Search

Objective: To examine the distributions of beta-catenin and adenomatous polyposis coli (APC) protein in the tooth germ, and obtain the messages of function of the two factors and the relationship between them., Methods: Mice were selected and cohabited with the ratio of female mice to male ones being 2:1, and Embryo day 0.5 was confirmed based on the finding of vaginal plug. The distributions of beta-catenin and APC protein in the Embryos on day 13.5, 14.5, 15.5, 16.5, 17.5 were examined in the paraffin-embedded sections by immunohistochemistry methods., Results: During E13.5 d to E17.5 d, positive expression of beta-catenin was found in the oral epithelium and the dental lamina, and became more and more strong. The staining were whole cell. During the bud stage, strong positive expression of APC protein was found in the oral epithelium and the dental lamina, but the expression displayed a down-regulation tendency. The staining was the cytomembrane and cytoplasm. There was negative correlation between beta-catenin and APC protein (P<0.01)., Conclusion: The result of beta-catenin suggests its contribution in the early development of enamel organ and the proliferation of cell. Coincidance of the two factors staining site was found, according to the statistics.

Objective: To determine the expression level of each gtf under different pH cultural conditions and to find the relationship between gtf expression levels with environmental pH in different strains of Streptococcus mutans (S.mutans)., Methods: S. mutans form clinical isolation with different extracellular polysaccharides (EPS) producibility and UA159 were selected. Their ability to produce EPS under pH5.5 and pH7 were tested. Then in two strains, the relative quantity of gtfA, gtfB, gtfC, gtfD's mRNA which were related to S. mutan's ability to produce EPC, were examined by real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) methods under different pH culture condition., Results: At pH5.5, expression levels of gtfA, gtfB, gtfD were increased while that of gtfC were decreased in both strains, and that of gtfB, gtfC were higher in strain which produces more ECP., Conclusion: The expression levels of gtfs related closely to the cariogenicity of S. mutan.

Objective: The expression of heterogenic virulence properties depends on its clonal diversity. The aim of the study was to investigate the mechanism of interleukin-8 (IL-8) regulations of oral epithelial cells by challenge of Porphyromonas gingivalis (P. gingivalis) with different fimA genotypes, discuss the relation between fimA genotype and its pathogenicity., Methods: P. gingivalis ATCC 33277 (type I), W83 (type IV), 47A-1 (type IV) were assessed for their inductions of IL-8 expression in human oral epithelial cells (KB cell line, ATCC CCL-17). KB cells without stimulation of P. gingivalis were used as control group. IL-8 mRNA expression was de termined by reverse transcription polymerase chain reaction (RT-PCR) at different time intervals (1, 3, 6, 24 h) following continuous co culture of bacteria with KB cell line, and IL-8 protein levels in culture supernatant was determined by enzyme-linked immunosorbent assay., Results: IL-8 mRNA levels were up-regulated and reached its high peak at 1 h following both genotypes infection, then decreased to base level till 24 h. Attenuation of IL-8 protein levels was down-regulated when KB cell co-cultured with both genotypes for 3 h till 24 h, and type IV was lower than type I. IL-8 and IL-6 mRNA expression were not consistent with their protein levels, which indicated post-transcriptional regulations., Conclusion: fimA genotypes of P. gingivalis are related with the effect of IL-8 inductions, which indicates fimA genotype is associated with pathogenesis of P. gingivalis.

Objective: To investigate the correlation between moderately and severely chronic periodontitis and coronary heart disease, as well as the role of fibrinogen in the mechanisms responsible for the correlation between periodontitis and coronary heart disease., Methods: 95 subjects who were systemic health or patients of coronary heart disease with or without periodontitis were enrolled. All the subjects were placed into 4 groups based on their periodontal status and cardiovascular health. The 4 groups were healthy control group (HC), moderately and severely chronic periodontitis group (MSP), coronary heart disease group(CHD), and MSP coexisted with CHD group (MSP+CHD). Clinical periodontal index were examined, at the same time, plasma fibrinogen levels and serological changes used in diagnosing of cardiovascular disease routinely were determined. ANOVA and ANCOVA were used in the statistical analysis., Results: Fibrinogen levels of HC, MSP, CHD, and MSP+CHD group were (2.36+/-0.37), (3.63+/-0.73), (4.08+/-0.84), and (4.14+/-0.96) g/L, respectively. Fibrinogen levels of MSP and MSP+CHD group were significantly higher than that of healthy controls (P<0.01). The patients with moderately to severely chronic periodontitis were more likely to have coronary heart disease as compared to periodontally healthy controls (OR=2.527, P=0.047) after adjusted for blood pressure and body mass index., Conclusion: Moderately and severely chronic periodontitis maybe a risk factor of coronary heart disease and fibrinogen could be one of the biological basis which links periodontitis with coronary heart disease.

