Is fluoride application safe?

This is the 3157th article of Da Yi Xiao Hu

The previous article in this magazine has discussed the necessity of fluoride application. Today's article will talk about whether fluoride application is safe.

Because excessive intake of fluoride in the body can indeed cause fluorosis, the public has always been concerned about whether they should use fluoride-containing health products to prevent moths. How to eliminate this concern is a key issue that must be addressed in the process of actively promoting fluoride moth prevention measures. Is it really safe to apply fluoride to prevent moths?

How to solve the problem of fluoride poisoning?

Whether it is systemic fluoride application - drinking fluoridated water, etc., or local fluoride application - using fluoride toothpaste, etc., to ensure that fluoride poisoning will not occur, it is necessary to adhere to the bottom line of fluoride use - the amount of fluoride entering the body.

When fluoride is used systemically, it must enter the body completely. Different methods of addition have different standards for fluoridation levels, such as the standard for drinking water fluoridation is 0.7-1.0 ppm. The optimal intake dose of fluoride is 0.05-0.07 mg/kg/d, and its potential toxic dose (PTD) is 5 mg/kg.

Under normal circumstances, topical fluoride should not be ingested, but special circumstances should be considered. When children use fluoride toothpaste, because the toothpaste may be swallowed, the original topical fluoride may eventually evolve into "systemic fluoride" (just an accident, not the original intention, so the anti-caries effect cannot be discussed in this regard). Therefore, the fluoride content (controlled by the manufacturer) and the amount of use (controlled by the guardian) of children's toothpaste must be strictly limited.

For example, a 2-year-old child weighing 15 kg will ingest 0.2 mg of fluoride if he brushes his teeth twice a day with a "grain of rice"-sized toothpaste and swallows all the toothpaste. This is a dose of 0.013 mg/kg. If the same child brushes his teeth twice a day with a "pea"-sized toothpaste and swallows all the toothpaste, he will ingest 0.5 mg of fluoride, a dose of 0.033 mg/kg. Compared with the former, the latter more than doubles the amount of fluoride entering the body. Given that beverages, foods, toothpaste, supplements, topical applications, etc. can all be potential sources of fluoride and that there is a risk of fluorosis during the tooth development stage, the American Dental Association (ADA) recommends using a "grain of rice"-sized toothpaste from the first tooth eruption to the age of 3, and then a "pea"-sized toothpaste for children aged 3 to 6.

Can fluoride-containing coatings avoid the risk of entering the body?

As a form of topical fluoride application, fluoride coatings do not normally enter the body. For most people, fluoride coatings are feasible for two reasons:

1. Fluoride coatings can harden and solidify quickly, thus adhering tightly to the tooth surface, so the risk of absorption into the body is low;

2. Because fluoride-containing paint has a high fluoride concentration, the amount used in one operation is very small. Although the amount used varies from person to person due to the number of teeth, usually 0.3 to 0.5 ml is enough and will not exceed 1 ml.

Some researchers have measured the plasma fluoride level of patients after fluoride application and found that it is far below the recognized toxic level. Therefore, fluoride application is considered to be a preventive measure with the least side effects and high safety.

But there are exceptions to everything. If fluoride paint is swallowed by mistake, and the fluoride concentration is quite high, it is indeed more likely to cause fluoride poisoning. Therefore, although theoretically you can try fluoride coating from the time the first tooth erupts, in practice you should make a reasonable choice based on the risk of tooth decay in infants and young children and their compliance (degree of cooperation with the dentist). After all, there is a difference between whether or not to apply fluoride and whether you can apply it.

Other advantages of fluoride coating

1. Simple operation and low cost

The specific operation process of fluoride coating includes the following steps:

① Cleaning, that is, using a toothbrush to clean the surface of the teeth to remove the dirt on the surface of the teeth - dental plaque and food residues, which is conducive to the effect of fluoride coating, but some studies have shown that this step can be omitted;

② Drying, that is, use cotton rolls to keep the teeth moist and then use cotton swabs, cotton rolls or air guns to remove excess moisture in the patient's mouth, but strict drying is not required;

③ Fluoride coating, that is, using a disposable small brush or cotton swab to apply fluoride coating to the exposed tooth surface (lip/cheek surface, tongue/palate surface and occlusal surface), and the adjacent tooth surface needs to be coated with fluoride using dental floss. The whole process is a rubbing and brushing operation, which is a non-invasive operation, which is another manifestation of its safety.

2 No discomfort, easy to accept

This is the advantage of fluorine-containing coatings over fluorine-containing foams.

Disadvantages of fluoride coating

There are two main disadvantages to fluoride coating: first, it may cause tooth discoloration. However, this is only temporary and helps the dentist to confirm that every tooth has been treated; second, fluoride coating may cause gum burning when it comes into contact with the gums, and can also cause allergic reactions, so it is not recommended for people with bleeding gums.

Precautions after fluoride application

(1) You can close your mouth immediately, or drink warm water or rinse your mouth normally with warm water;

(2) It is best not to eat food within 4 hours, or only eat soft food, because hard food may wear the paint;

(3) Do not brush your teeth on the day of fluoride application, as brushing may remove the coating.

Author: Shanghai Health and Health Development Research Center

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