A new method for cranial vault reconstruction: Augmented reality in synostotic plagiocephaly surgery.

PURPOSE: Augmented reality (AR) is considered to be a valuable tool in craniofacial surgery for preoperative design, intraoperative navigation, and postoperative assessment. Corrective surgery is necessary synostotic plagiocephaly for functional and aesthetic outcomes. Open calvarial reconstruction is a difficult classic surgical procedure with a high accuracy requirement. The purpose of this study was to introduce an AR system application in synostotic plagiocephaly surgery. MATERIALS AND METHODS: Seven plagiocephaly patients (ages 6 months-24 months, average 16.7 months) were enrolled. Preoperative design was accomplished based on three-dimensional computed tomography (CT) data for patients with synostotic plagiocephaly. We completed the registration with the predefined markers through an image registration process preoperatively. Then, we overlaid the registration results into the surgical field to assist surgeons intraoperatively. CT scans were performed postoperatively. Intracranial volume was measured to judge the surgical outcomes. We performed a quantitative craniometric analysis between the planning of the reconstruction and post-operative results, and the main evaluation indicator was the intracranial volume asymmetry. RESULTS: We successfully applied the AR system in patients undergoing synostotic plagiocephaly, providing real-time navigational images of position and orientation information during open calvarial reconstruction surgery in 7 plagiocephaly patients within a span of 5 years. Good appearances were observed after the surgery. Cranial volume asymmetry was decreased from 27.87% to 16.57%, achieving precise intra-operative goals. No significant differences were found between planning and post-operative results. CONCLUSIONS: The AR system can be applied to plagiocephaly procedures guiding to obtain reliable and accurate results via a precise osteotomy.

[A study of genetic diversity in lactate dehydrogenase of Streptococcus mutans from clinical isolates].

OBJECTIVES: Lactate dehydrogenase (LDH) is shown to be an important virulence factor resulting in acid production of Streptococcus mutans (S. mutans), on which the cariogenic potential of S. mutans depends. Differences in cariogenic abilities of S. mutans isolates may be determined by genetic heterogeneity from virulent factors. The relationship between LDH activity or genetic diversity and cariogenicity of S. mutans (serotype c) isolates was studied in this research. METHODS: The genome DNA of S. mutans isolates were isolated and LDH gene (ldh) were amplified with specific primers. These isolates came from 34 caries-active individuals and 36 caries-free ones, in which 24 strains showed the high LDH activity and 21 strains showed the low LDH activity. Then genetic diversity of PCR products were analyzed or assessed by restriction fragment-length polymorphism (RFLP). Some of amplified LDH genes from different group were sequenced and assayed. RESULTS: It is testified that two genotypes A and B of ldh-RFLP were revealed when LDH genes were digested with Mse I, but Hph I, Mnl I, Dde I, Nla III and Alu I digesting fragments of Idh gene did not show different pattern. Furthermore, Fisher Exact one-Tail Test showed that the proportion of genotype B among strains from caries-free individuals was higher than that from caries-active ones (P = 0.033), while the distribution of genotypes with different LDH activity was different between two groups (two-Tail Test P = 0.017). The sequencing DNA testified that the specific base mutation would lead to multiple kind of genotype resulted. CONCLUSION: This study indicated that LDH gene of S. mutans clinical strains from different individuals is conservative, while there still is the gene mutation in. The ldh genetic diversity may be related to the low caries sensitivity, and closely correlated with the differences in LDH enzyme activity of S. mutans strains.

[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.

[Relationship of the genetic diversity within the V-region, P-region and C-terminus of surface protein of Streptococcus mutans to dental caries].

OBJECTIVE: To gain an understanding of the relationship between the genetic diversity within the V-region, P-region, C-terminus of surface protein of Streptococcus mutans (serotype c) and their adherent abilities. METHODS: The clinical isolates of S. mutans (serotype c) in two groups with different adherent abilities (cpm>2000, cpm<1000) had been prepared in our experimental laboratory. The genome DNA was extracted, and the spaP-pv (2060-3157 bp) and spaP-c (4003-4851 bp) were amplified by PCR, respectively. Genetic diversity was assessed by restriction fragment-length polymorphism (RFLP) with restriction endonucleases Alu I. RESULTS: (1) Two different patterns of spaP-pv RFLP among strains were revealed after the amplified product being digested with Alu I. The distributions of two genotypes (a and b) in the clinical strains with different adherent abilities differed significantly (P<0.05). The proportion of genotype b in the strains with higher adherent abilities was higher than that in the strains with lower adherent abilities. (2) Two different patterns (c and d) of spaP-c RFLP among strains were also revealed after the spaP-c being digested with Alu I. No statistically significant difference was observed in the distribution of the two genotypes in the clinical strains. CONCLUSION: The genetic diversity within spaP-pv of clinical isolates of S. mutans might be related to the differences of their adherent abilities.

