Is the fluoride level in drinking water a gold standard for the control of dental caries?

AIM: To obtain baseline knowledge of levels of dental caries in 12-year-old children residing in areas with varying levels of fluoride in drinking water in Pakistan; and to observe a dose-response relationship between the prevalence of dental caries at different concentrations of fluoride in drinking water. METHOD: Clinical examination of children and analysis of samples of drinking water. RESULTS: The maximum reduction of caries in relation to fluoride levels in Pakistan was witnessed between the fluoride concentrations of 0.00-0.33ppm. CONCLUSIONS: There are no gold standards for setting up a universal optimal level of fluoride in drinking water and each country needs to determine the concentration of fluoride in their drinking water in accordance with its socio-economic and climatic conditions, dietary and oral hygiene habits of its population, and local research to determine how much fluoride is beneficial in the control of caries.     

Retrospective detection of exposure to nerve agents: analysis of phosphofluoridates originating from fluoride-induced reactivation of phosphylated BuChE

The utility was explored of a new approach to detect retrospectively exposure to nerve agents by means of conversion of the inhibitor moiety bound to the active site of the enzyme BuChE in plasma with fluoride ions into a phosphofluoridate which is subsequently analyzed by means of gas chromatography (GC). This quantifies >or=0.01% inhibition of BuChE and identifies the structure of the inhibitor except for the original leaving group. A three-tiered approach was followed involving the five classical nerve agents GA, GB, GF, GD, and VX, as well as the active metabolite of parathion, i.e., paraoxon: in vivo experiments in rhesus monkeys after iv administration of a sign-free dose of agent and concomitant in vitro experiments in plasma of rhesus monkeys and humans should allow an assessment of in vivo retrospectivity in humans. A systematic investigation was performed in order to find a single set of reaction conditions which yields a maximum amount of phosphofluoridate for all nerve agents. Fluoride-induced reactivation at 25 degrees C at a final concentration of 250 mM KF during 15 min in a pH-range between 4 and 6 appears to be effective. The in vitro decrease with time in reactivatibility of inhibited BuChE in plasma from humans and rhesus monkeys was largely due to aging of the phosphyl moiety, except for VX where spontaneous reactivation was a major cause. The decrease followed first-order except for a biphasic course in the case of GF in human and rhesus monkey plasma as well as of GD in rhesus plasma. In vitro half-lifes in human plasma ranged between ca. 14 h for GB and ca. 63 h for GA. A comparison of the in vivo data from rhesus monkeys and the in vitro data is complicated by the observation that the in vivo decrease with time of fluoride-reactivated phosphofluoridate is biphasic for all nerve agents. The terminal in vivo phase pertains to a small fraction of the amount of initially regenerated phosphofluoridate but is responsible for a considerable degree of retrospectivity, ranging between 14 and 56 days for GF and GB, respectively. The new procedure can be used in a variety of practical applications, e.g., (i) biomonitoring in health surveillance at exposure levels that are several orders of magnitude lower than presently possible; (ii) diagnosis in case of alleged exposure to nerve agents in time of war or after terrorist attacks; (iii) in forensic cases against suspected terrorists that have handled organophosphate anticholinesterases; and (iv) in research applications such as investigations on lowest observable effect levels of exposure to nerve agents.     

The effect of fluoride on the scavenging of organophosphates by human butyrylcholinesterase in buffer solutions and human plasma

Fluoride ion is a reversible inhibitor of human butyrylcholinesterase (HuBChE) that is a viable drug candidate against organophosphates (OPs) toxicity. Since large numbers of communities in many countries are occasionally exposed to relatively high amount of fluoride, its effect on the kinetics of inhibition of HuBChE by OPs was investigated. In saline phosphate, pH 7.4, fluoride in the lower millimolar range significantly slowed the inhibition of HuBChE by paraoxon, DFP, echothiophate, soman, sarin, and VX. The kinetics of the inhibition was found consistent with the formation of a reversible fluoride-HuBChE complex that is at least 25-fold less active towards phosphorylation or phosphonylation than the free enzyme. Heat inactivation experiments indicate that the binding of fluoride to HuBChE probably involves enhanced cross-domain interaction via hydrogen bonds formation that may decrease enzyme activity. In spite of distinct structural differences among the OP used, the dissociation constants of the fluoride-HuBChE reversible complex varied over a narrow range (KF, 0.31-0.70 mM); however, KF in human plasma increased to 2.75-3.40 mM. 19F-NMR spectroscopy revealed that fluoride ion is complexed to plasma components, an observation that explains in part the apparent increase in KF. Results suggest that an estimate of the relative decrease in the rate of OPs sequestration in presence of fluoride can be obtained from the fraction of the free HuBChE (1 + [F]/K(F))(-1). Considering KF values in human plasma, it is concluded that the scavenging efficacy of OPs by HuBChE is not compromised by the normal concentration range of circulating fluoride ions.     

Fluoride content of alcoholic beverages

Background: In view of the conflicting reports of the extent and severity of dental caries in alcohol misusing subjects, a systematic survey of the fluoride content of alcoholic beverages was undertaken. Results: The fluoride content of beverages varied widely particularly if non-UK European products were considered. Conclusions: Beers brewed in locations with high fluoride water levels may contribute significantly to the daily fluoride intake, particularly in alcohol misusing subjects and this may contribute to alcohol-associated bone disease.     

