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To investigate the nucleotide-binding oligomerization domain-2 (NOD-2) gene expression in deep caries and the effects of NOD-2 agonist muramyl dipeptide (MDP) on the differentiation of human dental pulp cells (hDPC).NOD-2 gene level in deep caries and healthy pulp tissue was determined by real-time quantitative polymerase chain reaction (realtime-PCR). Realtime-PCR, Western blotting and immunofluorescence were performed to evaluate NOD-2 gene and protein expression. Dentin sialoprotein (DSP) protein level was assessed when hDPC were challenged by different concentrations of MDP for 24 hours, and sialophosphoprotein (DSPP), osteocalcin (OCN) mRNA and osteopontin (OPN) protein level were detected at different time points after incubation with 0.1 mg/L MDP.NOD-2 mRNA level was higher in pulp tissue of deep caries (0.2610 ± 0.0824) than that in healthy controls (0.0024 ± 0.0002), P0.05. The expression of NOD-2 gene and protein increased in a time denpendent manner upon stimulation with MDP. Immunofluorescence confirmed that NOD-2 protein was located in cytoplasm. Moreover, 0.1 mg/L MDP augmented DSP protein level. DSPP and OCN mRNA were elevated with time and reached the peak at 12 h and down-regulated. OPN protein level also increased with time.Dental pulp NOD-2 expression are up-regulated in pulp tissue of deep caries. MDP may be related to the differentiation of hDPC.

The application of adhesive root canal filling materials is the tendency in root canal obturation. The orientation is to develop the adhesive core material and sealer making a whole structure. In this review, we summarized the researches on the resin-dentin adhesion in the root canal obturation.

To investigate the morphological characteristics of the mandibular first premolars in people from Pearl River Delta region in Guangdong province using three techniques, including periapical radiographs, the radiographs with files inserted the canals and the clearing technique.A total of 363 extracted mandibular first premolars were collected and numbered. Two preoperative radiographs were taken in buccolingual and mesiodistal directions respectively. After access opening, the files were placed in the canals and two other radiographs were taken. The mandibular first premolars with multi-canal system were selected and observed under dental operating microscope (DOM). The mandibular first premolars were made transparent and were categorized using the Vertucci's classification.There were different results among the three approaches. Periapical radiographs could be used to distinguish only between one and multiple canals systems. The incidence of multiple canals was 33.33% from the radiographs with file. The mandibular first premolars had a high frequency (34.44%) of multi-canal system by clearing method. The root canal morphology of the mandibular first premolars showed great variance. The canal orifices of the mandibular first premolars with one or two canal distributed in a buccolingual line. The floor of pulp chamber of the mandibular first premolars with three or four canals was a plat form.The mandibular first premolars have a high frequency multi-canal system and could be classified in many categories. Using DOM and radiographs with file is a useful way in judging the canal numbers and categories.

To compare the sealing ability and fracture resistance of roots endodontically treated with bonded and unbonded filling materials.One hundred and fifteen straight mandibular premolar teeth with single canal were divided randomly into 6 experimental groups, with 15 samples each, and 3 control groups. The sealing ability was evaluated using a glucose quantitative microleakage mode and fracture resistance was tested by universal testing machine.The microleakage results showed that the bonded filling material had the lowest value while the unbonded filling material had the highest value in all groups. There were significant differences in microleakage value among the groups (P0.01), but no significant difference was noted in the fracture resistance among the testing groups (P = 0.7016).Bonded filling material enhanced the sealing ability but could not reinforce the fracture resistance of endodontically treated teeth.

To synthesize a new resin root canal filling material (NRCFM) and evaluate its stability in water and artificial saliva.The new root canal filling material was made of thermoplastic elastomer (TPE), ethylene vinyl acetate (EVA) and activity fillers. The NRCFM's stability in water and artificial saliva with different pH values was assessed using gravimetric analysis, ICP and FE-SEM.NRCFM1 and NRCFM2 were successfully made. Gravimetric evaluation showed that the changes in mass over 30 days different solution medium for NRCFM1 and NRCFM2 were comparable to that of GP (P0.05) and significantly different from Resilon (P0.001). ICP showed slight changes in Si concentration for NRCFM1 and NRCFM2, Zn for GP, Na and Si for Resilon in the alkaline artificial saliva (pH 9.5). GP and Resilon showed release of Zn and Na respectively in distilled water whereas NRCFM1 and NRCFM2 were stable. FE-SEM micrographs showed that there were slight changes on the surface topography of NRCFM1 and NRCFM2.The new resin root canal filling material NRCFM1 and NRCFM2 had good stability in different experimental solutions.

Objective The aim of this study was to evaluate the sealing ability of Resilon after retreatment. Study design Sixty-six single-rooted mandibular premolars were enlarged to apical size 45 and then obturated with Resilon. The roots were randomly divided into 3 groups (n = 22/group). In group 1 no further treatment was done. Groups 2 and 3 were reinstrumented to apical size 60 using K-files and ProFile, respectively. In each group, 4 samples were kept for environmental scanning electron microscopy (ESEM) analysis. The remaining roots from groups 2 and 3 were refilled with Resilon. Sixteen roots from each group were then evaluated for microleakage; two roots served as controls. Data were analyzed statistically by Kruskall-Wallis test. Results There were no significant differences between the experimental groups ( P > .05). The ESEM showed new attachment of resin tags on the dentin surface of retreated roots. Conclusion Resilon can be used for retreatment, but it still allowed microleakage.

To investigate the effect of adenovirus expressing human bone morphogenetic protein-7 (hBMP-7) on proliferation and differentiation of human dental pulp cells.The replication-deficient adenoviral vector encoding hBMP-7 gene was constructed by using homologous recombinant modality. The efficiency of transfection was evaluated by fluorescent microscopy and flow cytometry. The expression of hBMP-7 protein in adenovirus-infected dental pulp cells was determined by Western blot. The proliferation of cells was tested by MTT method, the activity of alkaline phosphatase was assayed, von Kossa staining was used to detect mineralized nodule formation, and the expression of DSPPmRNA in cells was detected using semi-quantitative RT-PCR.Green fluorescent protein was visible under fluorescent microscopy. Higher transfection efficiency (91.1 +/- 1.0)% could be obtained at MOI of 75. Western blot from dental pulp cells infected with Ad-hBMP-7 for 48h detected protein expression of a hBMP-7 gene. The activity of alkaline phosphatase in cells was significantly higher than those of the control groups (P0.05). The cells infected with Ad-hBMP-7 had the ability of mineralization. DSPP mRNA expression of cells was in a time- and dose- dependent manner.Ad-hBMP-7 can induce human pulp cells into odontoblasts, but has no obvious effect on their proliferation.