[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.

[The influence of gene vaccines pcDNA3-pac and pcDNA3-gtfB of Streptococcus mutans on plaque index and S. mutans score in rats].

OBJECTIVE: This study was aimed at using the gene vaccines pcDNA3-pac and pcDNA3-gtfB which were constructed on PAc and GTF-B gene vaccinating gnotobiotic rats by submandibular gland-target injection to observe the level of salivary S. mutans and dental plaque inhabitation. METHODS: Thirty-six 28-day-old Wistar rats were divided into 6 groups, including those vaccinated with pcDNA3-pac, pcDNA3-gtfB, pcDNA3-pac combined with pcDNA3-gtfB, inactive whole cell of S. mutans JBP, and those injected with pcDNA3 and 0.1 mol/L PBS buffer respectively. Each rat was administrated with 100 micrograms vaccines or controlled materials by submandibular gland-target injection, vaccinated three times at 1-2 weeks interval. Then the gnotobiotic rat model was constructed, following that all rats were fed with cariogenic diet 2000# for 3 months. Rat saliva was collected to assay the level of S. mutans in saliva and evaluate the dental plaque index. RESULTS: The level of S. mutans in saliva and the dental plaque index of the group vaccinated with pcDNA3-pac combined with pcDNA3-gtfB and the group with inactive S. mutans cell were lower than those of other groups. And they were the highest in the groups injected with pcDNA3 or PBS buffer (P < 0.01 or P < 0.05). No statistically significant differences were observed between the group vaccinated with pcDNA3-pac and the group vaccinated with pcDNA3-gtfB, between the group vaccinated with pcDNA3-pac combined with pcDNA3-gtfB and the group for positive control, and between the pcDNA3 group and PBS buffer group (P > 0.05). CONCLUSION: The two gene anticaries vaccines induce the specific antibodies and thus produce effects on the level of S. mutans in saliva and dental plaque index. Therefore gene vaccines pcDNA3-pac and pcDNA3-gtfB are effective, and joint gene vaccines inoculation is optimal.

[The effect of Galla chinensis on the demineralization of enamel].

OBJECTIVE: To investigate the effect of Galla Chinensis with or without fluoride on demineralization of enamel. METHODS: Galla Chinensis with or without fluoride and acid buffer were used to treat the samples alternately and the treatment was repeated 8 times. Then the calcium of acid buffer was measured by American PE HTS 7000 plus and the specimens were observed with laser scanning confocal microscope. RESULTS: Compared with the calcium concentration of control group (deionized water or fluoride), the calcium concentration of all tested groups (except the 1 mg/ml group without fluoride) decreased significantly (P < 0.25). There was marked difference in total fluorescence (TF) and average fluorescence (AF) between the tested groups and control group (P < 0.05). As for the area of lesion, only groups without fluoride and the 4 mg/ml group containing fluoride decreased (P < 0.01). Confocal images showed that the zone of red area of tested groups was narrower than that of control group. CONCLUSION: Galla Chinensis can reinforce the resistance of enamel to acid, either with or without fluoride.

[Effect of tea polyphenol on the demineralization and remineralization of enamel in vitro].

OBJECTIVE: To investigate the effect of tea polyphenol (TP) on the mineralization behaviour of enamel in two sterile, in vitro systems. METHODS: In the demineralization study, sound enamel sections were pH-cycled. Treatments were 2000 mg/L TP, 200 mg/L TP, 2000 mg/L TP + 100 mg/L fluoride, 100 mg/L fluoride, and deionized water. In the remineralization study, surface-softened enamel was used and pH-cycled as above. Test treatments were 2000 mg/L TP, 2000 mg/L TP + 250 mg/L fluoride, 250 mg/L fluoride, and deionized water. The acidic buffers were retained for calcium analysis. The enamel was analysed before and after pH-cycling by microhardness. RESULTS: In the demineralization study, the calcium depletion rates(CDR) were (0.43 +/- 0.05), (0.49 +/- 0.006), (0.21 +/- 0.02), (0.21 +/- 0.03) and (0.50 +/- 0.11) microgram/(mm2.h) respectively. The Knoop hardness values(KHV) percent reduction were 94.19 +/- 3.50, 96.62 +/- 0.63, 74.74 +/- 4.09, 77.79 +/- 3.11 and 97.32 +/- 4.03 respectively. There were no significant differences within either the TP-only groups or the fluoride groups, but the fluoride groups were significantly more efficacious than the TP-only groups (P < 0.05). In the remineralization study, the KHV percent increase were -11.96 +/- 10.1, -21.32 +/- 11.3, -49.52 +/- 24.6 and -4.24 +/- 8.51 respectively. Notably more remineralization was observed in the fluoride group. There were no significant differences between the other groups (P > 0.05). CONCLUSION: The data of this in vitro study suggest that TP has no effect on de/remineralization of enamel blocks and there is no synergetic action of TP and fluoride in a sterile system. This finding supports the proposition that tea polyphenols exert an anti-caries effect via an anti-microbial mode-of-action.

