Association of ALDH2 genotypes with periodontitis progression.

The progression of periodontitis may be affected by ALDH2 genotypes with respect to the oxidation of acetaldehyde to acetate, which leads to the accumulation of acetaldehyde in plasma and potential toxic effects. We examined the prospective association of ALDH2 genotypes in terms of alcohol sensitivity between alcohol consumption and periodontal disease progression. In 2003, 224 of 256 (87.5%) individuals examined at baseline (1999) completed probing pocket depth measurements for the evaluation of periodontitis progression. Missing data on self-reported questionnaires and blood samples were excluded; therefore, 183 samples were analyzed. Individuals who consumed > or = 33.0 g/day of alcohol exhibited high periodontal disease progression risk (OR = 3.54). ALDH2 *1/*2 individuals who consumed > or = 33 g/day of alcohol displayed a significant odds ratio (OR = 4.28) of periodontitis progression risk, in contrast to ALDH2 *1/*1 individuals. These results suggested that alcohol consumption as well as alcohol sensitivity may be a risk factor for periodontitis progression.

Homotypic biofilm structure of Porphyromonas gingivalis is affected by FimA type variations.

INTRODUCTION: Porphyromonas gingivalis is a periodontal pathogen whose long fimbriae (FimA) are classified into six genotypes (types I-V and Ib) based on the diversity of the fimA genes. FimA variations were previously shown to be related to the onset and development of adult periodontitis in a general population, while FimA were recently found to be critical mediators of initial biofilm formation. However, it is unclear if FimA variations have effects on biofilm features. Here, we compare the characteristic structures of homotypic biofilms developed by P. gingivalis strains with different FimA types. METHODS: Biofilms were formed on saliva-coated glass bottom wells in phosphate-buffered saline and their structures were analysed using confocal laser scanning microscopy. Furthermore, the biovolumes of the biofilms were quantified with a three-dimensional fluorophotometric method. RESULTS: Biofilm structures formed by the six representative FimA-type strains apparently differed. Type I and Ib P. gingivalis formed biofilms with a dense basal monolayer and dispersed microcolonies, whereas those formed by types II, III and IV strains had markedly luxuriant biofilms filled with widely clumped and tall colonies, and their biovolumes were significantly greater than those of types I and Ib. These characteristic features were confirmed to be closely related to FimA type in assays that utilized fimA-substituted mutants from type I to II and those from type II to I. CONCLUSION: Our results suggest that FimA variations have effects on the structures of biofilms formed by P. gingivalis, which may be an important factor in the pathogenesis of periodontitis.

Relationship of Porphyromonas gingivalis with glycemic level in patients with type 2 diabetes following periodontal treatment.

INTRODUCTION: The aim of this study was to assess the relationship between serum glycemic levels and subgingival microbial profile alteration following periodontal treatment in patients with type 2 diabetes mellitus. METHODS: We studied 30 periodontitis patients with type 2 diabetes mellitus who received full-mouth subgingival debridement by analyzing their subgingival microbial profiles using a polymerase chain reaction method at baseline and various time-points for 12 months following treatment. Concurrently, probing pocket depth, bleeding on probing, and metabolic parameters, including glycated hemoglobin A1c (HbA1c), blood sugar level, C-reactive proteins, total cholesterol, triglyceride, and high-density and low-density lipoprotein cholesterol, were recorded. RESULTS: Periodontal conditions were significantly improved after treatment, and the occurrence rates of periodontal bacterial species, including Porphyromonas gingivalis, Tannerella forsythensis, Treponema denticola, and Prevotella intermedia, were also reduced. Interestingly, P. gingivalis was detected more frequently in subjects with increased HbA1c values after periodontal treatment than in those patients with decreased HbA1c values. Furthermore, P. gingivalis with type II fimbriae was detected only in HbA1c-increased subjects, while improvements in HbA1c values were observed only in subjects without type II clones. CONCLUSIONS: These results suggest that glycemic level in diabetes is affected by the persistence of P. gingivalis, especially clones with type II fimbriae, in periodontal pockets.

