Antimicrobial activity and toxicity of glass ionomer cement containing an essential oil.

The aim of this study was to evaluate the antimicrobial activity and toxicity of glass ionomer cement (GIC) modified with 5-methyl-2-(1-methylethyl)phenol (thymol) against Streptococcus mutans in silico and in vitro. The antimicrobial activity of thymol on GIC modified with concentrations of 2% (GIC-2) and 4% (GIC-4) was evaluated in a model of planktonic cell biofilm using agar diffusion test, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), dynamic biofilm (continuous flow cell parallel), and bacterial kinetics. Conventional GIC (GIC-0) was used as a control. Thymol toxicity was evaluated in Artemia salina and in silico using Osiris® software. Differences between groups were estimated by analysis of variance, followed by Tukey post hoc test, with a 5% significance level. The results of the agar diffusion test between groups were not significantly different (P≥0.05). Thymol had potential bacteriostatic and bactericidal activity against Streptococcus mutans with respect to planktonic growth, with MIC of 100 µg/mL and MBC of 400 µg/mL. The groups GIC-0, GIC-2, and GIC-4 reduced the biofilm by approximately 10, 85, and 95%, respectively. Bacterial kinetics showed efficiency of the modified GICs for up to 96 h. GIC with thymol was effective against S. mutans, with significant inhibition of the biofilms. Analyses in silico and using Artemia salina resulted in no relevant toxicity, suggesting potential for use in humans. GIC-2 was effective against S. mutans biofilm, with decreased cell viability.

Antimicrobial activity and toxicity of glass ionomer cement containing an essential oil

The aim of this study was to evaluate the antimicrobial activity and toxicity of glass ionomer cement (GIC) modified with 5-methyl-2-(1-methylethyl)phenol (thymol) against Streptococcus mutans in silico and in vitro. The antimicrobial activity of thymol on GIC modified with concentrations of 2% (GIC-2) and 4% (GIC-4) was evaluated in a model of planktonic cell biofilm using agar diffusion test, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), dynamic biofilm (continuous flow cell parallel), and bacterial kinetics. Conventional GIC (GIC-0) was used as a control. Thymol toxicity was evaluated in Artemia salina and in silico using Osiris® software. Differences between groups were estimated by analysis of variance, followed by Tukey post hoc test, with a 5% significance level. The results of the agar diffusion test between groups were not significantly different (P≥0.05). Thymol had potential bacteriostatic and bactericidal activity against Streptococcus mutans with respect to planktonic growth, with MIC of 100 µg/mL and MBC of 400 µg/mL. The groups GIC-0, GIC-2, and GIC-4 reduced the biofilm by approximately 10, 85, and 95%, respectively. Bacterial kinetics showed efficiency of the modified GICs for up to 96 h. GIC with thymol was effective against S. mutans, with significant inhibition of the biofilms. Analyses in silico and using Artemia salina resulted in no relevant toxicity, suggesting potential for use in humans. GIC-2 was effective against S. mutans biofilm, with decreased cell viability.

Maternal report underestimates the amount of dentifrice used by children during toothbrushing: a cross-sectional study.

PURPOSE: This study investigated whether the report of mothers about the amount of dentifrice applied on a toothbrush could be a reliable method to estimate the inadvertent use of dentifrices. METHODS: A cross-sectional study was conducted in a randomly selected sample of 334 mothers of children enrolled in public day care centres of a city in the Brazilian northeast. Initially, the mothers chose the figure corresponding to the amount of dentifrice used during their children's daily toothbrushing. Then, they simulated real-life conditions with the toothbrush routinely used to brush the children's teeth. The amount of dentifrice on toothbrush was weighted using an analytical scale. Data were analysed by the Kruskal-Wallis followed by the Dunn test (α = 0.05). RESULTS: The weight of dentifrice on the toothbrush was high (> 0.3 g), mainly considering the categories 'covered only' and 'completely covered' that showed no statistical difference (p > 0.05). The proportion of agreement between the mothers' reports and the weight of dentifrice on the toothbrush was 0.23 (CI 0.18-0.28). CONCLUSION: The mothers' report regarding the amount of dentifrice on the toothbrush by demonstrative figures was not a reliable method to estimate the inadvertent ingestion of fluoride from dentifrices.

