Mutans Streptococci and Dental Caries: A New Statistical Modeling Approach.

Survival analyses have been used to overcome some of the limitations encountered with other statistical analyses. Although extended Cox hazard modeling with time-dependent variables has been utilized in several medical studies, it has never been utilized in assessing the complex relationship between mutans streptococci (MS) acquisition (time-dependent covariate) and time to having dental caries (outcome). This study involved secondary analyses of data from a prospective study conducted at the University of Alabama at Birmingham. Low socioeconomic status, African-American preschool children from Perry County, AL, USA (n = 95) had dental examinations at age 1 year and annually thereafter until age 6 years by three calibrated dentists. Salivary MS tests were done at ages 1, 1.5, 2, 2.5, 3, and 4 years. The patterns of and relationship between initial MS detection (time-dependent covariate) and dental caries experience occurrence were assessed, using extended Cox hazard modeling. The median time without MS acquisition (50% of the children not having positive MS test) was 2 years. Approximately 79% of the children had positive salivary MS tests by the age of 4 years. The median caries experience survival (50% of the children not having dental caries) was 4 years. During the follow-up period, 65 of the children (68.4%) had their initial primary caries experience. Results of the extended Cox hazard modeling showed a significant overall/global relationship between initial caries experience event at any given time during the follow-up period and having a positive salivary MS test at any time during the follow-up period (hazard ratio = 2.25, 95% CI 1.06-4.75). In conclusion, the extended Cox modeling was used for the first time and its results showed a significant global/overall relationship between MS acquisition and dental caries. Further research using causal mediation analysis with survival data is necessary, where the mediator "presence of MS" is treated as a time-dependent variable.

Influence of smoking on gingival crevicular fluid cytokines in severe chronic periodontitis.

AIM: The aim of this study was to compare the expression of 22 chemokines and cytokines in gingival crevicular fluid (GCF) from smokers and non-smokers with periodontitis and periodontally healthy control subjects. MATERIALS AND METHODS: Forty subjects with generalized severe chronic periodontitis (20 smokers and 20 non-smokers) and 12 periodontally healthy control subjects participated in this study. Four diseased and two healthy sites were selected from each of the periodontitis subjects. GCF samples were collected and cytokines analysed utilizing a multiplexed immunoassay (Luminex(®) ). Statistical analyses employed non-parametric tests including the Mann-Whitney and Wilcoxon matched-pairs signed-rank tests. RESULTS: Compared with healthy control subjects, GCF in subjects with chronic periodontitis contained significantly higher amounts of interleukin (IL)-1α, IL-1ß, IL-6, IL-12(p40) (pro-inflammatory cytokines); IL-8, macrophage chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, regulated on activation normal T-cell expressed and secreted (RANTES) (chemokines); IL-2, IFN-γ, IL-3, IL-4 (Th1/Th2 cytokines); IL-15 [regulator of T-cells and natural killer (NK) cells]. Smokers displayed decreased amounts of pro-inflammatory cytokines [IL-1α, IL-6, IL-12(p40)], chemokines (IL-8, MCP-1, MIP-1, RANTES), and regulators of T-cells and NK cells (IL-7, IL-15). CONCLUSIONS: Periodontitis subjects had significantly elevated cytokine and chemokine profiles. Smokers exhibited a decrease in several pro-inflammatory cytokines and chemokines and certain regulators of T-cells and NK-cells. This reflects the immunosuppressant effects of smoking which may contribute to an enhanced susceptibility to periodontitis.

Longitudinal associations between children's dental caries and risk factors.

