Watch Your Mouth: What Sugar Actually Does to Your Teeth


Senior male dentist in dental office talking with female patient and preparing for treatment.
Senior male dentist in dental office talking with female patient and preparing for treatment.
We’ve all know that sugar isn’t the best thing for our teeth. But after countless lecturers from parents scaring us about inevitable teeth rotting, science lessons from dentists, and numerous TV ads, we’re still really not sure WHY sugar is so bad for us. Seeing as it’s Dental Health Week, we talked to dental expert Dr Michael Foley, who shared the impact that sugar is actually having on your pearly whites…

When it comes to tooth decay (dental caries) sugar is always, whether directly or indirectly, the culprit.

How does sugar cause decay?

When food or drinks contain sugar, some of that sugar stays in our mouth and around our teeth.  We all have millions of bacteria of different shapes and sizes in our mouths, and bacteria feed on sugar.  Some of those bacteria absorb sugar, then put out acids, and it’s those acids that weaken the enamel crystals in our teeth and soften the tooth surface very slightly.  

When we brush and floss our teeth, we remove most of the harmful bacteria from around our teeth, and the fluoride from our toothpaste and the minerals in saliva strengthen the tooth enamel again. The problems arise when we have too much sugar in our diet or consume sugar too regularly, and we don’t brush and floss well enough or regularly enough.  The demineralisation process then overwhelms the remineralisation process. Gradually the enamel becomes weaker and weaker until a small cavity appears, and at that stage, a filling is usually needed.

Will a filling fix the problem?

One of the big dental myths is that a filling ‘fixes’ the problem. Well… it doesn’t!  A filling is only a temporary fix unless the imbalance between demineralisation and remineralisation is corrected.  We need to fix the disease process, not just the cavity.

The dos and don’ts of sugar

The amount of sugar we eat and drink can be a big problem for our teeth, but equally important is the length of time that the sugar remains on our teeth.  If we only brush our teeth once a day, or if we brush our teeth at night but then have something sweet before we go to bed, sugar stays on our teeth for hours and hours, allowing plenty of time for the demineralisation process to take hold.

Acidic foods (some citrus fruits, pickled foods, honey) and drinks (soft drinks, sports drinks, fruit juices, beer, wine) can be a problem if they’re taken too often.  Not only do acids slowly dissolve tooth enamel and wear teeth down over time, most of the bacteria that cause tooth decay like an acidic environment. If our mouths are often acidic, we’ll have many more of the ‘bad’ bacteria, and our risk of tooth decay is higher.

If you have just taken acidic food or drinks, don’t brush your teeth straight away!  Your enamel will be slightly softened, and brushing immediately could wear some of the enamel away.  Have a drink of water to dilute the acid, and wait an hour for the minerals in your saliva to strengthen the tooth enamel again before brushing.  

About Dental Health Week

Dental Health Week is an annual oral health initiative lead by the Australian Dental Association, aimed at promoting the importance of oral health for all Australians. Dental Health Week kicks off on Monday 6th August, with a focus on helping Australians to recognise the importance of oral hygiene practices as well as highlighting the preventative importance of regular visits with their dentist. The emphasis for 2018 is Watch Your Mouth, which brings to light the importance of caring for your whole mouth. Visit, for more information.




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