Objective To examine Streptpcoccus mutans,Streptpcoccus sobrinus and Streptpcoccus sanguis in the early formation of native dental plaque biofilm. Methods An experimental dental plaque biofilm model in the oral cavity was established using enamel slabs. The spatial distribution of S. mutans, S.sobrinus and S. sanguis in the early colonization of dental plaque biofilms on the enamel surface was observed bv in situ, real-time and dynamic observations and optical sections utilizing confocal laser scanning microscopy(CLSM) and fluorescence in situ hybridization(FISH). The experiment data were analyzed with One-Way AVOVA, α=0.05 using SPSS11.5. Results Dental biofilm had a certain degree of thickness and various forms in three-dimensioned structure. The bacteria in the structure were sparse at the inner layers and the outer layers. In the middle layers the bacteria were closely compacted. There were many voids traversing from the outside of the biofilm to the enamel surface. At the initial stage of dental biofilm formation, the scanned average thickness of S. mutans,S. sobrinus and S. sanguis increased with time elapsing,the mean thicknesses of 1 h biofilms were 20.43 μm,11.50 μm and 14.76 μm,respectively,and those of 24 h were the thickest in terms of average level,the mean values were 70.25 μm,75.40 μm and 79.98 μm,respectively. Conclusion The fluorescence in situ hybridization combined with CLSM are thought to be convenient and sensitive to detect S. mutans, S. sobrinus and S. sanguis in the dental plaque biofilms.

Harmonious relationship between medicine and patients is an important component constructing harmonious society. Bad harmonious relationship between medicine and patients and medical tangle case is increasing. The article introduced the concept and the causes of medical disputes. Clinical examples of medical disputes are analysed in department of cariology and endodontolo-gy,guanghua school of stomatology,sun yat-sen university.

【Objective】 To sequence P1 gene(184～1946 bp) includ ing SBR gene in expressional plasmid of transgenic plant. 【Methods】 pROP1 plas mid was extracted from E. coli DH5α, P1 gene was sequenced by PCR sequence kit and DNA autosequencer and compared with surface protein gene of Streptococc us mutans in GenBank. 【Results】 616 base pairs from 5′ end and 466 base pairs from 3′ end were sequenced, its accuracy is up to 98%. 【Conclusion】 The seq uence of P1 gene's 5′ end and 3′ end is consistent with DNA sequence of SBR re gion of Streptococcus mutans surface protein pac gene and may provide useful in formations to construct the transgenic plant anticaries vaccine.

Gene Expression Regulation, Bacterial ; Genes, Regulator ; Humans ; Streptococcus mutans ; genetics

Objective:To evaluate the effects of various tapers of canal preparations on the retention of cast posts in endodontically treated upper incisors in vitro.Methods: Forty human central or lateral maxillary incisors were prepared by removing the clinical crown at 1 mm above the approximal CEJ and treated the canals with instruments of varying tapers. The groups comprising 10 teeth of each group were divided as follows: Taper 0.02 /15~40#SS (stainless steel K-files) with step-back technique as control, PF (ProFile)OS 3#/0.06 with taper 0.06/PF 25#/ in apical third, PF OS 4#/0.07 with taper PF 0.06/30# in apical third, PF OS 5#/0.08 with PF taper 0.06/35# in apical third. Then, canals were filled with gutta percha and AH Plus sealer using vertical condensation technique with a level of 5 mm of gutta-percha left in the apical segment of the root. Metal cast posts were made by direct method and then the post was cemented with HY-BOND GLASIONMER CX (Shofu,Inc)cement. The roots were fixed in copper rings with mounting plaster and mounted on a WD-5A machine.The posts were subjected to gradually increasing vertical tensile force until dislodgment of the post occurred. Force (N) required to dislodge the post was obtained for each tooth, and the average force of the groups was compared using a one-way ANOVA and SNK multiple comparisons with SAS V8.1. Results:The highest resistance to dislodgment was obtained with PF OS 4#/0.07, whereas the lowest was obtained by the PF OS 3#/0.06. Nonstatistical difference was found between Taper 0.02 /15~40# and PF OS 3#/0.06. PF OS 4#/0.07 was statistically superior to Taper 0.02 /15~40# and PF OS 3#/0.06 but not PF OS 5#/0.08. Conclusion: The retention of posts is affected strongly with the increase in the diameter than with the increase in the taper angle. PF OS 4#/0.07 with taper PF 0.06/30# in apical third seems to be the best taper for maximal resistance to post dislodgment.

