If your child is having problems with their teeth, then your dentist may suggest that they give some or all of your child's teeth a fluoride varnish. While you agree that your child needs treatment, you may worry about the effects of adding extra fluoride. For example, you may have heard that too much fluoride can create a condition known as fluorosis. This condition discolours the teeth by affecting their enamel coverage.

However, fluorosis tends to cause damage while enamel is being formed rather than after it is in place. Fluoride varnishes aren't likely to cause this kind of problem if they are administered by a dentist. Fluoride varnishes may, however, change the colour of your child's teeth, at least temporarily. Why does this happen and what can you do about any colour changes?

How Fluoride Varnishes Affect Teeth Colour

A fluoride varnish is usually used on teeth that are in danger of developing problems with decay. The varnish gives the teeth a fluoride boost that strengthens the teeth and gives them some extra protection against potential problems.

When your dentist applies a fluoride varnish, they paint a gel onto a tooth or multiple teeth. This gel contains a concentration of fluoride. The varnish sets extremely quickly and coats the teeth once it has set. This can change the colour of the teeth. For example, some varnishes dry into a yellow shade, so your child's teeth may look less white than usual.

Even if your dentist uses a white fluoride varnish, it won't dry white. It won't yellow the teeth, but it may make them look a little duller than usual.

How to Deal with Varnish Colour Changes

While a fluoride varnish sets on the teeth, it doesn't stay in place permanently. It gives the teeth prolonged exposure to fluoride, but the coating wears off over time. Often, you'll see the colour of your child's teeth change back to normal as soon as they brush their teeth again. It may take a few brushes for the varnish to come off completely, but it won't leave a permanent colour change.

Your family dentist can fill you in on how this colour-change process works. Bear in mind that your dentist may ask your child not to brush their teeth for a few hours after the varnish is applied. Your child may not like the colour change, but you should encourage them to follow your dentist's schedule to make sure the varnish has time to work.