氟对体内和体外酶活性的影响

目的 探讨氟对抗氧化活性的影响。方法 随机选择氟暴露工人20名、健康的非氟暴露工人15名,测量尿氟含量,外周血AKP、SOD、GSH－Px活性及Cu、Zn、Ca、Mg离子含量。另随机选择健康非氟暴露者10名,抽取静脉血,分离血清,均加入氟化钠,使反应体系中氟浓度分别达到0、2．63、10．52和21．04mmol/L;室温下反应30min后,测定AKP、SOD和GSH－Px活性。结果 氟暴露工人尿氟、血清AKP、全血GSH－Px活性高于非氟暴露者,而血精SOD活性和Cu、Zn、Ca、Mg含量低于非氟 暴露者。体外加氟实验显示,氟浓度21．04mmol/L组AKP活性高于对照组,而SOD和GSH－Px活性低于对照组。结论 氟可致抗氧化酶活性改变。     

Is fluoride treatment justified today?

Fluoride has been used for the treatment of osteoporosis since 1961, because it increases trabecular bone mass in the spine and may be effective in the treatment of spinal osteoporosis. Fluoride treatment is still controversial because of its side effects, the high rate of non-responders, possible osteomalacic effect on bone, deleterious effects on cortical bone, and especially because of its uncertain effect on fracture rate. At present, fluoride therapy is highly questionable in the prophylaxis and treatment of osteoporosis.     

电极法测氟的△mv值守恒定律

1989年,我们报告了采用添加固定量的标准氟所得△mv值计算样品氟含量的方法。本文介绍此方法中的一项新定律——△mv值守恒定律,描述如下:若用蒸馏水将测定体系作数倍稀释,则在一定条件下不论测定体系的液量多少,只要其中氟量恒定,其△mv值总是保持同样(或很相近)值,例如,当测定体系含氟10μg时,其液量在3～32ml范围内所得△mv值为16.3～16.7,其中3～17ml范围内△mv值基本上为恒值,同时从数学上进行了论证。     

Odontoblast transport of sulphate--the in vitro influence of fluoride

The present study reports the development of a culture system for the analysis of 35S-sulphate release from odontoblasts in vitro. Pulpless longitudinally split rat incisors were cultured in supplemented minimum essential medium (alphaMEM) with 20 microCi 35S-sulphate per ml, 20 microCi 3H-mannitol per ml for 1h. Teeth were then transferred to fresh unlabelled media and aliquots of media were removed and the level of 35S-sulphate 3H-mannitol determined. Results indicated a two phase release of 35S-sulphate into the media, and comparison with pulp tissue indicated a specific release pattern. Transport of sulphate is essential for correct synthesis and glycosylation of macromolecules such as proteoglycans (PG). Previous studies have shown that post-translational modifications of these proteins can be influenced by excess fluoride, resulting in decreased sulphation and elongation of glycosaminoglycan (GAG) chains. Therefore the influence of fluoride on sulphate transport, using the optimised culture system was also investigated. Inclusion of 6mM fluoride during pulse labelling caused a significant decrease of 35S-sulphate (P<0.0001) during the initial release phase. Inclusion of 3 and 6mM fluoride only in the post-labelling incubation media resulted in a significant decrease in the release of 35S-sulphate (P<0.0001), during the total time course. The influence of fluoride was not dose dependent. Inclusion of a specific chloride channel blocker SITS, into the culture system indicated that 35S-sulphate transport may in part be via this route. Fluoride would therefore appear to influence the transport of 35S-sulphate across the odontoblast membrane, potentially via a chloride channel.     

氟化物的分析方法进展

综述了近10年来对饮水、食品、牙膏及化妆品等样品中氟化物的测定方法及其适用性。离子选择电极法简便、快速且仪器价格低廉,可测定水中氟化物低达5.26×10-6mol/L。氟试剂分光光度法引用乙酰丙酮为掩蔽剂,提高了灵敏度、精密度和准确度。离子色谱法可同时测定尿中F-和I-,且F-在100～1500μg/L之问呈线性关系。     

Fluoride-induced disruption of reproductive hormones in men

Fluoride-induced reproductive effects have been reported in experimental models and in humans. However, these effects were found in heavily exposed scenarios. Therefore, in this work our objective was to study reproductive parameters in a population exposed to fluoride at doses of 3-27 mg/day (high-fluoride-exposed group-HFEG). Urinary fluoride levels, semen parameters, and reproductive hormones in serum (LH, FSH, estradiol, prolactin, inhibin-B, free and total testosterone) were measured. Results were compared with a group of individuals exposed to fluoride at lower doses: 2-13 mg/day (low-fluoride-exposed group-LFEG). A significant increase in FSH (P<0.05) and a reduction of inhibin-B, free testosterone, and prolactin in serum (P<0.05) were noticed in the HFEG. When HFEG was compared to LFEG, a decreased sensitivity was found in the FSH response to inhibin-B (P<0.05). A significant negative partial correlation was observed between urinary fluoride and serum levels of inhibin-B (r=-0.333, P=0.028) in LFEG. Furthermore, a significant partial correlation was observed between a chronic exposure index for fluoride and the serum concentrations of inhibin-B (r=-0.163, P=0.037) in HFEG. No abnormalities were found in the semen parameters studied in the present work, neither in the HFEG, nor in the LFEG. The results obtained indicate that a fluoride exposure of 3-27 mg/day induces a subclinical reproductive effect that can be explained by a fluoride-induced toxic effect in both Sertoli cells and gonadotrophs.