Objective: The purpose of this research was to study the genetic diversity of F-ATPase subunit gene uncEBF derived from Streptococcus mutans (S. mutans) clinical isolates, furthermore to investigate the relationship between the genetic diversity of F-ATPase and S. mutans aciduric ability., Methods: 38 S. mutans strains included 18 high acid tolerance strains and 20 low acid tolerance strains. Gene uncEBF of these isolates were amplified with specific primers from S. mutans genomic DNA, and the PCR products were analyzed by RFLP and sequenced. SPSS 11.0 statistic software assayed the results., Results: It was testified that two genotypes A and B of PCR-RFLP were revealed when digested with Alu I and Dde I digested fragments of uncEBF displayed two different patterns C and D. Fisher exact two-tail test showed that the distributions of A and B genotype strains with different acidurance were different (P < 0.05), and the proportion of A genotype strains from high acidurance group was higher than that from low acidurance one. Some of these amplified uncEBF genes from different genotype were sequenced and testified that there existed variation of Alu I and Dde I recognized sites., Conclusion: This study indicated that uncEBF gene of S. mutans F-ATPase obviously exhibited genetic diversity.

Objective: To study the genetic diversity and the gene expression of membrane-bound proton-translocating ATPase (F-ATPase) subunit gene uncG derived from Streptococcus mutans (S. mutans) clinical isolates., Methods: 38 S. mutans strains derived from caries-active and caries-free individuals including 18 strains displaying high acid tolerance and 20 strains displaying low acid tolerance. Gene uncG was amplified with specific primers from S. mutans genomic DNA, then the PCR product was analyzed by RFLP and sequenced. The relative expression quantity of uncG gene against the housekeeping gene recA was determined by using RT-PCR method. A gel documentation system and QUANTITY ONES software were used to analyze the data results., Results: It was testified that four genotypes A, B, C and D of PCR-RFLP were revealed when respectively digested with Alu I and Bsr I, but the distributions of the four genotype strains showed no difference (P > 0.05). The differences of uncG gene transcript quantities derived from different genotype or different aciduranc strains had no significance (P > 0.05)., Conclusion: This study indicated that uncG gene of F-ATPase obviously displayed genetic diversity and existed polymorphism at mRNA expression level, while the Alu I-RFLP genotypes and the expression levels would not be responsive to different acid tolerance of S. mutans strains.

Objective: To study the effect of concentrations of glucose on the initial adherence of Streptococcus mutans (S. mutans) to saliva-coated hydroxyapatite (SHA), and to compare the initial adherence of S. mutans from caries-active group with that of S. mutans from caries-free group., Methods: Each 10 clinical isolates of S. mutans from caries-active and caries-free subjects were used in this study. And S. mutans UA159 was also included in this experiment. SHA was used to simulate tooth surface in oral cavity. S. mutans clinical isolates and strain UA159 were cultured in TPY liquid medium containing 3H-TdR in the same radioactive concentration and glucose in 0.2%, 1.0%, 5.0% concentration. Then grown cells were harvested to produce a suspension. SHA and radiolabelled bacterial suspension (A550(nm) = 0.52) were mixed for 90 minutes, samples were assayed by using liquid scintillation counter, and binding abilities of strains were evaluated by the count per minute (CPM)., Results: The initial adherence ability of S. mutans from caries-active group was higher than that of S. mutans from caries-free group (P < 0.05). And the initial adherence ability of S. mutans cultured in different concentration of glucose was also significantly different (P < 0.05), 5.0% glucose group had the highest adherence ability, and 0.2% glucose group had the lowest adherenceability., Conclusion: (1)Difference of the initial adherence of S. mutans might relate to difference of carious experiences; (2) Glucose may play an important role in S. mutans initial adherence, to some extent, S. mutans cultured in the higher concentration of glucose has the higher initial adherence property.

Objective: To analysis the homology among the extended-V region of the surface proteins in different serotype Streptococcus mutans (c, f, d, g) and to find out it's significance in anti-caries vaccine., Methods: The DNA of the bacteria (standarded serotype c, d, f, g and partial serotype c clinicals) was extracted and the extended-V region (SrV+, 1 384-2 514 bp) was amplified using polymerase chain reaction (PCR). Then the products were assessed using restriction fragment length polymorphism (RFLP) by endonuclease Dde I. The genotypings were sequenced and analysised using the program of BLAST on NCBI Gene Bank database., Results: About 1.13 kb fragments were produced both in serotype c and f, the serotype d and g were failed. The RFLP results showed that five different patterns(A, B, C, D, E) among the 117 PCR products were reveled by Dde I. The ration of the genotypings A and B were the most among the strains, the C was lower, the D and E respectively was 1 and 3 strains per genotype. OMZ175 (serotype f) was belong to B genotype. Selected one of the A, B, C genotypings to sequenced and blasted. Then the results of the blastn showed that the identities of the gene sequence were 92%-98% between the serotype c and serotype f, part sequence of the serotype g was homology with the SrV+ of the serotype c, the protein sequence among serotype c, d, f, g were 77%-82%., Conclusion: It is reasonable to use some putative pipetides to study the anti-caries vaccine among the extended-V regions of the surface proteins in different serotype (c, d, f, g) in S. mutans.