Tooth loss in middle-aged adults with diabetes and hypertension: Social determinants, health perceptions, oral impact on daily performance (OIDP) and treatment need.

BACKGROUND: This study aimed to explore the association between tooth loss and social determinants, health self-perceptions, OIDP and self-concept of dental treatment need in middle-aged adults with diabetes and hypertension. MATERIAL AND METHODS: A cross-sectional study was developed with 212 hypertensive and diabetic middle-aged adults (50-65 years). Data were collected from clinical examinations (DMFT) and a questionnaire regarding socioeconomic status, dental health assistance, self-perceptions of oral and general health, OIDP, and the self-concept of dental treatment need. Tooth loss was dichotomized considering the cutoff point of 12 (Model I) or 24 missing teeth (Model II). Data were analyzed using Chi-square, Fisher's exact test and logistic regression (p≤0.05). RESULTS: Tooth loss was significantly associated with variables such as last dental visit, reason for dental visit, OIDP, perception of dental treatment need, and general self-perception (Model I). Schooling, last dental visit, oral health self-perception and perception of dental treatment need were significantly associated with tooth loss in the Model II. When Model 1 and 2 were adjusted, they demonstrated that last dental visit and perception of dental treatment need were predictor variables. CONCLUSIONS: The annual dental visit and the self-concept of dental treatment need were associated with tooth loss, demonstrating that these variables reduce the tooth loss prevalence.

Total fluoride intake and excretion in children up to 4 years of age living in fluoridated and non-fluoridated areas.

Fractional fluoride retention is important during the early years of life when considering the risk of development of dental fluorosis. This study aimed to measure fractional fluoride retention in young children. The objectives were to investigate the relationships between fractional fluoride retention and total daily fluoride intake, age, and body mass index (BMI). Twenty-nine healthy children, up to 4 yr of age, participated; 14 lived in a fluoridated area (0.64 µg ml(-1) of fluoride in drinking water) and 15 lived in a non-fluoridated area (0.04 µg ml(-1) of fluoride in drinking water). The total daily fluoride intake of each child was calculated from the daily dietary fluoride intake and toothpaste ingestion (if fluoride toothpaste was used). Total daily fluoride excretion was measured by collecting voided urine and faeces over a 24-h period, and fractional fluoride retention was calculated by dividing the amount of fluoride retained in the body (total daily fluoride intake minus total daily fluoride excretion) by the total daily fluoride intake. Nine children were excluded from data analysis because of suspected invalid samples. Mean (range) fractional fluoride retention for the remaining 20 children was 0.61 (0.06-0.98). There were no statistically significant correlations between fractional fluoride retention and either age or BMI. However, fractional fluoride retention was correlated with total daily fluoride intake: fractional fluoride retention = 1 - exp (-C × total daily fluoride intake), where C = 28.75 (95% CI = 19.75-37.75). The wide variation in fluoride retention in young children could have important implications when recommendations for fluoride use are being considered.

Fitoterápicos na odontologia: estudo etnobotânico na cidade de Manaus / Phytotherapics in Odontology: ethnobotanical study in Manaus

O reconhecimento oficial da fitoterapia na odontologia no Brasil veio acompanhado de diversas lacunas na pesquisa científica e na utilização de plantas medicinais, especificamente para espécies vegetais com aplicação nas doenças da cavidade oral. O estado do Amazonas, especificamente a cidade de Manaus, não possui um diagnóstico da aplicabilidade de plantas medicinais nos serviços de atenção Odontológica. Esse estudo propôs realizar um estudo do tipo quali-quantitativo, descritivo e exploratório visando o levantamento da comercialização de plantas medicinais e o estudo etnobotânico para identificação das principais plantas medicinais indicadas e utilizadas nas patologias orais nos atendimentos odontológicos ambulatoriais na cidade de Manaus. Foram entrevistados 197 usuários do serviço odontológico, 150 Cirurgiões-Dentistas, e 47 comerciantes credenciados na prefeitura Municipal de Manaus. A amostragem foi realizada por acessibilidade ou conveniência para os Cirurgiões-Dentistas, enquanto os usuários foram selecionados através de amostragem aleatória simples, e os comerciantes de plantas medicinais foram entrevistados em sua totalidade. Os resultados demonstraram a existência de comercialização de plantas medicinais para patologias orais, destacando-se as seguintes espécies: Pedra ume cãa (Aulomyrcia sphareocarpa), Crajiru (Arrabidae chica), além da planta, sem identificação botânica, conhecida popularmente como Sara tudo. Entre os Cirurgiões-Dentistas e entre os pacientes, apenas 8% e 7,61%, respectivamente, utilizaram plantas medicinais para alterações patológicas orais. Os autores concluíram que as plantas medicinais comercializadas na cidade de Manaus são utilizadas de maneira empírica e que, apesar da Política Nacional de Práticas Integrativas e Complementares (PNPIC), novas políticas públicas de saúde devem inserir plantas medicinais e fitoterápicos de uso oral na rede pública de saúde na cidade de Manaus.

