A comparison of simple analytical methods for determination of fluoride in microlitre-volume plasma samples

The aim was to compare potential methods for fluoride analysis in microlitre-volume plasma samples containing nano-gram amounts of fluoride. Methods: A group of 4 laboratories analysed a set of standardised biological samples as well as plasma to determine fluoride concentration using 3 methods. In Phase-1, fluoride analysis was carried out using the established hexamethyldisiloxane (HMDS)-diffusion method (1 mL-aliquot/analysis) to obtain preliminary measurement of agreement between the laboratories. In Phase-2, the laboratories analysed the same samples using a micro-diffusion method and known-addition technique with 200 µL-aliquot/analysis. Coefficients of Variation (CVs) and intra-class correlation coefficients (ICCs) were estimated using analysis of variance to evaluate the amount of variation within- and between-laboratories. Based on the results of the Phase-2 analysis, 20 human plasma samples were analysed and compared using the HMDS-diffusion method and known-addition technique in Phase-3. Results: Comparison of Phase-1 results showed no statistically significant difference among the laboratories for the overall data set. The mean between- and within-laboratory CVs and ICCs were < 0.13 and ≥0.99, respectively, indicating very low variability and excellent reliability. In Phase-2, the overall results for between-laboratory variability showed a poor CV (1.16) and ICC (0.44) for the micro-diffusion method, whereas with the known-addition technique the corresponding values were 0.49 and 0.83. Phase-3 results showed no statistically significant difference in fluoride concentrations of the plasma samples measured with HMDS-diffusion method and known- addition technique, with a mean (SE) difference of 0.002 (0.003) µg/mL. In conclusion, the known-addition technique could be a suitable alternative for the measurement of fluoride in plasma with microlitre-volume samples

Impact of experimental Nano-HAP pastes on bovine enamel and dentin submitted to a pH cycling model

This in vitro study evaluated the preventive potential of experimental pastes containing 10% and 20% hydroxyapatite nanoparticles (Nano-HAP), with or without fluoride, on dental demineralization. Bovine enamel (n=15) and root dentin (n=15) specimens were divided into 9 groups according to their surface hardness: control (without treatment), 20 Nanop paste (20% HAP), 20 Nanop paste plus (20% HAP + 0.2% NaF), 10 Nanop paste (10% HAP), 10 Nanop paste plus (10% HAP + 0.2% NaF), placebo paste (without fluoride and HAP), fluoride paste (0.2% NaF), MI paste (CPP-ACP, casein phosphopeptide-amorphous calcium phosphate), and MI paste plus (CPP-ACP + 0.2% NaF). Both MI pastes were included as commercial control products containing calcium phosphate. The specimens were treated with the pastes twice a day (1 min), before and after demineralization. The specimens were subjected to a pH-cycling model (demineralization–6-8 h/ remineralization-16-18 h a day) for 7 days. The dental subsurface demineralization was analyzed using cross-sectional hardness (kgf/mm 2 , depth 10-220 µm). Data were tested using repeated-measures two-way ANOVA and Bonferroni's test (p<0.05). The only treatment able to reduce the loss of enamel and dentin subsurface hardness was fluoride paste (0.2% NaF), which differed significantly from the control at 30- and 50-µm depth (p<0.0001). The other treatments were not different from each other or compared with the control. The experimental Nanop pastes, regardless of the addition of fluoride, were unable to reduce dental demineralization in vitro

Bone Response to Fluoride Exposure Is Influenced by Genetics

Genetic factors influence the effects of fluoride (F) on amelogenesis and bone homeostasis but the underlying molecular mechanisms remain undefined. A label-free proteomics approach was employed to identify and evaluate changes in bone protein expression in two mouse strains having different susceptibilities to develop dental fluorosis and to alter bone quality. In vivo bone formation and histomorphometry after F intake were also evaluated and related to the proteome. Resistant 129P3/J and susceptible A/J mice were assigned to three groups given low-F food and water containing 0, 10 or 50 ppmF for 8 weeks. Plasma was evaluated for alkaline phosphatase activity. Femurs, tibiae and lumbar vertebrae were evaluated using micro-CT analysis and mineral apposition rate (MAR) was measured in cortical bone. For quantitative proteomic analysis, bone proteins were extracted and analyzed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS), followed by label-free semi-quantitative differential expression analysis. Alterations in several bone proteins were found among the F treatment groups within each mouse strain and between the strains for each F treatment group (ratio ≥1.5 or ≤0.5; p<0.05). Although F treatment had no significant effects on BMD or bone histomorphometry in either strain, MAR was higher in the 50 ppmF 129P3/J mice than in the 50 ppmF A/J mice treated with 50 ppmF showing that F increased bone formation in a strain-specific manner. Also, F exposure was associated with dose-specific and strain-specific alterations in expression of proteins involved in osteogenesis and osteoclastogenesis. In conclusion, our findings confirm a genetic influence in bone response to F exposure and point to several proteins that may act as targets for the differential F responses in this tissue