Inhibitory effects of macrocarpals on the biological activity of Porphyromonas gingivalis and other periodontopathic bacteria.

BACKGROUND/AIMS: Macrocarpals, which are phloroglucinol derivatives contained in eucalyptus leaves, exhibit antimicrobial activity against a variety of bacteria including oral bacteria. This study examined effects of macrocarpals A, B, and C on periodontopathic bacteria, especially Porphyromonas gingivalis. METHODS: Macrocarpals A, B, and C were purified from a 60% ethanol-extract of Eucalyptus globules leaves. To investigate antibacterial activity, representative periodontopathic bacteria were cultured in media with or without various amounts of macrocarpals; subsequently, the optical density at 660 nm was measured. Macrocarpal inhibition of P. gingivalis Arg- and Lys-specific proteinases was assessed by spectrofluorophotometric assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The effect of macrocarpals on P. gingivalis binding to saliva-coated hydroxyapatite beads was examined with (3)H-labeled P. gingivalis. RESULTS: Growth of P. gingivalis was inhibited more strongly than growth of Prevotella intermedia or Prevotella nigrescens and Treponema denticola by macrocarpals, however, Actinobacillus actinomycetemcomitans and Fusobacterium nucleatum were much more resistant. Macrocarpals inhibited P. gingivalis Arg- and Lys-specific proteinases in a dose-dependent manner. The enzyme-inhibitory effect of macrocarpals was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis in which hemoglobin degradation by P. gingivalis proteinase was inhibited by macrocarpals. P. gingivalis binding to saliva-coated hydroxyapatite beads was also strongly attenuated by macrocarpals. CONCLUSIONS: Macrocarpals A, B and C demonstrated antibacterial activity against periodontopathic bacteria. Among tested bacteria, P. gingivalis displayed the greatest sensitivity to macrocarpals; additionally, its trypsin-like proteinase activity and binding to saliva-coated hydroxyapatite beads were inhibited by macrocarpals. These results indicate that eucalyptus leaf extracts may be useful as a potent preventative of periodontal disease.

Relationship between attitudes toward oral health at initial office visit and compliance with supportive periodontal treatment.

OBJECTIVES: The objectives of the present study include investigation of the relationship between attitudes and desires with respect to oral health at initial office visit and compliance with supportive periodontal treatment (SPT) and identification of prognostic factors with respect to low-compliance with SPT. MATERIALS AND METHODS: Four hundred thirty-one patients were evaluated. Subjects completed a questionnaire concerning attitude and desire with respect to oral health and subjective symptoms prior to periodontal treatment. Survival probabilities of SPT were estimated by the Kaplan-Meier method and compared between answers for each item of the questionnaire via the Cox-Mantel test. Finally, a multivariate Cox proportional hazards regression model was constructed, which included age and gender. RESULTS: Greater than 95% of participants desired toothbrushing proficiency and lifelong retention of teeth at the initial office visit; however, the overall survival probabilities of SPT were only 52.7% after about 5 years. Patients exhibiting unfavourable attitudes toward oral health at the initial office visit, in comparison with those displaying favourable attitudes, exhibited greater tendency to abandon SPT. A Cox regression model revealed that lack of brushing on the gingival margin, non-use of an inter-dental brush or dental floss, non-use of fluoride toothpaste and frequent consumption of sugar-containing drinks were significant independent prognostic factors for low-compliance with SPT (p<0.05; Hazard ratios=2.27, 2.00, 2.56 and 2.06, respectively). CONCLUSIONS: Desire for satisfactory oral health is not related consistently to continuation of SPT. Unfavourable attitudes toward oral health were correlated to low-compliance with SPT. Clinicians may wish to establish methods for improvement of patient compliance employing behavioural approaches applicable to the attitudes of potential low-compliance individuals.

Clinical assessment of oral malodor intensity expressed as absolute value using an electronic nose.

