Fluoride Basics and Applications

Fluoride Basics

• Fluoride is the most electronegative and reactive element.
• It reacts with all elements.
• It's not found free in nature.
• Difficult to isolate.
• Cannot be stored in glass or silicon environments.
• Found in nature as fluorine salts (fluorides).
• Commonly found in volcanic areas, groundwater, and near seawater.
• Present in water, soil, rocks, air, food, drinks, plants, animals, and living tissues.
• Mostly found in tea, tobacco, and fish.

Fluoride in Industry

• Used in metal alloy melting.
• Used as an electrolyte in aluminum synthesis.
• Used in Teflon and high-hardness plastic production.
• Sodium fluoride is a pesticide and insecticide.
• Hydrofluoric acid (HF) is used to etch glass (e.g., light bulbs).
• Calcium fluoride (CaF2) is used to make lenses for infrared light.
• Fluoride combines with carbon to form fluorocarbons, used in AC and refrigerators.

Fluoride Metabolism

• 75-90% of oral fluoride is absorbed by the GI system, directly into the blood.
• Absorption is primarily via passive diffusion.
• Highest plasma concentration occurs within 20-60 minutes.
• Excreted through urine and feces.
• High levels of calcium or other cations (Fe, Al, Mg, Na, K) can impede fluoride absorption in the stomach (due to insoluble compound formation).

Fluoride in Plasma

• Two forms exist: ionic (inorganic) and organic.
• Ionic form: unbound to protein or other plasma components.
• Organic form: complex forms, predominantly bound to proteins.
• Plasma fluoride levels directly correlate to levels in hard and soft tissues.
• Fluoride concentration slowly increases with age (organic fluoride).

Fluoride Distribution in Tissues

• 99% is in calcified tissues (bone, cartilage, teeth, tendons, nails, hair).
• 50% of daily fluoride intake in adults binds to calcified tissues within 24 hours.
• Remainder is excreted.
• In children, fluoride fixation in hard tissues can be up to 65% (higher bone and tissue development).
• Fluoride binds strongly to apatite but the binding isn't irreversible (dissolves during resorption-apposition mechanisms).

Fluoride Metabolism: Additional Factors

• Nutritional status and diet: Fluoride absorption increases on an empty stomach, reduced by foods with fluoride-binding substances (e.g., calcium).
• Acid-base disorders: Excretion delayed due to drugs, metabolic/respiratory issues affecting body balance.
• Renal disorders (kidney issues): Delays excretion and may cause enamel hypoplasia in children.
• Altitude and physical activity effect urinary pH and excretion.
• Circadian rhythm and hormones: Influence plasma fluoride levels.

Fluoride Toxicity: Acute

• Lethal Dose: Proportional to body weight (32-64 mg F/kg or 0.07-0.14 g NaF/kg).
• Symptoms depend on amount, age, and weight.
• High intake speed is another important factor.
• Potential sources include industrial inhalation, ingestion of soluble compounds (contaminated water/food/poisons), and topical fluoride applications.
• Early signs include nausea, abdominal cramps, vomiting, diarrhea, increased salivation, and dehydration.
• Severe cases involve muscle contractions, cardiac arrest, loss of consciousness, and coma (death without intervention).

Fluoride Toxicity: Chronic (Fluorosis)

• Chronic, long-term, low-dose exposure.
• Called fluorosis.
• Severity dependent on exposure duration, frequency, and individual age.
• Affects all calcified tissues.
• Skeletal fluorosis: Painful joint issues, movement limitations, osteosclerosis, osteoporosis, thickened hip bones, and other related findings.
• Dental fluorosis: Discoloration, pitting, and/or structural defects in teeth.
• Fluorosis risk increased in areas with high fluoride levels (volcanic areas, industrial zones).
• Pathological skeletal fluorosis requires 10-25mg/day fluoride for 10-20 years (variable).

Fluoride in Saliva and Oral Environment

• Saliva fluoride concentration increases after fluoride intake (2-5%).
• Oral cavity fluoride level will remain elevated.
• Fluoride absorption is faster if the oral environment has more fluoride.

Fluoride Effect Mechanisms

• Fluoride helps prevent demineralization and aids remineralization.
• Promotes enamel hardening and inhibits bacterial metabolism/enzyme activity in plaque, thus preventing acid production.
• Fluoride acts as a reservoir to counteract acid attacks.
• Fluoride replaces hydroxyl groups in hydroxyapatite contributing to more resistant teeth.
• Fluoride ions can be adsorbed into tooth enamel.

Explore the essential properties and applications of fluoride in various fields. This quiz covers fluoride's chemistry, its role in industry, and its metabolism in the human body. Test your knowledge on this fascinating and reactive element!