Are the counts of Streptococcus mutans and Staphylococcus aureus changed in complete denture wearers carrying denture stomatitis? A systematic review with meta-analyses

STATEMENT OF PROBLEM

Despite the importance of Candida spp. on the etiology of denture stomatitis (DS), information on the role of the bacterial component is still scarce.

PURPOSE

The purpose of this systematic review was to evaluate whether the counts of Staphylococcus aureus and Streptococcus mutans were changed in complete denture wearers diagnosed with Candida-associated DS.

MATERIAL AND METHODS

The literature search was performed in 8 databases and by hand searching. The risk of bias was assessed according to the Newcastle-Ottawa qualifier. Meta-analyses were performed considering the microorganism evaluated (S. aureus or S. mutans) and the collection area (mucosa or dentures). The certainty of evidence was assessed according to the grading of recommendations assessment, development and evaluations (GRADE) criteria.

RESULTS

Participants with DS presented higher counts of S. aureus in the mucosa compared with those from the control group (OR, 3.16 [1.62, 6.15]; P<.001). No significant difference between the groups was observed for samples collected from dentures (OR, 0.73 [0.50, 1.07]; P=.110). Conversely, participants without DS presented higher counts of S. mutans both in the mucosa (OR, 0.19 [0.06, 0.63]; P=.006) and dentures (OR, 0.64 [0.41, 1.0]; P=.050).

CONCLUSIONS

Microbial counts in participants with DS changed as a function of the type of microorganism and collection site. The certainty of evidence ranged from very low to low. The findings reinforce the fact that bacteria also play a relevant role in DS and should be more extensively studied. Such information may be useful to guide further therapies to prevent or control DS.

Use of fluoridated dentifrices by children in Araçatuba, Brazil: factors affecting brushing habits and amount applied on the brush

PURPOSE

To evaluate the type and the amount of fluoridated dentifrice applied on children's toothbrushes by parents/guardians according to descriptions typically recommended by scientific societies, as well as to assess the influence of demographic and socioeconomic variables on dentifrice use.

METHODS

Parents/guardians of children (0-7 years old; n = 306; convenience sample) attending vaccination centres from Araçatuba (Brazil), answered to a structured questionnaire comprising items related to interviewees' education, child's age, gender, brushing habits and use of fluoridated dentifrice. The amount of toothpaste used by children during toothbrushing was estimated using a portable scale. Similarly, the interviewees were requested to apply dentifrices on toothbrushes according to eight descriptions, ranging from "smear" to "all bristles", following a random sequence. Data were submitted to Mann-Whitney's, Kruskal-Wallis' and Friedman's tests, and Spearman's correlation coefficient (p < 0.05).

RESULTS

The type of toothpaste and the amount of product used at home were not affected by the respondents' educational level or family income. However, child's age was significantly correlated with the amount of toothpaste placed on the toothbrush (r = 0.324, p < 0.001). Also, the amount of toothpaste placed on the toothbrush increased according to what would be expected from the descriptions, although wide variations were observed within each description, with large interquartile and overall ranges.

CONCLUSION

The amount and the type of dentifrice used by children were influenced by their age, while parents/caregivers' interpretation on verbal instructions regarding appropriate dentifrice quantities varied widely. This reinforces the need for educative measures on the appropriate use by dentifrices by children.

Assembly and antifungal effect of a new fluconazole-carrier nanosystem

Aim: To assemble, characterize and assess the antifungal effects of a new fluconazole (FLZ)-carrier nanosystem. Materials & methods: The nanosystem was prepared by loading FLZ on chitosan (CS)-coated iron oxide nanoparticles (IONPs). Antifungal effects were evaluated on planktonic cells (by minimum inhibitory concentration determination) and on biofilms (by quantification of cultivable cells, total biomass, metabolism and extracellular matrix) of Candida albicans and Candida glabrata. Results: Characterization results ratified the formation of a nanosystem (<320 nm) with FLZ successfully embedded. IONPs-CS-FLZ nanosystem reduced minimum inhibitory concentration values and, in general, showed similar antibiofilm effects compared with FLZ alone. Conclusion: IONPs-CS-FLZ nanosystem was more effective than FLZ mainly in inhibiting Candida planktonic cells. This nanocarrier has potential to fight fungal infections.

