Fluoride toothpastes of different strengths for preventing tooth decay

Review question
This review has been produced to assess the effects of toothpastes of different fluoride strengths on preventing tooth decay in children, adolescents and adults.

Background
Tooth decay (caries) is a widespread disease, affecting billions of people worldwide. Fluoride has long been used to prevent decay, through a variety of different methods including toothpaste, water, milk, mouthrinses, tooth gels and varnish. Regular toothbrushing is recommended to prevent decay and other oral diseases, and toothbrushing for 2 minutes twice daily with a fluoride toothpaste is generally recommended. The typical strength of regular or family toothpaste is around 1000 to 1500 parts per million (ppm) fluoride, but many other strengths are available worldwide. There is no minimum fluoride concentration, but the maximum permissible fluoride concentration for a toothpaste varies according to age and country. Higher concentrations are rarely available over the counter, and are classed as a prescription-only medicine. Stronger fluoride toothpaste may offer greater protection against decay but also increases the risk of fluorosis (enamel defects) in developing teeth. This is an update of the Cochrane Review first published in 2010.

Study characteristics
Authors from Cochrane Oral Health carried out this review and the evidence is current up to 15 August 2018. It includes 96 studies published between 1955 and 2014: seven studies with 11,356 randomised participants reported the effects of fluoride toothpaste up to 1500 ppm on the primary teeth; one study with 2500 randomised participants reported the effects of 1450 ppm toothpaste on the primary and permanent dentition; 85 studies with 48,804 randomised participants reported the effects of toothpaste up to 2400 ppm on the permanent teeth of children up to 18 years of age; and three studies with 2675 randomised participants reported the effects of up to 1100 ppm toothpaste on the permanent teeth of adults. Most studies assessed decay after participants had been using the toothpastes for 36 months.

Main results
We present below findings for which there is moderate- or high-certainty evidence.

In primary teeth of young children, brushing teeth with a toothpaste containing 1500 ppm fluoride reduced the amount of new decay when compared with non-fluoride toothpaste; the amount of new decay was similar with 1055 ppm compared with 550 ppm fluoride toothpaste; and there was a slight reduction in the amount of new decay with 1450 ppm toothpaste compared with 440 ppm fluoride toothpaste.

Eighty-one studies assessed the effects of different strengths of fluoride toothpaste compared against each other (seven different strengths in 21 combinations) in permanent teeth of children and adolescents. We found that there was less new decay when toothbrushing with toothpaste containing 1000 to 1250 ppm or 1450 to 1500 ppm fluoride compared with non-fluoride toothpaste, and that toothbrushing with 1450 to 1500 ppm fluoride toothpaste reduced the amount of new decay more than 1000 to 1250 ppm toothpaste. We found that there was a similar amount of new decay when children and adolescents used a toothpaste of 1700 to 2200 ppm or 2400 to 2800 ppm fluoride compared to 1450 to 1500 ppm toothpaste. The evidence for the effects of other strengths of toothpaste was less certain.

In permanent teeth of adults of all ages, 1000 or 1100 ppm toothpaste reduced decay compared with non-fluoride toothpaste.

Most studies did not measure harmful effects of toothpaste use, but when reported, effects such as soft tissue damage and tooth staining were minimal.

Certainty of the evidence
There is high-certainty evidence that toothpaste containing 1000 to 1250 ppm fluoride is more effective than non-fluoride toothpaste. There is moderate-certainty evidence for the other findings reported in 'Main results' above. For other toothpaste strengths compared against each other or against non-fluoride toothpaste, there are too few studies with too few participants to have any clarity about the effects.

Authors conclusions
There are benefits of using fluoride toothpaste at certain strengths to prevent tooth decay when compared with non-fluoride toothpaste. The stronger the fluoride concentration, the more decay is prevented. For many of the comparisons of different strengths of toothpaste, the findings are uncertain and could be challenged by further research. The choice of fluoride toothpaste for young children should be balanced against the risk of fluorosis.

Authors' conclusions: 

This Cochrane Review supports the benefits of using fluoride toothpaste in preventing caries when compared to non-fluoride toothpaste. Evidence for the effects of different fluoride concentrations is more limited, but a dose-response effect was observed for D(M)FS in children and adolescents. For many comparisons of different concentrations the caries-preventive effects and our confidence in these effect estimates are uncertain and could be challenged by further research. The choice of fluoride toothpaste concentration for young children should be balanced against the risk of fluorosis.

