RESUMO
It has been suggested that fluoride binding to dental biofilm is enhanced when more bacterial calcium binding sites are available. However, this was only observed at high calcium and fluoride concentrations (i.e., when CaF2 precipitation may have occurred). We assessed fluoride binding to Streptococcus mutans pellets treated with calcium and fluoride at concentrations allowing CaF2 precipitation or not. Increasing calcium concentration resulted in a linear increase (p < 0.01) in fluoride concentration only in the pellets in which CaF2 precipitated. The results suggest that CaF2 precipitation, rather than bacterially bound fluoride, is responsible for the increase in fluoride binding to dental biofilm with the increase in calcium availability.
Assuntos
Biofilmes/efeitos dos fármacos , Cálcio/química , Cariostáticos/química , Esmalte Dentário/microbiologia , Fluoretos/química , Streptococcus mutans/fisiologia , Análise de Variância , Fluoreto de Cálcio/química , Precipitação Química , Cárie Dentária/microbiologia , Cárie Dentária/prevenção & controle , Sinergismo Farmacológico , Humanos , Concentração Osmolar , Análise de RegressãoRESUMO
Calcium fluoride-like materials ("CaF2") formed on dental surfaces after professional fluoride application are unstable in the oral environment but can be retained longer with a daily NaF mouthrinse. We tested the effect of twice daily 0.05% NaF rinses on the retention of "CaF2" formed on enamel and dentine after applying acidulated phosphate fluoride (APF). "CaF2" formed on enamel/dentine by APF application significantly decreased after exposure to artificial saliva and the 0.05% NaF rinse was ineffective to avoid this reduction. These findings suggest that the combination of APF and 0.05% NaF is not clinically relevant, either for caries or dental hypersensitivity.
Assuntos
Fluoreto de Cálcio/química , Cariostáticos/química , Esmalte Dentário/efeitos dos fármacos , Dentina/efeitos dos fármacos , Fluoreto de Sódio/química , Animais , Bovinos , Esmalte Dentário/química , Dentina/química , Fluoretos Tópicos/química , Imersão , Distribuição Aleatória , Reprodutibilidade dos Testes , Saliva Artificial/química , Propriedades de Superfície/efeitos dos fármacos , Fatores de TempoRESUMO
We study the high- to low- temperature signal ratio (HLTR) of the CaF2:Tm glow curve as a function of beam quality for low-energy photon beams with effective energy between 15.2 and 33.6 keV, generated with W, Mo and Rh anodes. CaF2:Tm dosemeters (TLD-300) were exposed to x-rays and (60)Co gamma-rays. Glow curves were deconvoluted into 7 peaks, using computerized glow curve deconvolution and HLTR was evaluated. Air kerma and dose in water were between 2.1-15.0 mGy and 49.8-373.8 mGy, respectively. All peaks in the glow curve showed a linear response with respect to air kerma and dose in water. HLTR values decreased monotonically between 1.029 ± 0.010 (at 15.2 keV) and 0.821 ± 0.011 (33.6 keV), and no effects due to the use of different anode/filter combinations were observed. The results indicate a relatively high value of HLTR (about 1 for 17 keV effective energy, or 3 keV µm(-1) track-average LET) and a measurable dependence on the photon beam quality. Comparison of these photon data with HLTR for ions shows good quantitative agreement. The reported evolution of the CaF2:Tm glow curve could facilitate the estimation of the effective energy of unknown photon fields by this technique.
Assuntos
Fótons , Dosimetria Termoluminescente/métodos , Fluoreto de Cálcio/química , Raios gama , Doses de Radiação , Tálio/química , Dosimetria Termoluminescente/instrumentação , Raios XRESUMO
OBJECTIVE. Our in vitro study evaluated calcium fluoride formation in enamel and the anticaries effect of seven resin-based varnishes under cariogenic challenge. METHODS. Enamel blocks were subjected to pH cycling. The experimental groups received fluoride varnish application, the positive control received topical fluoride gel treatment, and the negative control did not receive any treatment. The pH cycling surface hardness (SH1 ) and integrated loss of subsurface hardness (ΔKHN) were then determined. We measured the amount of fluoride released into the demineralizing and remineralizing (DE-RE) solutions used in pH cycling. The fluoride concentration in the enamel was determined 24 h after application of the products as loosely bound fluoride and firmly bound fluoride. RESULTS. Higher deposits of loosely bound fluoride were observed for Duofluorid, followed by Biophat. For Duraphat, Bifluorid, Duraflur, and Duofluorid, no difference was observed in the SH1 and ΔKHN values, with the lowest mineral loss compared to the other groups. The Bifluorid and Duofluorid groups released high fluoride amounts into the DE-RE, and statistically significant difference was noted between them. CONCLUSIONS. The anticaries effect showed no correlation with higher deposited fluoride amounts, resin type, or fluoride source.
