The orthodontist behind it says that putting your tongue on the roof of your mouth can enhance your jawline and even give you more defined cheekbones. But can it?

From feathered brows and sun-burn inspired makeup to halo brows and floral eyeliner, we thought we'd seen it all in beauty trends. But there’s a new unconventional mouth exercise technique that's amassing thousands of YouTube views and Reddit threads. It claims to change the shape of your face and jawline without any surgical assistance and it's called Mewing. If you’re not familiar with the term, just one Google search will bring upward of 700,000 results.

Mewing was by British orthodontists Dr John Mew and his son Dr Mike Mew. Dr John Mew, who posts videos to his Orthotropic YouTube channel and whose video ‘Doing Mewing’ has amassed over 890,000 views, says it involves keeping the tongue on the roof of the mouth while your mouth is closed pushing your tongue upwards into the palette and pressing your molar teeth together. Having the correct tongue, jaw and neck posture can help improve jaw problems, mouth muscle pains, and sleep apnea - a disorder characterised by pauses in breathing or periods of shallow breathing during sleep, it's claimed.

In an interview with The Times, Dr Mew (above) said he believes many people are not genetically reaching their full potential. “I see face disasters walking down the street all the time and it breaks my heart,” he said. “Ultimately we’re going to die younger, less happy and less attractive if we don’t improve our facial structure now.”

Dr Mew also suggests that not chewing our food enough and breathing through our mouths more due to the explosion of allergies has made our jaw muscles lazy.

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Dr Mew has more than 130,000 users subscribe to his YouTube channel and his technique has triggered threads dedicated to Mewing (and his Orthotropics page), as well as a number of copycat videos on YouTube. While Dr Mew admits that he created the technique for health purposes, many users online have been using the technique to try to non-surgically enhance their faces, raising questions as to whether it is yet another tweakment trend  .

Dr Sarah Tonks , cosmetic physician, maxillo-facial (jaw muscle) surgeon, dentist and founder of The Lovely Clinic , said that while the Mewing technique could be sufficient to move the jaw, there is no scientific evidence or research backing the technique. "This has been around for a long time and the author was ejected from the British Orthodontic Society," she told GTG. "I doubt that the pressure given by tongue position would be sufficient to move bone although it's true that, for example, you could make the masseter muscle larger which would make the face wider. At the moment, Mewing is not accepted by any orthodontic body. But that's not to say that with further study at some point in the future it may be."

According to cosmetic dentist  Dr Uchenna Okoye , Clinical Director of London Smiling, the Mewing technique won't do any harm but she is sceptical. "There is no research to show that it [Mewing] works unless it is with a growing jaw. We know certain movements - such as when a child sucks their thumb - makes the jaw narrow. Mewing can be used to expand the jaw which means you can breathe better, but there is no literature anywhere that shows that this technique works for adults." It's no substitute for orthodontic treatment, however. "Mewing on its own won't work - maybe with a child - but they won't remember to sit down and do these exercises every day."

Dr Okoye believes the teeth clenching technique is only a problem if overused. "If you are disciplined on a day to day basis using the technique for only a couple of minutes a day, then you will see changes. However, if someone becomes obsessed it will do damage. The clenching will cause pain because the muscles will be overworking. I don't have any problems with anyone trying it. There's no evidence to suggest that the technique works, but the key thing is that it doesn't damage your mouth or jaw."

Follow Jessica on Instagram at  @jessicanoahmorgan  and on Twitter at  @jnoahmorgan

Dr Sarah Tonks  is a cosmetic physician and founder of  The Lovely Clinic .

Dr Uchenna Okeye  is the clinical director of  London Smiling.