Resting salivary flow independently associated with oral malodor.

BACKGROUND: Dryness of the oral cavity is considered one cause of oral malodor. However, it is unclear which of the factors regulating the wetness of the oral cavity are involved in oral malodor development. This study investigated the effects of salivary flow and oral mucosal moisture on oral malodor. METHODS: The study population comprised 119 patients (48 men and 71 women, mean age of 50.6 ± 15.4 years) with complaint of oral malodor. After the oral malodor level had been evaluated by the organoleptic test and gas chromatography, the rates of stimulated saliva and resting saliva and the moisture levels of the tongue and buccal mucosa were measured. The plaque index, bleeding on pocket probing, probing pocket depth, and tongue coating score were also assessed. Strong oral malodor was defined as an organoleptic test score of ≥3. RESULTS: The flow rate of resting saliva in women was significantly lower than in men. The flow rate of resting saliva and the moisture levels of the tongue and buccal mucosa showed significant negative correlations with age. The flow rate of resting saliva was significantly lower in patients with strong oral malodor than in those with no or weak oral malodor. The flow rate of stimulated saliva and the moisture levels of the tongue and buccal mucosa had no relationship with strong oral malodor. Logistic regression analysis showed that a ≥5-mm probing pocket depth with bleeding on pocket probing, an increased tongue coating score, and decreased resting salivary flow were strong explanatory factors in clinical findings for oral malodor. CONCLUSION: This study suggests that the flow rate of resting saliva is a significant modulating factor for oral malodor.

VDR gene polymorphisms, interaction with smoking and risk of periodontal disease in Japanese women: the Kyushu Okinawa maternal and child health study.

Epidemiological evidence on the relationship between vitamin D receptor (VDR) polymorphisms and periodontal disease is inconsistent. We investigated associations between four VDR single-nucleotide polymorphisms (SNPs) including rs731236 (TaqI), rs7975232 (ApaI), rs1544410 (BsmI) and rs2228570 (FokI), and the risk of periodontal disease among young Japanese women. Cases included 131 women who had at least one tooth with a probing depth of 3.5 mm or deeper. Controls included 1019 women without periodontal disease. Adjustment was made for age, region of residence, education, toothbrushing frequency and use of an interdental brush. Compared with the AA genotype of SNP rs731236, the GG genotype had a significantly increased risk of periodontal disease: the adjusted OR was 3.68 (95% confidence interval: 1.06-12.78). There were no significant relationships between SNPs rs7975232, rs1544410 or rs2228570 and periodontal disease. None of the haplotypes were significantly related to periodontal disease. Compared with subjects with the AA or AG genotype of SNP rs731236 who had never smoked, those with the GG genotype who had ever smoked had a significantly increased risk of periodontal disease; nevertheless, neither multiplicative nor additive interaction was significant. The additive interaction between SNP rs7975232 and smoking was significant, although the multiplicative interaction was not statistically significant. No multiplicative or additive interactions were observed between the other SNPs and smoking. Our results indicated that VDR SNP rs731236 might be associated with periodontal disease. In addition, we present new evidence for a biological interaction between VDR SNP rs7975232 and smoking that affects periodontal disease.

Active and passive smoking and prevalence of periodontal disease in young Japanese women.

BACKGROUND AND OBJECTIVE: Studies reporting on the association between smoking and periodontal disease have mostly focused on active smoking. The purpose of this study was to examine the relationships between active smoking and exposure to second-hand smoke at home and at work and the prevalence of periodontal disease among young Japanese women. MATERIAL AND METHODS: Study subjects were 1167 postpartum women with a mean age of 31.5 years. Information on smoking and potential confounding factors was obtained through a self-administered questionnaire. Partial-mouth recording was used to determine probing pocket depth at six sites per tooth for six teeth in the mouth. Periodontal disease was defined as positive if a woman had at least one tooth with a probing pocket depth of 3.5 mm or deeper. Adjustment was made for age, region of residence, household income, education, toothbrushing frequency and use of an interdental brush. RESULTS: Compared with never smoking, ever smoking was independently positively associated with the prevalence of periodontal disease: the adjusted odds ratio was 1.56 (95% confidence interval: 1.02-2.36). There was a marginally significant positive dose-response relationship between pack-years of smoking and the prevalence of periodontal disease (p for linear trend = 0.08). No material associations were observed between second-hand smoke exposure at home or at work and periodontal disease. CONCLUSION: Our findings suggest that active smoking, but not passive smoking, might be associated with an increased prevalence of periodontal disease among young women in Japan.