Aquaporin 5 Interacts with Fluoride and Possibly Protects Against Caries

Aquaporins (AQP) are water channel proteins and the genes coding for AQP2, AQP5, and AQP6 are clustered in 12q13. Since AQP5 is expressed in serous acinar cells of salivary glands, we investigated its involvement in caries. DNA samples from 1,383 individuals from six groups were studied. Genotypes of eight single nucleotide polymorphisms covering the aquaporin locus were tested for association with caries experience. Interaction with genes involved in enamel formation was tested. The association between enamel microhardness at baseline, after creation of artificial caries lesion, and after exposure to fluoride and the genetic markers in AQP5 was tested. Finally, AQP5 expression in human whole saliva, after exposure to fluoride in a mammary gland cell line, which is known to express AQP5, and in Wistar rats was also verified. Nominal associations were found between caries experience and markers in the AQP5 locus. Since these associations suggested that AQP5 may be inhibited by levels of fluoride in the drinking water that cause fluorosis, we showed that fluoride levels above optimal levels change AQP5 expression in humans, cell lines, and rats. We have shown that AQP5 is involved in the pathogenesis of caries and likely interact with fluoride.Fil: Anjomshoaa, Ida. University of Pittsburgh; Estados UnidosFil: Briseño Ruiz, Jessica. University of Pittsburgh; Estados UnidosFil: Deeley, Kathleen. University of Pittsburgh; Estados UnidosFil: Poletta, Fernando Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET.; ArgentinaFil: Mereb, Juan C.. Provincia de Río Negro. Ministerio de Salud. Hospital de Área El Bolsón ; ArgentinaFil: Leite, Aline L.. Universidade de Sao Paulo; BrasilFil: Barreta, Priscila A. T.. Universidade de Sao Paulo; BrasilFil: Silva, Thelma L.. Universidade de Sao Paulo; BrasilFil: Dizak, Piper. University of Pittsburgh; Estados UnidosFil: Ruff, Timothy. University of Pittsburgh; Estados UnidosFil: Patir, Asli. İstanbul Medipol Üniversitesi; TurquíaFil: Koruyucu, Mine. İstanbul Üniversitesi; TurquíaFil: Abbasoğlu, Zerrin. Yeditepe Üniversitesi; TurquíaFil: Casado, Priscila L.. Universidade Federal Fluminense; BrasilFil: Brown, Andrew. University of Pittsburgh; Estados UnidosFil: Zaky, Samer H.. University of Pittsburgh; Estados UnidosFil: Bayram, Merve. İstanbul Medipol Üniversitesi; TurquíaFil: Küchler, Erika C.. University of Pittsburgh; Estados UnidosFil: Cooper, Margaret E.. University of Pittsburgh; Estados UnidosFil: Liu, Kai. University of Pittsburgh; Estados UnidosFil: Marazita, Mary L.. University of Pittsburgh; Estados UnidosFil: Tanboğa, İlknur. Marmara Üniversitesi; TurquíaFil: Granjeiro, José M.. Universidade Federal Fluminense; Brasil. Instituto Nacional de Metrologia, Qualidade e Tecnologia; BrasilFil: Seymen, Figen. İstanbul Üniversitesi; TurquíaFil: Castilla, Eduardo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET.; Argentina. Fundación Oswaldo Cruz; BrasilFil: Orioli, Iêda M.. Universidade Federal do Rio de Janeiro; BrasilFil: Sfeir, Charles. University of Pittsburgh; Estados UnidosFil: Owyang, Hongjiao. Marmara Üniversitesi; TurquíaFil: Rabelo Buzalaf, Marilia Afonso. Universidade de Sao Paulo; BrasilFil: Vieira, Alexandre R.. University of Pittsburgh; Estados Unido

Effect of titanium tetrafluoride and amine fluoride treatment combined with carbon dioxide laser irradiation on enamel and dentin erosion

