More than almost any other part of our body, it's essential that we give our mouths daily attention to keep them healthy. From preventing cavities and gum disease to looking after your oral microbiome, oral hygiene is about more than just keeping our teeth shiny.


Everyone has a different oral care routine, whether that's a quick scrub with a manual toothbrush or a full regimen of brushing, flossing and gargling mouthwash. But we only see a dentist a few times a year, so what should we really be doing in between check-ups to keep our gnashers in tip-top shape?

We spoke to Dr Kami Hoss, dentist and author of If Your Mouth Could Talk (£22.99, BenBella Books), on the Instant Genius podcast to find out what we've been doing wrong and how to brush our teeth properly.

How should I be brushing my teeth?

A lot of us probably get up in the morning, eat and drink acidic foods and beverages like fruit, coffee and juice, and then immediately brush our teeth. We'll maybe follow that up with mouthwash, and then floss (...if we've got an appointment with the dentist coming up). But Hoss says this isn't the order we should be doing it in.

Before you eat breakfast in the morning, you should do the following, according to Hoss:

  1. Use an alkaline mouthwash
  2. Floss
  3. Use a tongue scraper
  4. Brush

Yes, brush last, not first!

"When you wake up in the morning, plaque has built up overnight," says Hoss. Mouthwash will help to loosen food particles and plaque from your teeth, making them easier to remove.

"Then I would recommend using a floss first to clean between the teeth," says Hoss. Choose your floss carefully: some have a petroleum-based wax or other ingredients that aren't suitable for mouths. Hoss recommends floss made of silk or nylon, and a beeswax coating is also a good choice.

"Then you want to use a tongue scraper to make sure your tongue is clean, because that's also a source of a lot of microbes that can cause bad breath and it can even interfere with taste."

Finally, you want to brush your teeth with a slightly alkaline toothpaste.

What mouthwash should I use?

You've probably heard you should be using mouthwash to kill all the bacteria in your mouth, and that in turn will protect you from cavities. But Hoss says this is not actually the best way to use mouthwash to look after your teeth.

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"Think of your mouth as a garden and your oral microbiome as the beautiful flowers and the vegetation and the plants. How do you take care of your garden?" says Hoss. "Well, you probably trim it to make sure it gets the Sun where it needs to, and you water it and you give the nutrients to the soil, right?

"If there is a weed here and it grows, what do you do? Do you pour acid all over your garden, or do you just take out those weeds selectively?" That is, using a powerful, antiseptic mouthwash can actually do more harm than good by decimating your oral microbiome, and killing the 'good' microbes as well as the 'bad'.

"Instead of using an antiseptic mouthwash, you can use an alkaline mouthwash that actually restores the pH." The pH of your mouth is vital – too acidic and the 'bad bacteria' that lead to cavities and oral diseases can thrive.

What causes cavities?

"The way you get cavities or you get oral diseases is when that pH becomes acidic," says Hoss.

Ordinarily, your mouth should be a neutral pH of around 7, neither acidic or alkaline. When you eat or drink, the pH drops to around 5.5, thanks both to the food itself and the enzymes your mouth produces to digest it. "Also, as your mouth becomes more acidic, the bacteria that love acid, which are the 'bad bacteria', they are the ones who thrive in that environment," says Hoss. "And what do they do? They eat that food, let's just say sugar, and they excrete more acid. And so that creates this cycle of acidic environment in the mouth."

When your mouth's pH hits 5.5, the acid starts to dissolve hydroxyapatite, the mineral enamel is made of, out of your teeth. This process is called 'demineralisation'. It sounds scary, but don't worry – it's reversible. When you stop eating, the pH is raised again. Your teeth are bathed in saliva, and over 30 minutes to an hour, they are remineralised.

"As long as you don't eat a lot of 'bad food' and you don't eat too frequently, there's a balance between this demineralisation and remineralisation and you don't get a cavity," Hoss explains. "However, if you eat a lot of bad foods – 'bad foods' means sugar and processed foods and simple carbohydrates and acidic foods – or if you do this too frequently, there's more demineralisation than remineralisation and you get these holes in the teeth called cavities."


Listen to the full podcast below:

About our expert, Dr Kami Hoss

Kami is a dentist with a master’s in craniofacial biology from USC, a doctorate in dental surgery from UCLA and a post-doctorate in orthodontics and dentofacial orthopedic. He is co-founder of The Super Dentists and author of If Your Mouth Could Talk.

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Sara RigbyOnline staff writer, BBC Science Focus

Sara is the online staff writer at BBC Science Focus. She has an MPhys in mathematical physics and loves all things space, dinosaurs and dogs.