The Mail on Sunday, Sunday Mirror and Sunday People newspapers have reported that Londoners are the “most likely” people in the country to search for teeth whitening treatments.
The figures used do not adjust for population, which means that while London—by far the most populous city in the country—may have made the most search enquiries about teeth whitening, it does not mean that Londoners are more likely to search for the dental treatment.
The articles all cited Express Dentist as the source of this claim. Express Dentist is an emergency dentist provider in the US.
Full Fact attempted to contact the company directly via the number on their website and reached a call centre, but we were hung up on before being able to speak to anyone about the study in more detail. The Sunday Mirror and Sunday People shared the data they had used with us, which confirms the numbers the story is based on are raw “average monthly search results”.
Reportedly, Express Dentist obtained figures for the number of searches for “teeth whitening” across 50 countries for one month and then multiplied these results to work out an annual figure. They found that the USA searched for teeth whitening most frequently, while Iceland and Malta searched for them least frequently.
Again, this appears to reflect the population of the countries, rather than telling us anything specific about how likely they are to search for teeth whitening.
We can’t adjust the UK city figures for population size because we don’t know, for instance, whether the figure for Manchester represents just the city of Manchester, or Greater Manchester.
But we can use Google Trends data as an alternative, which ranks cities by the percentage of all searches in the area which were for the term in question. Over the past 12 months in England, “teeth whitening” was a more common search in Manchester, Birmingham, Sheffield and Leeds than in London.
These were all cities the Express Dentist research reported had lower total numbers of searches for “teeth whitening” than London.