Cochrane on fluoride toothpaste concentrations (2019): 1,000 ppm and up is where the evidence is, and above 1,500 ppm the gain stops

What it says#

Cochrane Oral Health updated its 2010 review of fluoride toothpaste concentrations and published the result in March 2019. The reviewers included 96 studies published between 1955 and 2014, with searches current to 15 August 2018, and sorted them by dentition: 7 studies with 11,356 randomized participants on the primary dentition with toothpaste up to 1,500 ppm; 1 study with 2,500 randomized participants on the primary and permanent dentition at 1,450 ppm; 85 studies with 48,804 randomized participants on the immature permanent dentition with toothpaste up to 2,400 ppm; and 3 studies with 2,675 randomized participants on the mature permanent dentition with toothpaste up to 1,100 ppm. Follow-up in most studies was 36 months.

The centerpiece is a network meta-analysis of 81 studies covering 21 comparisons of 7 fluoride concentrations, with decayed, missing and filled surfaces in the permanent dentition of children and adolescents as the outcome. The reviewers judged most of that network low certainty, with four exceptions they name. There was high-certainty evidence that 1,000 to 1,250 ppm fluoride toothpaste reduces caries increments compared with non-fluoride toothpaste (standardized mean difference -0.28; 95% CI, -0.32 to -0.25; 55 studies) and moderate-certainty evidence for the same comparison at 1,450 to 1,500 ppm (SMD -0.36; 95% CI, -0.43 to -0.29; 4 studies). There was moderate-certainty evidence that 1,450 to 1,500 ppm slightly reduces caries increments compared with 1,000 to 1,250 ppm (SMD -0.08; 95% CI, -0.14 to -0.01; 10 studies). And there was moderate-certainty evidence that caries increments are similar for 1,700 to 2,200 ppm and for 2,400 to 2,800 ppm when compared with 1,450 to 1,500 ppm (SMD 0.04; 95% CI, -0.07 to 0.15, indirect evidence only; and SMD -0.05; 95% CI, -0.14 to 0.05; 2 studies).

Below 1,000 ppm the picture is thinner. In the network, 250 ppm versus non-fluoride gave an SMD of -0.15 (95% CI, -0.25 to -0.05) on 3 studies at low certainty, and 440 to 550 ppm versus non-fluoride gave -0.12 (95% CI, -0.31 to 0.07) on 2 studies at low certainty, a difference that does not exclude no effect.

In the primary dentition of young children, 1,500 ppm fluoride toothpaste reduces caries increment compared with non-fluoride toothpaste (mean difference -1.86 dfs; 95% CI, -2.51 to -1.21; 998 participants, 1 study, moderate certainty). The head-to-head of 1,055 against 550 ppm was similar (MD -0.05 dmfs; 95% CI, -0.38 to 0.28; 1,958 participants, 2 studies, moderate certainty), while 1,450 ppm slightly reduced dmft increment compared with 440 ppm (MD -0.34; 95% CI, -0.59 to -0.09; 2,362 participants, 1 study, moderate certainty). The rest of that comparison was low certainty. In adults, 1,000 or 1,100 ppm fluoride toothpaste reduced DMFS increment compared with non-fluoride toothpaste (MD -0.53; 95% CI, -1.02 to -0.04; 2,162 participants, 3 studies, moderate certainty); the DMFT evidence was low certainty. Only a minority of studies assessed adverse effects; when reported, effects such as soft tissue damage and tooth staining were minimal.

The reviewers' conclusion is two-sided. A dose-response effect was observed for D(M)FS in children and adolescents, and the review supports the benefits of fluoride toothpaste over non-fluoride toothpaste. But for many comparisons of different concentrations the caries-preventive effects and the reviewers' confidence in those estimates are uncertain and could be challenged by further research, and the choice of concentration for young children should be balanced against the risk of fluorosis.

Who it applies to#

Everyone the practice sells or recommends a toothpaste to. The review's plain-language summary describes the retail landscape it is judging: the typical strength of regular or family toothpaste is around 1,000 to 1,500 ppm fluoride, many other strengths are available worldwide, there is no minimum fluoride concentration, and the maximum permissible concentration varies according to age and country, with higher concentrations rarely available over the counter and classed as prescription-only medicine.

It does not cover professionally applied fluoride, water fluoridation or supplements. For those, see the ADA's 2013 topical fluoride guideline and the AAPD's fluoride therapy best practice, which also sets the toothpaste amount by age. It also stops below the prescription band: the highest concentration in the network is 2,400 to 2,800 ppm, so the 5,000 ppm (1.1% sodium fluoride) paste that the ADA's 2018 nonrestorative guideline prioritizes for root surface lesions is outside the range this review compared.

What changed#

This is an update of the Cochrane review first published in January 2010. The update adds the network meta-analysis, which is what makes the head-to-head concentration ladder possible: 81 studies, 21 comparisons, 7 concentrations, and a certainty rating on every rung. That is why the practical answer is sharper than it was, and why the useful finding is a ceiling as much as a floor. Going from non-fluoride to 1,000 ppm is the step with the most evidence behind it; going from 1,500 ppm to 2,800 ppm is a step the evidence says is not there.

Where the source is#

The link under the title opens the full review as deposited at PubMed Central, which was read for this entry, including the abstract, the plain-language summary, the authors' conclusions and the summary-of-findings table for the network meta-analysis, from which every effect estimate, study count and certainty rating above is taken. The published version on the Cochrane Library is subscription-limited and refused automated access when checked, so no link to it is listed here. The review is Walsh and colleagues, Cochrane Database of Systematic Reviews 2019, Issue 3, CD007868, and it updates the version first published in January 2010.