Fluoride toothpaste

Does your dentist always remind you to use fluoride toothpaste? Many of us are aware of the  importance   of using an appropriate toothpaste but little do we know about the ingredients in the  toothpaste which protects our tooth from dental decay. There are several components in a  toothpaste which help in protecting the tooth:

1. Water

2. Abrasives: Examples of abrasives are aluminum hydroxide, calcium carbonate, calcium hydrogen phosphate, silica and hydroxyapatite. The abrasive has a polishing action and helps in removing plaque and debris from the tooth surface. It also removes stains on the tooth. Abrasives form almost 50% of the toothpaste.

3. Fluoride: Fluoride is the most important constituent of a toothpaste. The most common source of fluoride is sodium fluoride, but stannous fluoride and sodium monofluorophospate are also used. The recommended amount of fluoride in a toothpaste is 1300 to 1500 parts per million(full strength toothpaste). Most toothpastes in the United States has 1000 to 1100 parts per million fluoride. This dosage is lower in children’s toothpaste, and varies according to the risk factors of dental caries. Fluoride has the effect of protecting the tooth from dental decay and forming a much stronger tooth component.

The outermost layer of a tooth is known as enamel. It is composed of  calcium phosphate based crystalline mineral known as hydroxyapatite (HAP). In the presence of fluoride, fluoride is incorporated into the solid crystal lattice by ionic exchange, forming what is known as fluorohydroxyapatite (FAP). FAP is much harder than the naturally occurring HAP and stronger. It is also more resistant to the acid produced by oral bacteria, hence rendering the tooth less prone to dental decay.

When the outer surface of enamel is exposed to fluoride, calcium fluoride can also be formed. The calcium fluoride is precipitated on the enamel surface and acts as a source of fluoride ions. This acts as a barrier to demineralization. In acidic conditions, fluoride from calcium fluoride is released and this diffuses rapidly into the enamel, forming the much stronger and harder fluorohydroxyapatite, which is also more resistant to dental decay. It also increases the concentration of fluoride in the saliva. It promotes remineralization of tooth enamel in areas that have been demineralized, by favouring the precipitation of fluorohydroxyapatite from saliva.

In addition to forming harder,stronger,acid resistant enamel and promoting remineralization, fluoride also has antimicrobial property.

Fluoride inhibits a step in glycolysis, which slows down plaque metabolism. The rate of bacterial reproduction may be decreased leading to a reduction in rate of plaque growth and acid production.

4. Antibacterial agent: Example of an antibacterial agent used in toothpaste is triclosan, which helps in preventing bad breath and formation of calculus.

5. Flavourings such as pepperming, spearmint and wintergreen

6. Sugar alcohol such as xylitol, sorbitol

7. Strontion chloride: Reduces sensitivity

A pea sized toothpaste strip is sufficient to cleanse the whole dentition. The toothpaste has to be spit out once brushing is completed. This is because ingestion of large amounts of fluoride over a long period of time may cause toxicity. Fluoride toxicity is common in children as they have the tendency to swallow toothpaste, especially when it is fruity flavored and smells good. Children most commonly experience gastrointestinal distress, diarrhea, and vomiting with high levels of fluoride in the body system. Fluoride, when occurs in large amount in the body can also cause enamel mottling or ‘dental fluorosis’. The tooth appears mottled, brownish or yellowish in color. It appears chalky white in the early stages of fluorosis. This is because the fluoride is incorporated in the enamel layer during development. The resultant tooth structure, though aesthetically not pleasing, is much stronger and resistant to acid.