A TV advertisement for Aquafresh toothpaste has been banned for making false claims that it provides 24-hour protection.
The ad, which ran on television and on YouTube, featured cartoon superhero Captain Aquafresh knocking over a circle of sugary products that was surrounding him.
"Sugar can attack any time. Get around the clock defence against everyday sugars with Aquafresh 24-hour sugar acid protection toothpastes. Aquafresh, 24-hour sugar acid protection," said the voiceover. Meanwhile, on-screen text read, "Protection provided by fluoride, with twice-daily brushing."
However, rival toothpaste manufacturer Colgate-Palmolive questioned whether the fluoride in the toothpaste really could offer 24-hour protection.
GlaxoSmithKline, which owns the Aquafresh brand, produced a report from three dental experts who said it could. But Clearcast, which approves British advertising, found its own expert, who concluded that viewers might think there was some other active ingredient beyond common-or-garden fluoride.
And the Advertising Standards Authority (ASA) has now ruled against the ad, saying that the length of protection depends on how much and what people eat.
It's certainly easy to become confused by the health claims of toothpaste, with dozens of differently-branded versions on the market.
Last year, Which? researched budget brands and found that some 99p products contained just as much fluoride as others costing five times as much.
As for other whitening or enamel-restoring ingredients, it said, there was little evidence that they worked.
Indeed, earlier this year, a leading dentist warned that many whitening toothpastes can actually be bad for you. Those that use bleach can damage the gums, said Dr Tony Talbot of the Royal College Of Surgeons, while abrasives not only do the same but also erode the enamel.
It's not the first time, incidentally, that Captain Aquafresh has been challenged, although last time he fought off the attack. In a 2014 ad, he battled a slice of bread, with a voice-over stating "Sugar is everywhere". The Federation of Bakers complained, but lost.