Intensive smoking-cessation intervention in the dental setting.

Smoking exerts detrimental effects on dental treatment and oral health. Our goal was to evaluate effectiveness in terms of the abstinence rate in smoking-cessation intervention delivered by dental professionals. Individuals who were willing to quit smoking were randomly assigned to either an intervention or a non-intervention group. Intensive intervention was provided, consisting of 5 counseling sessions, including an additional nicotine replacement regimen. Reported abstinence was verified by the salivary cotinine level. Thirty-three persons in the intervention and 23 in the non-intervention group started the trial. On an intent-to-treat basis, 3-, 6- and 12-month continuous abstinence rates in the intervention group were 51.5%, 39.4%, and 36.4%, respectively, while the rates in the non-intervention group were consistent at 13.0%. Adjusted odds ratios (95% confidence interval) by logistic stepwise regression analyses were 7.1 (1.8, 28.5), 8.9 (1.7, 47.2), and 6.4 (1.3, 30.7), respectively. Intensive smoking-cessation intervention in the dental setting was therefore effective.

Long-term effect of xylitol gum use on mutans streptococci in adults.

Many studies have shown the effects of chewing xylitol gum on mutans streptococci (MS) over short- and long-term periods in children; however, few studies have addressed long-term periods in adults. The objective of this investigation was to examine for 6 months the effects of chewing xylitol gum on MS in saliva and plaque in 127 adults (mean age 28.0 years). The participants were assigned to three groups according to gum type, in part taking preference for flavor into account and in part at random: xylitol (XYL), maltitol (MAL) and control (CR); 33, 34 and 27 subjects in each group, respectively, completed the trial. Daily gum use of the XYL and MAL groups was 7.9 and 7.1 g, respectively. MS levels, which declined significantly in saliva (p < 0.05) and plaque (p < 0.001) in the XYL group after 6 months, exhibited a significant increase in plaque in the MAL group (p < 0.001). Differences in relative changes of MS levels in plaque during the experimental period were significant between the XYL group and the CR (p < 0.05) and MAL groups (p < 0.001). Differences in relative change of amount of plaque during the experimental period were not statistically significant between the groups. The present study demonstrated that chewing xylitol gum for 6 months continued to inhibit the growth of mutans streptococci in adults.

Association of lip pigmentation with smoking and gingival melanin pigmentation.

OBJECTIVE: We investigated the association of lip pigmentation with smoking and melanin pigmentation in the gingiva. DESIGN: Case-control study. SETTING: Health check-up in an institute. SUBJECTS AND METHODS: Photos of 213 males employed in an institution were assessed in terms of pigmentation in lip and gingiva. MAIN OUTCOME MEASURES: Prevalence and scores of lip and gingival pigmentation and smoking status. RESULTS: Among subjects displaying lip and gingival pigmentation, 73% and 87% respectively, were current smokers, whereas 33% and 27% of individuals lacking pigmentation were current smokers respectively. Odds ratios of current smoking relative to lip and gingival pigmentation were 5.6 (95% confidence interval: 2.8-11.1) and 17.0 (8.1-36.0) respectively. Daily consumption, duration of smoking and lifetime exposure exhibited significant correlation with scores of lip and gingival pigmentation (P<0.0001). Odds ratios increased in lip and gingival pigmentation upon exposure. In current smokers, scores of lip and gingival pigmentation demonstrated meaningful correlation (P<0.0001); moreover, 95% of participants with lip pigmentation were positive for gingival pigmentation. CONCLUSION: These results indicated the presence of a striking association between smoking and pigmentation in the lip and gingiva, which was stronger with respect to gingival pigmentation. Health professionals could educate smokers, utilizing visible symptoms in the lip and gingiva.

Relationship between smoking status and periodontal conditions: findings from national databases in Japan.