Objective: To evaluate the beagles' pulp response following direct pulp capping with Clearfil SE BOND (SB)., Methods: 130 sound teeth were used. 120 had their pulps mechanically exposed and were divided in two groups. In group A, teeth were capped with SB. In group B, teeth were capped with calcium hydroxide (CH). The left 10 teeth were used as control. After 7, 30 and 90 days, the teeth were extracted and processed for light microscopical examination., Results: In 7 day observation period, inflammatory reaction in SB group was slighter than that of CH group, but the difference was statistical insignificant. In the 30 day and 90 day observation period, inflammatory reaction was slight in both groups, but specimens with dentin bridge formation was significantly less in SB group than in CH group (P < 0.05)., Conclusion: SB showed acceptable biocompatibility with pulp, but its ability to induce hard tissue barrier on pulp exposure is weaker than CH.

Objective: To preliminarily investigate the relationship between the Lactate dehydrogenase (LDH) activity of Streptococcus mutans (S. mutans) and dental caries initiation., Methods: 100 S. mutans strains derived from caries-active and caries-free individuals were cultured in BHI medium supplemented with glucose. Cells were extracted and ruptured, and the extracted liquid protein was quantified with Coomassie brilliant blue G250 staining methods. LDH activity was assayed using the pyruvate-dependent oxidation of NADH-with and without FDP., Results: LDH activity of the two groups strains had no difference (P > 0.05), but the distribution of differ class enzyme activity strains in the two groups was different (P < 0.05)., Conclusion: LDH activity of S. mutans is correlated to the initiation of dental caries to some extent. The measurement methods in this study can be applied in preliminary quantitation of LDH activity and the screening of S. mutans strains.

Objective: To investigate the distribution of fimA genotype of P. gingivalis in chronic periodontitis patients., Methods: Subgingival plaque samples were collected from 101 chronic periodontitis patients. P. gingivalis was detected by both culture method and P. gingivalis 16S rRNA PCR. fimA type-specific primer were designed, and the distribution of fimA genotype of P. gingivalis in periodontitis patients were detected by PCR., Results: The detective ratio of P. gingivalis was 88.1%. Among them, a single fimA genotype was detected in most subgingival plaque samples (65.1%), and the distribution of five fimA genotypes among P. gingivalis positive patients was as follows: type I, 24.7%; type II, 43.8%; type III, 15.7%; type IV, 40.4%; type V, 3.4%; respectively., Conclusion: P. gingivalis with various fimA genotypes were present in subgingival plaque samples from chronic periodontitis patients, and P. gingivalis with type II fimA and IV fimA were more predominant in chronic periodontitis patients, and they may be associated with the development of periodontitis.

Objective: Curved canal preparation is much difficult in root canal therapy(RCT). Step back technique and routine technique are still regular methods in curved canal preparation. The purpose of this study was to introduce a new method reverse flaring technique, and to investigate its preparation efficiency in intermediate-curvature canals., Methods: 48 cases of lower first molars RCT were collected, which were first treated because of pulpitis or apical periodontitis in West China College of Stomatology, Sichuan University from Nov. 2001 to Aug. 2003, mesial canal curvature was intermediate (30 degrees-60 degrees), determined by Schineider method. Cases were divided into two groups, in reverse flaring technique group, canal preparation in 27 cases were finished by reverse flaring technique, 21 cases by step back technique as control. In working length determination and fitting master cone stages, cases in two groups which fit full working length were recorded, determined by radiograph, and analyzed by chi 2 test., Results: In working length determination stage, cases which fit full working length in reverse flaring technique group were significantly more than that of step back technique group (P < 0.05), in fitting master cone stage, cases which fit full working length in reverse flaring technique group were also significantly more than that of step back technique group(P < 0.05)., Conclusion: In working length determination stage, cases which fit full working length in reverse flaring technique group were significantly more than that of step back technique group (P < 0.05), in fitting master cone stage, cases which fit full working length in reverse flaring technique group were also significantly more than that of step back technique group(P < 0.05).