Quantitative proteomic analysis in symptomatic and asymptomatic apical periodontitis

AIM

To quantitatively and qualitatively compare the host proteomic profile in samples of symptomatic and asymptomatic apical periodontitis (AP) using nano-liquid chromatography-electron spray tandem mass spectrometry.

METHODOLOGY

Samples were obtained from 18 patients with radiographically evident AP, divided into symptomatic and asymptomatic groups (nine per group) according to clinical characteristics. After sample collection, protein extraction, purification and quantification of the samples were performed, which were analysed by reverse-phase liquid chromatography coupled to mass spectrometry. Label-free quantitative proteomic analysis was performed by Protein Lynx Global Service software. Differences in expression of proteins between the groups were calculated using the Monte Carlo algorithm, considering P < 0.05 for down-regulated proteins and 1 - P > 0.95 for up-regulated proteins. Proteins were identified with the embedded ion accounting algorithm in the software and a search of the Homo sapiens UniProt database.

RESULTS

A total of 853 individual human proteins were identified. In the quantitative analysis, common proteins to both groups accounted for 143 proteins. Differences in expression between groups resulted in 51 up-regulated proteins (1 - P > 0.95) in the symptomatic group, including alpha-1-antitrypsin, protein S100-A8, myeloperoxidase, peroxiredoxin and lactotransferrin. This group also had 43 down-regulated proteins (P < 0.05), comprising immunoglobulin, neutrophil defensin, pyruvate kinase and alpha-enolase. The qualitative analysis considered only the exclusive proteins of each group. For the symptomatic group, 318 complete proteins and 29 fragments were identified, such as dedicator of cytokinesis protein, intersectin, prostaglandin, phospholipase DDHD2 and superoxide dismutase. For the asymptomatic group, 326 complete proteins and 37 fragments were identified, including azurocidin, C-reactive protein, collagen alpha, cathepsin, heat shock and laminin.

CONCLUSIONS

Quantitative differences in the expression of common proteins in cases of symptomatic and asymptomatic AP were found, which were mostly related to host immune response in both groups. Exclusive proteins in the symptomatic group were mainly related to the host response to the presence of viruses in endodontic infections, oxidative stress and proteolytic enzymes. The results provide a basis for a better understanding of cellular and molecular pathways involved in AP, establishing specific proteomic profiles for symptomatic and asymptomatic conditions.

Maxillary arch dimensions in the first 6 months of life and their relationship with pacifier use

PURPOSE

This study evaluated the maxillary arch dimensions at birth and 6 months of life, and to verify the influence of pacifier use on palatal development.

METHODS

Maxillary arch impressions were taken from 80 full-term newborns, appropriate for gestational age, from 24 to 72 h of life, and repeated after 6 months. Anatomical references were mapped on dental casts and measurements were taken. Parents were questioned about feeding practices and sucking habits. Data were analysed by Kruskal-Wallis test and hierarchical mixed regression model (p < 0.05).

RESULTS

Anterior maxillary segment (median [interquartile range]) presented an increase in transverse (Δ% = 81.90 [74.40-89.70]) and in length (Δ% = 76.20 [49.10-102.70]) relative growth. No differences were detected in palatine depth from birth (11.00 mm [10.30-11.70]) to 6 months (12.60 mm [12.0-13.90]).

CONCLUSIONS

Pacifier use was positively related to the increase in anterior segment length. In the first 6 months of life, the greatest relative growth of the maxillary arch occurs in the anterior region, showing this growth does not occur homogeneously. The use of pacifiers came to influence this process, even before the eruption of the upper incisors.