BACKGROUND AND OBJECTIVE: The association between cigarette smoking and periodontitis was examined employing two nationally representative samples of adults in Japan. MATERIAL AND METHODS: Data were derived from the Survey of Dental Diseases (SDD) and the National Nutrition Survey (NNS) in 1999. In the SDD, periodontal conditions were evaluated by calibrated dentists utilizing the Community Periodontal Index (CPI), whereas in the NNS, participants were interviewed on the basis of smoking status by enumerators. Among 6805 records electronically linked via a household identification code, 4828 records of individuals aged 20 yr or older were analyzed. RESULTS: The prevalence of periodontal disease varied significantly by smoking status (p < 0.0001): 39.3%, 49.5% and 47.3% (CPI > or = 3), and 7.9%, 11.7% and 12.4% (a more severe form of periodontitis, CPI = 4), for nonsmokers, former smokers and current smokers, respectively. In adults aged > or = 40 yr (n = 3493), logistic regression models revealed greater probabilities (approximately 1.4 times higher) of periodontitis [CPI > or = 3, odds ratio = 1.38 (1.12-1.71), p = 0.0024] and a more severe form of periodontitis [odds ratio = 1.40 (1.04-1.89), p = 0.0288] in current smokers compared with nonsmokers, following adjustment for possible confounding factors. CONCLUSION: Based on the findings of this study and other numerous reports, cigarette smoking leads to deterioration of periodontal conditions in Japanese adults.

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.

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.

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.

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.

Association of oxygen tension in human periodontal pockets with gingival inflammation.

The objective of this study was to investigate the association of the oxygen tension in the periodontal pockets with clinical parameters of gingival inflammation of the maxillary anterior teeth of 32 patients. The pocket oxygen tension (pO2) was measured by a polarographic method with electronic compensation for temperature change. The oxygen saturation of hemoglobin (SO2) in the gingiva was determined with tissue reflectance spectrophotometry. Gingival crevicular fluid flow (GCF) was measured with electronic impedance. No significant association was found between pocket pO2 and the modified gingival index, the plaque index, and GCE Pocket pO2 showed significant correlation with probing depth (r = -0.57, P = 0.0005). Significant correlation was observed between pocket pO2 and gingival SO2 (r = 0.69, P < 0.0001). When all variables were entered into a multiple regression model, only gingival SO2 had a significant independent effect on the pocket pO2 (P = 0.0005). These results indicate that the oxygen sufficiency in the gingiva has a significant independent influence on the pocket oxygen tension. These studies provide the basis for understanding the oxygen tension in the periodontal pocket, which likely is a major determinant of the subgingival microflora. The studies may also lead to the development of methods for diagnosing and monitoring periodontal diseases.

Lifestyle and periodontal health status of Japanese factory workers.

The present study investigated the association of lifestyles to periodontal health status of workers in a manufacturing company in Japan. In a annual health checkup, periodontal health status was assessed by using the Community Periodontal Index (CPI) criteria and analysed by modified Miller's CPI score. Lifestyle information was also obtained by a self-administered questionnaire. Bivariate and multivariate analyses were used to examine the relationship between lifestyle and oral health care variables and 2 indicators of periodontal health status. These were the modified Miller's CPI score and the probability of subjects in the upper 25th percentile of CPI distribution as an indicator of poor periodontal health. The modified Miller's CPI score was found to increase with age, but to vary according to the workers' lifestyles. In bivariate analyses, significant variables were age, smoking, alcohol consumption, toothbrushing frequency, toothbrushing method, and use of interdental cleaners. In multivariate analyses, age, smoking, and use of interdental cleaners had significantly independent effects. Amount of smoking or alcohol consumption was associated with periodontal health status. Excessive use of alcohol may contribute to the development of periodontal disease, although further investigations are required to confirm this finding. The data from this study indicate that lifestyles which include smoking and insufficient oral health care have an independent association with periodontal disease.

Semi-automated measurement of motility of human subgingival microflora by image analysis.