OBJECTIVE: This in vitro study aimed to analyze the influence of carbon dioxide (CO(2)) laser irradiation on the efficacy of titanium tetrafluoride (TiF(4)) and amine fluoride (AmF) in protecting enamel and dentin against erosion. METHODS: Bovine enamel and dentin samples were pretreated with carbon dioxide (CO(2)) laser irradiation only (group I), TiF(4) only (1% F, group II), CO(2) laser irradiation before (group III) or through (group IV) TiF(4) application, AmF only (1% F, group V), or CO(2) laser irradiation before (group VI) or through (group VII) AmF application. Controls remained untreated. Ten samples of each group were then subjected to an erosive demineralization and remineralization cycling for 5 days. Enamel and dentin loss were measured profilometrically after pretreatment, 4 cycles (1 day), and 20 cycles (5 days) and statistically analyzed using analysis of variance and Scheffe's post hoc tests. Scanning electron microscopy (SEM) analysis was performed in pretreated but not cycled samples (two samples each group). RESULTS: After 20 cycles, there was significantly less enamel loss in groups V and IV and significantly less dentin loss in group V only. All other groups were not significantly different from the controls. Lased surfaces (group I) appeared unchanged in the SEM images, although SEM images of enamel but not of dentin showed that CO(2) laser irradiation affected the formation of fluoride precipitates. CONCLUSION: AmF decreased enamel and dentin erosion, but CO(2) laser irradiation did not improve its efficacy. TiF(4) showed only a limited capacity to prevent erosion, but CO(2) laser irradiation significantly enhanced its ability to reduce enamel erosion

Salivary protein candidates for biomarkers of oral disorders in people with a crack cocaine use disorder

The use of cocaine and its main derivative, crack, can cause some systemic effects that may lead to the development of some oral disorders. Objective: To assess the oral health of people with a crack cocaine use disorder and identify salivary protein candidates for biomarkers of oral disorders. Methodology: A total of 40 volunteers hospitalized for rehabilitation for crack cocaine addiction were enrolled; nine were randomly selected for proteomic analysis. Intraoral examination, report of DMFT, gingival and plaque index, xerostomia, and non-stimulated saliva collection were performed. A list of proteins identified was generated from the UniProt database and manually revised. Results: The mean age (n=40) was 32 (±8.88; 18–51) years; the mean DMFT index was 16±7.70; the mean plaque and gingival index were 2.07±0.65 and 2.12±0.64, respectively; and 20 (50%) volunteers reported xerostomia. We identified 305 salivary proteins (n=9), of which 23 were classified as candidate for biomarkers associated with 14 oral disorders. The highest number of candidates for biomarkers was associated with carcinoma of head and neck (n=7) and nasopharyngeal carcinoma (n=7), followed by periodontitis (n=6). Conclusions: People with a crack cocaine use disorder had an increased risk of dental caries and gingival inflammation; less than half had oral mucosal alterations, and half experienced xerostomia. As possible biomarkers for 14 oral disorders, 23 salivary proteins were identified. Oral cancer and periodontal disease were the most often associated disorders with biomarkers

LACK OF A SIGNIFICANT RELATIONSHIP BETWEEN TOENAIL FLUORIDE CONCENTRATIONS AND CARIES PREVALENCE

The relationship between fluoride (F) concentrations in toenails and prevalence of caries using the International Caries Detection and Assessment System (ICDAS-II) criteria was evaluated. Fifty-four children (4-13 years of age) from Rio de Janeiro, Brazil, had their teeth surfaces examined and toenails clipped and analyzed for F. Toenail F concentrations in children presenting ICDAS-II &lt;= 10 or &gt;10 were compared by unpaired t test with Welch correction. Dichotomized data were analyzed by Fisher's exact test. Children presenting ICDAS-II &lt;= 10 (n=23) had 1.85 +/- 1.32 (Mean +/- SD) mu g/g [F]; these values were higher than children having ICDAS-II&gt;10 (n=31), whose toenails had 1.58 +/- 0.78 mu g/g [F], a nonsignificant difference. The sensitivity and specificity of toenail F concentrations in identifying children with ICDAS-II &lt;= 10 were 0.22 and 0.77, respectively. We conclude that children with low caries prevalence tend to have higher toenail F concentrations, but the validity of this biomarker as a diagnostic tool for caries prevalence is low, possibly owing to the fact that the mechanism of action of F on caries control appears to be essentially topical