OBJECTIVES: In our previous study, scores determined via a multiple linear regression method (EN-MLR) involving an electronic nose provided objective halitosis-related measurements; however, this model afforded only relative expression exclusively. The objective of this investigation was to assess clinically oral malodor intensity expressed as an absolute value using an electronic nose. SUBJECTS AND METHODS: Sixty-six subjects were evaluated based on results of an actual organoleptic test (OLT), measurements of volatile sulfur compound (VSC) concentrations, a score representing malodor intensity (EN-MI) as the absolute value and EN-MLR measured with an electronic nose system. Oral health parameters were also examined. RESULTS: The OLT score served as a benchmark. The area under the receiver-operating characteristic (ROC) plots of EN-MI score (0.975) was significantly larger than that of log VSC (0.896) (P = 0.036); however, the area did not differ significantly from that of EN-MLR score (0.932). Percentage of teeth with pocket depth greater than or equal to 4 mm, tongue coating score and plaque control record displayed meaningful association with EN-MI score in multiple logistic regression analyses. CONCLUSION: Oral malodor intensity expressed as an absolute value employing an electronic nose may be a suitable method for clinical evaluation of oral malodor.

Quantitative detection of periodontal pathogens using real-time polymerase chain reaction with TaqMan probes.

Quantitative analysis, with identification of periodontopathic bacteria, is important for the diagnosis, therapeutic evaluation and risk assessment of periodontal disease. We developed a highly sensitive and specific method using real-time polymerase chain reaction (PCR) to detect and quantify six periodontal bacteria: Porphyromonas gingivalis, Tannerella forsythia, Actinobacillus actinomycetemcomitans, Treponema denticola, Prevotella intermedia, and Prevotella nigrescens. Species-specific TaqMan probe/primer sets were designed according to 16S ribosomal RNA gene sequences. Plaque and tongue debris specimens were collected from 10 patients with advanced periodontitis and 10 periodontal healthy individuals and analyzed. All species, except for P. nigrescens, were detected in samples from diseased sites in significantly greater numbers than in those from healthy sites, whereas greater numbers of P. nigrescens were found in the controls. These results suggest that the present real-time PCR method with the designed probe/primer sets enabled sensitive detection of the six periodontal bacteria, and may also assist future microbial studies of periodontal diseases.

Clinical assessment of oral malodor by the electronic nose system.

A recently developed electronic nose has not yet been clinically applied to evaluations of oral malodor. This investigation sought to determine whether an electronic nose could clinically assess oral malodor. Twenty-nine healthy adults and 49 patients were assessed by results of an actual organoleptic test, a score representing malodor strength with an electronic nose in "top-note" mode (top-note score), and measurements of volatile sulfur compound (VSC) concentrations. The correlation coefficient between top-note and actual organoleptic scores (r = 0.71) was comparable with the log VSC and actual organoleptic scores (r = 0.63). However, the area under the receiver-operating characteristic plots for top-note score was significantly larger than that for log VSC. In logistic regression analyses with top-note score as a dependent variable, probing depth, tongue coating, and plaque control record each had independent associations. Our findings suggest that the top-note score from an electronic nose examination may be useful for the clinical evaluation of oral malodor.

Association of ALDH(2) genotypes and alcohol consumption with periodontitis.

There is little information regarding the association between alcohol consumption and periodontitis risk. We assessed whether alcohol consumption and ALDH(2) genotypes were associated with periodontitis. Subjects' lifestyle was examined by a self-administered questionnaire, and the percentage of pocket depths > or = 3.5 mm was used as a periodontal parameter. ALDH(2) genotypes were determined with the use of a PCR/RFLP method. Multiple logistic analyses showed that alcohol consumption was significantly associated with periodontitis, and its odds ratio was 1.98. There was no significant relationship between periodontal status and ALDH(2) genotypes. However, ALDH(2)*1/*2 subjects who consumed > or = 33 g/day of alcohol had a significantly greater percentage of pocket depths > or = 3.5 mm than those whose daily consumption was lower, while there was no significant difference in periodontal status associated with alcohol consumption in ALDH(2)*1/*1 subjects. Our results suggest that alcohol consumption may be a risk indicator for periodontitis in ALDH(2)*1/*2 subjects who consume larger amounts of alcohol.

