Table of Contents


Volume 4, Issue 1, March 2020


Volume 4, