[Distribution of fimA genotype of Porphyromonas gingivalis in Chinese periodontitis patients and its relationship with chronic periodontitis].

OBJECTIVE: To investigate the distribution of fimA genotype of Porphyromonas gingivalis in Chinese periodontitis patients and try to find the relationship between fimA genotype and chronic periodontitis. METHODS: Subgingival plaque samples were collected from 101 periodontitis patients. P. gingivalis 16S rRNA primer and fimA type-specific primer were designed. The distribution of fimA genotype in periodontitis patients was detected by PCR. Clinical periodontal indices (PPD, CAL and BOP) were measured at the sample tooth's six points; namely, the mesio-, mid-, distobuccal and mesio-, mid-, distolingual points. RESULTS: P. gingivalis was detected in 89 periodontitis patients (88.1%). Among them, a single fimA genotype was detected in most subgingival plaque samples (65.1%), and the most prevalent fimA genotype was type II (43.8%), followed by type IV (40.4%); Type II fimA and IV fimA were more frequently detected in mild/moderate periodontitis group and severe periodontitis group. CONCLUSION: The findings indicate that P. gingivalis with type II fimA and IV fimA are more predominant in Chinese periodontitis, and the organisms are involved in the destructive progression of periodontitis in Chinese.

Effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria in vitro.

BACKGROUND: Cecropin-XJ belongs to cecropin-B, which is the most potent antibacterial peptide found naturally. The aim of this study was to investigate the effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria. METHODS: Four oral cariogenic bacteria (Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus and Actinomyces naeslundii) were chosen for this experiment. The minimal inhibitory concentrations (MICs) and reductive percent of bacterial growth were used to assay the antibacterial activity of cecropin-XJ. Mammalian cytotoxicity of cecropin-XJ was tested with human periodontal membrane fibroblasts by tetrazolium (MTT) colorimetric assay. The bacterial morphological changes induced by cecropin-XJ were examined on scanning electron microscope (SEM). The influence of cecropin-XJ on bacterial adhesion to saliva-coated hydroxyapatite (S-HA) was measured by scintillation counting. RESULTS: The MICs of cecropin-XJ for inhibition of the growth of four bacteria ranged from 4.0 to 42.8 micromol/L with the highest susceptible to A. naeslundii and the lowest susceptible to L. acidophilus. At pH 6.8, 5.5 and 8.2, 1/2 MIC of cecropin-XJ reduced the number of viable bacteria by 40.9%, 67.8% and 32.8% for S. mutans and by 28.1%, 57.2% and 37.9% for L. acidophilus. The activities against S. mutans and L. acidophilus increased at pH 5.5 compared with pH 6.8 (P < 0.01, respectively). In present of 50% saliva, 1/2 MIC of the peptide decreased the direct count of viable cells by 29.2% and 14.4% for S. mutans and L. acidophilus, respectively (P < 0.01 and P > 0.05, respectively), whereas almost no reduction counts were detected in the presence of 20% serum for both bacteria (P > 0.05, respectively). Mammalian cytotoxicity of cecropin-XJ from 1.0 to 100 micromol/L exhibited no cytotoxicity against human periodontal membrane fibroblasts (P > 0.05). Bacterial morphological changes induced by MIC of cecropin-XJ examined on SEM showed cell surface disruption. Furthermore, the ability of A. naeslundii adhesion to S-HA decreased significantly with MIC of cecropin-XJ for 10 and 20 minutes (P = 0.001 and 0.000, respectively), and S. mutans, A. viscosus to S-HA decreased significantly with MIC of cecropin-XJ for 20 minutes (P = 0.000, respectively). CONCLUSIONS: Cecropin-XJ exhibited bactericidal action against cariogenic pathogens, and the antibacterial activity enhanced in the acid environment. The results also demonstrate that cecropin-XJ prevents S. mutans and actinomyces adsorption to S-HA. These findings suggest that Cecropin-XJ may have potential to prevent caries.

[Acquisition of Mutans streptococci by children of 3-4 years with possible source of the pathogen from their mothers].