Reliability of clinical parameters for predicting the outcome of oral malodor treatment.

We conducted the present study to determine which clinical parameters for diagnosing halitosis are most reliable in the development of an accurate prognosis for oral malodor treatment. Clinical evaluation included a questionnaire, oral examination and volatile sulfur compounds (VSC) measurement, and organoleptic test (OLT) at baseline. Ninety-two patients classified with oral pathologic halitosis were treated in a similar manner. Improved treatment outcome was defined as < 0.25 ppm of total VSC, < or = 2 OLT score, and < 30 on the "sad feeling" scale as subjective stress level by oral malodor 6 months after baseline. Thirty-four patients demonstrated improvement due to the treatment. In a multiple logistic model, pocket depth, OLT score, intra-oral discomfort, and self-perception of oral malodor at baseline displayed significant association with "not improved outcome". These results suggest that malodor- and periodontal-disease-related parameters and self-estimation of malodor at baseline are effective for prediction of outcome.

Characterization of binding and utilization of hemoglobin by Prevotella nigrescens.

The ability of Prevotella nigrescens to utilize and bind to hemoglobin was investigated. Growth studies showed that P. nigrescens was able to utilize hemoglobin efficiently as an iron source. Binding of P. nigrescens to hemoglobin was demonstrated by dot blot assay. Heat and trypsin treatments of the bacteria led to a decrease in activity. Globin gave nearly complete inhibition of activity. Additionally, lactoferrin partially inhibited activity. In contrast, transferrin, cytochrome C and catalase exerted little or no inhibitory effect. Although the sugars tested did not affect activity, several of the amino acids tested, including arginine, cysteine, histidine and lysine, inhibited activity. In a solid phase assay, 41-, 56- and 59-kDa proteins of P. nigrescens reacted with hemoglobin. These results suggest that P. nigrescens utilizes hemoglobin for growth and 41-, 56- and 59-kDa proteins may be involved in hemoglobin binding.

Survival analysis for degree of compliance with supportive periodontal therapy.

BACKGROUND, AIMS: The purpose of this investigation was to evaluate the degree of compliance for supportive periodontal therapy (SPT) and to determine factors in relation to patients who failed to continue SPT programs. METHOD: A sample of 1896 patients who were treated between 1988 and 1999 was studied. The patients were classified by gender, age group and the distance between their house and the hospital. The number of visits was counted based on an electronic patient record for SPT. Data were analyzed by survival analysis. Survival probabilities in SPT were estimated by the Kaplan-Meier method and compared by the generalized Wilcoxon test. RESULTS: 28% of patients did not comply with the first visit for SPT. The older patients had higher tendencies to continue the SPT program than the younger patients. No significant differences in compliance were found between males and females or between short-distance and long-distance groups. However, when these factors were adjusted by age, significantly different patterns were shown on the curves of survival probability: in males, significant differences were found between the 20 s and 30 s (p<0.00001) and between the 50 s and 60 s (p<0.01). In females, significant differences were found between the 40 s and 50 s (p<0.001) and between the 60 s and 70 s (p<0.001). The differences of the survival probability by age group were greater in the short-distance group than in the long-distance group. CONCLUSIONS: The results suggest that age is the most important factor for compliance of the patients with SPT, not only alone but also in relation to the other factors.

Specific antibodies to Porphyromonas gingivalis Lys-gingipain by DNA vaccination inhibit bacterial binding to hemoglobin and protect mice from infection.