Objective: To synthesize and identify the peptide HDS derived from S.mutans GTF-B N-terminal 552-570. Methods: The peptide HDS derived from S.mutans GTF-B N-terminal 552-570 was synthesized by Merrifold peptide synthesor AB1433A and its amino acid sequence was detected by FAST technique.Results: The peptide HDS was synthesized accurately and purified by 97%. Conclusion: The synthesis of HDS makes it possible to study its immunologic characteristics.

0.05),respectively.Conclusion:LED curing light can reach the performance level of halogen curing light and is suitable for routine oral clinical application for resin curing.

Objective:To evaluate the shaping ability of nickel-titanium (NiTi) rotary instrument Hero 642 combined with SX of ProTaper in moderately and severely curved root canals.Methods:42 teeth with moderately and severely curved canals in 42 patients were prepared by Hero 642 and SX of ProTaper using crown-down technique and obturated with lateral condensation method. The efficiency of the preparation and obturation were analyzed by radiographs before and after treatment. Results:After preparation by the rotary instrument the original curvature and alignment of the canals were kept. No transportation, apical blockage, ledge or perforation was found in all cases. In one case,the file was broken during operation.After treatment light pain was complained in 4 cases and the pain alleviated and disappeared spontaneously. Conclusion:The NiTi rotary instrumentation technique with Hero 642 and ProTaper can be used to prepare curved root canals effectively and quickly.

Objective:To investigate the effects of E.coli lipopolysaccharide(LPS) stimulus on the synthesis of TLR4 protein and its mRNA expression in human dental pulp cells(HDPCs), and to explore the roles of TLR4 on the activation of HDPCs induced by LPS. Methods:The expressions of TLR4 mRNA and the synthesis of TLR4 protein in HDPCs induced by LPS were detected by real-time fluorescence quantitative RT-PCR(FQ RT-PCR) and immunofluorescence technique.IL-1? concentrations in the supernatant of cultured HDPCs pretreated with TLR4 antibody were assayed with ELISA. Results: The expressions of TLR4 could not be detected in normal HDPCs.After being stimulated with 1?10-4 g/L LPS for 6,12 or 24 h, immunostaining showed that TLR4 was expressed in cytomembrane and cytoplasm of HDPCs,while in nucleus the expressions were negative. FQ RT-PCR showed their expressions significantly increased after being stimulated with LPS (P

Objective:To discuss the clinical feature and treatment of second mesiobuccal canal (MB2)of permanent maxillary molars. Methods:The root canals of 106 maxillary first molars and 80 maxillary second molars were explored with small size K files. The frequency and morphology of root canals were recorded. The canals of all cases were instrumented by Ni-Ti rotary instruments Hero 642, and obturated with lateral condensation technique. The efficiency of preparation and obturation was analyzed with radiographs before and after treatment. Results:The frequency of MB2 canal in maxillary first and second molars were 82.1% and 45.0%. Most MB2 was very fine and negotiated by size 8 or 10 file combined with EDTA. No transportation, ledge, or perforation was found except that one hand file was separated. Good result of treatment was achieved in most cases. Conclusion:The incidence of MB2 canals of maxillary first molars was higher than that of second molars, and most of them were very fine. The MB2 canals can be negotiated with small size file combined with EDTA, and shaped well with Ni-Ti rotary instruments.