The official recognition of herbal medicine in dentistry in Brazil was accompanied by several gaps in scientific research and the use of medicinal plants, specifically for plant species applied to diseases of the oral cavity. The state of Amazonas, specifically the city of Manaus, does not have a diagnosis of applicability of medicinal plants in Dental care services. This research intended to conduct a qualitative and quantitative-type, descriptive and exploratory study in order to conduct a survey on the commercialization of medicinal plants and an ethnobotanical study to identify the main medicinal plants indicated and used in oral pathologies in outpatient dental care in the city of Manaus. We interviewed 197 users of dental services, 150 dentists, and 47 accredited traders in the Municipality of Manaus. The sampling was performed by accessibility or convenience for surgeon-dentists, while users were selected through simple random sampling, and all traders of medicinal plants were interviewed. The results demonstrated that medicinal plants for oral diseases are commercialized, among which the following species are highlighted: Pedra ume Caa (Aulomyrcia sphareocarpa), Crajiru (Arrabidaea chica), in addition to an unidentified botanical plant popularly known as Sara Tudo. 8% of dentists and 7.61% of patients used medicinal plants for oral pathological changes. The authors concluded that medicinal plants commercialized in the city of Manaus are used empirically, and that, despite the rules from the National Policy on Integrative and Complementary Practices (PNPIC), new public health policies must add medicinal plants and herbal medicines for oral use to the public health system of the city of Manaus.

Validation of fingernail fluoride concentration as a predictor of risk for dental fluorosis.

The aim of this study was to validate the use of fingernail fluoride concentrations at ages 2-7 years as predictors of the risk for developing dental fluorosis in the permanent dentition. Fifty-six children of both genders (10-15 years of age) had their incisors and premolars examined for dental fluorosis using the Thylstrup-Fejerskov index. Fingernail fluoride concentrations were obtained from previous studies when children were 2-7 years of age. Data were analyzed by unpaired t test, ANOVA, and Fisher's exact test when the fingernail fluoride concentrations were dichotomized (≤ 2 or >2 µg/g). Children with dental fluorosis had significantly higher fingernail fluoride concentrations than those without the condition, and the concentrations tended to increase with the severity of fluorosis (r(2) = 0.47, p < 0.0001). Using a fingernail fluoride concentration of 2 µg/g at ages 2-7 years as a threshold, this biomarker had high sensitivity (0.84) and moderate specificity (0.53) as a predictor for dental fluorosis. The high positive predictive value indicates that fingernail fluoride concentrations should be useful in public health research, since it has the potential to identify around 80% of children at risk of developing dental fluorosis.

Factors associated with fluoride concentrations in whole and parotid ductal saliva.

BACKGROUND/AIMS: There are still uncertainties regarding the use of whole and parotid ductal saliva as indicators of chronic exposure to fluoride. This study evaluated the effect of water fluoride concentration, age, gender, geographical area and localization (urban/rural) on fluoride concentrations in whole and ductal saliva. METHODS: Subjects (n = 300) aged 3-7, 14-20, 30-40 and 50-60 years, from five communities (A-E) with different fluoride concentrations in the drinking water, participated in the study. Two samples of drinking water and parotid and whole saliva were collected for each subject and were analyzed for fluoride using appropriate electrode techniques. RESULTS: Mean water F concentrations (±SE, mg/l, n = 60) were 0.09 ± 0.01, 0.15 ± 0.01, 0.66 ± 0.01, 0.72 ± 0.02, and 1.68 ± 0.08 for A-E, respectively. Mean F concentrations (±SE, mg/l, n = 15) ranged between 0.014 ± 0.002 (A, 3-7 years) and 0.297 ± 0.057 (D, 14-20 years) for whole saliva and 0.009 ± 0.001 (C, 30-40 years) and 0.284 ± 0.038 (E, 50-60 years) for parotid saliva. Results of multivariate linear regression analysis showed that geographical area and water fluoride concentration exerted the strongest influence in whole and ductal saliva F concentrations, respectively. CONCLUSION: Therefore, parotid ductal saliva seems to be a more appropriate biomarker of fluoride exposure, and factors like age and localization should also be considered when using this biomarker.

