What does fluoride do to our teeth?

Fluoride has long been considered our ultimate weapon against cavities. Its precious virtues in inhibiting harmful bacteria and remineralizing teeth have made it an essential part of good oral hygiene. However, if consumed in excess, it can damage our teeth and lead to enamel defects.

In this article, we will break down the effects of fluoride on our mouths and teeth, the ways you can receive it, its toxicity potential, and the alternatives available.

What is fluoride?

Fluoride comes from fluorine, one of the most abundant minerals in nature. It is most commonly found near volcanic rocks, water sources, and in the form of gas.

The average daily intake of fluoride depends on age and gender. You can get it from different sources, including water, toothpaste, and certain foods such as fish and green tea.

When you ingest fluoride, 40% gets into hard tissues (bones and teeth), 1% into soft tissues, and the rest is eliminated from your body (through urine, sweat, and feces).

Although there is no evidence of its role in growth and development, it is well known to strengthen teeth and prevent cavities.

How can fluoride benefit your teeth?

To better understand what fluoride does to your teeth, we must first look at the demineralization/remineralization cycle.

What is the demineralization/remineralization cycle?

the demineralization and remineralization cycle

After a sugary meal, the bacteria in your mouth break down the sugar and release acid. This causes a spike in acidity in your mouth that lasts for about 30 minutes. During this time, the minerals in your teeth react with the acid and break down, causing what we call demineralization.

After 30 minutes, under the influence of saliva, the acidity gradually decreases and the teeth regain the lost minerals. This is called remineralization.

If you brush your teeth regularly and take care of your oral hygiene, this cycle works well and your teeth stay healthy. However, if you neglect your oral hygiene, harmful bacteria in your mouth will take over and form what is called plaque. This can break the cycle and lead to tooth decay.

What does fluoride do?

the benefits of fluoride in our teeth

When you consume fluoride, some of it is absorbed by the enamel, the outermost layer of the tooth, giving it extra strength and resistance.

Our teeth are made up of crystals called hydroxyapatite. When fluoride binds to the surface of the enamel, the hydroxyapatite crystals turn into fluorapatite, which is more resistant to acid attack and prevents the tooth from losing its minerals.

In addition, some of the fluorides you ingest bind to plaque and soft tissue in your mouth. When acidity increases, this fluoride is released, which promotes remineralization and reduces demineralization.

Fluoride is also toxic to cariogenic bacteria (which cause tooth decay). Furthermore, fluoride prevents the accumulation of dental plaque, thus reducing the risk of dental caries.

As well as being a preventive tool, fluoride can actually treat early cavities. These are also known as early white spots and represent the initial stage of tooth decay. Fluoride has been shown to reverse these lesions and prevent them from progressing.

How to get fluoride?

the different sources of fluoride

There are different sources of fluoride. The most common way to get it depends on the country you live in. For example, if you are in the United States, the United Kingdom, or Switzerland, you are likely to have access to fluoridated water.

In 2018, 73.0% of the US population on community water systems, or 207,426,535 people, had access to fluoridated water. Other sources include fluoridated milk, salt, and flour.

If you do not get enough fluoride during the day, your dentist may prescribe fluoride supplements (such as tablets or drops). They are known to have an anti-cavity effect, especially in children.

You can also benefit your teeth from fluoride by using topical fluoridated oral hygiene products such as toothpaste, mouthwashes, and gels. Some highly concentrated products, such as varnishes, can only be applied by your dentist in the dental office due to the high risk of ingestion and toxicity.

Certain foods, such as tea and sea fish, are rich in fluoride and can also be an excellent source.

When can fluoride be harmful?

To get the most out of fluoride, it needs to be in your mouth constantly and in small amounts. At high doses, potential side effects can occur. There are two forms of fluoride poisoning.

The first is when you take in too much fluoride at once. This can cause vomiting and damage to the liver, kidneys, and nervous system.

The second and more common form is when you take in large amounts of fluoride over a long period. This can lead to dental and skeletal fluorosis (damage to bone and tooth structure).

The maximum daily amount of fluoride that is unlikely to cause adverse health effects is 10 mg daily. If we look at the concentrations in our primary sources of fluoride, fluoridated water does not exceed 1 mg/l. As for toothpaste, the typical amount used per brushing is about 1.3 mg.

Therefore, the average individual intake is well below the limit. However, as a precaution, avoid ingesting the toothpaste and do not use highly concentrated supplements such as gels and tablets without consulting your dentist first.

When using toothpaste, ensure the fluoride content does not exceed 1500 ppm. Toothpaste with higher concentrations has a higher risk of toxicity and must be approved by your dentist.

Are there alternatives to fluoride?

While fluoride can strengthen enamel and prevent cavities, in high amounts, it can be toxic and cause serious complications. For this reason, you must use it cautiously without swallowing the product.

To overcome this side effect, a new mineral has emerged that can compete with fluoride. It is known as hydroxyapatite, which is a biocompatible mineral found naturally in our teeth and bones.

Toothpaste containing hydroxyapatite instead of fluoride can help remineralize teeth by providing a source of calcium and phosphate, which are the building blocks of enamel.
The idea is that hydroxyapatite can help rebuild tooth enamel, making it stronger and more resistant to cavities, all without toxicity or side effects.


In conclusion, fluoride is an essential mineral for our teeth and oral health. It helps fight tooth decay by remineralizing our teeth and preventing bacteria and plaque from building up. However, overconsumption can have adverse effects. Therefore, it is important to be aware of the fluoride sources and to limit exposure to excessive amounts. By understanding the effects of fluoride on our teeth and how to use it correctly, we can maximize its benefits and minimize its risks.