Effects of treatment with fluoride on bone mineral density and fracture risk - A meta-analysis

The Osteoporosis Clinic, Department of Endocrinology and Metabolism C, Aarhus University Hospital Aarhus Amtssygehus, Tage Hansens Gade 2, 8000 Aarhus C, Denmark.
Osteoporosis International (Impact Factor: 4.17). 03/2008; 19(3):257-68. DOI: 10.1007/s00198-007-0437-6
Source: PubMed


Fluoride has fallen into discredit due to the absence of an anti-fracture effect. However, in this meta-analysis, a fracture reducing potential was seen at low fluoride doses [< or =20 mg fluoride equivalents (152 mg monofluorophosphate/44 mg sodium fluoride)]: OR = 0.3, 95% CI: 0.1-0.9 for vertebral and OR = 0.5, 95% CI: 0.3-0.8 for non-vertebral fractures.
Fluoride is incorporated into bone mineral and has an anabolic effect. However, the biomechanical competence of the newly formed bone may be reduced.
A systematic search of PubMed, Embase, and ISI web of science yielded 2,028 references.
Twenty-five eligible studies were identified. Spine BMD increased 7.9%, 95% CI: 5.4-10.5%, and hip BMD 2.1%, 95% CI: 0.9-3.4%. A meta-regression showed increasing spine BMD with increasing treatment duration (5.04 +/- 2.16%/year of treatment). Overall there was no significant effect on the risk of vertebral (OR = 0.8, 95% CI: 0.5-1.5) or non-vertebral fracture (OR = 0.8, 95% CI: 0.5-1.4). With a daily dose of < or =20 mg fluoride equivalents (152 mg monofluorophosphate/44 mg sodium fluoride), there was a statistically significant reduction in vertebral (OR = 0.3, 95% CI: 0.1-0.9) and non-vertebral (OR = 0.5, 95% CI: 0.3-0.8) fracture risk. With a daily dose >20 mg fluoride equivalents, there was no significant reduction in vertebral (OR = 1.3, 95% CI: 0.8-2.0) and non-vertebral (OR = 1.5, 95% CI: 0.8-2.8) fracture risk.
Fluoride treatment increases spine and hip BMD, depending on treatment duration. Overall there was no effect on hip or spine fracture risk. However, in subgroup analyses a low fluoride dose (< or =20 mg/day of fluoride equivalents) was associated with a significant reduction in fracture risk.

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    • "Fluoride-containing glasses are of particular interest owing to their ability to form fluorapatite, which exhibits better chemical stability than fluoride-free apatites [2]. Fluoride has well documented antibacterial properties [3], and in low concentrations fluoride ions increase bone mass and mineral density [4]. Furthermore , fluoride-containing bioactive glasses enhance osteoblast proliferation, differentiation and mineralization [5]. "
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    ABSTRACT: Five bioactive glass compositions in the SiO2-P2O5-CaO-Na2O-CaF2 system (0 – 32 mol% CaF2) and Bioglass® 45S5 were evaluated for their apatite forming ability in serum-free and serum-containing cell culture media for up to seven days. While F- ions in low concentrations were found to enhance apatite formation, higher fluoride content caused formation of fluorite and calcite. The presence of serum proteins delayed apatite precipitation for all compositions, while Bioglass® 45S5, despite considerably higher phosphate content (2.6 vs. ≤ 1.1 mol% P2O5) and high concentrations of Ca2+ and PO43- in solution, formed only amorphous calcium phosphate.
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    • "The products used in the prevention of tooth decay (Stephen 1994) and in osteoporosis treatments constitute another major source of chronic ingestion of fluoride (Vestergaard et al. 2008). In the case of osteoporosis treatment, although the doses have been decreased substantially, about 10–20 mg of fluoride are ingested daily, 10–20 times more than the amounts ingested with drinking water. "
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    ABSTRACT: Daily intake of water with fluoride concentration higher than 1.5 mg l-1 produces insulin resistance. On the other hand, physical activity increases insulin sensitivity in the muscle. Therefore, the aim of this study was to evaluate the effect of physical activity on insulin resistance in rats treated with chronic ingestion of sodium fluoride (NaF). Sprage Dawley rats were divided into three groups (n=10 per group): Control (drinking water without NaF), NaF (drinking water with NaF 15 mg l-1 for 30 days) and Exercise (daily running on a treadmill during 60 minutes at 2,25 m min-1 and drinking water with NaF 15 mg l-1 for 30 days). Insulin resistance was evaluated with HOMA-IR index using fasting plasma levels of glucose and insulin. Insulin resistance increased in animals treated with 15 mg l-1 NaF in drinking water. A decrease in insulin resistance was observed in rats that performed physical activity and drank water with 15 mg l-1 NaF, also exercise group showed an increase in the amount of bone fluoride. The variation in the HOMA-IR values could be consequence of variation in the sensibility of tissues to insulin or decrease in plasma fluoride levels due to bone fluoride intake. These findings indicate that the performance of daily physical activity could reduce the negative effects of the chronic ingestion of NaF on glucose homeostasis.
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    • "Another occasionally observed condition (due to the long half-life of fluoride in bone) for individuals exposed to elevated fluoride intake, is fluorosis (Tamer et al 2007, Wang et al 2007). Different approaches by nations to the issues surrounding fluoride in drinking water have been described (Khandare et al 2005, Li et al 2001, Vestergaard et al 2008). Fluorine accumulated in the skeleton interacts with bone by displacing the hydroxide content of the bone mineral. "
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    ABSTRACT: Fluorine is an element that can be either beneficial or harmful, depending on the total amount accumulated in the teeth or bones. In our laboratory, we have developed a non-invasive technique for the in vivo measurement of fluoride in bone using neutron activation analysis and performed the first pilot human study. Fluoride in humans is quantified by comparing the γ-ray signal from a person to the γ-ray signal obtained from appropriate anthropomorphic calibration phantoms. An identified problem with existing fluoride phantoms is contamination with aluminum. Aluminum creates an interfering γ-ray signal which, although it can be subtracted out, increases the uncertainty in the measurement and worsens the detection limit. This paper outlines a series of studies undertaken to develop a better calibration phantom for fluorine measurement, which does not have aluminum contamination.
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