OBJECTIVE: The aim of this study was to investigate the prevalence of Mutans streptococci (MS) in children of 3-4 years and thus reveal the relationship between the children's acquisition of MS and their mothers' pathogen. METHODS: Fifty mother-child pairs were selected, examined and divided into three groups according to the children's caries. MS in plaque and mothers' salivary samples were detected by MSB medium. Then 200 MS strains from 20 mothers-children were analyzed by AP-PCR. RESULTS: Acquisition of MS was identified in 37 of 50 children (74%), including 11 of 24 caries-free children and all 26 children with caries. The difference was significant (P<0.01). Genotypes showed that 16 of 37 children (43.2%) had the same fingerprint as their mothers'. The level of MS identified in mothers' salivary sample was lower than that in mothers' plaque sample (32% and 56%). CONCLUSION: These results suggested that caries in children of 3-4 years are closely related with MS acquisition. Mothers are still their important source of MS. The sensitivity of mothers' salivery samples is much lower than that of plaque samples in studying the transmission of MS.

[Purification and characterization of sanguicin--a bacteriocin produced by Streptococcus sanguis].

OBJECTIVE: Streptococcus sanguis plays an important Role in maintaining the periodontal microecological balance. Previous studies have demonstrated that sanguicin--a kind of bacteriocin produced by S. sanguis has a prominent function of inhibiting the growth of putative periodontopathic bacteria (PPB). The aim of this study was to purify sanguicin and investigate its characters. METHODS: The raw extract of sanguicin was obtained from cells of S. sanguis by ultrasonication, salting out and dialysis. Then the diethyl-aminoethyl-sepharose gradual washing was done in conjunction with glucosan gel filtration for in the purfication of sanguicin. The characters of purified sanguicin were determined and its inhibitiory effect on PPB was measured by agar diffusion test. RESULTS: The purifed sanguicin was obtained; it was heat labile and proteinaceous; and by SDS-PAGE, it showed a main band with the relative molecular mass of 65 x 10(3). The purifed sanguicin had a strong inhibitory effect on P. gingivalis, P. intermedia and F. nucleatum in vitro. CONCLUSION: Our methods are useful for the purification of sanguicin. Sanguicin has inhibitory effect on PPB obviously and will have a good prospect in periodontal ecological therapy.

Effects of salt stress on antioxidant defense system in the root of Kandelia candel.

BACKGROUND: This study aimed to explore the active oxygen scavenging mechanism of Kandelia candel, in order to provide a theoretical basis for further analysis on the physiological mechanism of salt tolerance in mangrove plants. Different concentrations of NaCl solution (0, 150, 300 and 450 mmol/L) were used for salt stress treatments on Kandelia candel, physiological indicators in the root of Kandelia candel were measured in different processing time. RESULTS: With the increase of salt concentrations and processing time, the contents of total proteins in the root of Kandelia candel were reduced; the CAT activity, SOD activity, ASA content and MDA content all had decreased with the increase of salt concentrations and shown a trend from ascent to descent with the increase of processing time, the peak of ASA and MDA contents were observed at 6 h, that of SOD activity was observed at 9 h and that of CAT activity was at 12 h; POD activity had shown an overall upward trend with the increase of salt concentrations and processing time, which reached the maximum at 24 h; the variations of these physiological indicators were more significant in high concentrations of NaCl solution (450 mmol/L). CONCLUSIONS: A certain salt concentration (<300 mmol/L) was required for the growth of Kandelia candel seedlings. At the early stage of high-salt stress, Kandelia candel can rapidly activate antioxidant defense system to resist the salt induced oxidative stress, thus reducing the damages of oxidative stress to plasma membrane, which might be an effective means for Kandelia candel to resist high salt stress.

[The antagonistic effect of the oral Streptococcus on the Saccharomyces albicans in vitro].

OBJECTIVE: To investigate the antagonistic effects of three species of oral Streptococcus on the growth of oral Saccharomyces albicans in vitro. METHODS: Direct inoculation method, reverse inoculation method and mixed culture methods were respectively chosen to observe the changes of Saccharomyces albicans colony formation on the effects of Streptococcus mutans, Streptococcus sanguis and Streptococcus salivarius. RESULTS: 1) No clear inhibition zone was observed in each of the groups by direct inoculation method. 2) Compared with the control groups, Saccharomyces albicans colony formation on soft agar of Streptococcus sanguis decreased significantly (P < 0.05). 3) Mixed culture method results showed that Streptococcus mutans could inhibit the growth of Saccharomyces albicans significantly at different time points (P = 0.001). 4) Under the action of bacteria culture supernatant, the count of Saccharomyces albicans in experiment groups showed statistical significance when compared with the control groups at 24, 48, 72 h (P = 0.001); The differences among the experimental groups were of no statistical significance at majority times (P > 0.05). CONCLUSION: Streptococcus mutans, Streptococcus sanguis, and Streptococcus salivarius could obviously inhibit the growth of Saccharomyces albicans in vitro. However, it is still unclear that among which the inhibition effects is stronger. The antagonistic effects is weakened gradually.