UNLABELLED: Dental caries is a common disease in children of all ages. It is desirable to know whether children with primary, mixed, and permanent dentitions share risk factors for cavitated and non-cavitated caries. OBJECTIVE: To assess the longitudinal associations between caries outcomes and modifiable risk factors. METHODS: One hundred and fifty-six children in the Iowa Fluoride Study met inclusion criteria of three dental examinations and caries-related risk factor assessments preceding each examination. Surface-specific counts of new non-cavitated caries and cavitated caries at the primary (Exam 1: age 5), mixed (Exam 2: age 9) and permanent (Exam 3: age 13) dentition examinations were outcome variables. Explanatory variables were caries-related factors, including averaged beverage exposure frequencies, tooth brushing frequencies, and composite water fluoride levels collected from 3-5, 6-8, and 11-13 years, dentition category, socioeconomic status, and gender. Generalized linear mixed models (GLMMs) were used to explore the relationships between new non-cavitated or cavitated caries and caries-related variables. RESULTS: Greater frequency of 100 percent juice exposure was significantly associated with fewer non-cavitated and cavitated caries surfaces. Greater tooth brushing frequency and high socioeconomic status (SES) were significantly associated with fewer new non-cavitated caries. Children had significantly more new cavitated caries surfaces at the mixed dentition examination than at the primary and permanent dentition examinations. CONCLUSIONS: There were common caries-related factors for more new non-cavitated caries across the three exams, including less frequent 100 percent juice exposure, lower tooth brushing frequency and lower SES. Less frequent 100 percent juice exposures might be associated with higher exposures to several other cariogenic beverages.

Mixed dentition cavitated caries incidence and dietary intake frequencies.

PURPOSE: This study examined risk factors for children having new cavitated caries between 5 and 9 years old. METHODS: Subjects were Iowa Fluoride Study cohort children (mostly Caucasian and of relatively high socioeconomic status) with both primary and mixed dentition caries exams and at least 2 diet diaries recorded between 5 and 8 years old (N=198). Using surface-specific transitions, combined counts of new cavitated caries (d(2-3)f and/or D(2-3)F) were determined from 4 primary second molars, 8 permanent incisors, and 4 permanent molars. Food and beverage intake frequencies were abstracted. Other factors were assessed using periodic questionnaires. Logistic regression identified predictors of new cavitated caries. RESULTS: Thirty-seven percent had new cavitated caries. The mean new cavitated caries count for all children was 1.17 surfaces (±2.28 SD). In multivariable logistic regression, the following were significantly associated (P<.10) with having new cavitated caries: noncavitated caries experience at 5 years old (odds ratio [OR]=2.67, P=.03); cavitated caries experience at 5 years old (OR=3.39, P=.004); greater processed starch at snack frequency (OR=3.87, P=.07); being older (OR=1.68, P=.04); and less frequent tooth-brushing (P=.001). CONCLUSION: Results suggested that increased tooth-brushing frequency and reduced consumption of processed starches as snacks may reduce caries incidence in younger school-aged children.

Beverage Intakes and Toothbrushing During Childhood Are Associated With Caries at Age 17 Years.

BACKGROUND: Sugar-sweetened beverages (SSBs) have been associated with childhood caries; however, associations among lifelong beverage intakes and adolescent caries have received less attention. OBJECTIVE: To investigate associations between beverage intakes during childhood and adolescence and caries experience at 17 years of age, while adjusting for fluoride intakes and toothbrushing. DESIGN: Descriptive model analyses were conducted on data collected from a longitudinal birth cohort study. PARTICIPANTS/SETTING: Participants included Iowa Fluoride Study members (n = 318) recruited at birth between 1992 and 1995 with at least 6 beverage questionnaires completed from ages 1 to 17 years and a caries examination at age 17. EXPOSURE: Predictors included mean daily milk, juice (100% juice and juice drinks before age 9), SSB (including juice drinks after age 9), and water/sugar-free beverage (SFB) intakes; daily fluoride intakes; and daily toothbrushing frequencies for ages 1 to 17. MAIN OUTCOME MEASURES: The outcome was dental caries count at age 17, adjusted for the number of scored tooth surfaces (decayed and filled surfaces attack rate [DFSAR]). STATISTICAL ANALYSES PERFORMED: Univariable generalized linear models were fit for each predictor and the outcome DFSAR. Multivariable models assessed combined effects of beverage types, fluoride variables, toothbrushing, sex, and baseline socioeconomic status. RESULTS: Based on multivariable models, each 8 oz of additional daily juice and water/SFB decreased expected DFSAR by 53% (95% confidence interval [CI]: 17%-73%) and 29% (95% CI: 7%-46%), respectively, and 8 additional oz SSBs increased expected DFSAR by 42% (95% CI: 5%-92%), after adjustment for other beverage intakes, toothbrushing, total fluoride intake excluding SSB fluoride (non-SSB total fluoride), sex, and baseline socioeconomic status. Each additional daily toothbrushing event decreased expected DFSAR by 43% (95% CI: 14%-62%) after adjustment for beverage intakes, non-SSB total fluoride intake, sex, and baseline SES. CONCLUSIONS: Higher juice and water/SFB intakes and more toothbrushing were associated with lower caries at age 17, while higher SSB intakes were associated with higher caries.