Biomarkers of fluoride in children exposed to different sources of systemic fluoride.

There has been no comparison between fluoride concentrations in urine and nails of children exposed to different sources of systemic fluoride. The aim of this study was to compare the relationship between fluoride intake with urinary fluoride excretion and fluoride concentrations in fingernails and toenails of children receiving fluoride from artificially fluoridated water (0.6-0.8 mg F/L, n = 25), naturally fluoridated water (0.6-0.9 mg F/L, n = 21), fluoridated salt (180-200 mg F/Kg, n = 26), and fluoridated milk (0.25 mg F, n = 25). A control population was included (no systemic fluoride, n = 24). Fluoride intake from diet and dentifrice, urinary fluoride excretion, and fluoride concentrations in fingernails/toenails were evaluated. Fluoride was analyzed with an ion-selective electrode. Urinary fluoride excretion in the control community was significantly lower when compared with that in the fluoridated cities, except for the naturally fluoridated community. However, the same pattern was not as evident for nails. Both urinary fluoride output and fluoride concentrations in fingernails/toenails were significantly correlated to total fluoride intake. However, the correlation coefficients for fluoride intake and urinary fluoride output were lower (r = 0.28, p < 0.01) than those observed for fingernails/toenails (r = 0.36, p < 0.001), suggesting that nails might be slightly better indicators of fluoride intake at the individual level.

Effects of regular and low-fluoride dentifrices on plaque fluoride.

Previous studies have indicated that the use of low-fluoride dentifrices could lead to proportionally higher plaque fluoride levels when compared with conventional dentifrices. This double-blind, randomized, crossover study determined the effects of placebo, low-fluoride, and conventional dentifrices on plaque fluoride concentrations ([F]) in children living in communities with 0.04, 0.72, and 3.36 ppm F in the drinking water. Children used the toothpastes twice daily, for 1 wk. Samples were collected 1 and 12 hrs after the last use of dentifrices and were analyzed for fluoride and calcium. Similar increases were found 1 hr after the children brushed with low-fluoride (ca. 1.9 mmol F/kg) and conventional (ca. 2.4 mmol F/kg) dentifrices in the 0.04- and 0.72-ppm-F communities. Despite the fact that the increases were less pronounced in the 3.36-ppm-F community, our results indicate that the use of a low-fluoride dentifrice promotes a proportionally higher increase in plaque [F] when compared with that achieved with a conventional dentifrice, based on dose-response considerations.

Prevalence of enamel defects related to pre-, peri- and postnatal factors in a Brazilian population.

OBJECTIVES: The aim of this paper is to evaluate the prevalence of enamel defects in infants from a socially and economically poor population and the possible association of these defects with disturbances occurring in the pre-, peri- and postnatal periods of human development. PARTICIPANTS: 117 infants aged between 16 and 18 months old were included in four groups based on gestational age and whether part or full term pregnancy. METHOD: The data were collected in two stages: hospital-based, where gestational and birth records were examined, and home-based, where dental examinations and nutrition were evaluated. The teeth were cleaned and dried with gauze and examined in the open air, avoding direct sunlight in the knee-to-knee position. The enamel defects were coded according to the modified Developmental Defects of Enamel Index. Besides this, body weight and height were considered as anthropometric measures for the evaluation of nutritional status by the National Center for Health Statistics standards. MAIN OUTCOME MEASURES: The data were analyzed using the chi-square and Fisher Exact tests. Besides these tests, logistic regression models were used. RESULTS: The prevalence of enamel defects was 49.6%, higher in the group of male infants (p<0.001). The most frequent type of defect and the most affected surface were, respectively, diffuse opacity (9.5%) and the buccal surface (83.3%), located in the gingival half (6.7%). The logistic regression model showed that educational level, gestational age and intrauterine growth retardation (IUGR), besides a lack of breastfeeding, increased the probability of enamel defects up to level of 5%. CONCLUSIONS: The association between enamel defects and the etiologic factors shown in this study suggest the existence of social influences regarding oral health and teeth development.