[The disinfection efficiency observation of a compound disinfectant spray on dental impression and plaster].

OBJECTIVE: The disinfection efficiency of a compound disinfectant spray with trichioro hydroxyl diphenyl ether on dental impression and plaster model, which have been contaminated by pathogens, were evaluated in this study. METHODS: As experimental group, germ-free alginate impressions and plaster models were sprayed with the compound disinfectant of different density trichloro hydroxyl diphenyl ether or indophors for 5, 10 and is mm, after which were smeared with five tested pathogens, including Staphylococcus acre us, Escherichia cali, Saccharomyces albicans, Streptococcus mutans and black spore variants of Bacillus subtilis. The colonies were counted after sampling, inoculate and culture, which were used to deduce the killing logarithm value as the standard of the disinfecting efficiency. RESULTS: the compound disinfectant spray with 3000 mg x L(-1) triebloro hydroxyl diphenyl ether was effective to all tested pathogens for 10 mm whatever on the impressions or the plaster models. The disinfectant spray with tame concentration was more effective on the alginate impression than on the plaster model in the same time (P = 0.000). CONCLUSION: The compound disinfectant spray with trichioro hydroxyl diphenyl ether is an effective antiseptics for alginate impressions and plaster models.

[Matrix metalloproteinase 8 and 9 regulations of polymorphonuclear leukocytes stimulated by Porphyromonas gingivalis with different fimA genotypes].

OBJECTIVE: To investigate the pathogenicity of matrix metalloproteinase 8, 9 (MMP-8, MMP-9) regulations of polymorphonuclear leukocytes (PMNs) by challenge of Porphyromonas gingivalis (P. gingivalis) with different fimA genotypes. METHODS: The studies mainly adopt the isopycnic sedimentation separation to separate the PMNs from human peripheral blood. P. gingivalis ATCC 33277 (type I), WCSP 115 (type II), WCSP 1.5 (type III), W83 (type IV), WCSP 559 (type IV) were assessed for their inductions of MMP-8, MMP-9 expression in PMNs. MMP-8, MMP-9 protein levels in culture supernatant were determined by ELISA at different time intervals (5 min, 30 min, 1 h, 2 h) following continuous co-culture of bacteria with PMNs. RESULTS: MMP-8 and MMP-9 protein levels produced by PMNs co-culture with the I fimA-IV fimA P. gingivalis were significantly stronger than unsimulated group. The velocity and quantity of MMP-8 produced by PMNs co-culture with the II fimA P. gingivalis and IV fimA P. gingivalis were more than III fimA, IVfimA P. gingivalis. The MMP-9 protein levels produced by PMNs co-culture with the I fimA, II fimA, IV fimA P. gingivalis was significantly stronger than III fimA and IV fimA P. gingivalis. CONCLUSION: II fimA and IV fimA P. gingivalis have stronger pathogenicity relatively, which indicate that fimA genotype is associated with pathogenesis of P. gingivalis.

[Initial study on the discrimination of oral common Actinomycetes with metabonomics method].

OBJECTIVE: The method of metabonomics based on 1H-nuclear magnetic resonance (1H-NMR) was preliminarily applied to discriminate the oral common Actinomycetes, Actinomyces naeslundii ATCC12104 and Actinomyces israelii ATCC12102. METHODS: Solutions of Actinomyces naeslundii and Actinomyces israelii with same density were made and cultured respectively at BHI liquid culture medium. The concentration of bacteria was determined periodically, and then the growth curves were drawn. The culture solutions in stationary phase of the two bacteria were used to test with the 1H-NMR spectroscopy respectively. The data of 1H-NMR spectroscopy results were analyzed by principal components analysis (PCA). RESULTS: The PCA showed the obvious clustering phenomena and the points of two groups data stayed differentially together by two clusters. Therefore, the NMR-based metabolomics profiles can discriminate the two different kinds of bacteria. CONCLUSION: The analysis technology of metabonomics is expected to be applied to rapid identification of actinomycetes.