Considerations on optimal fluoride intake using dental fluorosis and dental caries outcomes--a longitudinal study.

OBJECTIVES: The "optimal" intake of fluoride has been widely accepted for decades as between 0.05 and 0.07 mg fluoride per kilogram of body weight (mg F/kg bw) but is based on limited scientific evidence. The purpose of this paper is to present longitudinal fluoride intake data for children free of dental fluorosis in the early-erupting permanent dentition and free of dental caries in both the primary and early-erupting permanent teeth as an estimate of optimal fluoride intake. METHODS: Data on fluoride ingestion were obtained from parents of 602 Iowa Fluoride Study children through periodic questionnaires at the ages of 6 weeks; 3, 6, 9, 12, 16, 20, 24, 28, 32, and 36 months; and then at 6-month intervals thereafter. Estimates of total fluoride intake at each time point were made by summing amounts from water, dentifrice, and supplements, as well as other foods and beverages made with, or containing, water. Caries data were obtained from examinations of children at ages 5 and 9 years, whereas fluorosis data were obtained from examinations of children only at age 9 years. RESULTS: The estimated mean daily fluoride intake for those children with no caries history and no fluorosis at age 9 years was at, or below, 0.05 mg F/kg bw for nearly all time points through the first 48 months of life, and this level declined thereafter. Children with caries had generally slightly less intakes, whereas those with fluorosis generally had slightly higher intakes. CONCLUSIONS: Given the overlap among caries/fluorosis groups in mean fluoride intake and extreme variability in individual fluoride intakes, firmly recommending an "optimal" fluoride intake is problematic.

Longitudinal associations between dental caries increment and risk factors in late childhood and adolescence.

OBJECTIVES: To assess longitudinal associations between permanent tooth caries increment and both modifiable and non-modifiable risk factors, using best subsets model selection. METHODS: The Iowa Fluoride Study has followed a birth cohort with standardized caries exams without radiographs of the permanent dentition conducted at about ages 9, 13, and 17 years. Questionnaires were sent semi-annually to assess fluoride exposures and intakes, select food and beverage intakes, and tooth brushing frequency. Exposure variables were averaged over ages 7-9, 11-13, and 15-17, reflecting exposure 2 years prior to the caries exam. Longitudinal models were used to relate period-specific averaged exposures and demographic variables to adjusted decayed and filled surface increments (ADJCI) (n = 392). The Akaike Information Criterion (AIC) was used to assess optimal explanatory variable combinations. RESULTS: From birth to age 9, 9-13, and 13-17 years, 24, 30, and 55 percent of subjects had positive permanent ADJCI, respectively. Ten models had AIC values within two units of the lowest AIC model and were deemed optimal based on AIC. Younger age, being male, higher mother's education, and higher brushing frequency were associated with lower caries increment in all 10 models, while milk intake was included in 3 of 10 models. Higher milk intakes were slightly associated with lower ADJCI. CONCLUSIONS: With the exception of brushing frequency, modifiable risk factors under study were not significantly associated with ADJCI. When possible, researchers should consider presenting multiple models if fit criteria cannot discern among a group of optimal models.

Carbamoylcholine chloride induces a rapid increase in IL6 in the nasal cavity of C57BL/6 mice.

Mice are widely used as models to study the roles of chemokines and cytokines in immune and inflammatory responses. In our work to determine the basal levels of cytokines in saliva, nasal wash fluid (NWF), bronchoalveolar lavage fluid (BALF), and serum of mice, we found that injection of carbamoylcholine chloride, used to stimulate saliva production, induced variations in the interleukin (IL) 6 levels of NWF and BALF supernatants. To characterize this response, C57BL/6 mice were given 10 microg carbamoylcholine chloride intraperitoneally and euthanized at 0, 1, 3, 6, 12, 24, 48, 72, and 96 h after injection. IL6 was increased in NWF supernatants by 2 to 3 h, remained elevated for 24 h, and declined by 48 h after injection. To determine whether carbamoylcholine chloride increased Th1 cytokine (IL2, IL12[p70], and interferon gamma), Th2 cytokine (IL4, IL5, and IL10), granulocyte-macrophage colony-stimulating factor (GM-CSF), or proinflammatory cytokine (IL1beta, tumor necrosis factor alpha, and IL6 in saliva and serum) levels, mice were given 10 microg carbamoylcholine chloride and euthanized. In 47 mice, all cytokine levels in saliva supernatants, NWF supernatants, BALF supernatants, and serum were within normal reported levels (range, 1 to 364 pg/ml); in the serum of the remaining 3 mice, GM-CSF, IL1beta, and IL2 levels were increased. In summary, carbamoylcholine chloride induces a rapid, elevated IL6 response in the nasal cavity and respiratory tract of mice but does not alter the levels of other Th1, Th2, or proinflammatory cytokines.

An investigation of bottled water use and caries in the mixed dentition.

OBJECTIVES: Bottled water consumption in the United States has greatly increased in the past decade. Because the majority of commercial bottled water is low in fluoride, there is the potential for an increase in dental caries. In these secondary data analyses, associations between bottled water use and dental caries were explored. METHODS: Subjects (n = 413) are in the Iowa Fluoride Study, which included dental examinations of the primary (approximately aged 5) and early erupting permanent (approximately aged 9) dentitions by trained dentist examiners. Permanent tooth caries and primary second molar increments were related to bottled water use using logistic and negative binomial regression models. All models were adjusted for age and the frequency of toothbrushing. RESULTS: Bottled water use in this cohort was fairly limited (approximately 10 percent). While bottled water users had significantly lower fluoride intakes, especially fluoride from water, there were no significant differences found in either permanent tooth caries (P = 0.20 and 0.91 for prevalence and D(2+)FS, respectively) or primary second molar caries (P = 0.94 and 0.74 for incidence and d(2+)fs increment, respectively). Results for smooth surfaces differed somewhat from those for pit and fissure surfaces, but neither showed significant differences related to bottled water use. CONCLUSION: While bottled water users had significantly lower fluoride intakes, this study found no conclusive evidence of an association with increased caries. Further study is warranted, preferably using studies designed specifically to address this research question.

AIC identifies optimal representation of longitudinal dietary variables.

OBJECTIVES: The Akaike Information Criterion (AIC) is a well-known tool for variable selection in multivariable modeling as well as a tool to help identify the optimal representation of explanatory variables. However, it has been discussed infrequently in the dental literature. The purpose of this paper is to demonstrate the use of AIC in determining the optimal representation of dietary variables in a longitudinal dental study. METHODS: The Iowa Fluoride Study enrolled children at birth and dental examinations were conducted at ages 5, 9, 13, and 17. Decayed or filled surfaces (DFS) trend clusters were created based on age 13 DFS counts and age 13-17 DFS increments. Dietary intake data (water, milk, 100 percent-juice, and sugar sweetened beverages) were collected semiannually using a food frequency questionnaire. Multinomial logistic regression models were fit to predict DFS cluster membership (n=344). Multiple approaches could be used to represent the dietary data including averaging across all collected surveys or over different shorter time periods to capture age-specific trends or using the individual time points of dietary data. RESULTS: AIC helped identify the optimal representation. Averaging data for all four dietary variables for the whole period from age 9.0 to 17.0 provided a better representation in the multivariable full model (AIC=745.0) compared to other methods assessed in full models (AICs=750.6 for age 9 and 9-13 increment dietary measurements and AIC=762.3 for age 9, 13, and 17 individual measurements). The results illustrate that AIC can help researchers identify the optimal way to summarize information for inclusion in a statistical model. CONCLUSIONS: The method presented here can be used by researchers performing statistical modeling in dental research. This method provides an alternative approach for assessing the propriety of variable representation to significance-based procedures, which could potentially lead to improved research in the dental community.