Flow rate, pH and calcium concentration of saliva of children and adolescents with type 1 diabetes mellitus

Alterations in salivary parameters may increase the caries risk in diabetic children, but, contradictory data on this issue have been reported. The aims of this study were to compare salivary parameters (flow rate, pH and calcium concentration) between healthy and type 1 diabetes mellitus (T1DM) individuals. The sample consisted of 7- to 18-year-old individuals divided into two groups: 30 subjects with T1DM (group A) and 30 healthy control subjects (group B). Fasting glucose levels were determined. Unstimulated and stimulated saliva was collected. The pH of unstimulated saliva was measured with paper strips and an electrode. Calcium concentrations in stimulated saliva were determined with a selective electrode. Group A individuals had inadequate blood glucose control (HbA1C >9%), with means ± SD unstimulated salivary flow rate of 0.15 ± 0.1 mL/min compared to 0.36 ± 0.2 mL/min for group B (P < 0.01). Stimulated salivary flow rate was similar by both groups and above 2.0 mL/min. Saliva pH was 6.0 ± 0.8 for group A and significantly different from 7.0 ± 0.6 for group B (P < 0.01). Salivary calcium was 14.7 ± 8.1 mg/L for group A and significantly higher than 9.9 ± 6.4 mg/L for group B (P < 0.01). Except for elevated calcium concentrations in saliva, salivary parameters favoring caries such as low saliva pH and unstimulated salivary flow rate were observed in T1DM individuals.

Flow rate, pH and calcium concentration of saliva of children and adolescents with type 1 diabetes mellitus.

Alterations in salivary parameters may increase the caries risk in diabetic children, but, contradictory data on this issue have been reported. The aims of this study were to compare salivary parameters (flow rate, pH and calcium concentration) between healthy and type 1 diabetes mellitus (T1DM) individuals. The sample consisted of 7- to 18-year-old individuals divided into two groups: 30 subjects with T1DM (group A) and 30 healthy control subjects (group B). Fasting glucose levels were determined. Unstimulated and stimulated saliva was collected. The pH of unstimulated saliva was measured with paper strips and an electrode. Calcium concentrations in stimulated saliva were determined with a selective electrode. Group A individuals had inadequate blood glucose control (HbA(1C) >9%), with means +/- SD unstimulated salivary flow rate of 0.15 +/- 0.1 mL/min compared to 0.36 +/- 0.2 mL/min for group B (P < 0.01). Stimulated salivary flow rate was similar by both groups and above 2.0 mL/min. Saliva pH was 6.0 +/- 0.8 for group A and significantly different from 7.0 +/- 0.6 for group B (P < 0.01). Salivary calcium was 14.7 +/- 8.1 mg/L for group A and significantly higher than 9.9 +/- 6.4 mg/L for group B (P < 0.01). Except for elevated calcium concentrations in saliva, salivary parameters favoring caries such as low saliva pH and unstimulated salivary flow rate were observed in T1DM individuals.

The effect of different fluoride concentrations and pH of dentifrices on plaque and nail fluoride levels in young children.

To evaluate the influence of dentifrice pH and fluoride (F) concentration on F uptake by plaque and nails, two sets of 5- to 6-year-old children were randomly allocated into four groups, according to the type of dentifrice they had been using for 1 year: (1) experimental liquid dentifrice (ELD), 1,100 ppm F, pH 7.0; (2) ELD, 1,100 ppm F, pH 4.5; (3) ELD, 550 ppm F, pH 4.5, and (4) commercial toothpaste, 1,100 ppm F, pH 7.0. In one set of children, nails were clipped. In the second, plaque samples were collected 1 h after the last use of dentifrice. F concentration in plaque and nails was analyzed. Plaque F concentration was significantly lower in group 4 than in groups 1-3. Nail F concentration was significantly higher in group 4, and significantly lower in group 3, than in group 1 or 2. Plaque F uptake was influenced significantly by dentifrice consistency and nonsignificantly by pH and F concentration. Reduction of dentifrice pH did not affect nail F concentration.