[Preliminary study on the discrimination of putative periodontal pathogens with a metabonomics method].

OBJECTIVE: To evaluate the feasibility of identifying oral pathogenic bacteria by comparing the metabolic profiling of putative periodontal pathogens and try to find a convenient and rapid way to discriminate oral microorganisms. METHODS: Suspensions of Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum with same density were prepared and cultured respectively at liquid BHI medium. Then the growth quantity was measured periodically through turbidimetry and the growth curves of the inoculated bacteria were completed. The culture solutions of stable growth phase were sampled and characterized by 1H-nuclear magnetic resonance 1H-NMR). The data of 1H-NMR spectroscope results were analyzed by principal components analysis (PCA). RESULTS: The PCA showed the obvious clustering phenomena and the points of three groups differentially centralized to three clusters. Therefore, the NMR-based metabonomics profiles could discriminate the three different kinds of bacteria. CONCLUSION: The metabonomics is a potential classable method to identify the oral pathogenic bacteria.

[Interleukin-8 regulations of oral epithelial cells by porphyromonas gingivalis with different fimA genotypes].

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.

[Study the inhibitory effects of three oral actinomyces on growth of oral Candida albicans in vitro].

OBJECTIVE: The aim of this study was to investigate whether the three species of oral Actinomyces have inhibitory effects on the growth of oral Candida albicans in vitro. METHODS: Straight o'clock method was used to observe the bacteriostasis circle. Reverse o'clock and mixed culture method were used to study the quantitative changes of Candida albicans colony respectively. RESULTS: (1) None of the groups had been viewed the bacteriostasis circle. (2) Compared with control groups, there was a significant decrease of Candida albicans colony on Actinomyces viscosus TPY soft agar (P < 0.05). Actinomyces naeslundii and Actinomyces odontolyticus TPY soft agar were both devoid of obvious Candida albicans colony (P < 0.01). The former group (Actinomyces viscosus) and the two latter groups (Actinomyces naeslundii and Actinomyces odontolyticus) showed a striking contrast (P < 0.01). (3) Compared with control groups, a decrease of Candida albicans showed up in the mixed culture, and the difference was significant (P < 0.05). The discrepancies among the three experimental groups were of no statistical value (P > 0.05). CONCLUSION: Oral Actinomyces viscosus, Actinomyces naeslundii and Actinomyces odontolyticus could inhibit the growth of Candida albicans in vitro. However, which of them contributed more to the inhibitory effects was still not affirmed.

[Sterilization effect analysis of B-class pulsation table top vacuum sterilizer to dental handpieces].

OBJECTIVE: Discuss sterilization effect of B-class pulsation table top vacuum pressure steam sterilizer for dental handpiece. METHODS: Analysis selection of sterilizer for dental handpiece and sterilization management processes and sterilization effect monitoring, evaluation of monitoring result and effective sterilization method. RESULTS: The B-class pulsation table top vacuum pressure steam sterilizer to dental handpiece in West China Stomatological Hospital of Sichuan University met the requirement of the chemical and biological monitoring. Its efficiency of sterilization was 100%. The results of aerobic culture, anaerobic culture, B-type hepatitis mark monitoring to sterilized dental handpiece were negative. CONCLUSION: It is effective method for dental handpiece sterilization to use B-class pulsation table top vacuum pressure steam sterilizer.

[Study of adherence of normal oral bacteria on polymethyl methyacrylate containing silver-supported silicate inorganic antibacteria].