Lys-gingipain (KGP), a lysine-specific cysteine proteinase, is one of the major virulence factors of Porphyromonas gingivalis. Here we examined the involvement of the catalytic domain of KGP (KGP(cd)) in hemoglobin binding by P. gingivalis, using a specific immunoglobulin G (IgG) elicited by the administration of plasmid DNA encoding KGP(cd) or the catalytic domain of Arg-gingipain (RGP(cd)). The pSeq2A/kgp(cd) and pSeq2B/rgp(cd) plasmids were constructed by the ligation of kgp(cd) and rgp(cd) DNA fragments, respectively. Female BALB/c mice were immunized with each of these plasmids. pSeq2A/kgp(cd) elicited a strong response to recombinant KGP(cd) (rKGP(cd)), as well as to comparably produced rRGP(cd)-reactive antibodies. The serum antibodies elicited by pSecTag2B/rgp(cd) also cross-reacted with rKGP(cd) as well as rRGP(cd). Anti-KGP(cd) IgG significantly inhibited hemoglobin binding by P. gingivalis. Furthermore, the inhibition of hemoglobin binding was markedly enhanced by a combination of anti-KGP(cd) and anti-fimbriae. Anti-RGP(cd) IgG showed a negligible inhibitory effect, while both anti-KGP(cd) and anti-RGP(cd) IgGs showed significant inhibitory effects on Lys- and Arg-specific proteolytic activities and on the growth of P. gingivalis under iron-restricted conditions where supplemented hemoglobin was the sole iron source. Immunized mice were challenged by intraperitoneal inoculation with P. gingivalis. All nonimmunized mice died within 72 h; however, vaccination with pSeq2A/kgp(cd) and pSeq2B/rgp(cd) prevented inflammatory responses and prolonged the survival rate of immunized mice by 43 and 27%, respectively. These results suggest that KGP(cd) acts as a hemoglobin-binding protein and can also be useful as an immunogen inducing a protective response to P. gingivalis infection.

Altered antigenicity in periodontitis patients and decreased adhesion of Porphyromonas gingivalis by environmental temperature stress.

Periodontopathogenic bacteria survive various environmental changes during the progression of periodontal disease. Alterations in metabolism and protein expression will have to take place to adapt their physiological functions to environmental stress. We examined the effects of an elevation of 2 degrees C in temperature on the adhesive ability and antigenicity of Porphyromonas gingivalis. Elevation of growth temperature of P. gingivalis from 37 degrees C to 39 degrees C remarkably suppressed the expression of surface filamentous structures, such as fimbriae, as well as the adhesive capacities to salivary components and Streptococcus oralis. Sera of severe periodontitis patients revealed a marked increase in serological activity with 39 degrees C cells than with 37 degrees C cells. The alteration of protein profiles of bacterial surface components by temperature elevation was demonstrated by SDS-PAGE, and their Western blot profiles were also different from those of cells grown at 37 degrees C. Although a uniform trend was not found in the altered patterns, sera from severe periodontitis patients detected more antigenic proteins in cells grown at 39 degrees C than 37 degrees C cells. These observations suggest that P. gingivalis downregulates the expression of fimbriae and alters its adhesive capacity and antigenicity by the temperature stress that could occur during the disease progression.

Relation of motility of subgingival microflora as a clinical parameter to periodontal disease status in human subjects.

BACKGROUND/AIMS: The purpose of this study was to evaluate the possible relationship between the motility of subgingival microflora and 5 clinical parameters commonly used in dental clinics. METHOD: The clinical parameters were pocket depth, gingival inflammation, plaque accumulation, bleeding on probing and pus discharge. The motility of human subgingival microflora was estimated as the number of pixels remaining after subtraction of serial video frames using a high speed shutter camera and image analysis system, and was defined as the sum of pixels of 10 successive subtractions per sample over a 10-s time period. RESULTS: The bacterial motility showed significant positive, moderate or low associations with the five clinical parameters. The highest correlation was observed between the bacterial motility and pocket depth (r=0.36, p=0.0001). Furthermore, clinically defined periodontal healthy and diseased sites were significantly different with respect to the bacterial motility (p<0.0001). To determine whether the bacterial motility was dependent or independent of the other clinical variables, the data were analyzed based on common factor analysis. Three factors were extracted and explained about 75% of the variance of the original 6 clinical parameters. Only the bacterial motility had a positive coefficient for all these three factors. The plot of bacterial motility was placed separately from those of other variables in the scatterplot of the loadings of factor 2 versus factor 1 and factor 2 versus factor 3. CONCLUSIONS: This suggests that bacterial motility may be an independent variable among the clinical parameters. Taken together, these data indicate that bacterial motility provides unique information about the clinical periodontal condition and may be a useful tool for the monitoring of subgingival plaque in relation to periodontal disease.

