Aliidongia dinghuensis gen. nov., sp. nov., a poly-ß-hydroxybutyrate-producing bacterium isolated from Pinus massoniana forest soil.

A Gram-stain-negative, aerobic, motile, rod-shaped bacterium, designated 7M-Z19T, was isolated from a soil sample collected from a Pinus massoniana forest of Dinghushan Biosphere Reserve, Guangdong Province, PR China. Strain 7M-Z19T grew at pH 4.5-7.5 (optimum pH 6.0-6.5), 10 to 37 °C (optimum 28 °C) and NaCl concentration up to 2.0 % (optimum 0 %, w/v). iso-C17 : 0, C18 : 1ω7c and C19 : 0ω8c cyclo were the major fatty acids (>10 %) while ubiquinone-10 was the only respiratory quinone detected in 7M-Z19T. The polar lipids of the strain consisted of phosphatidylethanolamine, phosphatidyldimethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, six unidentified aminophospholipids, three unidentified phospholipids, six unidentified lipids and a glycolipid. The DNA G+C content was 65.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate formed a distinct lineage with Dongia mobilis and Dongia rigui within the family Rhodospirillaceae, but with a low sequence similarity of 92.7 and 92.0 %, respectively. On the basis of phylogenetic, phenotypic, physiological and chemotaxonomic distinctiveness, strain 7M-Z19T should be placed in the family Rhodospirillaceae as a representative of a novel genus and species, for which the name Aliidongia dinghuensis gen. nov., sp. nov., is proposed. The type strain of the type species is 7M-Z19T (=NBRC 112240T=KCTC 52134T=CGMCC 1.15725T).

[Effect of titanium nitride coatings with different thickness on microhardness and cutting efficiency of nickel-titanium instruments].

PURPOSE: To investigate the effect of titanium nitride (TiN) coatings with different thicknesses on microhardness and cutting efficiency of nickel-titanium (NiTi) instruments, and to provide a basis for improving the efficiency of clinical root canal preparation. METHODS: Fifteen KV4 NiTi alloy sheets and sixty KV4 rotary NiTi files were selected and randomly divided into 5 groups: uncoated group, coating 1 h group, coating 2 h group, coating 3 h group and coating 4 h group. A layer of TiN coatings of different thicknesses was prepared on the surface of the coated groups by controlling the deposition time. The film thickness of each group was measured by scanning electron microscopy (SEM). The microhardness of each group of NiTi alloy sheets was measured by a Vickers hardness tester. Sixty transparent resin modules were selected and each resin module was prepared with one NiTi file. The cutting efficiency of each group was measured by the weight loss method. SEM was used to examine the surface of NiTi instruments in 5 groups before and after preparation. One-way variance analysis was used to determine the statistical differences with SPSS 22.0 software package. RESULTS: With the increase of the thickness of titanium nitride coating, the microhardness of NiTi alloy gradually increased(P＜0.05). With the increase of the thickness of titanium nitride coating, the cutting efficiency of NiTi instrument was improved, and the cutting efficiency was the largest when the coating thickness was 860 nm(P＜0.05). The surface morphology of the coated group was better than that of the uncoated group. CONCLUSIONS: The thickness of TiN coating affects microhardness and cutting efficiency of the nickel-titanium instruments, the microhardness and cutting ability enhanced as the thickness increased. If the thickness is too large, the cutting efficiency will be reduced.

[Effect of inhibition of Porphyromonas endodontalis on osteoblast differentiation].

