Abstract
Fluoride is widely believed to be a useful chemical substance for preventing dental caries. However, the mechanism underlying crystal perforation in the tooth enamel and the effect of fluoride on hard tissues are unclear. To clarify the mechanism of the biological action of fluoride in the mineralization process, we examined the hard tissues of rats having received water containing a relatively low fluoride level. Electron microscopy revealed that fluoride ions could interrupt the crystal nucleation process, resulting in crystal perforation in the developing tooth enamel and the presence of amorphous minerals in bone crystals. Furthermore, the results of enzymatic analyses indicated that fluoride directly interfered with the synthesis of carbonic anhydrase by the enamel-forming cells, rather than being directly involved in the crystal formation. From the results, we would like to provide a possible mechanism of crystal perforation in the enamel induced by fluoride intake. Also, we would like to suggest that regardless of its amount, fluoride intake has harmful effects on both tooth and bone formation.
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Fluoride affects enamel protein content via TGF-B1-mediated KLK4 inhibition
Dental fluorosis is caused by chronic high-level fluoride (F-) exposure during enamel development, and fluorosed enamel has a higher than normal protein content. Matrix metalloproteinase 20 cleaves enamel matrix proteins during the secretory stage, and KLK4 further cleaves these proteins during the maturation stage so that the proteins can be
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Fluoride induced endoplasmic reticulum stress and calcium overload in ameloblasts
OBJECTIVE: The aim of the study was to evaluate the involvement of endoplasmic reticulum stress and intracellular calcium overload on the development of dental fluorosis. METHODS: We cultured and exposed rat ameloblast HAT-7 cells to various concentrations of fluoride and measured apoptosis with flow cytometry and intracellular Ca2+ changes using confocal
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Micromolar fluoride alters ameloblast lineage cells in vitro.
Fluorosed enamel is caused by exposure to fluoride during tooth formation. The objective of this study was to determine whether epithelial ameloblast-lineage cells, derived from the human enamel organ, are directly affected by micromolar concentrations of fluoride. Cells were cultured in the presence of fluoride, and proliferation was measured by
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Uncoupling protein-2 is an antioxidant that is up-regulated in the enamel organ of fluoride-treated rats
Dental fluorosis is characterized by subsurface hypomineralization and retention of enamel matrix proteins. Fluoride (F-) exposure generates reactive oxygen species (ROS) that can cause endoplasmic reticulum (ER)-stress. We therefore screened oxidative stress arrays to identify genes regulated by F- exposure. Vitamin E is an antioxidant so we asked if a
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Protective effect of lycopene on fluoride-induced ameloblasts apoptosis and dental fluorosis through oxidative stress-mediated Caspase pathways
Fluoride is an environmental toxicant and induces dental fluorosis and oxidative stress. Lycopene (LYC) is an effective antioxidant that is reported to attenuate fluoride toxicity. To determine the effects of LYC on sodium fluoride (NaF) -induced teeth and ameloblasts toxicity, rats were treated with NaF (10 mg/kg) and/or LYC (10 mg/kg) by
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Mechanisms by Which Fluoride Causes Dental Fluorosis Remain Unknown
When it comes to how fluoride impacts human health, no tissue in the body has been studied more than the teeth. Yet, despite over 50 years of research, the mechanism by which fluoride causes dental fluorosis (a hypo-mineralization of the enamel that results in significant staining of the teeth) is not
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Dental Fluorosis Is a "Hypo-mineralization" of Enamel
Teeth with fluorosis have an increase in porosity in the subsurface enamel ("hypomineralization"). The increased porosity of enamel found in fluorosis is a result of a fluoride-induced impairment in the clearance of proteins (amelogenins) from the developing teeth. Despite over 50 years of research, the exact mechanism by which fluoride impairs amelogin
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"Pre-Skeletal" Fluorosis
As demonstrated by the studies below, skeletal fluorosis may produce adverse symptoms, including arthritic pains, clinical osteoarthritis, gastrointestinal disturbances, and bone fragility, before the classic bone change of fluorosis (i.e., osteosclerosis in the spine and pelvis) is detectable by x-ray. Relying on x-rays, therefore, to diagnosis skeletal fluorosis will invariably fail to protect those individuals who are suffering from the pre-skeletal phase of the disease. Moreover, some individuals with clinical skeletal fluorosis will not develop an increase in bone density, let alone osteosclerosis, of the spine. Thus, relying on unusual increases in spinal bone density will under-detect the rate of skeletal fluoride poisoning in a population.
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Diagnostic Criteria for Dental Fluorosis: The TSIF ("Total Surface Index of Fluorosis")
The traditional criteria (the "Dean Index") for diagnosing dental fluorosis was developed in the first half of the 20th century by H. Trendley Dean. While the Dean Index is still widely used in surveys of fluorosis -- including the CDC's national surveys of fluorosis in the United States -- dental
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Racial Disparities in Dental Fluorosis
In 2005, the Centers for Disease Control published the results of a national survey of dental fluorosis conducted between 1999 and 2002. According to the CDC, black children in the United States have significantly higher rates of dental fluorosis than either white or Hispanic children. This was not the first time that black children were found to suffer higher rates of dental fluorosis. At least five other studies -- dating as far back as the 1960s -- have found black children in the United States are disproportionately impacted by dental fluorosis.
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