OBJECTIVE: To study the oral normal bacteria adherence on polymethyl methyacrylate (PMMA) containing silver-supported silicate inorganic antibacterial, and the growth inhibitory concentration of silver-supported silicate inorganic antibacterial to normal oral bacteria were also investigated. METHODS: A certain volume of normal oral bacteria was inoculated on the RHI plate containing different dilution of silver-supported silicate inorganic antibacterial, then the growth of the bacteria was investigated by light microscope and biochemical methods; the oral bacteria plaque model in vitro was used to evaluate the adherence of 4 species normal oral bacteria mixture on the surface of PMMA which containing silver-supported silicate inorganic antibacterial in the proportion of 5% or 10%. RESULTS: The growth of normal oral bacteria was inhibited effectively by silver-supported silicate inorganic antibacterial within the concentration of 8%, and the growth of Porphyromonas gingivalis and Conclida albicans were inhibited at concentration from 1.25% to 2.50%, but the PMMA containing silver-supported inorganic antibacterial could not prevent the adherence of bacteria within a period of 16 days. CONCLUSION: Silver-supported silicate inorganic antibacterial has effectiveness on inhibiting the growth of normal oral bacteria, but could not prevent the adherence of oral normal bacteria mixture.

[Dynamic study on saccharomyces albicans drug efflux pumps gene expression during the biofilm formation].

OBJECTIVE: To observe the drug resistance and drug efflux pumps gene mRNA of Saccharomyces albicans, including CDR1 gene and MDR1 gene, at different stage of biofilm formation in chemostat, furthermore to analysis the relationship between the drug efflux pump gene expression and the biofilm related drug resistance. METHODS: To form the mature biofilm in vitro in chemostat, then collect the biofilm strains at different development stages (2, 12, 24, 48 h) to semi-quantified mRNA amount of CDR1 gene and MDR1 gene by one step RT-PCR method. Using XTT reduction method to test the dynamic change of Saccharomyces albicans drug resistance in biofilm. RESULTS: Antifungal resistance of biofilm-grown cells increased conjunction with the biofilm maturation. Compared with earth stage of biofiom strains, the amount of CDR1 mRNA gene in mature biofilm strains increased, while MDR1 gene did not. CONCLUSION: There is positive correlation between drug resistance and biofilm maturation of Saccharomyces albicans. Biofilm related drug resistance appears to be partially associated with the upregulation of drug efflux pumps, although the variation is not shown coincidence. During the biofilm formation, CDR1 gene expression is actively up-regulated, but MDR1 gene expression is stable.

[Antimicrobial activity of nano-hydroxyapatite/polyamide 66 as a pulp capping agent in vitro].

UNLABELLED: OBJECTIVE To investigate the in vitro antimicrobial activity of nano-hydroxyapatite/polyamide 66 composites (nHA-PA66) as a pulp capping agent. METHODS: The micro-organisims used in this study included Streptococcous mutans (S. mutans), Lactobacillus casei (L. casei) and Actinomyces viscosus (A. viscosus), three standard bacterial strains predominant in deep carious lesions. Agar diffusion test was used to determine the diameter of bacterial inhibition zones of nHA-PA66 compared with hydroxyapatite paste, calcium hydroxide paste and nHA-PA66 mixed with iodoform paste. RESULTS: It showed that the polymerized films and fresh paste of nHA-PA66 had no antimicrobial activity to S. mutans and very little to L. casei and A. viscosus. The antimicrobial activity of nHA-PA66 mixed with iodoform paste obviously increased, but no significant difference compared with calcium hydroxide paste. There, was no antimicrobial activity of hydroxyapatite paste to the three test bacterial strains. CONCLUSION: These findings suggest nHA-PA66 used as pulp capping agent alone almost has no antimicrobial effect to the three test bacteria, but the antimicrobial activity can be increased by combining with iodoform.

[Initial study on discrimination of oral microorganisms with the metabonomics technique].

OBJECTIVE: To evaluate the feasibility of employing metabonomics method in identification of oral pathogenic bacteria. METHODS: The Streptococcus mutans ATCC25175 and Actinomyces viscosus ATCC15987 were respectively inoculated in same certain culture medium. The growth curves of the inoculated bacteria were drown by turbidimetry. The culture solutions in four different growth phases of the both bacteria were used to test with the 1H-Nuclear magnetic resonance (1H-NMR) spectroscopy respectively. The data of 1H-NMR spectroscopy results were analyzed by principal components analysis (PCA). RESULTS: The PCA showed the obvious clustering phenomena and the points of two group data stayed differentially together by two clusters. Therefore, the NMR-based metabonomics profiles can discriminate the two different kind of bacteria. CONCLUSION: The metabonomics can be expected to be a kind of promising useful method in quick discrimination of oral pathogenic bacteria.