PURPOSE: Porphyromonas endodontalis (P.e) is the dominant bacterium in the infected canal of pulpal and periapical disease.Lipopolysaccharides (LPS) in the outer membrane of the cell wall is an important toxicity factor of P.e. In this study, the effect of P.e-LPS on osteoblast differentiation was studied, and the pathogenic mechanism of P.e-LPS in periapical bone resorption disease was explored. METHODS: Porphyromonas endodontalis was cultured under anaerobic conditions. P.e-LPS was extracted by thermophenol water method, and then the extracted LPS was qualitatively analyzed by gel limulireagent method. Preosteoblast cell line MC3T3-E1 were induced to differentiate into osteoblasts by osteoblast differentiation medium (50 µg/mL ascorbic acid，6 mmol/L beta-glycerphosphate). Expressions of osteogenic differentiation genes including distal-less homeobox 5（DLX5）, runt-related transcription factor 2(Runx2), Osterix, bone sialoprotein (BSP), OCN(osteocalcin) and Collagen were detected by RT-PCR. The activity of alkaline phosphatase(ALP)， alizarin red staining and Von Kossa staining were used to determine the mineralization level of osteoblasts.The expression of TOLL-like receptor-4 (TLR-4), the receptor of P.e-LPS, was silenced by siRNA transfection. SPSS 11.0 software package was used for statistical analysis of the data. RESULTS: The mRNA expressions of osteogenic differentiation genes including DLX5, Runx2, Osterix, OCN, BSP, and Collagen were significantly decreased after treated with P.e-LPS (10 µg/mL) for 3 d, compared with the control group（P<0.05）.After treated with P.e-LPS (10 µg/mL) for 7 d or 14 d, respectively, ALP and alizarin red staining intensity was decreased. P.e-LPS was applied to the si-TLR-4 transfection group and the control group for 7,14 and 21 d, respectively. Compared with the control group, the expression level of osteogenic differentiation genes, ALP, alizarin red staining and Von Kossa staining intensity of si-TLR-4 group were significantly higher than those of the control group (P<0.05). CONCLUSIONS: P.e-LPS inhibits the differentiation of osteoblasts through TLR-4 receptor, thus participating in bone resorption process of periapical lesions.

[Resveratrol suppressed the expression of MIP-2 induced by lipopolysaccharide in osteoblasts via up-regulating SOCS-3].

PURPOSE: To explore whether resveratrol dependents on the production of suppressor of cytokine signaling suppressor 3 (SOCS-3) in inhibiting mRNA production of macrophage inflammatory protein-2 (MIP-2) in osteoblasts induced by lipopolysaccharides(LPS) extracted from Porphyromonas endodontalis(P.e). METHODS: MC3T3-E1 cells were treated with different concentrations of resveratrol (0, 5, 10 and 20 µmol/L) and 20 µmol/L resveratrol for different time( 0, 10, 30, 60, 120 and 180 min). The expression of SOCS-3 protein was detected by Western blot. MC3T3-E1 cells were transfected with mouse SOCS3 siRNA (si-SOCS-3) and control siRNA(si-control). Reverse transcription real-time PCR(real-time RT-PCR) and Western blot was used to detect the silencing efficiency of SOCS-3. Cells were stimulated by 20 µg/mL P.e-LPS for 24 h after transfection, in the absence or presence of 20 µmol/L resveratrol for 1 h , and the changes of MIP-2 mRNA were determined by real-time RT-PCR. Statistical analysis was performed using one-way ANOVA and Dunnett t test with SPSS 13.0 software package. RESULTS: Treatment of MC3T3-El cells with different concentrations of resveratrol caused a significant increase in SOCS-3 protein expression in a dose-dependent manner. During the observation time of 180 min, SOCS-3 protein expression was the highest at 20 µmol/L resveratrol-treated osteoblasts for 60 min. The silencing efficiency of SOCS-3 mRNA was 63.7%. Transfection with SOCS-3 siRNA increased MIP-2 mRNA expression in LPS-stimulated MC3T3-E1 cells and negated the inhibitory effects of resveratrol on LPS-induced MIP-2 mRNA expression(P<0.05). CONCLUSIONS: Resveratrol inhibits the expression of MIP-2 mRNA in osteoblasts induced by P.e-LPS by up-regulating the expression of SOCS-3 protein.

[Comparison of mechanical properties of three machinable resin ceramic composite materials].

