Is the use of topical fluoride during early childhood associated with mottling of teeth?

Child brushing teeth with adult

Authors: May Chun Mei Wong, Rui Zhang, Bella Weijia Luo, Anne-Marie Glenny, Helen V Worthington, Edward Chin Man Lo 

Topical fluoride as a cause of dental fluorosis in children*  

Review question 

Is the use of topical fluoride during early childhood associated with mottling of teeth? 

Key messages

There is some evidence that higher levels of fluoride (1000 parts per million (ppm) or more) in toothpaste given to children from 1 to 2 years of age are associated with an increased risk of dental fluorosis (mottling/discolouration) in permanent teeth.

There is inconclusive evidence on the risk of having dental fluorosis in permanent teeth with regard to when children should start toothbrushing, the amount of toothpaste used, and the frequency of toothbrushing.

What is dental fluorosis (mottling)?

Previous research has indicated that the use of toothpaste containing fluoride can prevent tooth decay. However, young children exposed to too much fluoride while their teeth are developing may end up with dental fluorosis in the permanent teeth. Fluorosis can be seen as white stripes, streaks, larger opaque patches, brownish discolouration, pitting, or rupture on permanent teeth.

What did we want to find out?

In this updated review, we wanted to know if more well‚Äźdesigned studies have been published recently to determine if the use of topical fluoride during early childhood is associated with the mottling of permanent teeth.

What did we do?

We searched for studies that explored the association between various topical fluoride exposures in young children (such as the age at which they started toothbrushing, frequency of brushing, and concentration of fluoride toothpaste used) and their risk of having fluorosis in their permanent teeth. We compared and summarized the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.

What did we find?

We found a total of 43 studies published between 1988 and 2022, involving 32,181 children. The age range of the children at the time of the assessment of fluorosis was 6 to 18 years. The studies varied in how they were conducted: 3 were experimental studies and 40 were observational studies. The studies were conducted in Australia, Belgium, Brazil, Canada, Colombia, Germany, India, Ireland, Mexico, Norway, Poland, Sweden, Thailand, the UK, and the USA.

Main results

The fluorosis identified in most of the studies was considered to be mild fluorosis.

We could not tell if the risk of having fluorosis in the permanent teeth is associated with when a child starts receiving topical fluoride varnish applications and toothbrushing with fluoride toothpaste, the amount of toothpaste used by the child, or the frequency of toothbrushing.

Toothbrushing with toothpaste with a fluoride concentration of 1000 ppm or more from 1 to 2 years of age is likely to be associated with an increased chance of developing dental fluorosis in permanent teeth.

What are the limitations of the evidence?

Often, we had little confidence in the evidence due to the methods used within the included studies.

Sometimes the studies' reporting of the type of fluoride, the frequency of toothbrushing, and the amount of toothpaste used was poor, and we were unable to determine if the exposure to fluoride occurred before the children were 6 years old. We did not include these studies in the analysis, so some evidence may have been missed out.

How up to date is this evidence?

This review updates our previous review. The evidence is current to July 2022.

*This is a plain language summary of a review that is published in the Cochrane Library. You can find the full report of the review here: