[Observation of genetic diversity in dental plaque of elder people with root caries].

PURPOSE: Bacterial community in dental plaque of elder people was analyzed to learn about the microhabitat composition and diversity. METHODS: Dental plaque samples were collected from 25 elders. PCR-based denaturing gradient gel electrophoresis (PCR-DGGE) was used to evaluate the microbial diversity by displaying PCR-generated 16SrDNA fragments that migrate at different distances, reflecting the different sequence of fragment. SPSS12.0 software was used to analyze the variance of genotypes between different groups of bacteria. RESULTS: Genotypes of bacteria in dental plaques in the root caries group was significantly more than the other two groups. Crown caries group and caries-free group had no significant difference. CONCLUSIONS: The genetic diversity of the dental plaque microflora in the root caries group is significantly higher than coronal caries group and caries-free group.

[Analysis of community composition in dental plaque of elder people with root caries].

OBJECTIVE: To analyze the community in dental plaque of elder people with root caries. METHODS: Total DNAs were extracted from the root caries dental plaques of nine elders over 60 years of age. Polymerase chaid reaction-based denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial composition, DGGE bands were excised from the gels for sequencing and identification. RESULTS: The dominant genus in root caries dental plaque of elder people were: Acinetobacte [0.9% (1/114)], Actinobaculum [1.8% (2/114)], Actinomyces [15.8% (18/114)], Aggregatibacter [0.9% (1/114)], Capnocytophaga [14.0% (16/114)], Corynebacterium [0.9% (1/114)], Haemophilus [0.9% (1/114)], Mobiluncus [0.9% (1/114)], Naxibacter [0.9% (1/114)], Neisseriaceae [10.5% (12/114)], Porphyromonas [0.9% (1/114)], Prevotella [12.3% (14/114)], Selenomonas [6.1% (7/114)], Staphylococcus [1.8% (2/114)], Oralis streptococcus [6.1% (7/114)], Mutans streptococcu [7.9% (9/114)], Tannerella [0.9% (1/114)], Treponema [1.8% (2/114)], Veillonella [10.5% (12/114)] and two uncultured unknown genus [1.8% (2/114)]. Uncultred genotypes accounted for 19.30% of the total. Gram-positive bacteria genotype accounted for 31.6% (36/114), and Gram-negative bacteria genotype accounted for 66.7% (76/114). CONCLUSIONS: There were many bacteria genotypes in root caries dental plaque in the elderly, which were widely distributed. Gram-negative bacteria accounted for the majority. Genotype-specific pathogenic bacteria were not found.

[Quantitative evaluation of residual endodontic microorganisms after mechanical root canal preparation different chemical preparations by real-time PCR].

PURPOSE: To establish a quick, sensitive method for quantifying root canal flora and investigate the effects of different root canal preparations on the pathogenic bacteria at RNA level. METHODS: A total of 24 single-rooted teeth with chronic apical periodontitis were selected and prepared using 3% H2O2 combined with 1% NaClO, EDTA combined with 3% H(2)O(2),1% NaClO, respectively,the samples were taken before and after root canal preparation. After isolation of total RNA from the root canal samples, cDNA was synthesized by reverse transcription, and detected by real-time PCR. The data were analyzed with SAS 6.12 software package. RESULTS: The number of bacteria in the root canal reduced dramatically after mechanical preparation and irrigated using 3% H(2)O(2) and 1% NaClO(P<0.01). Further combined with EDTA, its effect was better than that of simply irrigated using 3% H(2)O(2) and 1% NaClO(P<0.05). CONCLUSIONS: Real-time PCR can be employed in the identification of bacteria flora in the root canal, both methods of root canal preparation can effectively reduce the number of bacteria flora.

[Comparison of the sucrose dependent cell adherence of Streptococcus mutans isolates from caries-active and caries-free children].

PURPOSE: To study the sucrose dependent cell adhesive ability of Streptococcus mutans islolated from the caries-active and caries-free children. METHODS: 60 isolated Streptococcus mutans strains were selected and identified from the dental plaque of 10 caries-active children and 10 caries-free children (3 to 5 years), in which 39 strains were from caries-active group(dmfs>or=6) and 21 strains from caries-free group(dmfs=0). With the use of ultraviolet spectrophotometer, the sucrose dependent cell adherence to glass wall of the sucrose-containing testing tubes was analyzed. One-way ANOVA was used by SPSS12.0 software package to determine the statistical difference of the adhesive ability between the two groups. RESULTS: The average adhesive ratio of the Streptococcus mutans strains isolated from caries-active group was 55.49%+26.16% in the 1% sucrose-containing culture medium, while the average adhesive ratio of the Streptococcus mutans strains isolated from caries-free group was 27.01%+18.39%. The difference between the two groups was statistically significant (P<0.01). CONCLUSION: In the sucrose-containing circumstance, the sucrose dependent cell adhesive ability of the Streptococcus mutans isolated from the caries-active children was significantly higher than that from the caries-free children. This indicated that the adhesive ability may be related to the caries-causing tendency.

[In vitro evaluation of the sealing ability of an iodoform-calcium phosphorate cement root canal filler].

PURPOSE: To evaluate the sealing ability of an injectable iodoform-calcium phosphate cement(CPC) root canal filler in vitro. METHODS: Sixty-two single-rooted human extracted teeth were selected and root canals were instrumented to 40# with K file. Fifty-eight teeth were randomly divided into two experimental groups. The root canals were filled by lateral condensation of gutta-purcha with iodoform-CPC or zinc-oxide-eugenol-iodoform paste used as sealer respectively. Other four teeth were used as control. When the sealer was solidified, the apical portion of tooth was soaked into 2% methylene blue for 6 days. After the tooth was longitudinally sectioned, the dye length was measured for apical microleakage.The data obtained were analysed with group t test. RESULTS: The average microleakage in iodoform-CPC group(8.400mm) was significantly larger than that in the control group(5.300mm), P=0.021. CONCLUSIONS: We conclude that iodoform-CPC does not provide a sealing ability as good as zinc-oxide-eugenol-iodoform paste in vitro.

[Preliminary evaluation of the clinical results of calcium phosphorate cement root canal sealer].

PURPOSE: To investigate the clinic effect of calcium phosphorate cement as a root canal sealer-filler material. METHODS: 136 teeth with chronic periapical disease were instrumented and obturated with laterally condensed gutta-percha and either calcium phosphate cement(CPC) or iodoform paste. The patients were recalled and observed according to the clinic symptom and radiography after 1 week,3 months, 6 months and 1 year. The data was processed using SAS6.2 software package for Chi-square test and Wilcoxon rank test. RESULTS: The patients of CPC group had mild reaction after treatment and the successful rate of 3-month was higher compared with the control group(with iodoform paste), however there was no different clinical effects between the two groups after one year. CONCLUSION: Calcium phosphate cement root canal sealer can be acceptable for root canal filling , but the long term clinical results are needed be investigated.