PURPOSE: This in vitro study was to compare the flexural properties, fracture toughness and hardness of three machinable composite materials. METHODS: Three kinds of resin composite ceramic Upcera Hyramic, 3M Lava Ultimate, Vita Enamic and a glass ceramic Vitablocs Mark II were chosen for the study. Bar-shaped specimens (16 mm×4 mm×1 mm, 2 mm) were prepared for flexural strength experiment; specimens (17 mm×4 mm×3 mm) were prepared for fracture toughness experiment and specimens of 4 mm thickness were prepared for hardness test. Flexural test and fracture toughness experiment were performed with an universal testing machine at a cross-head speed of 0.5 mm/min. Hardness test was performed with an micro hardness tester.Scanning electron microscope was used to observe the roughness of fracture surface. One-way variance analysis was used to determine the statistical differences with SPSS 17.0 software package. RESULTS: The mean flexural strength of the tested blocks at 1 mm thickness was Hyramic（207.7515±13.12）MPa＞Vita Enamic（182.0286±15.18）MPa＞Lava Ultimate（145.8469±8.98）MPa＞Vitablocs MarkⅡ（103.0542±18.19）MPa. The mean flexural modulus were Vitablocs MarkⅡ（49.49±5.50）GPa＞Vita Enamic（40.65±3.80）GPa＞Hyramic（14.89±2.38）GPa＞Lava Ultimate（7.09±1.24）GPa. The mean flexural strength of the tested blocks at 2 mm thickness was Hyramic（208.1986±25.07）MPa＞Lava Ultimate（172.9297±12.73）MPa＞Vitablocs MarkⅡ（158.6587±15.37） MPa＞Vita Enamic（155.3670±13.77）MPa. The mean flexural modulus were Vitablocs MarkⅡ（24.07±1.86）GPa＞Vita Enamic（19.64±0.98）GPa＞Hyramic（10.35±0.87）GPa＞Lava Ultimate（8.68±0.86）GPa. The mean fracture toughness was Vita Enamic（1.6357±0.16）MPa·m1/2＞Lava Ultimate（1.4286±0.11）MPa·m1/2>Vitablocs MarkII（1.3233±0.10）MPa·m1/2>Hyramic（1.0614±0.09）MPa·m1/2. The hardness of the experimental group was significantly lower than that of the control group. CONCLUSIONS: According to ISO 6872/2008, three kinds of machinable resin ceramic composites meet the needs of clinical strength.Hyramic showed higher flexural strength at different thickness, it is an ideal material for dental restoration. Vita Enamic has not only higher flexural strength at the thickness of 1 mm, but also good toughness, it is suitable for repair of patients that have limited occlusal space and great bite force, named occlusal veneer.

[Effect of resveratrol on the expression of MIP-2 in P.e-LPS-induced mouse osteoblasts].

PURPOSE: To investigate the effect of lipopolysaccharides(LPS) extracted from Porphyromonas endodontalis(P.e) on the expression of macrophage inflammatory protein-2 (MIP-2) mRNA and protein levels in MC3T3-E1 cells and the influence of resveratrol on the expression of MIP-2 protein in P.e-LPS induced cells. METHODS: MC3T3-E1 cells were treated with different concentrations of P.e-LPS(0-50 mg/L) and 20 mg/L P.e-LPS for different time (0-48 h). The expression of MIP-2 mRNA and protein was detected by real-time RT-PCR and enzyme linked immunosorbent assay (ELISA). MC3T3-E1 cells were pretreated with resveratrol for 1 h in the presence of 20 mg/L P.e-LPS for 24 h，which was detected by ELISA. Statistical analysis was performed using one-way ANOVA and Dunnett t test with SPSS 13.0 software package. RESULTS: Treatment of MC3T3-El cells with different concentrations of P.e-LPS(0-50 mg/L) caused a significantly increase in MIP-2 mRNA and protein expression in dose-dependent manners.The expression of MIP-2 protein increased from (41.86±2.49) ng/L to (3126.74±158.30) ng/L, and the difference was significant(P<0.05). In the observation time (0-48 h), the impact of 20 mg/L P.e-LPS on induction of MIP-2 in MC3T3-El cells exhibited a time-dependent manner. At 48 h, the maximal induction of MIP-2 protein expression was (2102.55±123.27) ng/L(P<0.01). Incubation of cells with 10 µmol/L resveratrol for 1h significantly decreased the expression of MIP-2 protein from (1805.33±67.54) ng/L to（813.82±47.21) ng/L, and the difference was significant(P<0.05). CONCLUSIONS: The results suggest that P.e-LPS may mediate MIP-2 expression in MC3T3-E1 cells, and resveratrol has a significant inhibitory effect on this process.

[Application of Flipped classroom combined with case-based learning in resident training of endodontics].

