Dentists warn that by trying to make our smiles whiter we could be doing serious damage to our teeth. (AP Photo/Carolyn Kaster, File)

Rubbing teeth with charcoal, swishing with coconut oil and wearing clip-on veneers — we do some pretty strange things in the name of beauty.

But dentists warn that by trying to make our smiles ever whiter and more gleaming, we could be doing serious and irreversible damage to our teeth.

We’re all more aware of our teeth and our smiles now because of selfie culture. It makes us very self-critical, which can lead us to try out some risky things.

Here are the dangerous fads your dentist wants you to avoid:

Trendy, tasty toothpastes

Beloved of the clean-eating, organic, all-natural brigade, ‘boutique’ toothpastes are on the rise, with weird and wonderful flavours ranging from cardamom and aloe vera to fennel and wasabi.

Some use fluoride to protect against decay, but most are fluoride-free. It’s not that herbal toothpastes are dangerous, but they are not going to do anything desperately good, either. 

Whitening kits with bleach:

These are bleaching gels which you syringe into a ‘mouth tray’. This presses the gel against the teeth, usually for 10-30 minutes — and bleaches them. But many contain a lot of hydrogen peroxide.

The maximum concentration of hydrogen peroxide allowed in a consumer whitening product in the UK is 0.1 per cent; dentists are allowed 6 per cent.

Most are sold by the percentage of carbamide peroxide (CP) they contain. CP contains hydrogen peroxide at a ratio of 1:3. So a gel labelled ‘35 per cent CP’ has about 11.7 per cent hydrogen peroxide — nearly twice the legal level for dentists.

Custom-made veneers

No, not fake Dracula teeth, but custom-made veneers you clip over your teeth to give you a whiter smile. They’re popular with the Instagram crowd: you can’t eat, drink or even really speak while wearing them, but your snap-on smile can give an instant lift in pictures.

What’s the problem? Apart from the possible comedy value, clip-on veneers can damage teeth because food gets trapped underneath, and plaque and bacteria are held against the teeth as you wear them. Teeth can be damaged even if you only wear them for an hour, as teeth are deprived of the cleansing action of saliva.’

If you must wear them, brush your teeth first.

Charcoal paste

It’s possibly the strangest dental trend of recent times, but rubbing charcoal paste over your teeth is supposed to leave them gleaming white.

Celebrities including singer Nicole Scherzinger swear by it, and the number of polishes and toothpastes made with ‘activated charcoal’ has risen. Charcoal is traditionally thought to remove toxins and lift stains by binding them to its porous surface.

What’s the problem? 

Charcoal is really abrasive — it can scratch away the enamel on your teeth. The dentine underneath is softer and more yellow, so if it’s exposed, not only will your teeth be more sensitive, they will also be less white..

Apple Cider Vinegar 

Pop star Katy Perry’s favourite little miracle drink, apple cider vinegar, tossed back before breakfast once a day, is supposed to suppress appetite so you can lose weight, improve skin tone and lower cholesterol.

What’s the problem? One word: acid. Most apple cider vinegars have a pH of around 3 — not as acidic as lemon juice, but acidic enough to erode enamel.

The problem is that it tastes so horrible that people want to brush their teeth afterwards, but this is the worst thing you can do as t acid has softened the enamel, so if you then brush you’re brushing your enamel away. Wait an hour to brush after any acidic drink.

‘People also get addicted to using them, and want whiter and whiter teeth. But they cause irreversible damage to their teeth.’