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(in the 21st century, it’s basically all of them)
When I first bought an electric toothbrush on the advice of a dentist in January 2000, its instructions had a clear warning not to use any toothpaste that contained a whitening agent, because this can damage enamel when used with an electric brush.
A search on PubMed finds a 2017 experiment in the “mega journal” PLoS One (Bizhang et al) called “Toothbrush abrasivity in a long-term simulation on human dentin depends on brushing mode and bristle arrangement” which concluded that using an electric brush with a whitening toothpaste is significantly worse than using a manual brush with a whitening toothpaste.
However, this was a study on teeth that had already been removed, and therefore could not account for natural processes that might limit or repair the damage in a living person. Also, they didn’t have time to repeat their test with a non-whitening toothpaste, to confirm it was the toothpaste at fault and not just the electric brush in their setup. Instead, they cited two studies on manual toothbrushes that had suggested the paste was more of a factor than the brush (Voronets et al 2008 “Controlled toothbrush abrasion of softened human enamel” found no difference between soft and hard bristles but some difference caused by the toothpaste, and Absi et al 1992 “the effect of toothbrushing and dietary compounds on dentine in vitro” found no damage when brushing without paste).
The 2017 study did mention a scale called the relative dentin abrasiveness (RDA) index, a number indicating how abrasive a particular toothpaste is to teeth. (The standard they cited, BS 5136:1981 “Specification for toothpastes”, which was subsequently withdrawn, actually said RDA stood for “radio-active dentine abrasivity” and there was a separate measure REA which stood for “radio-active enamel abrasivity” although dentine being softer than enamel became the main concern. The context shows that this radioactivity was introduced by the measuring method and was not a suggestion that toothpaste itself be radioactive, so it’s not surprising if the “R” got changed to “relative” just as NMR got changed to MRI to avoid unnecessary alarm.)
Very few toothpaste manufacturers print the RDA number on the packaging. They don’t even say “suitable for electric toothbrushes” like food manufacturers say “suitable for vegetarians”, so I was just avoiding any packet that had references to “whitens” or “whitening”, but nowadays it’s very difficult to find a toothpaste that doesn’t say this.
My strategy used to be “always buy Colgate Total” (preferably when the supermarket puts it on special offer) because I had been recommended that by a dentist. When they brought out variations of it, such as Colgate Total Whitening, I changed to insisting on Colgate Total *Original*, whose packaging looks too similar to the other versions of Colgate Total and under time pressure it’s easy to buy the wrong one by mistake. In 2014 Dr Mike Williamson of Texas published a PDF file called “Toothpaste Abrasiveness Ranked by RDA” which said the RDA of Colgate Total is 70, Colgate Total Whitening is 142 and Colgate Total Advanced Fresh is 160. (The toothpaste in the 2017 experiment was 150.) I don’t know if Colgate Total Advanced Fresh is the same thing as Colgate Total Active Fresh, and the PDF did not mention Colgate Total Advanced Deep Clean or Colgate Total Advanced Gum Care which were presumably brought out more recently, but this PDF did seem to support the strategy of sticking to Colgate Total Original.
But in the 2020s the packaging of Colgate Total Original started to say it “whitens teeth”, which caused me to wonder if the product had been changed. (Their previous packaging had simply said “Cavities, Tartar, Plaque, Enamel, Gum problems, Staining, Sensitive teeth, Bad breath” and they apparently forgot to add the word “treats” before these things, which could be a reason to change the wording but not to add in a reference to whitening.)
The packaging had a telephone number for questions, but it gave me a voice saying the number is out of service. Their website had a contact form with a highly JavaScript-dependent CAPTCHA which required both eyesight and a suitable browser (I couldn’t get it to work on the desktop and had to use a smartphone), but I was able to send a message, limited to 1000 characters. I got no reply for 6 weeks, and then I phoned the UK’s 195 disabled Directory Enquiries service and asked if there was a phone number registered for Colgate-Palmolive’s last known address in Guildford, and they gave me one (which turned out also to be listed on the website of the British Dental Industry Association), and the number was working and the switchboard put me through to Customer Services, where an operator was able to tell me that:
1. Yes the formula for Colgate Total Original has indeed been changed (and when I said it’s not really “original” if it’s been changed, she said they meant it’s the “plain” version),
2. yes the new version of the formula does have whitening properties,
3. they consider all their toothpastes to be usable with any brush, but they know some people are more concerned than others about the level of abrasion so they won’t print “suitable for” on the box, and
4. the customer services team didn’t have RDA numbers to hand, but they were able to take my email address for getting back to me.
A couple of hours later they sent me an email saying:
All Colgate toothpastes comply with the ISO standard RDA<250, measured according to the originally described method (Hefferren, 1976), thus are safe for normal daily use.
Using the terms in that message as search queries led me to ISO 11609, first published in December 1995 which is 4 years before I bought the toothbrush whose instructions warned me against using a whitening toothpaste. I didn’t check the date of those instructions—could the original author have been concerned because ISO 11609 had not yet been widely implemented at the time of printing? That could explain why a more recently-sold electric toothbrush did not come with this warning.
The ISO standard says in Section 4.5 (I checked the 2010 edition) “The abrasivity of the dentifrice [in other words the toothpaste] shall not exceed the following limits for dentine: 2.5 times that of the primary reference material, if using the procedure specified in Annex A” which is the American Dental Association method reported by J J Hefferren in 1976 “A laboratory method for assessment of dentrifrice [sic] abrasivity” that has an upper limit of 250 (the reference material is 100).
Dentist Pamela Maragliano-Muniz wrote in 2016 that there is no difference in the safety levels of toothpastes below RDA 250, including when used with “power toothbrushes” (I always call them electric toothbrushes but whatever), which can actually make it safer if the brush moves less “aggressively” than we’d do by hand. She cited (among other things) a paper from 2010 in the Journal of Clinical Dentistry and a 50-page collection of papers from 2014 supported by Procter & Gamble in the International Dental Journal (Stabilised stannous fluoride and dental erosion).
I haven’t read all of those references, but so far it’s looking like:
1. the 2017 paper was PLoS One being PLoS One—yes it’s peer reviewed, but they put less emphasis on the *importance* of the result than the more specialist journals do, so there’s a higher requirement for readers to figure that out for themselves;
2. the instructions that came with my toothbrush in 2000 probably predated the widespread adoption of ISOÂ 11609 which now makes them unnecessary, and
3. I was needlessly taking care to avoid toothpastes with “whiten” on the packaging for a couple of decades.
Perhaps it would be nice if the manufacturers of electric toothbrushes started saying in the instructions that it’s no longer necessary to avoid toothpastes that have whitening agents, rather than just dropping the warning and letting those of us who saw the warning previously think they’d simply forgotten to include it this time round, because if you did try to avoid whitening agents it’s increasingly difficult to do so, and I know someone else who stopped using an electric brush for this reason, which is not a good outcome.
This page is not medical advice. E&OE. All material © Silas S. Brown unless otherwise stated. Colgate is a trademark of the Colgate-Palmolive Company. Palmolive is a trademark of the Colgate-Palmolive Company. PubMed is a registered trademark of the U.S. Department of Health and Human Services (HHS). Any other trademarks I mentioned without realising are trademarks of their respective holders.