PURPOSE: To apply Flipped classroom combined with case-based learning(CBL) in resident training of endodontics, in order to improve training efficiency. METHODS: Fifty-one residents from China Medical University, School of Stomatology were randomly divided into 2 groups, twenty-six students in the experimental group were trained with Flipped classroom combined with CBL, the other twenty-five students in the control group were trained with traditional teaching method. At the end of the course, exams and questionnaires were conducted to evaluate the training quality of two different methods. The exams consisted of didactic and operational assessment. The data were analyzed with SPSS 13.0 software package. RESULTS: The results of didactic exam and comprehensive evaluation indicated that experimental group was significantly higher than the control group(P<0.05). The results of questionnaires indicated that residents showed much more satisfied with Flipped classroom combined with CBL (P<0.05).However, there was no significant difference in operational assessment(P>0.05). CONCLUSIONS: Compared with traditional teaching method, Flipped classroom combined with CBL can achieve better training effect, which is worthy of further application in dental resident training.

[Application of micro-lecture in standardized training of endodontic residents].

PURPOSE: To apply micro-lecture in standardized training of endodontic residents, in order to improve training quality. METHODS: Twenty endodontic residents were randomly divided into 2 groups, 10 students in each group. One group were taught with micro-lecture while the other group with lecture-based learning (LBL). The teaching effect was measured with examination and questionnaire survey. The examination results were analyzed by Student's t test using SPSS 18.0 software package. RESULTS: Micro-lecture group was better than LBL group in practical test and total scores, there were significant differences between the two groups (P＜0.05). Micro-lecture group was better than LBL group in didactic test, but there was no significant difference between the two groups (P＞0.05). Questionnaire survey showed that micro-lecture was well accepted by residents for its novelty and flexibility, self-motivated learning ability was trained, communication between teachers and residents was enhanced, but the production level of micro-lecture video needs to be improved. CONCLUSIONS: Micro-lecture achieves satisfactory teaching effect, and can be applied in standardized training of endodontic residents.

[Effects of Porphyromonas endodontalis lipopolysaccharides on the expression of monocyte chemotactic protein-1 in mouse osteoblasts].

PURPOSE: To investigate the effects of lipopolysaccharide (LPS) extracted from Porphyromonas endodontalis (P.endodontalis) on expression of monocyte chemotactic protein-1 (MCP-1) mRNA and protein in MC3T3-E1 cells and the role of p38 mitogen-activated　protein　kinase (MAPK) and nuclear factor-kB(NF-kB）in the process. METHODS: MC3T3-E1 cells were treated with different concentrations of P.endodontalis LPS(0-50mg/L) and 20 mg/L P.endodontalis LPS for different hours (0-48 h). The expression of MCP-1 mRNA was detected by real-time reverse transcription PCR(RT-PCR) and protein was detected by enzyme-1inked immunosorbent assay (ELISA). MC3T3-E1 cells were pretreated with SB203580 (inhibitor of p38MAPK) and BAY11-7082 (inhibitor of NF-kB) for 1h, and then were treated with 20 mg/L P.endodontalis LPS for 24 h, the expression of MCP-1 mRNA was also detected by RT-PCR. Statistical analysis was performed using one-way ANOVA and Dunnett t test with SPSS 13.0 software package. RESULTS: The level of MCP-1 mRNA and protein increased significantly after treatment with different concentrations of P.endodontalis LPS (0-50 mg/L), which indicated that P.endodontalis LPS induced osteoblasts to express MCP-1 in a dose dependent manners. During the observation time (0-48 h), the impact of 20 mg/L P.endodontalis LPS on induction of MCP-1 in MC3T3-E1 cells exhibited a time-dependent manner. The expression of MCP-1 mRNA decreased significantly after pretreated with 10 mol/L SB203580 and BAY11-7082 for 1 h,and the inhibitory effect of SB203580 was stronger than BAY11-7082. CONCLUSIONS: P.endodontalis LPS may induce the expression of MCP-1 mRNA and protein in MC3T3-E1 cells through the signaling pathway of p38MAPK and NF-kB.

[Clinical observation on different kinds of laser on 60 molars with abrasion].