Protein Profile of the Acquired Enamel Pellicle after Rinsing with Whole Milk, Fat-Free Milk, and Water: An in vivo Study

This study detected changes in the protein profile of the acquired enamel pellicle (AEP) formed in vivo after rinsing with whole milk, fat-free milk, or water. Nine subjects in good oral condition took part in the study. The acquired pellicle was formed in the morning, for 120 min, after prophylaxis with pumice. Following this, the volunteers rinsed with 10 mL of whole milk, fat-free milk, or deionized water for 30 s, following a blinded crossover protocol. After 60 min, the pellicle was collected with filter paper soaked in 3% citric acid and processed for analysis by liquid chromatography-electrospray ionization tandem mass spectrometry. The obtained tandem mass spectrometry spectra were searched against a human protein database (Swiss-Prot). The proteomic data related to protein quantification were analysed using the PLGS software. A total of 260 proteins were successfully identified in the AEP samples collected from all groups. Forty-nine were common to all 3 groups, while 72, 62, and 49 were specific to the groups rinsing with whole milk, fat-free milk, and water, respectively. Some were typical components of the AEP, such as cystatin-B, cystatin-SN, isoforms of α-amylase, IgA and IgG, lysozyme C, protein S100 A78, histatin-1, proline-rich protein 27, statherin, and lactotransferrin. Other proteins are not commonly described as part of the AEP but could act in defence of the organism against pathogens. Distinct proteomic profiles were found in the AEP after rinsing with whole or fat-free milk, which could have an impact on bacterial adhesion and tooth dissolution. The use of fat-free milk could favourably modulate the adhesion of bacteria to the AEP as well as biofilm formation when compared with whole milk.

Microhardness and Roughness of Infiltrated White Spot Lesions Submitted to Different Challenges

A white spot lesion is the first clinical sign of a caries lesion and represents mineral loss from the enamel subsurface. The purpose of this study was to evaluate the microhardness and surface roughness of white spot lesions after application of a resin infiltrant and subjection to different challenges. Caries-like lesions were induced in bovine enamel discs (n=50), and the specimens were randomly divided into five study groups (n=10): demineralized enamel (negative control, G1), infiltrated enamel (G2), infiltrated enamel submitted to brushing (G3), infiltrated enamel submitted to pH cycling (G4), and infiltrated enamel submitted to artificial aging (G5). Half of each enamel surface was used as its own positive control. Roughness data were analyzed using the Kruskal-Wallis test followed by the Dunn test. Results from microhardness were analyzed by two-way analysis of variance, followed by the Tukey test for multiple comparisons. The level of significance was set at 5%. Microhardness and roughness values obtained from the test side of the specimens were significantly lower compared with the sound enamel for all groups. Microhardness values obtained for G2, G3, and G5 were not significantly different. Values found for G1 were significantly lower compared with those for G2, G3, and G5. The lowest microhardness values were observed for G4, which was significantly different from the other groups. Surface roughness was not significantly different between G2 and G3. The resin infiltrant presented superiority over the unprotected white spot lesions, as they were more resistant to mechanical and aging challenges. However, resin infiltration was not able to reestablish the properties of sound enamel and was not resistant to a new cariogenic challenge.

Fluoride varnishes containing sodium trimetaphosphate reduce enamel demineralization in vitro

OBJECTIVE

This study evaluated the effects of fluoride varnishes containing sodium trimetaphosphate (TMP) on bovine enamel demineralization in vitro.

MATERIAL AND METHODS

Enamel bovine discs were randomly assigned into six groups (n = 20/group): placebo, 2.5% NaF, 2.5% NaF/5% TMP, 5% NaF, 5% NaF/5% TMP, and a commercial formulation (Duraphat, 5% NaF). Varnishes were applied on all enamel discs and kept for 6 h. Loosely and firmly bound fluoride formed on/in enamel after treatment were analyzed in 10 discs from each group. The other 10 discs were subjected to a pH-cycling regimen for 7 days, and analyzed for surface (SH) and cross-sectional hardness (ΔKHN), as well as for loosely and firmly bound fluoride in/on enamel. Data were analyzed by analysis of variance (ANOVA) followed by Student-Newman-Keuls' test (p < .05).

RESULTS

The lowest SH change and ΔKHN were observed for the 5%NaF/5%TMP varnish, which was significantly different from all the other groups. Both fluoridated varnishes containing TMP promoted significantly lower SH change and ΔKHN when compared with their counterparts without TMP. Loosely and firmly bound fluoride was significantly lower in groups treated with varnishes containing TMP.

CONCLUSION

TMP and fluoride added to varnishes have a synergistic effect against enamel demineralization in vitro.