[The effects of traditional Chinese medicines on the adherence of Streptococcus mutans to salivary acquired pellicle in vitro].

OBJECTIVES: To investigate the effects of traditional Chinese medicines on the preliminary adherence of Streptococcus mutans to salivary acquired pellicles. METHODS: The hydroxyapatites beads were coated by saliva to form S-HA, an in vitro model of experimental pellicle. Streptococcus mutans was chosen as the experiment strain, and radiolabeled with 3H-thymidine. Two parts of adherence inhibit study were carried on with medicines pretreated S-HA and medicines pretreated bacteria. The numbers of 3H-thymidine labeled bacteria attached to S-HA were counted by scintillation counting to indicate the amount of adherence. RESULTS: It was found that most of the traditional Chinese medicines tested could inhibit the adherence to S-HA to different extent, especially the Galla Chinensis, which has significant inhibitory action. CONCLUSION: Galla Chinensis may be a prospective medicine to inhibit the cariogenic bacteria's preliminary adherence to salivary acquired pellicles.

[Evaluation of the in vitro cariogenic potential of Streptococcus mutans (serotype C) strains isolated from caries-free and -active people: the ability of acidogenicity].

OBJECTIVE: To investigate the ability of acidogenicity of S. mutans (serotype C) strains isolated from the people with different caries experience. METHODS: Same density solutions of all isolated S. mutans were made and cultured in different pH TPPE liquid for the same period of time. Terminal pH of the solutions was measured. The values of delta pH were compared. RESULTS: Significant difference of acidogenicity was observed between the strains of different genotypes isolated from the same person. The ratio of high acidogenicity isolates harbored in caries-active people was greater than that of caries-free people; a significant difference was noted (P<0.05). CONCLUSION: The high cariogenicity of isolated S. mutans strains of caries-active people shows a close relationship with the high acidogenicity of the isolated S. mutans (serotype C) strains.

[Clinical evaluation of composite inlays in defective molars].

OBJECTIVE: To evaluate clinical effect of composite inlays in the defective molars. METHODS: A total of 200 defective molars from 163 patients were divided into two groups, including 100 molars of each. One group was restored with the direct composite inlays and another group with the traditional composite fillings. All the restorations were evaluated in oral cavity after 6-month and 5-year filling or insertion with United States public health service criterions. The data were analyzed using SPSS 11.0 software with the chi-square test. The significance level was set at 5%. RESULTS: In clinical service for 6 months, the successful rate of composite inlays was 91.8% (90/98) and the corresponding figure for traditional composite fillings was 91.8% (89/97), but there was no statistically significant difference (P > 0.05). In clinical service for 5 years, the successful rate of composite inlay was 87.9% (80/91), the corresponding figure for the traditional composite fillings being 67.4% (60/89) and the difference was statistically significant (P < 0.05). CONCLUSIONS: In clinical, the defective molars can be well restored with the direct composite inlays. Especially in the long-term clinical service, the composite inlays show significant superiority over the traditional composite fillings.

[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 of the correlation between moderately and severely chronic periodontitis and coronary heart disease].

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.

[Correlation between levels of fibrinogen, beta455 g/A fibrinogen gene polymorphism and chronic periodontitis].

OBJECTIVE: To investigate the relationship between plasma levels of fibrinogen, the-beta455 G/A fibrinogen gene polymorphism and the severity of periodontal inflammation and to explore the possible role of fibrinogen in the association of periodontitis with coronary heart disease (CHD). METHODS: A total of 121 patients with moderate to severe periodontitis and periodontally healthy and gingivitis controls were enrolled in the study. Peripheral blood samples were collected and the plasma fibrinogen levels were determined by the clotting method of Clauss. Polymerase chain reaction and restriction fragment length polymorphism analysis with Hae III were used to examine the -beta455 G/A fibrinogen gene polymorphism. RESULTS: Fibrinogen levels were significantly higher in moderately or severely chronic periodontitis patients [(3.45 +/- 0.68) g/L] than periodontally healthy and gingivitis controls [(2.47 +/- 0.42) g/L, P < 0.001]. The carrier status of the A allele at position -455 in the beta fibrinogen gene was associated with elevated fibrinogen levels and the frequency of the-A455 allele in the beta fibrinogen gene in the patient group was significantly higher than in the control group (P = 0.032). Carriers of the -A455 allele were about 3-fold more likely to have moderate or severe periodontitis as compare to individuals without the -A455 allele( OR = 3. =135, P= 0.008). CONCLUSIONS: Fg-beta455 G/A polymorphism may contribute to the elevated plasma fibrinogen levels and put individuals at higher risk of having severe periodontitis. As the independent risk factor of CHD, fibrinogen levels and Fg-beta455 G/A polymorphism may play a role in the pathogenesis of periodontitis.