PURPOSE: To evaluate the clinical effect of different kinds of laser on 60 molars with abrasion. METHODS: Thirty patients with 60 abrasive molars were selected according to the inclusion criteria. Molars and premolars were divided into 2 groups randomly. Teeth in the experimental group were treated with Er,Cr:YSGG laser combined with AdperTM Easy One, while teeth in the control group were treated with Nd:YAG laser combined with AdperTM Easy One, composite resin Z350 was selected to restore the defect. The modified USPHS criteria was used to evaluate the treatment effects at recall periods.The data were analyzed using SPSS 13.0 software package. RESULTS: On retention, the B level rate of the experimental group was significantly lower than that of the control group(P<0.05) 12 months later. For success rate at 18 months，the difference between the experimental group and the control group was significant（P<0.05）. At the same time, sensitivity of tooth and overall response in the two groups had no significant difference (P>0.05). CONCLUSIONS: Although the overall response between the two groups had no significant difference,Er,Cr:YSGG laser shows better effect of retention, which is the preferred option for treatment of abrasive molars.

[Inhibiting effect of transforming growth factor ß3 on IL-6 expression in MG63 induced by lipopolysaccharide].

PURPOSE: To explore the effect of transforming growth factor ß3 (TGF-ß3) on IL-6 expression in inflammatory MG63, and the mechanism by which TGF-ß3 exert its anti-inflammatory effect. METHODS: Cell line MG63 was stimulated by 20 µg/mL lipopolysaccharide of Porphyromonas endodontalis (P.e-LPS) to establish the inflammatory model of osteoblast. TGF-ß3 or TGFß1 varying from 5 to 20 ng/mL was added together with P.e-LPS for 24 h, then the mRNA expression of IL-6 was detected by real-time PCR, the role of TGF-ß3 on IL-6 protein was further verified by ELISA. MG63 was pretreated with 10 ng/mL TGF-ß3 for 30 min in RPMI 1640 medium without fetal bovine serum (FBS), then the cells were cultured for another 20 min with 20 µg/mL P.e-LPS, the phosphorylation level of ERK1/2 was measured by Western blot. Statistical analysis was performed using one-way ANOVA with SPSS13.0 software package. RESULTS: The results of real-time PCR revealed that, when MG63 was treated with 20 µg/mL P.e-LPS alone, the mRNA expression of IL-6 increased significantly(P<0.01). When TGF-ß1 was added with P.e-LPS, it could barely decrease IL-6 prominently at the highest concentration (P<0.05).Whereas, the inhibition effect of TGF-ß3 on IL-6 was dramatic (P<0.01), ELISA results showed that 10-20 ng/mL TGF-ß3 blocked the IL-6 expression at protein level (P<0.05). 20 µg/mL P.e-LPS promoted the phosphorylation level of ERK1/2 in MG63(P<0.01), while with 10 ng/mL TGF-ß3, the effect of P.e-LPS on ERK1/2 was blocked(P<0.05). CONCLUSIONS: TGF-ß3 is more potent than TGF-ß1 in inhibiting MG63, and ERK1/2 is involved in its anti-inflammatory effect.

[Effect of the thickness of reinforced glass ceramics on the degree of conversion of dual-cure resin cements].

PURPOSE: To determine the effect of the thickness of reinforced glass ceramics on the degree of conversion (DC) of three dual-cure resin cements (Multilink N, RelyX Ultimate and NX3-Nexus). METHODS: Upcera reinforced glass ceramics and IPS e.max CAD test specimen were processed, with different thickness, transmittance was tested by ultraviolet and visible spectrometer. The DC was evaluated using Fourier transform infrared (FT-IR) spectrometer, then the degree of conversion of polymerization before and after curing was calculated. SPSS 21.0 software package was used for data analysis. RESULTS: Transmittance decreased along with the thickness of reinforced glass ceramics increased. At 2 mm -thickness transmittance of upcera lithium disilicate glass ceramics was superior to IPS e.max CAD. The DC of dual-cured resin cement was decreased with the increase of thickness. At the same 2 mm group, the DC of Multilink N and RelyX Ultimate under upcera lithium disilicate glass ceramics were superior to that under IPS e.max CAD groups. CONCLUSIONS: At 2 mm-thickness transmittance of upcera lithium disilicate glass ceramics was superior to IPS e.max CAD. At the same 2 mm group, the DC of Multilink N and RelyX Ultimate under upcera lithium disilicate glass ceramics were superior to that under IPS e.max CAD groups.