Assuntos
Fluoreto de Cálcio/química , Cariostáticos/química , Fluoretos Tópicos/química , Fluoretos/química , Fluoreto de Fosfato Acidulado/química , Animais , Bovinos , Esmalte Dentário/química , Esmalte Dentário/ultraestrutura , Dureza , Concentração de Íons de Hidrogênio , Teste de Materiais , Distribuição Aleatória , Resinas Sintéticas/química , Fluoreto de Sódio/química , Fatores de Tempo , Desmineralização do Dente/metabolismo , Desmineralização do Dente/patologia , Remineralização DentáriaRESUMO
High-resolution continuum source molecular absorption of the calcium mono-fluoride molecule CaF in a graphite furnace has been used to determine fluorine in tea after acid digestion, alkaline solubilization and preparation of a conventional aqueous infusion. The strongest absorption 'line' of the CaF molecule is at 606.440 nm, which is part of the rotational fine structure of the X(2)Σ(+)-A(2)Π electronic transition; it has a bond dissociation energy of 529 kJ mol(-1), which is comparable with other molecules used for fluorine determination. One advantage of using Ca as the molecule-forming reagent is that spectral interferences are extremely unlikely in the spectral range of its strongest absorption. Another advantage is that Ca acts both as molecule forming reagent and chemical modifier, so that no other reagent has to be added, making the method very simple. The only disadvantage is that Ca has a somewhat negative influence on the graphite tube lifetime. The limit of detection was found to be 0.16 mg L(-1) F, corresponding to 1.6 ng F absolute, and the calibration curve was linear in the range between 0.5 and 25 mg L(-1) with a correlation coefficient of R=0.9994. The results obtained for a certified tea reference material were in agreement with the certified value on a 95% confidence level. There was also no difference between the results obtained after an acid digestion and an alkaline solubilization for 10 tea samples, based on a paired t-test. The values found in the 10 samples ranged between 42 µg g(-1) and 87 µg g(-1) F; the tea infusions contained between 21 µg g(-1) and 56 µg g(-1) F, with an extraction rate between 48% and 74%.
Assuntos
Fluoreto de Cálcio/química , Flúor/análise , Espectrofotometria Atômica/métodos , Chá/química , Indicadores e ReagentesRESUMO
OBJECTIVE: The objective of this study was to evaluate the effect of desensitizing agents containing different amounts of fluoride on the shear bond strength of a dual polymerized resin cement and a resin-modified glass ionomer cement (RMGIC) to dentin. MATERIAL AND METHODS: One hundred human molars were mounted in acrylic resin blocks and prepared until the dentin surface was exposed. The specimens were treated with one of four desensitizing agents: Bifluorid 12, Fluoridin, Thermoline and PrepEze. The remaining 20 specimens served as untreated controls. All groups were further divided into 2 subgroups in which a dual polymerized resin cement (Bifix QM) or a resin-modified glass ionomer cement (AVANTO) was used. The shear bond strength (MPa) was measured using a universal testing machine at a 0.5 mm/min crosshead speed. The data were analyzed statistically with a 2-way ANOVA, Tukey HSD test and regression analysis (alpha=0.05). The effect of the desensitizing agents on the dentin surface was examined by scanning electron microscopy. RESULTS: The fluoride-containing desensitizing agents affected the bond strength of the resin-based cements to dentin (p<0.001). PrepEze showed the highest bond strength values in all groups (p<0.001). CONCLUSION: Regression analysis showed a reverse relation between bond strength values of resin cements to dentin and the amount of fluoride in the desensitizing agent (p<0.05).
Assuntos
Cariostáticos/química , Colagem Dentária , Dessensibilizantes Dentinários/química , Adesivos Dentinários/química , Dentina/ultraestrutura , Fluoretos/química , Cimentos de Resina/química , Adesividade , Fluoreto de Cálcio/química , Resinas Compostas/química , Análise do Estresse Dentário/instrumentação , Fluoretos Tópicos/química , Cimentos de Ionômeros de Vidro/química , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Resistência ao Cisalhamento , Fluoreto de Sódio/química , Estresse Mecânico , Temperatura , Fatores de Tempo , Água/químicaRESUMO
OBJECTIVE: The objective of this study was to evaluate the effect of desensitizing agents containing different amounts of fluoride on the shear bond strength of a dual polymerized resin cement and a resin-modified glass ionomer cement (RMGIC) to dentin. MATERIAL AND METHODS: One hundred human molars were mounted in acrylic resin blocks and prepared until the dentin surface was exposed. The specimens were treated with one of four desensitizing agents: Bifluorid 12, Fluoridin, Thermoline and PrepEze. The remaining 20 specimens served as untreated controls. All groups were further divided into 2 subgroups in which a dual polymerized resin cement (Bifix QM) or a resin-modified glass ionomer cement (AVANTO) was used. The shear bond strength (MPa) was measured using a universal testing machine at a 0.5 mm/min crosshead speed. The data were analyzed statistically with a 2-way ANOVA, Tukey HSD test and regression analysis (α=0.05). The effect of the desensitizing agents on the dentin surface was examined by scanning electron microscopy. RESULTS: The fluoride-containing desensitizing agents affected the bond strength of the resin-based cements to dentin (p<0.001). PrepEze showed the highest bond strength values in all groups (p<0.001). CONCLUSION: Regression analysis showed a reverse relation between bond strength values of resin cements to dentin and the amount of fluoride in the desensitizing agent (p<0.05).