Dental caries clusters among adolescents.

OBJECTIVES: There have been very few longitudinal studies of dental caries in adolescents, and little study of the caries risk factors in this age group. The purpose of this study was to describe different caries trajectories and associated risk factors among members of the Iowa Fluoride Study (IFS) cohort. METHODS: The IFS recruited a birth cohort from 1992 to 1995, and has gathered dietary, fluoride and behavioural data at least twice yearly since recruitment. Examinations for dental caries were completed when participants were ages 5, 9, 13 and 17 years. For this study, only participants with decayed and filled surface (DFS) caries data at ages 9, 13 and 17 were included (N=396). The individual DFS counts at age 13 and the DFS increment from 13 to 17 were used to identify distinct caries trajectories using Ward's hierarchical clustering algorithm. A number of multinomial logistic regression models were developed to predict trajectory membership, using longitudinal dietary, fluoride and demographic/behavioural data from 9 to 17 years. Model selection was based on the akaike information criterion (AIC). RESULTS: Several different trajectory schemes were considered, and a three-trajectory scheme-no DFS at age 17 (n=142), low DFS (n=145) and high DFS (n=109)-was chosen to balance sample sizes and interpretability. The model selection process resulted in use of an arithmetic average for dietary variables across the period from 9 to 17 years. The multinomial logistic regression model with the best fit included the variables maternal education level, 100% juice consumption, brushing frequency and sex. Other favoured models also included water and milk consumption and home water fluoride concentration. The high caries cluster was most consistently associated with lower maternal education level, lower 100% juice consumption, lower brushing frequency and being female. CONCLUSIONS: The use of a clustering algorithm and use of Akaike's Information Criterion (AIC) to determine the best representation of the data were useful means in presenting longitudinal caries data. Findings suggest that high caries incidence in adolescence is associated with lower maternal educational level, less frequent tooth brushing, lower 100% juice consumption and being female.

Dental Caries in High-risk, School-age African American Children in Alabama: A Six-year Prospective.

PURPOSE: The purpose of this study was to assess the prevalence and incidence of dental caries in school-age African American children who received semi-annual fluoride varnish applications. METHODS: A cohort of six-year-old high caries-risk African American children (n equals 98) was recruited in Uniontown, Ala., USA, and followed for six years. Oral examinations were done annually by three trained/calibrated dentists. Tooth surfaces with cavitated caries, teeth missing due to caries, and teeth with filled surfaces were recorded using World Health Organization criteria. Also, as part of the study, children received periodic oral health instruction, fluoride varnish applications, and referrals to dentists starting at baseline. RESULTS: The person-level prevalence of decayed, missing, and filled surfaces of primary and permanent teeth (dmfs/DMFS) was: 61.2 percent at mean age of 5.9 years old (n equals 98, mean dmfs/DMFS equals 11.6); 63.8 percent at 6.7 years old (n equals 80, mean dmfs/ DMFS equals 13.2); 70.6 percent at 7.8 years old (n equals 68, mean dmfs/DMFS equals 14.2); 65.7 percent at 8.8 years old (n equals 68, mean dmfs/DMFS equals 11.8); 55.6 percent at 9.7 years old (n equals 63, mean dmfs/DMFS equals 8.8); 40.3 percent at 10.7 years old (n equals 62, mean dmfs/DMFS equals 3.4); and 37.1 percent at 11.7 years old (n equals 62, mean dmfs/DMFS equals 2.3). The six-year person-level incidence of dmfs/DMFS was 32.3 percent (mean dmfs/DMFS equals 1.6) from 5.9 to 11.7 years old (N equals 62). CONCLUSIONS: In spite of the oral health education and fluoride varnish applications, there was substantial new dental caries in this high-risk sample. Additional studies evaluating risk factors for caries development are ongoing.