[Effect of lipopolysaccharides from Porphyromonas endodontalis on the expression of interleukin-34 in mouse osteoblasts].

PURPOSE: To investigate the effects of lipopolysaccharides (LPS) extracted from Porphyromonas endodontalis (P.e) on the expression of interleukin-34 (IL-34) mRNA in MC3T3-E1 cells and the role of p38MAPK, ERK1/2, NF-κB and SIRT1 in the process. METHODS: MC3T3-E1 cells were treated with different concentrations of P.e-LPS(0-50 mg/L) and 20 mg/L P.e-LPS for different time (0-24 h). The expression of IL-34 mRNA was detected by real-time reverse transcription-polymerase chain reaction (real time RT-PCR). MC3T3-E1 cells were pretreated with inhibitor of NF-κB(BAY 11-7082),inhibitor of p38MAPK (SB203580), inhibitor of ERK1/2 (PD98059), agonist of sirtuin1 (SIRT1) [resveratrol (RES)] and inhibitor of SIRT1 (EX-527) for 1 h, and then were treated with 20 mg/L P.e-LPS. The expression of IL-34 mRNA was detected by real time RT-PCR. Statistical analysis was performed using one-way ANOVA and Dunnett t test with SPSS 13.0 software package. RESULTS: The level of IL-34 mRNA increased significantly after treatment with different concentrations of P.e-LPS(0-50 mg/L)，which indicated that P.e-LPS induced osteoblasts to express IL-34 mRNA in a dose-dependent manner. Maximal induction of IL-34 mRNA expression was observed in MC3T3-E1 cells treated with 20 mg/L P.e-LPS for 24 h.At 48 h, the expression of IL-34 mRNA decreased gradually. The mRNA of IL-34 decreased significantly after pretreatment with 10 µmol/L BAY-117082, SB203580 and PD98059 for 1 h. P.e-LPS-induced IL-34 upregulation was attenuated by pretreatment with RES, but increased by EX-527. CONCLUSIONS: These results suggest that P.e-LPS may mediate IL-34 mRNA expression in MC3T3-E1 cells. This process is dependent, at least in part, on p38MAPK, ERK1/2, NF-κB and SIRT1 signaling pathways.

[Expression of SOCS-1 and SOCS-3 in chronic periapical lesions and its clinical significance].

PURPOSE: To detect the expression of suppressor of cytokine signaling-1 (SOCS-1) and suppressor of cytokine signaling-3 (SOCS-3) in chronic periapical lesions and to clarify their roles in pathogenesis of apical periodontitis. METHODS: A total of 25 chronic periapical lesion tissues and 16 normal periodontal ligament tissues were collected respectively. The expression of mRNA was measured by real-time PCR, the protein expression was measured by immunohistochemical analysis. Statistical analysis was performed using SPSS 13.0 software package. RESULTS: Immunohistochemical results indicated that expression levels of SOCS-1 and SOCS-3 protein in chronic periapical lesions were significantly higher than that in normal tissues (P<0.01); Moreover, SOCS-1 and SOCS-3 protein expression levels in severe inflammation group were significantly higher than that in mild inflammation group (P<0.01). In mild inflammation group, severe inflammation group and control group, the expression levels of SOCS-1 mRNA were 2.620±1.552, 2.373±1.083 and 1.277±1.040, whereas those of SOCS-3 were 9.308±5.901, 7.565±3.233 and 1.232±1.099, respectively. CONCLUSIONS: The expression levels of SOCS-1 mRNA and SOCS-3 mRNA are significantly higher both in mild inflammation group and severe inflammation group than that in control group (P<0.01), while no significant difference is found in mild and severe inflammation group.

[Effects of lipopolysaccharides from Porphyromonas endodontalis on the expression of MIP-1α in mouse osteoblasts].