Read the full abstract...
Background: 

Caries (dental decay) is a disease of the hard tissues of the teeth caused by an imbalance, over time, in the interactions between cariogenic bacteria in dental plaque and fermentable carbohydrates (mainly sugars). Regular toothbrushing with fluoride toothpaste is the principal non-professional intervention to prevent caries, but the caries-preventive effect varies according to different concentrations of fluoride in toothpaste, with higher concentrations associated with increased caries control. Toothpastes with higher fluoride concentration increases the risk of fluorosis (enamel defects) in developing teeth. This is an update of the Cochrane Review first published in 2010.

Objectives: 

To determine and compare the effects of toothpastes of different fluoride concentrations (parts per million (ppm)) in preventing dental caries in children, adolescents, and adults.

Search strategy: 

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 15 August 2018); the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 7) in the Cochrane Library (searched 15 August 2018); MEDLINE Ovid (1946 to 15 August 2018); and Embase Ovid (1980 to 15 August 2018). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials (15 August 2018). No restrictions were placed on the language or date of publication when searching the electronic databases.

Selection criteria: 

Randomised controlled trials that compared toothbrushing with fluoride toothpaste with toothbrushing with a non-fluoride toothpaste or toothpaste of a different fluoride concentration, with a follow-up period of at least 1 year. The primary outcome was caries increment measured by the change from baseline in the decayed, (missing), and filled surfaces or teeth index in all permanent or primary teeth (D(M)FS/T or d(m)fs/t).

Data collection and analysis: 

Two members of the review team, independently and in duplicate, undertook the selection of studies, data extraction, and risk of bias assessment. We graded the certainty of the evidence through discussion and consensus. The primary effect measure was the mean difference (MD) or standardised mean difference (SMD) caries increment. Where it was appropriate to pool data, we used random-effects pairwise or network meta-analysis.

Main results: 

We included 96 studies published between 1955 and 2014 in this updated review. Seven studies with 11,356 randomised participants (7047 evaluated) reported the effects of fluoride toothpaste up to 1500 ppm on the primary dentition; one study with 2500 randomised participants (2008 evaluated) reported the effects of 1450 ppm fluoride toothpaste on the primary and permanent dentition; 85 studies with 48,804 randomised participants (40,066 evaluated) reported the effects of toothpaste up to 2400 ppm on the immature permanent dentition; and three studies with 2675 randomised participants (2162 evaluated) reported the effects of up to 1100 ppm fluoride toothpaste on the mature permanent dentition. Follow-up in most studies was 36 months.

In the primary dentition of young children, 1500 ppm fluoride toothpaste reduces caries increment when compared with non-fluoride toothpaste (MD -1.86 dfs, 95% confidence interval (CI) -2.51 to -1.21; 998 participants, one study, moderate-certainty evidence); the caries-preventive effects for the head-to-head comparison of 1055 ppm versus 550 ppm fluoride toothpaste are similar (MD -0.05, dmfs, 95% CI -0.38 to 0.28; 1958 participants, two studies, moderate-certainty evidence), but toothbrushing with 1450 ppm fluoride toothpaste slightly reduces decayed, missing, filled teeth (dmft) increment when compared with 440 ppm fluoride toothpaste (MD -0.34, dmft, 95%CI -0.59 to -0.09; 2362 participants, one study, moderate-certainty evidence). The certainty of the remaining evidence for this comparison was judged to be low.

We included 81 studies in the network meta-analysis of D(M)FS increment in the permanent dentition of children and adolescents. The network included 21 different comparisons of seven fluoride concentrations. The certainty of the evidence was judged to be low with the following exceptions: there was high- and moderate-certainty evidence that 1000 to 1250 ppm or 1450 to 1500 ppm fluoride toothpaste reduces caries increments when compared with non-fluoride toothpaste (SMD -0.28, 95% CI -0.32 to -0.25, 55 studies; and SMD -0.36, 95% CI -0.43 to -0.29, four studies); there was moderate-certainty evidence that 1450 to 1500 ppm fluoride toothpaste slightly reduces caries increments when compared to 1000 to 1250 ppm (SMD -0.08, 95% CI -0.14 to -0.01, 10 studies); and moderate-certainty evidence that the caries increments are similar for 1700 to 2200 ppm and 2400 to 2800 ppm fluoride toothpaste when compared to 1450 to 1500 ppm (SMD 0.04, 95% CI -0.07 to 0.15, indirect evidence only; SMD -0.05, 95% CI -0.14 to 0.05, two studies).

In the adult permanent dentition, 1000 or 1100 ppm fluoride toothpaste reduces DMFS increment when compared with non-fluoride toothpaste in adults of all ages (MD -0.53, 95% CI -1.02 to -0.04; 2162 participants, three studies, moderate-certainty evidence). The evidence for DMFT was low certainty.

Only a minority of studies assessed adverse effects of toothpaste. When reported, effects such as soft tissue damage and tooth staining were minimal.

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