Environmental and individual factors associated with nail fluoride concentration.

Nails have been suggested as suitable biomarkers of exposure to F, with the advantage of being easily obtained. The effect of water F concentration, age, gender, nail growth rate and geographical area on the F concentration in the fingernail and toenail clippings were evaluated. Volunteers (n = 300) aged 3-7, 14-20, 30-40 and 50-60 years from five Brazilian communities (A-E) participated. Drinking water and nail samples were collected and F concentration was analyzed with the electrode. A reference mark was made on each nail and growth rates were calculated. Data were analyzed by ANOVA and linear regression (alpha = 0.05). Mean water F concentrations (+/- SE, mg/l) were 0.09 +/- 0.01, 0.15 +/- 0.01, 0.66 +/- 0.01, 0.72 +/- 0.02, and 1.68 +/- 0.08 for A-E, respectively. Mean F concentrations (+/- SE, mg/kg) ranged between 1.38 +/- 0.14 (A, 50-60 years) and 10.20 +/- 2.35 (D, 50-60 years) for fingernails, and between 0.92 +/- 0.08 (A, 14-20 years) and 7.35 +/- 0.80 (E, 50-60 years) for toenails. Among the tested factors, geographical area and water F concentration exerted the most influence on finger- and toenail F concentrations. Subjects of older age groups (30-40 and 50-60 years) from D and E showed higher nail F concentrations than the others. Females presented higher nail F concentration than males. Water F concentration, age, gender and geographical area influenced the F concentration of finger- and toenails, and hence should be taken into account when using this biomarker of exposure to predict risk for dental fluorosis.

Dietary fluoride intake by children receiving different sources of systemic fluoride.

There has been no comparison of fluoride (F) intake by pre-school children receiving more traditional sources of systemic F. The aim of this study was to estimate the dietary F intake by children receiving F from artificially fluoridated water (AFW-Brazil, 0.6-0.8 mg F/L), naturally fluoridated water (NFW-Brazil, 0.6-0.9 mg F/L), fluoridated salt (FS-Peru, 180-200 mg F/Kg), and fluoridated milk (FM-Peru, 0.25 mg F). Children (n=21-26) aged 4-6 yrs old participated in each community. A non-fluoridated community (NoF) was evaluated as the control population. Dietary F intake was monitored by the "duplicate plate" method, with different constituents (water, other beverages, and solids). F was analyzed with an ion-selective electrode. Data were tested by Kruskall-Wallis and Dunn's tests (p<0.05). Mean (+/- SD) F intake (mg/Kg b.w./day) was 0.04+/-0.01(b), 0.06+/-0.02(a,b), 0.05+/-0.02(a,b), 0.06+/-0.01(a), and 0.01+/-0.00(c) for AFW/NFW/FS/FM/NoF, respectively. The main dietary contributors for AFW/NFW and FS/FM/NoF were water and solids, respectively. The results indicate that the dietary F intake must be considered before a systemic method of fluoridation is implemented.

Pharmacokinetics of ingested fluoride: lack of effect of chemical compound.

UNLABELLED: Fluoride in drinking water may be present from natural sources or added as sodium fluoride (NaF), sodium silicofluoride (Na(2)SiF(6)) or fluorosilicic acid (H(2)SiF(6)). Results from an early study with rats suggested that, when ingested as Na(2)SiF(6), the absorption and excretion of fluoride were greater than when ingested as NaF. OBJECTIVE: The present single-blind, crossover study with 10 adults was done to determine three key pharmacokinetic parameters: the maximum plasma fluoride concentrations (C(max)), the elapsed time to reach the maximum concentrations (T(max)) and the 6-h areas under the time-plasma concentration curves (AUCs) after ingestion of 500 mL of water containing 0.67 or 5.45 mg F/L present naturally or added as NaF or H(2)SiF(6). DESIGN: Blood was collected prior to and at nine time points during 6h after ingestion of the test solutions. Plasma was analysed by electrode after HMDS-facilitated diffusion and the data were analysed for statistically significant differences using repeated measures ANOVA. RESULTS: The C(max), T(max) and AUC values after ingestion of the solutions containing natural fluoride, NaF or H(2)SiF(6) did not differ significantly at either dose level. Further, the T(max) values associated with the 0.67 and 5.45 mg/L solutions did not differ significantly indicating that the absorption, distribution and elimination rates were not affected by the dose size. CONCLUSIONS: Considered together with published reports, the present findings support the conclusion that the major features of fluoride metabolism are not affected differently by the chemical compounds commonly used to fluoridate water nor are they affected by whether the fluoride is present naturally or added artificially.