Pocket oxygen tension in smokers and non-smokers with periodontal disease.

BACKGROUND: Smoking is associated with destructive periodontal disease. Pocket oxygen tension (pO2) is likely to be a major environmental determinant of the subgingival microflora, which is a primary etiological factor of the disease. This study aimed to compare the pocket pO2 in smokers and non-smokers with periodontal disease. METHODS: Pocket oxygen tension was compared in 27 smokers and 34 non-smokers by considering 2 confounding factors, probing depth and oxygen saturation of hemoglobin (S(O2)), in the gingiva. The pO2 was determined using oxygen microelectrode by polarographic method with an electronic compensation circuit for subgingival temperature. Gingival S(O2) was determined using tissue reflectance spectrophotometry. RESULTS: No significant difference was found in the modified gingival index and the plaque index between smokers and non-smokers. The pO2 was significantly lower in smokers (21.9+/-9.6 mmHg) than in non-smokers (33.4+/-8.4 mmHg). The difference was highly significant (P <0.0001) and was consistent when the confounding factors were considered. Correlation between the PO2 and probing depth approached statistical significance in smokers (r = -0.36, P = 0.0674) and significance in non-smokers (r = -0.41, P = 0.0174). Correlation of the PO2 to the gingival S(O2) was highly significant in non-smokers (r = 0.57, P = 0.0005), but no association was found in smokers (r = -0.08, P= 0.6975). CONCLUSIONS: These findings indicate that pO2 is lower in smokers than in non-smokers, and that the pO2 in smokers is not influenced by gingival oxygen sufficiency. The present study may provide the basis of understanding environmental factors possibly associated with microbial flora in the pockets of smokers.

Relationship of the substance P to indicators of host response in human gingival crevicular fluid.

BACKGROUND: The substance P (SP) level in human gingival crevicular fluid (GCF) was studied in relation to clinical periodontal variables and to various indicators of host response in the GCF. METHODS: GCF was collected from periodontal sites with gingival inflammation and shallow or moderately deep pocket in 48 subjects. The total amount of SP and the substances based on host response factors in a 30-s sample were determined by ELISA and enzymatic methods. RESULTS: Significant correlation was found between SP and probing depth (r= 0.637, p<0.001), while correlation was weak between SP and either gingival (r= 0.177, p=0.23) or plaque index (r=0.008, p=0.96). SP also showed significant correlation with the indicators of host response: prostaglandin E2, aspartate aminotransferase, alkaline phosphatase, myeloperoxidase, interleukin-1beta, tumor necrosis factor-alpha, interleukin-8 and monocyte chemoattractant protein-1 (r=0.434-0.867, p<0.01-0.001). CONCLUSION: These results indicate that neuropeptide SP in GCF may have a potential as an indicator of periodontal inflammation and the host response.

Oxygen sufficiency in the gingiva of smokers and non-smokers with periodontal disease.