PURPOSE: To investigate the effects of lipopolysaccharides(LPS) extracted from Porphyromonas endodontalis(P.e) on the expression of macrophageinflammatoryprotein-1α (MIP-1α) mRNA and protein levels in MC3T3-E1 cells and the influence of curcumin in the process. METHODS: MC3T3-E1 cells were treated with 20 mg/L P.e-LPS for different times (0-48 h). The expression of MIP-1α mRNA and protein was detected by real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) and enzyme linked immunosorbent assay(ELISA). MC3T3-E1 cells were pretreated with inhibitor of (curcumin) for 1 h, and then treated with 20 mg/L P.e-LPS. The expression of MIP-1α was also detected by real-time RT-PCR and ELISA.Statistical analysis was performed using one-way ANOVA and Dunnett's t test with SPSS 13.0 software package. RESULTS: In the observation time (0-48 h), the impact of 20 P.e-LPS mg/L on induction of MIP-1α in MC3T3-El cells exhibited a time-dependent manner. The expression of MIP-1α mRNA and protein decreased significantly after pretreatment with 10 µmol/L curcumin for 1 h. CONCLUSIONS: The results suggest that P.e-LPS may mediate MIP-1α expression in MC3T3-E1 cells, and curcumin has a significant inhibitory effect on this process.

[Application of PBL combined with SP method in during-course practice of endodontics for undergraduate dental students].

PURPOSE: To apply problem-based learning (PBL) combined with standardized patients(SP) in during-course practice of endodontics for undergraduate dental students, in order to improve the teaching quality. METHODS: One hundred and four undergraduate dental students of China Medical University School of Stomatology were randomly divided into 2 groups, 52 students in each group. One group were taught with PBL combined with SP while the other group with lecture-based learning (LBL) alone. The teaching effect was measured with examination and questionnaire survey. The data were analyzed by Student's t test using SPSS 11.5 software package. RESULTS: Students in PBL combined with SP group was better than LBL group in case analysis, didactic tests, practical tests and total scores, and there was significant difference between the two groups (P<0.05). LBL group was better than PBL combined with SP group in basic theoretical knowledge scores, and there was significant difference between the two groups (P<0.05). SP and PBL combined with SP method were welcomed by undergraduate dental students. CONCLUSIONS: The abilities of undergraduate dental students can be improved by PBL combined with SP in different aspects. PBL combined with SP achieves satisfactory teaching effect, and can be applied in during-course practice of endodontics to undergraduate dental students.

[Comparison of wear resistance and flexural strength of three kinds of bulk-fill composite resins].

PURPOSE: To compare the abrasion resistance and flexure strength of three bulk-fill resin composites with an universal nano-hybrid composite resins. METHODS: The specimens were prepared with three kinds of bulk fill composites (SDR , sonicfill, Tetric N-Ceram Bulk Fill) and an universal nano-hybrid composite resins(Herculite Precis). 10 mm in diameter × 2mm in height specimens were prepared for abrasion resistance, while 2 mm in width × 2 mm in depth×25 mm in length specimens were prepared for flexure strength. The specimens were mounted in a bal1-on-disc wear testing machine and abraded with the media artificial saliva(50 N loads, 10000 cycles).Flexural test was performed with an Universal Testing Machine at a cross-head speed of 1mm/min. One-way variance analysis was used to determine the statistical differences of volume loss and flexural strength among groups with SPSS 13.0 software package(P<0.05). RESULTS: The volume loss was as follows: SDR (1.2433±0.11) mm30.05). CONCLUSIONS: With regard to wear resistance and flexural strength, Tetric N-Ceram Bulk Fill is recommended as an alternative for posterior restorations.

[Mechanism of TNF-α in bone defect of chronic apical periodontitis].