Protective Effect of Phosphates and Fluoride on the Dissolution of Hydroxyapatite and Their Interactions with Saliva

This study aimed to investigate the effect of phosphates and fluoride, alone or in combination, and the influence of salivary pellicle on hydroxyapatite (HA) dissolution. The baseline dissolution rate of HA discs was measured using a pH-stat system (0.3% citric acid, pH 3.2). In the first series of experiments, HA discs (n = 8/group) were treated with: a placebo solution (PLA, deionised water); sodium trimetaphosphate (TMP), sodium tripolyphosphate (TRI) and sodium pyrophosphate (PYRO) at 1 or 8%; 500 ppm F; 1,100 ppm F; 1,100 ppm F/1% TMP; 1,100 ppm F/8% TMP; 1,100 ppm F/1% TRI; 1,100 ppm F/8% TRI. In the second phase, HA discs were immersed in pooled human saliva (37°C/2 h) and treated with PLA, 1,100 ppm F/1% TMP, 1,100 ppm F/8% TMP, 1,100 ppm F/1% TRI, and 1,100 ppm F/8% TRI. After treatments, final dissolution rates were measured from 3 consecutive 30-min assays. Statistical analyses were performed using 2-way ANOVA followed by the Fisher test (α = 0.05). The type and concentration of phosphate tested significantly influenced HA dissolution; 8% TRI showed the highest reduction (36.9%) among all treatment solutions. Fluoride alone (1,100 ppm F) significantly reduced HA dissolution by 20.7%. When fluoride and phosphates were associated, 1,100 ppm F/1% TMP, 1,100 ppm F/8% TMP, and 1,100 ppm F/8% TRI showed the highest percentage reductions of dissolution (40.3-46.1%). Salivary pellicle led to a greater and more sustained protective effect of the treatment solutions compared to their counterparts without salivary coating. It was concluded that the association of phosphate and fluoride enhanced their protective effect against HA dissolution when compared with these compounds alone, especially in the presence of salivary pellicle.

Protective Effect of Whole and Fat-Free Fluoridated Milk, Applied before or after Acid Challenge, against Dental Erosion

This study analysed in vitro the effect of milk against dental erosion, considering three factors: the type of milk (bovine whole/fat-free), the presence of different fluoride concentrations and the time of application (before/after erosive challenge). Bovine enamel (n = 15/group) and root dentine (n = 12/group) specimens were submitted to the following treatments: after the first erosive challenge - 0.9% NaCl solution (negative control), whole milk with 0, 2.5, 5.0 and 10.0 ppm F, fat-free milk with 0, 2.5, 5.0 and 10.0 ppm F, and 0.05% NaF solution (positive control); before the first erosive challenge - whole milk with 0, 2.5, 5.0 and 10.0 ppm F, fat-free milk with 0, 2.5, 5.0 and 10.0 ppm F, and 0.05% NaF solution (positive control). Specimens were submitted to demineralisation-remineralisation regimes 4 times/day for 5 days. The response variables were enamel and dentine loss (in micrometres). Data were analysed using Kruskal-Wallis/Dunn's test (p < 0.05). For enamel, whole milk containing 10 ppm F, applied before the erosive challenge, was the most protective treatment, but with no significant difference compared with the same treatment carried out after the erosive challenge. For dentine, whole fluoridated milk (all concentrations, after), fat-free 10 ppm F milk (after, before) and whole milk with or without F (except 2.5 ppm F, all before) significantly reduced dentine erosion. It seems that the presence of fluoride, especially at 10 ppm, is the most important factor in reducing dental erosion.

Intraoral fluoride levels after use of conventional and high-fluoride dentifrices

OBJECTIVES

This study aimed to evaluate saliva and plaque as indicators of intraoral fluoride (F) levels after the use of conventional and high-fluoride dentifrices.

MATERIALS AND METHODS

Subjects were randomly assigned to brush their teeth with conventional (1000 ppm F), high-fluoride (5000 ppm F), and placebo dentifrices (fluoride free) for 10 days, following a double-blind, crossover protocol. Saliva and plaque samples were collected on the morning of the 5(th) and 10th days, respectively at 1 and 12 h after brushing, and analyzed with an ion-selective electrode after HMDS-facilitated diffusion. Data were analyzed by two-way repeated measures ANOVA, Tukey's test and Spearman's correlation coefficient (p < 0.05).