Assuntos
Humanos , Cariostáticos/química , Colagem Dentária , Dessensibilizantes Dentinários/química , Adesivos Dentinários/química , Dentina/ultraestrutura , Fluoretos/química , Cimentos de Resina/química , Adesividade , Fluoreto de Cálcio/química , Resinas Compostas/química , Análise do Estresse Dentário/instrumentação , Fluoretos Tópicos/química , Cimentos de Ionômeros de Vidro/química , Teste de Materiais , Microscopia Eletrônica de Varredura , Resistência ao Cisalhamento , Estresse Mecânico , Fluoreto de Sódio/química , Temperatura , Fatores de Tempo , Água/químicaRESUMO
Los cementos de vidrio ionómero (CVI) fueron introducidos en el mercado odontoestomatológico durante la década del setenta. Desde entonces, tanto su empleo como sus variaciones, mejoras e indicaciones han ido aumentando año tras año. Una de las características más importantes de los cementos de vidrio ionómero es la liberación de flúor, cualidad que no es superada actualmente por ningún otro material de restauración o cementado. A pesar de su frecuente empleo y su carácter preventivo gracias a esta propiedad, el mecanismo de liberación y de recarga de flúor, así como su efecto anticariogénico, no son totalmente conocidos, por lo que se siguen realizando múltiples e interesantes investigaciones a este respecto (AU)
Assuntos
Cimentos de Ionômeros de Vidro/química , Fluoretos/química , Restauração Dentária Permanente/instrumentação , Cimentos Cermet/química , Resinas Compostas/química , Cimentos de Ionômeros de Vidro/classificação , Cárie Dentária/terapia , Fluoreto de Cálcio/químicaRESUMO
Enamel specimens from unerupted third molars were treated with the supernatant of monofluorophosphate (MFP)-containing toothpaste slurries in water. Calcium fluoride-like particles were formed on the enamel surface during a 24-h exposure. The globules were soluble in alkali. More particles were seen on enamel treated with a toothpaste containing both MFP and NaF. The experiments showed that the calcium fluoride-like material formed on enamel after treatment with MFP-containing toothpaste probably originates from the free fluoride present in the pastes. The relatively moderate deposition of fluoride may be of clinical significance because the teeth are so frequently exposed to toothpaste. No firmly bound fluoride was found on treatment of enamel with MFP-containing toothpaste.
Assuntos
Fluoreto de Cálcio/farmacocinética , Esmalte Dentário/metabolismo , Fluoretos/administração & dosagem , Fluoretos/farmacocinética , Fosfatos/administração & dosagem , Cremes Dentais , Adsorção , Fluoreto de Cálcio/análise , Fluoreto de Cálcio/química , Esmalte Dentário/química , Esmalte Dentário/ultraestrutura , Fluoretos/análise , Fluoretos/química , Humanos , Hidróxidos , Microscopia Eletrônica de Varredura , Fosfatos/química , Compostos de Potássio , Fluoreto de Sódio/administração & dosagem , SolubilidadeRESUMO
The uptake of alkali-soluble fluoride (calcium fluoride-like material and adsorbed fluoride) and alkali-insoluble fluoride (apatitically bound fluoride) on sound human enamel from treatment with Duraphat or a neutral 2% NaF solution was investigated in vitro. Blocks from impacted third molars were used. More fluoride was deposited on the enamel from the neutral 2% NaF solution than from the Duraphat treatment. All the fluoride could be dissolved in alkali. Globules of calcium fluoride-like material were demonstrated by scanning electron microscopy. Chemical analysis showed no measurable increase in the apatitically bound fluoride (alkali-insoluble fluoride) after brief exposures. Duraphat-treated samples submerged in water after the exposure lost only about 50% of the deposited fluoride, whereas samples treated with 2% NaF are known to lose all their fluoride under similar circumstances, a condition which may be related to the favorable clinical effect of Duraphat.