Liquid iron supplements can cause noticeable, though usually temporary, discoloration on teeth. This cosmetic side effect is common, especially with liquid supplements given to infants and young children for iron deficiency. Staining occurs when the iron formulation comes into direct contact with the tooth surface during administration. The dark stains result from a chemical reaction in the mouth, creating a superficial deposit on the outer layer of the tooth structure.
The Chemical Process of Iron Staining
The mechanism of tooth staining by liquid iron is rooted in a simple chemical reaction that takes place in the oral environment. Iron salts, especially ferrous sulfate, react with compounds naturally present in the mouth. The primary culprits are hydrogen sulfide and other sulfur-containing compounds. These compounds are produced by the metabolic activity of oral bacteria found in the pellicle and plaque on the tooth surface.
When the liquid iron mixes with saliva and encounters these sulfur compounds, an insoluble dark-colored substance called iron sulfide is formed. This iron sulfide readily adheres to the dental enamel, resulting in the characteristic black or dark brown extrinsic stain. Some iron formulations can also contain or create iron oxide, which contributes to the discoloration. Because the staining is extrinsic, it does not involve a change to the internal structure of the tooth.
Techniques for Preventing Stains
Preventing iron stains involves minimizing the contact time and concentration of the supplement on the teeth during administration.
Administration Techniques
- Use a straw for older children and adults, ensuring the liquid bypasses the front teeth and is delivered toward the back of the mouth.
- For infants or toddlers, use a dropper or syringe to place the dose directly onto the back of the tongue or inside of the cheek, away from the newly erupted teeth.
- Dilute the liquid iron with water or juice to reduce the concentration of staining agents.
- Use vitamin C-rich juices, like orange juice, for dilution, as the vitamin can enhance iron absorption (avoid dairy products as they inhibit absorption).
Post-Dosing Care
Immediately after taking the supplement, rinsing the mouth thoroughly with water is important to wash away residual iron particles. For infants, gently wiping the teeth and gums with a soft, moist cloth or gauze pad achieves the same goal. Brushing the teeth shortly after dosing is also a strong preventative measure to remove the iron before the staining reaction can fully set.
Addressing Existing Iron Stains
If stains have already developed, gentle home care methods can sometimes lighten mild discoloration. Brushing the teeth with a regular fluoride toothpaste twice daily helps manage surface stains. Occasionally using a paste made from baking soda and water provides a mild abrasive action that can lift the discoloration. Aggressive or excessive brushing should be avoided, as this can potentially damage the enamel.
Persistent, dark, or widespread stains typically require professional intervention to remove completely. A dental professional can effectively remove these extrinsic iron stains through prophylaxis. This procedure often involves using a low-speed handpiece with a rotary brush and a specialized polishing paste to buff the stains away. The stains are cosmetic and generally reversible once the iron supplementation regimen is complete or modified.