Fluoride uptake by plaque from water and from dentifrice.

It has been suggested that fluoride retention in plaque is limited by available binding sites. We determined the effects of fluoridated or placebo dentifrices on plaque and salivary fluoride concentrations [F]s in communities with different water fluoride concentrations (0.04, 0.85, 3.5 ppm). After one week of dentifrice use, samples were collected 1.0 and 12 hrs after the last use of dentifrices. After the use of fluoridated dentifrice, plaque fluoride concentrations were higher at both times, except at 12 hrs in the 3.5-ppm community. Plaque concentrations at 1.0 hr after the use of fluoridated dentifrice increased almost constantly (6.5 mmol/kg), but then decreased approximately 50% at 12 hrs in each community. Unlike previous studies, the present findings suggest that the use of fluoridated dentifrice is likely to increase plaque fluoride concentrations significantly for up to 12 hrs in areas where the water contains fluoride close to 1.0 ppm. As previously reported, plaque fluoride concentrations were directly related to calcium concentrations.

The activity of beta-galactosidase and lactose metabolism in Kluyveromyces lactis cultured in cheese whey as a function of growth rate.

AIMS: Kluyveromyces lactis was cultured in cheese whey permeate on both batch and continuous mode to investigate the effect of time course and growth rate on beta-galactosidase activity, lactose consumption, ethanol production and protein profiles of the cells. METHODS AND RESULTS: Cheese whey was the substrate to grow K. lactis as a batch or continuous culture. In order to precise the specific growth rate for maximum beta-galactosidase activity a continuous culture was performed at five dilution (growth) rates ranging from 0.06, 0.09, 0.12, 0.18 to 0.24 h(-1). The kinetics of lactose consumption and ethanol production were also evaluated. On both batch and continuous culture a respirofermentative metabolism was detected. The growth stage for maximum beta-gal activity was found to be at the transition between late exponential and entrance of stationary growth phase of batch cultures. Fractionating that transition stage in several growth rates at continuous culture a maximum beta-galactosidase activity at 0.24 h(-1) was observed. Following that stage beta-gal activity undergoes a decline which does not correlate to the density of its corresponding protein band on the gel prepared from the same samples. CONCLUSION: The maximum beta-galactosidase activity per unit of cell mass was found to be 341.18 mmol ONP min(-1) g(-1) at a dilution rate of 0.24 h(-1). SIGNIFICANCE AND IMPACT OF THE STUDY: The physiology of K. lactis growing in cheese whey permeate can proven useful to optimize the conversion of that substrate in biomass rich in beta-gal or in ethanol fuel. In addition to increasing the native enzyme the conditions established here can be set to increase yields of recombinant protein production based on the LAC4 promoter in K. lactis host.

[Dental fluorosis in children from Princesa Isabel, Paraiba]. / Fluorose dentária em crianças de Princesa Isabel, Paraíba.

Several communities in Paraíba have moderate or high levels of fluoride naturally present in the drinking water. A moderate prevalence of dental fluorosis (30-40%) has been observed in some areas where the levels of fluoride are regarded as "optimal" for the region (0.6 ppm). The aim of the present study was to determine the prevalence of dental fluorosis in Princesa Isabel, a city with "sub-optimal" fluoride levels (0.4 ppm). The sample comprised 142 schoolchildren (10- to 15-year-old subjects) randomly selected and examined by means of the TF (Thylstrup & Fejerskov) index. The clinical exams were carried out under indirect natural light by three calibrated examiners. Prior to the examination the teeth were cleaned and dried. Approximately 20% of the subjects examined presented with some degree of fluorosis. Seventy per cent were classified as TF 1 while 30% were classified as TF 2 to 5. The prevalence of fluorosis was higher in male subjects and in premolars. Although the observed prevalence of dental fluorosis was within the expected levels, other sources of systemic fluoride must be controlled. The observed prevalence of dental fluorosis is not a public health problem in this community.