Factors associated with early childhood caries incidence among high caries-risk children.

OBJECTIVES: To assess the relationships between different behavioral factors and Early Childhood Caries (ECC) in African-American pre-school children. METHODS: Ninety-six African-American children aged 3-22 months old at baseline were recruited from a high caries risk, non-fluoridated African-American community in Uniontown, Alabama. The children had dental examinations annually following World Health Organization (WHO) criteria at mean ages 1.1, 2.0, 3.1 and 4.0 years. All children received fluoride varnish application at each study visit. Parents provided oral hygiene and dietary information semiannually by completing questionnaires. Area-under-the-curve (AUC) with the trapezoidal rule was used to summarize longitudinal exposure data. Bivariate and multivariable relationships between ECC incidence and behavioral risk factors were assessed using logistic regression and negative binomial modeling for dichotomous and count dependent variables, respectively, with the independent variables defined at age 1, age 3 and as the AUC. RESULTS: Greater frequency of toothbrushing and greater AUC composite of daily frequency of consumption of 100% juices were associated with lower incidence of dental caries (P-values = 0.01 and 0.049, ORs = 0.34 and 0.37, respectively). Greater AUC of daily frequency of consumption of sweetened foods and history of a previous visit to a dentist by age 3 were associated with greater incidence of ECC (ORs = 9.22 and 4.57, P-values = 0.002 and 0.03, respectively). CONCLUSION: For these children living in a non-fluoridated community, more frequent consumption of sweetened food, less frequent consumption of 100% juice, less frequent toothbrushing, and reporting a previous visit to a dentist were significantly associated with greater ECC incidence.

The associations between dietary intakes from 36 to 60 months of age and primary dentition non-cavitated caries and cavitated caries.

OBJECTIVE: To examine risk factors for non-cavitated caries, as well as cavitated caries. METHODS: Subjects were participants in the Iowa Fluoride Study cohort. Dietary data were collected at 36, 48, and 60 months old using 3-day dietary diaries, and a dental examination was conducted at about age 5. We compared the frequencies of dietary intakes of three groups: a) children having only d1 caries (n = 41); b) children having only cavitated (d2+f) caries (n = 46); and c) children having both d1 and d2+f caries (n = 49) with a forth group; d) those of caries-free children (n = 257). RESULTS: Multinomial and binomial logistic regression was used, where the categorical outcome was based on the 4 caries groups, and the caries-free group was designated as the reference. In the final model, sevenvariables were associated with the caries outcome. Lower milk consumption frequency at meals and greater presweetened cereal consumption frequency at meals were significantly associated with a greater likelihood of being in the d1 group. Greater regular soda pop consumption frequency and greater added sugar consumption frequency at snacks were significantly associated with being in the cavitated caries (d2+f and/or d1 d2+f) groups. Lower socioeconomic status and less frequent toothbrushing increased the likelihood of being in the d1 group. CONCLUSIONS: The results suggest that different food and beverage categories are associated with being in the d1 group compared with the cavitated caries groups. More frequent toothbrushing, greater milk consumption at meals, and avoiding presweetened cereal consumption at meals might reduce the risk of developing non-cavitated caries.

Prevalence and incidence of early childhood caries among African-American children in Alabama.