BACKGROUND: Epidemiological studies have demonstrated deteriorating effects of smoking on periodontal tissue. The aims of this study were to compare oxygen saturation of hemoglobin in the gingiva (GSo2) of smokers and non-smokers and to evaluate the chronic effect of smoking on gingival oxygen sufficiency. METHODS: GSo2 was determined using tissue reflectance spectrophotometry in 110 papillary gingival sites of 62 smokers and 100 sites of 60 non-smokers. RESULTS: No significant difference was found in GSo2 between smokers and non-smokers. In the model of ANOVA with covariates, age (P= 0.0048) and probing depth (P= 0.0012) had significant effects on GSo2. No significant effect was found in either smoking status (P= 0.3557) or the modified gingival index (MGI) (P= 0.3824). The interaction effect between smoking status and the MGI was highly significant (P = 0.0003) indicating that the effect of smoking status on the GSo2 should be compared at each level of the MGI score. GSo2 in healthy gingiva was significantly lower in smokers than non-smokers (P = 0.0014), while smokers showed higher GSo2 than non-smokers in moderately inflamed gingiva (P = 0.0356). The GSo2 in inflamed gingiva was significantly decreased compared with healthy gingiva in non-smokers (P = 0.0044), while smokers showed no significant difference between healthy and inflamed gingiva (P= 0.2772 to 0.8665). GSo2 in smokers was consistently and significantly lower than that of healthy gingiva of non-smokers (P = 0.0391 to 0.0004). CONCLUSIONS: Smokers exhibit possibly lower function of oxygen sufficiency in healthy gingiva and reduced ability to adapt the function in inflamed gingiva than non-smokers. This suggests that smokers have functional impairments in the gingival microcirculation.

Secretion of functional salivary peptide by Streptococcus gordonii which inhibits fimbria-mediated adhesion of Porphyromonas gingivalis.

Porphyromonas gingivalis, a putative periodontopathogen, can bind to human salivary components with its fimbriae. We have previously shown that fimbriae specifically bind to a peptide domain shared by a major salivary component, i.e., proline-rich (glyco)proteins (PRPs). The synthetic domain peptide PRP-C (pPRP-C) significantly inhibits the fimbrial binding to PRPs. In this study, a recombinant strain of Streptococcus gordonii secreting pPRP-C was generated as a model of a possible approach to prevent the oral colonization by the pathogen. A duplicate DNA fragment (prpC) encoding pPRP-C was obtained by self-complementary annealing of synthetic oligonucleotides. prpC was connected downstream to a promoter and a gene encoding a signal peptide of Streptococcus downei glucosyltransferase I in frame. The linked fragments were inserted into the plasmid pMNK-4 derived from pVA838. The constructed plasmid was inserted to produce the transformant S. gordonii G9B, which then successfully secreted recombinant pPRP-C (r-pPRP-C) of the expected size. The concentrated bacterial culture supernatant containing r-pPRP-C inhibited the binding of P. gingivalis cells and fimbriae to PRP1 in a dose-dependent manner up to 72 and 77%, respectively. The r-pPRP-C concentrate also inhibited the coaggregation of P. gingivalis with various streptococcal strains as effectively as synthetic pPRP-C in a dose-dependent manner. Collectively, pPRP-C was found to be able to prevent P. gingivalis adherence to salivary receptor protein and plaque-forming bacteria. These results suggest that this recombination approach with a nonperiodontopathic bacterium may be suitable for the therapeutic prevention of P. gingivalis adherence to the oral cavity.

Plaque removal efficacy of the V-shaped toothbrush with new designs in bristle arrangement.

Experimental bristle arrangements were applied to a conventional V-shaped bristle-design toothbrush in an effort to improve plaque removal efficacy in interproximal areas. A single-blind cross-over study was performed to evaluate the plaque removal efficacy of this new bristle arrangement by comparing it to either a more conventional V-shaped toothbrush or a flat-headed toothbrush. Plaque removal efficacy was determined by assessing the percentage of plaque score reduction following a single controlled brushing. The new toothbrush bristle arrangement had a significantly higher plaque removal percentage efficacy than both the V-shaped toothbrush (59.1% vs. 48.5%; p = 0.0092) and the flat-headed toothbrush (65.3% vs. 55.3%; p = 0.0260) in interproximal areas. These differences were also consistent with whole mouth comparisons. When the subjects were asked about their preferences for the three different bristle formats used in this study, there was no significant difference of opinion found. These findings indicated a superiority of the new toothbrush to the other two, more conventional toothbrush bristle styles on plaque removal efficacy with these study subjects, but no particular preference for bristle design.