[Genetic diversity of F-ATPase subunits gene uncEBF amplified from Streptococcus mutans clinical isolates].

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.

[Genetic diversity and mRNA expression of F-ATPase subunit uncG gene of streptococcus mutans clinical isolates].

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.

Histologic evaluation of direct pulp capping with a self-etching adhesive and calcium hydroxide in beagles.

OBJECTIVE: To evaluate the pulpal response of beagles following direct pulp capping with Clearfil SE Bond (SB), a self-etching adhesive. STUDY DESIGN: One hundred thirty sound teeth from 6 male beagles were used. One hundred twenty teeth had their pulp mechanically exposed at the bottom of the class V cavities and were divided into 2 groups. In group 1, teeth were capped with SB; group 2 teeth were capped with calcium hydroxide cement (CH). Ten teeth were kept intact as an untreated control group. After 7, 30, and 90 days, 40 teeth from 2 beagles were extracted and processed for light microscopic examination. RESULTS: After the 7-day observation period, inflammatory reaction in the SB group was similar to that of the CH group (P > .05). After the 30-day and 90-day observation periods, inflammatory reaction was slight in both groups, but less dentin bridge formation was observed in specimens from the SB group than in those from the CH group (P < .05). CONCLUSION: SB showed good biocompatibility with pulp, but its ability to induce reparative dentin was lower than that of CH.

[Study on the effect of concentrations of glucose on initial adherence of Streptococcus mutans].

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.

[Genetic diversity of F-ATPase subunits gene uncA amplified from Streptococcus mutans clinical isolates].

OBJECTIVE: To study the genetic diversity of F-ATPase alpha subunit gene uncA derived from Streptococcus mutans (S. mutans) clinical isolates and to investigate the relationship between the genetic diversity of acidurance factor and S. mutans aciduric ability, also and the cariogenicity. METHODS: Sixty-four S. mutans strains derived from 34 caries-active individuals and 30 caries-free individuals, including 18 strains displaying high acid tolerance and 20 strains displaying low acid tolerance. Gene uncA was amplified with specific primers from S. mutans genomic DNA, then the PCR products were analyzed by RFLP and sequenced. RESULTS: Two genotypes A and B of PCR-RFLP were revealed when digested with Hph I. Mbo II also produced two different pattern C and D. The distributions of A and B genotype strains with different caries-sensitivity groups were different (P < 0.05), and the proportion of A genotype strains from caries-activity group was higher than that from caries-free one. The distributions of C and D genotype strains with different acidurance strains were different (P < 0.05), and the proportion of C genotype strains from high acid tolerance group was higher than that from low acid tolerance group. These amplified uncA genes from different group were sequenced and there existed variation of Hph I and Mbo II recognized sites. CONCLUSIONS: This study indicates that uncA gene of S. mutans F-ATPase obviously displayed genetic diversity. The different Hph I-RFLP and Mbo II-RFLP genotypes could be related to the cariogenicity and acid tolerance of S. mutans strains.

[Effect of fibrinogen on the adherence of Porphyromonas gingivalis to human oral epithelial cells].

OBJECTIVE: To study the role of fibrinogen molecule in the pathogenesis of periodontal diseases. METHODS: An in vitro cell culture model was used. Methyl-(3)H Thymidine radiolabeled Porphyromonas gingivalis (Pg) ATCC 33277 were examined for their ability to adhere to and invade the confluent monolayers of human oral epithelial KB cells with or without exogenous human fibrinogens by scintillation spectrometry. RESULTS: The addition of exogenous fibrinogens made more amount of and higher ratios of adhesive and invasive Pg, in contrast to the group without exogenous fibrinogen (P < 0.001). At different concentrations of exogenous fibrinogen, the amount and ratios of adhesive and invasive Pg varied significantly (P < or = 0.007). The higher concentrations of exogenous fibrinogen was added, the greater amount and ratios of adhesive and invasive Pg were found. CONCLUSIONS: Fibrinogen promotes the adherence of Pg to human oral epithelial cells and may play an important role in the pathogenesis of periodontal diseases.