Fluoride Uptake

The issue of rinsing versus not rinsing and the effect on fluoride uptake – a review

For many patients, rinsing after brushing with dentifrice is common, whether with water or a fluoridated mouth rinse. An important question is whether rinsing with water reduces fluoride uptake, and whether this remains the case with a fluoridated mouth rinse, or whether the fluoride contained in the mouth rinse is sufficient to ensure fluoride uptake.

Rinsing with water has been shown to increase the level of caries. Four studies have reported the caries increment to be higher in people who reported rinsing with large volumes of water after brushing compared with those who used little or no water. The difference in caries increment across these studies ranged from 6% to 16%. Three studies reported that the difference was statistically significant – the more thorough the rinse, the greater the caries increment. Such studies have led to recommendations to spit out excess toothpaste and avoid rinsing with (excessive) water after brushing.1

The issue of a fluoridated mouth rinse is more complex. Mouth rinses have more actions than merely supplying fluoride – ingredients of different products variously include chlorhexidine, essential oils, triclosan, cetylpyridinium chloride, sanguinarine, sodium dodecyl sulphate and metal ions (read more about the composition of mouth rinses here). Mouth rinses containing fluoride have the largest body of scientific evidence supporting their anticaries efficacy and health benefits.1

Duckworth demonstrated in 2009 that the inclusion of 100 ppm fluoride in a mouth rinse compensated for the loss of oral fluoride due to rinsing. The authors concluded that rinsing with a 100 ppm fluoride mouth rinse soon after brushing with a standard fluoride toothpaste should not interfere with the toothpaste’s anticaries protection. However, rinsing with a non-fluoride mouth rinse soon after brushing with standard fluoride toothpaste may reduce the anticaries protection provided by brushing with a fluoride toothpaste.1

To maintain the anticaries benefit of brushing with a standard fluoride toothpaste, a mouth rinse should therefore contain at least 100 ppm fluoride if it is to be used soon after brushing. The ‘wash-out phenomenon’ that impacts on the benefit of the fluoride toothpaste is thus avoided.1


  1. Pitts N et al. Post-brushing rinsing for the control of dental caries: exploration of the available evidence to establish what advice we should give our patients. Br Dent J 2012; 212(7): 315–320.