Dose-response relationship between toothpaste soluble fluoride absorbed in the gastrointestinal tract and saliva fluoride secretion

Aim: This study aimed to evaluate if there is a dose-response relationship between toothpaste chemically soluble fluoride absorbed in the gastrointestinal tract and fluoride secreted by saliva, giving support to the use of saliva as surrogate for plasma fluoride. Methods: A 4-phase single blind study was conducted, in which 10 participants were subjected in each phase to one of the assigned treatment groups: group I: fresh sample of a Na2FPO3/CaCO3-based toothpaste with 1,334 µg F/g of total soluble fluoride (TSF) and groups II­IV: aged samples of this toothpaste presenting TSF concentrations of 1,128, 808, and 687 µg F/g, respectively. In all phases, the participants ingested an amount of toothpaste equivalent to 70.0 µg F/Kg body weight, as total fluoride (TF). Saliva and blood samples were collected before (baseline) and up to 180 min after toothpaste ingestion as indicator of fluoride bioavailability. F concentration in saliva and blood plasma was determined with a fluoride ion-specific electrode. The areas under the curve (AUC) of F concentration versus time (AUC = ng F/mL × min) and the peaks of fluoride concentration (Cmax) in saliva and plasma were calculated. Results: A significant correlation between mg of TSF ingested and the AUC (r=0.47; p<0.01), and Cmax (r=0.59; p<0.01) in saliva was found; for TF, the correlation was not significant (p>0.05). In addition, the correlations between plasma and saliva fluoride concentrations were statistically significant for AUC (r=0.55; p<0.01) as for Cmax (r=0.68; p<0.01). Conclusion: The findings support that saliva can be used as a systemic biomarker of bioavailable fluoride present in Na2FPO3/CaCO3-based toothpaste

Fluorosis in rats exposed to oscillating chronic fluoride doses

Considering that blood fluoride concentration varies according to fluoride exposure and that dental fluorosis is related to the amount of enamel formed under a given fluoride dose, the present study investigated whether the fluorosis produced by an oscillating chronic fluoride dose would be similar to that caused by exposure to a constant dose, representing the mean of the oscillation during a given time. Rats received during 78 days water with fluoride concentrations of 0, 12.5, 25 or 37.5 µg F/mL, or oscillating concentrations of 12.5 and 37.5 µg F/mL every 72 h (mean exposure=25 µg F/mL). The concentrations of fluoride in the plasma, femur and incisors of the rats were determined at the end of the experimental period. Also, the enamel dental fluorosis index was determined in the incisors using a quantitative method developed by our research group named Dental Fluorosis by Image Analysis (DFIA). Fluoride concentrations in plasma, femur and teeth, and DFIA increased linearly for constant fluoride concentrations in water (p<0.0001, r values=0.87-0.98). The results of the oscillating group and the groups receiving 25 µg F/mL did not differ significantly (p>0.05). The findings of this study suggest that in animals chronically exposed to symmetrically oscillating fluoride doses, the resulting dental fluorosis reflects the metabolic effect of the mean of the oscillating doses.

Considerando que a concentração de fluoreto no sangue varia de acordo com a exposição ao fluoreto, e que a fluorose dental está relacionada com a quantidade de esmalte formado sob determinada dose de fluoreto, este estudo avaliou se a fluorose resultante da exposição a doses oscilantes de fluoreto seria semelhante àquela causada pela exposição a uma dose constante, representativa da média das oscilações durante um determinado tempo. Durante 78 dias, ratos receberam água com concentrações constantes de fluoreto de 0; 12,5; 25 ou 37,5 µg F/mL, ou concentrações oscilantes de 12,5 e 37,5 µg F/mL alternados a cada 72 h (média de exposição = 25 µg F/mL). Concentrações de fluoreto no plasma, fêmur e dentes incisivos dos ratos foram determinadas após o período experimental. O índice de fluorose, observado nos incisivos dos ratos, foi quantificado usando um método de análise de imagem desenvolvido para essa pesquisa, denominado de índice de fluorose por análise de imagem (DFIA, em Inglês). A concentração de fluoreto no plasma, fêmur e incisivo dos ratos, assim como o DFIA, aumentaram de forma linear para as concentrações constantes de fluoreto na água (p<0,0001, r=0,87-0,98). Não houve diferença significativa entre o grupo que recebeu doses oscilantes e o grupo que recebeu 25 µg F/mL (p>0,05). Os resultados sugerem a fluorose dental decorrente de exposição crônica de animais a doses de fluoreto oscilantes e simétricas reflete o efeito metabólico da média da oscilação.

Renal functions and serum fluoride concentrations in chronic renal failure patients after sevoflurane or isoflurane anaesthesia

Sevoflurane is metabolised to hexa-fluoro-isopropanol and inorganic fluoride ions by human liver. The peak plasma fluoride level is higher after sevoflurane than after isoflurane. Although this has no effect on renal functions in normal patients and volunteers, it might be risky on those with chronic renal insufficiency. In this study, 60 patients with stable chronic renal insufficiency who required surgical intervention were randomly allocated into one of two groups each of 30 patients; sevoflurane and isoflurane groups. We compared the renal functions [serum creatinine, urea, osmolality, sodium and urine osmolality] and the serum inorganic fluoride levels afler sevoflurane to those after isoflurane anaesthesia. Peak serum inorganic fluoride concentrations were significantly higher after sevoflurane than after isoflurane anesthesia [26 +/- 3 Vs 14 +/- 2 um/L]. Laboratory measures or renal functions remained stable throughout the postoperative period in both groups. No patient suffered a permanent renal damage of preexisting renal insufficiency and non required postoperative dialysis. There is no evidence that the increased fluoride levels after sevoflurane worsened the preexisting renal impairment. We concluded that the increase in serum inorganic fluoride after sevoflurane to levels as seen in this study are of little risk to patients with chronic renal insufficiency. Further studies to evaluate the effect of compound A on the renal functions on those chronic renal impairment patients are required

Haemodynamic, early recovery and renal function effects of desflurane anasesthesia in renal transplant

Twenty adult patients scheduled for liver related renal transplant with ASA physical status III were randomly allocated into two groups; desflurane and isoflurane, each of 10 patients. All patients were optimized pre-operatively by haemodialysis, homeostasis and control of all reversible pathological parameters as high blood pressure, blood sugar and serum electrolytes. They were given midazolam i.m. premedication and received either desflurane or isoflurane in N2O/O2-fentanyl during inaintenance. Atracurium in mcremental doses was given as a muscle relaxant. Full haemodynamic monitoring started in the pre-anaesthesia room and continue perioperatively every 3min NIBP, 5-chest leads ECG, CVP [every 5-10 min], HR., Sp O2, end-t-CO2 and neuromuscular transmission. Patients were ventilated to normocarbic with a closed circuit using soda lime. Anaesthesia and operative times were recorded as well as recovery parameters times. Urine was examined for organic and inorganic fluorides and blood inorganic fluorides was measured also [at 0. 4, 24, 72h] and I, as well as full renal functions and urine volume and osmolarity were measured [at 0, 4, 24 and 192 h]. There was a significant early recovery in desflurane than isoflurane group, Heamodynamically there were no significant differences between the two groups although the response to surgical stimulation was better controlled in desflurane than isoflurane groups. Renal function was markedly improved after transplantation without significant differences between groups. There was a slight insignificant increase of serum inorganic and urinary organic and inorganic fluorides in isoflurane than desflurane groups. The low solubility and very minimal metabolism of desflurane make it a safe and reliable inhalational anaesthetic agent compared to isoflurane specially in high risk patients as renal transplant patients

Un nuevo método para determinar excreción urinaria de fluoruro a nivel comunitario en preescolares / A new method for determining fluoride urinary excretion in preschool children population

En este estudio se estableció que existe una correlación lineal (r=0.94, p < 0.001), entre la excreción urinaria diaria de fluoruro y el cuociente de concentraciones de fluoruro y creatinina (Q), de una muestra única, matinal de orina, en 42 niños preescolares que viven en comunidades con agua no fluorada y con agua óptimamente fluorada. La facilidad y rapidez de los análisis bioquímicos que son necesarios para determinar el valor del cuociente Q, simplifican la estimación, a nivel comunitario, de la excreción urinaria promedio de un número representativo de muestras únicas de orinas matinales de niños preescolares. El método propuesto, puede resultar útil para proveer un estimador de ingesta diaria promedio de fluoruro de comunidades infantiles, en aquellos casos en que las autoridades sanitarias tengan que adoptar decisiones sobre la implementación de medidas colectivas de fluoración sistémica, minimizando el riesgo de fluorosis del esmalte dental. Los parámetros de la regresión obtenida para la excreción de fluoruro diario concuerdan con los de un trabajo previo. Con el fin de mostrar la potencialidad del método propuesto, se analizan en este trabajo los diferentes valores de la relación Q obtenidos en dos comunidades chilenas con aguas no fluoradas

Comparison of plasma inorganic fluoride concentration with sevoflurane-N2O and enflurane-N2O anesthesia

Plasma inorganic fluoride concentrations were measured in adult patients without hepatic or renal disease following sevoflurane-N2O anesthesia (n = 7) or enflurane-N2O anesthesia (n = 6). The anesthetic dosage of sevoflurane and enflurane was 6.48 +/- 2.15 %-hours and 6.57 +/- 2.50 %-hours, respectively. The mean peak plasma inorganic fluoride concentration in the sevoflurane group was 19.5 +/- 13.4 mumol/L 1 hour after anesthesia, which decreased to preanesthetic levels 24 hours after anesthesia. In the enflurane group the values were 13.2 +/- 5.8 mumol/L at the end of anesthesia and decreased, but remained, still twice as high as the preanesthetic level 24 hours after anesthesia. The relationship of plasma inorganic fluoride concentration and anesthetic dosage was more pronounced in the sevoflurane group (r = 0.68, slope = 4.2) than in the enflurane group (r = 0.39, slope = 1.2). In conclusion, sevoflurane-N2O anesthesia results in similar subnephrotoxic levels of plasma inorganic fluoride as enflurane-N2O anesthesia, and although the fluoride concentration had a better correlation to anesthetic dosage in the sevoflurane group than in the enflurane group, its excretion was faster in the sevoflurane group than in the enflurane group.

Placental transfer of fluoride in pregnant women consuming optimum fluoride in drinking water.

The study was conducted on 25 healthy women residing in optimum fluoride areas, who were to deliver normally through vaginal route, to correlate the maternal and cord plasma fluoride levels and evaluate the placental transfer of fluoride. A wide variation was found in the maternal and cord plasma fluoride levels. In only 8 percent of the cases the fluoride levels in cord plasma were higher than maternal plasma. It was deduced that the placenta allows passive diffusion of fluoride from mother to foetus and does not act as a barrier.