PURPOSE: To investigate the effect of lipopolysaccharides(LPS) extracted from Porphyromonas endodontalis(P.e) on the expression of tumor necrosis factor-α(TNF-α) mRNA in MC3T3-E1 cells and the role of NF-κB signaling on the expression of macrophage colony stimulating factor (M-CSF) induced by TNF-α in MC3T3-El cells． METHODS: MC3T3-E1 cells were treated with different concentrations of P.e-LPS(0-50 mg/L) and 10 mg/L P.e-LPS for different time (0-24 h). The expression of TNF-α mRNA was detected by reverse transcription polymerase chain reaction(RT-PCR). MC3T3-E1 cells were treated with different concentrations of TNF-α(0-10 ng/L) for 6 h. The expression of M-CSF mRNA and protein was detected by RT-PCR and enzyme-linked immunoadsordent assay(ELISA).The expression of M-CSF protein was also detected in 10 ng/L TNF-α treated MC3T3-E1 cells after pretreated with BAY 11-7082 for 1 h, a special NF-κB inhibitor . Statistical analysis was performed using Multi-way ANOVA and Dunnett t test with SPSS 13.0 software package. RESULTS: The level of TNF-α mRNA increased significantly after treatment with different concentrations of P.e-LPS(0-50 mg/L)，which indicated that P.e-LPS induced osteoblasts to express TNF-α mRNA in dose dependent manners. Maximal induction of TNF-α mRNA expression was seen in the MC3T3-E1 cells treated with 10 mg/L P.e-LPS for 6 h. After 6 h, the expression of TNF-α mRNA decreased gradually .The expression of M-CSF mRNA and protein was increased in a does- dependent manner by different concentrations of TNF-α treatment（0-10 ng/L）. The expression of M-CSF protein increased from (37±2) ng/L(control group) to (301±8) ng/L(10 ng/L group).The protein of M-CSF decreased significantly after pretreatment with 10 µmol/L BAY 11-7082 for 1 h, and the expression of M-CSF proteins was reduced from (253±14) ng/L to (154±2) ng/L .BAY group had no significant difference from the control group. CONCLUSIONS: The expression of TNF-α mRNA was increased by P. endodontalis LPS treatment in osteoblast. TNF-α may induce the expression of M-CSF in MC3T3-E1 cells through the signaling of NF-κB. It suggests that TNF-α affect osteoblasts through autocrine way for bone destruction in chronic apical periodontitis induced by P.e-LPS.

[The effect of calcium hydroxide on IL-6 and TNF-α expression of osteoblast in periapical tissues].

PURPOSE: To compare the effect of calcium hydroxide in different position on pH and inflammation factor expression of periapical osteoblasts. METHODS: 140 sterilized single-rooted human teeth models were randomly divided into 6 experiment groups and one control group: Group 1-3:calcium hydroxide paste was placed in the apical half of root canal, the upper half of root canal and the pulp champer; Group 4-6:Apexcal was placed in the apical half of root canal, the upper half of root canal and the pulp champer; Group 7: the control group without medication. 10 teeth of each group were placed in P.e suspension, the IL-6 and TNF-α expression of MC3T3-E1 was tested at 3 d and 7 d. The other teeth of each group were placed in distilled water, and the pH in periapical region was tested at 3, 7, 14 and 21 d. SPSS 13.0 software package was used for statistical analysis. RESULTS: Calcium hydroxide placed in different position of the root canal increased periapical pH value and reached its peak at 14 d. The group in which calcium hydroxide paste was placed in pulp chamber gained lower pH level than other experimental groups. IL-6, TNF-α expression of MC3T3-E1 pretreated by P.e suspension of experimental groups was significantly reduced compared with control group, and there was no significant difference between the experimental groups. CONCLUSIONS: Calcium hydroxide placed in different position of the root canal could increase periapical pH value and reduce IL- 6, TNF-α expression of periapical osteoblasts.

[Expression of IL-34 in chronic periapical lesions and its clinical significance].

PURPOSE: To observe the expression of IL-34 mRNA in chronic periapical lesions and healthy periodontal ligaments and discuss the role of IL-34 in the etiology of chronic apical periodontitis. METHODS: A total of 25 periapical tissues from chronic apical periodontitis and 22 normal periodontal ligament tissue from extracted healthy teeth for orthodontic reason were selected. The expression of IL-34mRNA was detected by real-time PCR; the expression of IL-34 protein was detected by immunohistochemical analysis. Statistical analysis was performed using SPSS 13.0 software package. RESULTS: The level of IL-34 mRNA expression in periapical lesions (3.53±3.07) was significantly higher than that of the normal control (1.07±0.76); IL-34 was positively expressed in lymphocytes, plasma cells and macrophages. Image analysis software indicated that the level of IL-34 protein was significantly higher in periapical lesions than that in normal control (P<0.01). CONCLUSIONS: IL-34 may be closely related to inflammation of chronic apical periodontitis.