OBJECTIVES: This study aims to assess the prevalence and incidence of early childhood caries (ECC) in African-American children. METHODS: A cohort of 96 African-American children approximately 1 year of age at baseline were recruited in Uniontown, Alabama, and followed for 3 years. Oral examinations were conducted annually by one of three trained/calibrated dentists using portable equipment, without radiographs, following WHO criteria. RESULTS: The prevalence of decayed/missing/filled surfaces (dmfs) was: 1.1 percent (all d) at approximately age 1 (n = 90, six children were excluded for having no erupted teeth); 12.8 percent (d = 10.5 percent & f = 4.7 percent) at age 2 (n = 86); 39.3 percent (d = 21.4 percent, m = 2.4 percent & f = 22.6 percent) at age 3 (n = 84); and 65.8 percent (d = 28.8 percent, m = 5.5 & f = 46.6 percent) at age 4 (n = 73). The percentages of incisors, canines, first molars, and second molars with dmfs were: 0.1 percent, 0.0 percent, 0.0 percent, and 0.0 percent, at age 1; 2.4 percent, 0.1 percent, 0.8 percent, and 0.6 percent at age 2; 8.2 percent, 0.8 percent, 7.6 percent, and 6.3 percent at age 3; and 10.2 percent, 2.2 percent, 12.6 percent and 16.7 percent at age 4, respectively. The three, 1-year, person-level incidence rates were 12.8 percent (age 1 to age 2), 38.6 percent (age 2 to age 3), and 56.2 percent (age 3 to age 4). From baseline, the 2-year incidence was 39.3 percent and 3-year incidence was 65.8 percent, whereas the 2-year caries incidence from age 1 to age 3 was 66.7 percent (n = 72). CONCLUSION: The majority of children developed caries during the 3-year follow-up, which is much higher than the 32 percent prevalence of caries among African-American children under age 6 years in National Health and Nutrition Examination Survey from 1999 to 2002.

Differential cytotoxicity of long-chain bases for human oral gingival epithelial keratinocytes, oral fibroblasts, and dendritic cells.

Long-chain bases, found in the oral cavity, have potent antimicrobial activity against oral pathogens. In an article associated with this dataset, Poulson and colleagues determined the cytotoxicities of long-chain bases (sphingosine, dihydrosphingosine, and phytosphingosine) for human oral gingival epithelial (GE) keratinocytes, oral gingival fibroblasts (GF), dendritic cells (DC), and squamous cell carcinoma (SCC) cell lines [1]. Poulson and colleagues found that GE keratinocytes were more resistant to long-chain bases as compared to GF, DC, and SCC cell lines [1]. In this study, we assess the susceptibility of DC to lower concentrations of long chain bases. 0.2-10.0 µM long-chain bases and GML were not cytotoxic to DC; 40.0-80.0 µM long-chain bases, but not GML, were cytotoxic for DC; and 80.0 µM long-chain bases were cytotoxic to DC and induced cellular damage and death in less than 20 mins. Overall, the LD50 of long-chain bases for GE keratinocytes, GF, and DC were considerably higher than their minimal inhibitory concentrations for oral pathogens, a finding important to pursuing their future potential in treating periodontal and oral infections.

Differential cytotoxicity of long-chain bases for human oral gingival epithelial keratinocytes, oral fibroblasts, and dendritic cells.

Long-chain bases are present in the oral cavity. Previously we determined that sphingosine, dihydrosphingosine, and phytosphingosine have potent antimicrobial activity against oral pathogens. Here, we determined the cytotoxicities of long-chain bases for oral cells, an important step in considering their potential as antimicrobial agents for oral infections. This information would clearly help in establishing prophylactic or therapeutic doses. To assess this, human oral gingival epithelial (GE) keratinocytes, oral gingival fibroblasts (GF), and dendritic cells (DC) were exposed to 10.0-640.0 µM long-chain bases and glycerol monolaurate (GML). The effects of long-chain bases on cell metabolism (conversion of resazurin to resorufin), membrane permeability (uptake of propidium iodide or SYTOX-Green), release of cellular contents (LDH), and cell morphology (confocal microscopy) were all determined. GE keratinocytes were more resistant to long-chain bases as compared to GF and DC, which were more susceptible. For DC, 0.2-10.0 µM long-chain bases and GML were not cytotoxic; 40.0-80.0 µM long-chain bases, but not GML, were cytotoxic; and 80.0 µM long-chain bases induced cellular damage and death in less than 20 min. The LD50 of long-chain bases for GE keratinocytes, GF, and DC were considerably higher than their minimal inhibitory concentrations for oral pathogens, a finding important to pursuing their future potential in treating periodontal and oral infections.