RESULTS

Plaque and salivary F levels were significantly increased after the use of conventional and high-fluoride dentifrices when compared to values obtained for placebo, except plaque 12 h after the use of conventional dentifrice. A positive and significant correlation was found between fluoride concentrations in plaque and saliva for both times of sample collection.

CONCLUSION

Both indicators assessed were able to detect significant differences among treatments and between times after brushing. The use of a high-fluoride dentifrice is able to significantly increase intraoral fluoride levels throughout the day, being therefore a useful therapy for patients at high caries risk.

CLINICAL RELEVANCE

A dentifrice with high fluoride concentration could be regarded as a useful therapy of F delivery for high caries-risk patients, since intraoral F levels were sustained throughout most of the day after using this formulation.

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.

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.

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.

Consumption of bottled water by children in the city of Bauru, State of São paulo, Brazil -- a brief communication

OBJECTIVES

To determine the consumption of bottled water by children in the city of Bauru, State of São Paulo, Brazil.

METHODS

A stratified sample of the 17 areas established by the city plan was used to identify a total of 1,000 homes for visitation. Information was collected using a questionnaire concerning the type of water consumed and population demographics.

RESULTS

Overall, around 30 percent of all residences used bottled water. Among all households where bottled water was consumed, about 26 percent had children residing. For those with children and bottled water, 81 percent reported to use bottled water for the preparation of the children's foods and beverages.

CONCLUSIONS

An important percentage of children consume bottled water in the city of Bauru, State of São Paulo, Brazil. Considering previous studies showing that fluoride concentrations vary in bottled water, public health measures should be implemented in order to guarantee adequate levels of fluoride in commercialized water.

Effect of an iron mouthrinse on enamel and dentine erosion subjected or not to abrasion: An in situ/ex vivo study

OBJECTIVES

This in situ/ex vivo study evaluated whether a rinse with an iron solution could reduce wear and the percentage of microhardness change of human enamel and dentine submitted to erosion followed by brushing after 1 or 30min.

DESIGN

During 2 experimental 5-day crossover phases (wash-out period of 10 days), 10 volunteers wore intraoral palatal devices, with 12 specimens (6 of enamel and 6 of dentine) arranged in 3 horizontal rows (4 specimens each). In one phase, the volunteers immersed the device for 5min in 150mL of cola drink, 4 times a day. Immediately after immersion, no treatment was performed in one row. The other row was brushed after 1min using a fluoride dentifrice and the device was replaced into mouth. After 30min, the remaining row was brushed. In the other phase, the procedures were repeated, but after immersion the volunteers rinsed for 1min with 10mL of a 10mM ferrous sulphate solution. Changes in surface microhardness (%SMH) and wear (profilometry) of enamel and dentine were measured. Data were tested using ANOVA and Tukey's tests (p<0.05).

RESULTS

The enamel presented more wear than dentine, under all experimental conditions. The iron solution caused a significant reduction on the %SMH in enamel, and a significant reduction on the wear in dentine, regardless the other conditions.

CONCLUSIONS

Rinsing with an iron solution after an erosive attack, followed or not by an abrasive episode, may be a viable alternative to reduce the loss of dental structure.

In vitro Evaluation of the Effectiveness of Acidic Fluoride Dentifrices

This study evaluated the effectiveness of acidic low-fluoride dentifrices compared to conventional neutral dentifrices. Enamel blocks were submitted to pH cycling and treatment with slurries of dentifrices containing 0, 275, 412, 550 and 1,100 microg F/g (pH 4.5 or 7.0), and also a commercial dentifrice (1,100 microg F/g) and a commercial children's dentifrice (500 mug F/g). Variations in surface microhardness and in the mineral content in enamel after pH cycling were calculated. Enamel blocks treated with acidic dentifrices exhibited less mineral loss compared to neutral dentifrices (ANOVA; p < 0.05). The acidic dentifrices with 412 and 550 microg F/g had the same effectiveness as the neutral 1,100-microg F/g dentifrice and commercial 1,100-microg F/g dentifrice.

