What's in your toothpaste, and are 'natural' pastes as good?

Fluoride: the active ingredient

A Cochrane review of 96 trials found that fluoride toothpaste prevents decay compared with fluoride-free paste: 1,000 to 1,250 ppm in children's permanent teeth (high-certainty), 1,000 to 1,100 ppm in adults, and 1,500 ppm in young children's baby teeth¹. An earlier Cochrane review of 74 trials found the effect grew with higher fluoride concentration, more frequent use and supervised brushing, and was not influenced by water fluoridation². The trade-off is fluorosis, a mild change in enamel from too much fluoride while teeth form. Moderate-certainty trials show lower-fluoride pastes (550 or 440 ppm) cause less of it in under-6s⁴. For the wider debate, see The Fluoride Debate.

The other ingredients

• Abrasives. These polish off stains, and their strength is rated by RDA (dentin) and REA (enamel). The two numbers can diverge sharply, so a single figure can mislead⁹.
• SLS. This foaming detergent matters mainly for people prone to recurrent mouth ulcers, for whom SLS-free paste helped in small trials^5,6.
• Charcoal. A literature review found insufficient evidence for its safety or efficacy claims¹⁰.
• Xylitol. Fluoride paste with 10% xylitol may cut decay by 13% versus fluoride alone, but the evidence is low-quality¹¹. See Xylitol.

Are "natural" pastes as good?

Herbal pastes cleaned plaque about as well as ordinary pastes in short trials, but the evidence is low-quality and measured plaque, not cavities¹². Hydroxyapatite is the exception: four in-situ trials found no significant difference from fluoride⁸; see Nano-Hydroxyapatite.

What to do

Pick a fluoride paste you will actually use every day. If you prefer a fluoride-free option, choose one with evidence, such as hydroxyapatite, and discuss your cavity risk with your dentist.

Fluoride and cavities

The newer Cochrane review covered 96 studies from 1955 to 2014. In children's permanent teeth, a network meta-analysis found 1,000 to 1,250 ppm fluoride reduced caries increments versus fluoride-free paste (standardized mean difference -0.28; 95% CI -0.32 to -0.25; 55 studies, high-certainty). Pastes of 1,450 to 1,500 ppm gave -0.36 (-0.43 to -0.29; four studies) and were slightly better than 1,000 to 1,250 ppm (-0.08; -0.14 to -0.01; 10 studies, moderate-certainty). In adults, 1,000 or 1,100 ppm lowered decayed and filled surfaces by 0.53 (0.04 to 1.02; 2,162 participants, moderate-certainty). In baby teeth, one study of 998 children found 1,500 ppm reduced decay increment by 1.86 surfaces (1.21 to 2.51). Few studies reported adverse effects, and those that did found soft-tissue damage and staining minimal¹. The older review pooled 70 trials in 42,300 children and found a 24% prevented fraction (21% to 28%)².

The fluorosis trade-off

A Cochrane review of 43 studies found that two randomized trials (1,968 children) showed lower-fluoride paste reduced fluorosis: 550 versus 1,000 ppm gave a risk ratio of 0.75 (0.57 to 0.99), and 440 versus 1,450 ppm gave 0.72 (0.58 to 0.89). Children who brushed with 1,000 ppm or more from age one or two to five or six probably had more fluorosis, mostly mild. Evidence on amount, frequency and starting age was low or very low certainty⁴. A systematic review found fluoride paste effective for high-risk children under 6, and that pea-sized amounts or more can cause mild fluorosis³.

Abrasivity

In a bovine-tooth study, four pastes with different enamel (REA) and dentin (RDA) values were brushed for 21,600 strokes. The paste with REA 244 and RDA 12 caused the most enamel wear (9.86 micrometres) but the least dentin wear (17.0), while one with REA 4 and RDA 100 caused the most dentin wear (166.7). The authors argued that both values should be declared on every tube⁹. This is a lab model, not a measure of wear in mouths.

Charcoal and SLS

A literature review screened 118 potentially eligible articles on charcoal products. Thirteen studied brushing with raw charcoal or soot, none met its inclusion criteria, and three reported harm such as more decay or enamel abrasion. Advertisements made unsubstantiated claims, including "oral detoxification"¹⁰. A systematic review of 11 studies, mostly in vitro, found charcoal pastes whitened less than alternatives and were more abrasive⁷. For SLS, four double-blind crossover trials (124 participants) found SLS-free paste lowered ulcer number, duration, episodes and pain, though more trials are needed⁵. In a 90-person randomized trial with 8-week phases, SLS-free paste did not reduce ulcer number or episodes but shortened ulcers and eased pain⁶. Neither shows SLS harms people without ulcers.

Xylitol and herbal pastes

A Cochrane review of 10 studies (5,903 participants) found that fluoride toothpaste with 10% xylitol may reduce decay by 13% (prevented fraction 0.13; 0.08 to 0.18; 4,216 children) versus fluoride alone. That result came from two studies by the same authors in the same population, so it is low-quality¹¹. A meta-analysis of 24 trials (1,597 adults) found herbal toothpaste about as effective as conventional toothpaste at reducing plaque in the short term, and better than fluoride-free paste, with low-quality evidence¹². Four small in-situ trials of hydroxyapatite versus fluoride found no significant differences in new or progressing lesions (risk ratio 0.98; 0.85 to 1.12), though lesion size and fluorescence measures did differ at six months, so the picture is not fully settled⁸.

Where the evidence is mixed

Three results cut across the headline. The SLS evidence is split: the pooled analysis says fewer ulcers, while a 90-person trial found only shorter, less painful ones^5,6. The xylitol benefit rests on two studies by one group¹¹. Herbal and hydroxyapatite pastes were compared mostly on plaque or early lesions over months, not on cavities over years^12,8. Fluoride is the opposite: dozens of long trials, with the main trade-off being mild fluorosis in young children^1,4.

Bottom line

Confidence 4 of 5. Fluoride's benefit is well established, and what you choose after that is mostly preference. Evidence for natural alternatives is thinner, and mostly measures plaque or early lesions rather than years of cavity prevention.