Histatin 5 binds to Porphyromonas gingivalis hemagglutinin B (HagB) and alters HagB-induced chemokine responses.

Histatins are human salivary gland peptides with anti-microbial and anti-inflammatory activities. In this study, we hypothesized that histatin 5 binds to Porphyromonas gingivalis hemagglutinin B (HagB) and attenuates HagB-induced chemokine responses in human myeloid dendritic cells. Histatin 5 bound to immobilized HagB in a surface plasmon resonance (SPR) spectroscopy-based biosensor system. SPR spectroscopy kinetic and equilibrium analyses, protein microarray studies, and I-TASSER structural modeling studies all demonstrated two histatin 5 binding sites on HagB. One site had a stronger affinity with a KD1 of 1.9 µM and one site had a weaker affinity with a KD2 of 60.0 µM. Binding has biological implications and predictive modeling studies and exposure of dendritic cells both demonstrated that 20.0 µM histatin 5 attenuated (p < 0.05) 0.02 µM HagB-induced CCL3/MIP-1α, CCL4/MIP-1ß, and TNFα responses. Thus histatin 5 is capable of attenuating chemokine responses, which may help control oral inflammation.

Factors associated with surface-level caries incidence in children aged 9 to 13: the Iowa Fluoride Study.

OBJECTIVE: As dental caries can progress throughout a person's lifetime, understanding caries risk factors unique to specific life phases is important. This study aims to assess caries incidence and risk factors for young adolescents. METHODS: Participants in the longitudinal Iowa Fluoride Study were assessed for dental caries at approximately age 9 and again at age 13. These participants also filled out questionnaires concerning water sources, oral health habits, beverage intakes, parent education and family income. Caries progression (D2+ F) was analyzed at the surface level. Mixed effects logistic regression was used to assess associations between surface-specific first molar occlusal caries incidence and risk factors. RESULTS: Caries incidence was quite low except on the first molar occlusal surfaces. In initial models of specific risk factors, incidence was positively associated with the surface having a D1 lesion at baseline, low family income, having untreated decay or fillings on other teeth at baseline, lower home water fluoride level, and higher soda pop consumption. In the final multiple variable model, significant interactions were found between tooth brushing frequency and initial D1 status, and also between family income and home tap water fluoride level. CONCLUSIONS: D2+ F incidence on first molar occlusal surfaces in these young adolescents was associated with prior caries experience on other teeth as well as prior evidence of a D1 lesion on the occlusal surface. More frequent tooth brushing was protective of sound surfaces, and fluoride in home tap water was also protective, but significantly more so for adolescents in low-income families.

Defensin DEFB103 bidirectionally regulates chemokine and cytokine responses to a pro-inflammatory stimulus.

Human ß defensin DEFB103 acts as both a stimulant and an attenuator of chemokine and cytokine responses: a dichotomy that is not entirely understood. Our predicted results using an in silico simulation model of dendritic cells and our observed results in human myeloid dendritic cells, show that DEFB103 significantly (p < 0.05) enhanced 6 responses, attenuated 7 responses, and both enhanced/attenuated the CXCL1 and TNF responses to Porphyromonas gingivalis hemagglutinin B (HagB). In murine JAWSII dendritic cells, DEFB103 significantly attenuated, yet rarely enhanced, the Cxcl2, Il6, and Csf3 responses to HagB; and in C57/BL6 mice, DEFB103 significantly enhanced, yet rarely attenuated, the Cxcl1, Csf1, and Csf3 responses. Thus, DEFB103 influences pro-inflammatory activities with the concentration of DEFB103 and order of timing of DEFB103 exposure to dendritic cells, with respect to microbial antigen exposure to cells, being paramount in orchestrating the onset, magnitude, and composition of the chemokine and cytokine response.