The purpose of this investigation was to quantitatively estimate bacterial motility by image analysis, and to apply this method for the measurement of motility of human subgingival microflora. We developed a semi-automated method for the quantification of bacterial motility using video microscopy, digitization and image processing. Moving images of both authentic bacterial samples and clinical samples were recorded using a phase contrast microscope with a high speed (1/100 s) shutter camera. The motility was evaluated by measuring the total number of pixels remaining after the subtraction of 2 serial video images. The total number of pixels was significantly correlated with both the sum of the velocity of each bacterial cell and the number of motile bacteria on the same original images. Motility of subgingival microflora from 140 clinical samples tested was measured at 0 pixels to 3600 pixels, whereas the effect of Brownian movement was less than 150 pixels. The motility of subgingival microflora estimated with this image analysis system did not differ much from objective judgments by the naked eyes of experts. These results suggest that a semi-automated image analysis system may be useful in the evaluation of the motility of human subgingival microflora.

Effect of mechanical toothbrush stimulation on gingival microcirculatory functions in inflamed gingiva of dogs.

The effect of mechanical toothbrush stimulation on gingival microcirculatory functions was examined with and without removal of supragingival plaque in inflamed gingiva of 6 dogs. After removal of the ligatures, 4 treatment modalities: mechanical stimulation by vibration (MS), removal of supragingival plaque (PR), combination (MS+PR) and no treatment (NT), were administered to each quadrant for 2 weeks. Both quadrants with plaque removal showed a marked decrease in the gingival index score, while slight and moderate decreases were observed in NT and MS quadrants, respectively. Changes in gingival crevicular fluid flow, pocket oxygen tension and hemoglobin oxygen saturation in the gingiva were significant in the MS, PR and MS+PR quadrants. Significant treatment-by-time effects were found for all of the parameters of microcirculatory function between NT and MS quadrants, and gingival crevicular fluid flow between PR and MS+PR quadrants, respectively. These findings suggest that mechanical stimulation with a toothbrush may offer an additional benefit to gingival microcirculatory functions in inflamed gingiva.

Comparisons of modalities of mechanical stimulation with a toothbrush on improvement of oxygen sufficiency in dog gingiva.

Mechanical stimulation with a toothbrush was applied to each quadrant of 10 dogs at a force of 200 g for 10 s using following modalities: vibration at attached gingiva, pressurization at attached gingiva, vibration at marginal gingiva and no treatment as a control. Hemoglobin oxygen saturation (SO2) in the gingiva was measured by non-invasive tissue reflectance spectrophotometry. Simultaneously, oxygen tension (pO2) in gingival tissue was monitored with an oxygen microelectrode. Both SO2 and pO2 increased within 10-20 min after stimulation and then slowly returned to the initial level at all treatment sites. The response was most prominent after vibration at attached gingiva. SO2 and pO2 increased by 12% and 42%, respectively, and significant increase continued for 75-85 min. Response after vibration at marginal gingiva was moderate in pO2 and transient in SO2. Pressurization at attached gingiva caused moderate response in SO2, but the increase in pO2 was slight. Control showed little change in both indices. These results suggest that vibration with a toothbrush at attached gingiva may cause a maximal response in improving oxygen sufficiency to gingival tissue.

Interaction of Porphyromonas gingivalis with transferrin.

In this study, we characterized the binding of transferrin to Porphyromonas gingivalis using a classical receptor-binding assay, and examined the relationship between the binding and availability of transferrin for the growth of P. gingivalis. The binding of 125I-labeled human transferrin to P. gingivalis occurred rapidly, reversibly and specifically. Scatchard analysis yielded a Kd of 1.37 +/- 0.16 microM and an apparent number of 1.13 +/- 0.26 x 10(5) receptors per cell. The binding of transferrin was much increased when organisms were grown in iron-limited conditions. Among the species of black-pigmented anaerobic.rods, those strains of P. gingivalis which had high transferrin-binding activity exhibited unrestricted growth following the addition of transferrin to the hemin-free culture medium. On the other hand, the presence of transferrin in the culture medium did not support unrestricted growth of organisms that had low transferrin-binding activity. These results suggest that the binding of transferrin to P. gingivalis cells may be a preliminary step in iron acquisition, which allows them to survive in the healthy periodontal environment.