Fluoride concentrations in dental plaque and saliva after the use of a fluoride dentifrice preceded by a calcium lactate rinse

Plaque fluoride concentrations ([F]) are directly related to plaque calcium concentrations [Ca]. Attempts to increase plaque F uptake from dentifrices or rinses have used methods designed to increase plaque [Ca] but with inconsistent results. This double-blind, double-crossover study tested the effect of a 150 mM calcium lactate rinse used prior to brushing with placebo or fluoridated dentifrices (1030 p.p.m. as NaF) on plaque and salivary [F] and [Ca]. Sixteen children (8-10 yr of age) were randomly assigned to four different groups according to the four treatments (placebo dentifrice or fluoridated dentifrice preceded by calcium lactate or deionized water prerinses). Plaque and saliva were collected 1 and 12 h after brushing on day 7 after starting to use the dentifrices. F was determined using the electrode and Ca was determined using atomic absorption spectrometry. Plaque and salivary [Ca] were not significantly increased after use of the calcium lactate prerinse, except for plaque [Ca] 1 h after the use of the placebo dentifrice. A significant increase in salivary [F] was associated with the calcium lactate prerinse only at 1 h after the use of the fluoridated dentifrice. The the calcium lactate prerinse did not significantly affect plaque [F] under any condition.

Influence of growth rate and length on fluoride detection in human nails

This study aimed to determine the lag time between increased fluoride (F) intake and F detection in human nails, as well as the influence of nails growth rate and length on this. Ten 20- to 35-year-old volunteers received 1.8 mg F daily, for 30 days. Nail growth rate and length were determined for all fingernails and toenails. Nail samples were collected at the beginning of the study and every 2 weeks (15 collections in all) and F concentrations were determined. The growth rate was statistically higher in fingernails than in toenails. No statistically significant differences were observed between right and left sides. Growth rate was significantly greater for big toenails than for the other toenails, but this pattern was not found for fingernails. The estimated mean lag times for F detection in fingernails and toenails were 101 and 123 days, respectively. An apparent increase in fingernail F concentrations was observed 84 days after the beginning of the study, although this was not statistically different from baseline. For toenails, statistically significant increases in F concentration in relation to baseline were observed 112 and 140 days after increased F ingestion. These increases occurred within the 95% confidence intervals for the calculated mean lag time for fluoride detection in nails. Considering the large amount of sample provided by the big toenails, together with their faster growth rate, as well as the fact that toenails are less prone to environmental contamination, our data suggest that big toenails are more suitable biomarkers of fluoride intake.

Analysis of fingernails and urine as biomarkers of fluoride exposure from dentifrice and varnish in 4- to 7-year-old children

The use of fingernails and urine as biomarkers of exposure to fluoride (F) from fluoridated dentifrice and varnish was evaluated in twenty 4- to 7-year-old children, who were divided into two groups: group A (9 caries-free children) and group B (11 children with past caries experience). They used a placebo dentifrice for 28 days, fluoridated dentifrice (1,570 ppm F) for the following 28 days, and placebo dentifrice for an additional 28 days, then returned to their usual dentifrices. Group B children also received 4-week applications of a varnish (2.26% F) while using the fluoridated dentifrice. Urinary collections were performed 24 h before the use of fluoridated dentifrice and 24 h (group A) or 48 h (group B) after. Fingernails were clipped every 2 weeks, for 26 weeks. Total F intake from diet and dentifrice was estimated. Fingernail F concentrations did not vary significantly throughout the study. Twenty-four-hour urinary F outputs (mean +/- SD, microg) were: 414 +/- 200 and 468 +/- 253 for placebo and F dentifrices, respectively (group A) and 402 +/-206, 691 +/- 345, 492 +/- 243 for placebo dentifrice, F dentifrice plus F varnish and F dentifrice, respectively (group B). The use of F dentifrice did not cause a significant increase in the urinary F output. However, when F varnish was used, a transitory increase in the urinary F output was detected (p = 0.001), returning to baseline levels in the last 24 h. Thus, F varnish is a safe method for topical F application even in children that use F dentifrice regularly. According to our protocol, urine was a suitable biomarker of exposure to F from dentifrice plus varnish, but not from dentifrice alone, while nails were not.