1.00 mm does not affect the mechanical property of laser-welded titanium.