[Correlation of oral Candida spp. and denture-wearing in healthy elderly].

OBJECTIVE: To investigate the frequency and intensity of Candida spp. incidence from the oral cavities of the healthy elderly in Chengdu, and to study the role of the dentures in the distribution of oral Candida spp. METHODS: A total of 212 individuals(age > 60 years) were divided into four groups: A1 (48 man with dentures), B1 (61 man without dentures), A2 (53 women with dentures) and B2 (50 women without dentures). Samples of their oral flora were obtained by rinsing with 10 mL PBS solution. The samples were centrifuged and resuspended in PBS (500 microL), and plated onto Sabouraud's dextrose agar. CHROMagar Candida, sugar assimilation patterns (API 20C AUX tests) were used to determine Candida spp. The total number of yeast colonies on the plates was considered as the relative intensity of oral Candida. RESULTS: Candida spp. was isolated from 116 healthy elderly individuals (54.72%), such as C. albicans, C. parapsilosis, C. krusei, C. guilliermondii, C. tropicalis, etc. The frequency of Candida spp. in A1, B1, A2 and B2 was 66.67%, 36.07%, 64.15%, and 56.00%, respectively. The frequency of C. albicans in A1, B1, A2 and B2 was 56.25%, 21.31%, 56.60% and 38.00%, respectively. The frequency of Candida spp. and the intensity of Candida spp. were greater for individuals in the denture-wearing group than that in the control. CONCLUSION: The frequency and intensity of Candida spp. incidence from the healthy elderly are closely correlated with denture-wearing, and the differences of the frequency and intensity of Candida spp. incidence in the elderly are due to the differences of frequency and intensity of C. albicans incidence.

[Study of susceptibility of oral bacteria biofilm to traditional Chinese drug preventing caries].

OBJECTIVE: Using MBEC-Assay to assay minimal biofilm eradication concentration (MBEC) of Galla Chinensis and Nidus Vespae to oral bacterial biofilm. To set up traditional Chinese medicine susceptibility pharmacodynamic empirical study methods of oral bacterial biofilm. METHODS: Cariogenic bacteria strains were selected (Streptococcus mutans ATCC 25175, Streptococcus sanguis ATCC 10556, Lactobacillus rhamnosus AC 413, Actinomyces naeslundii WVU 627) in this study. Extraction components of Galla Chinensis were GCE (aqueous extract), GCE-B (30% alcohol extract) and extraction components of Nidus Vespae were NVE1 (95% alcohol extract). (1) To observe oral bacterial biofilm formatiom in MBEC-Device at different time. (2) MBEC-HTP-Assay: The minimal inhibitory concentration (MIC) and minimal biofilm eradication concentration (MBEC) of GCE, GCE-B and NVE1 to oral bacteria strains were determined. RESULTS: Oral bacterial biofilm were readily formed on the lid of MBEC-Device under selected condition (observed by SEM). Oral cariogenic bacteria growing as plankton populations were sensitive to GCE, GCE-B and NVE1. To GCE, GCE-B and NVE1, oral cariogenic bacterial biofilm were 2-16 times less susceptible than growing plankton bacteria. GCE and GCE-B were the most effective medicine against oral cariogenic bacterial biofilm. NVE1 were effective in killing oral-bacterial biofilm at relatively high concentration. CONCLUSION: GCE and GCE-B were effective medicine against oral cariogenic bacterial biofilm. MBEC (minimal biofilm eradication concentration) can provide a relative accurate medicine concentration for clinical test.

[Antibacterial effect of nHA-PA66 in vitro].

OBJECTIVE: To evaluate the antibacterial activity of nHA-PA66 on the predominant bacteria of infected root canal in vitro. METHODS: Agar diffusion method was the testing method. Porphyromonas gingivalis (P. gingivalis), Fusobacteria nucleatum (F. nucleatum) and Prevotalla intermedius (P. intermedius) were the tested bacteria. The powder and polymerized film of nHA-PA66 were the test mateials while the CCQ and filter paper as the control. RESULTS: nHA-PA66's powder showed good antebacterial effect on the P. gingivalis and P. intermedius, its film was weaker. Both of them had no effect on F. nucleatum. CONCLUSION: nHA-PA66's antibacterial effect was not ideal, for better clinical results, some additives can be included.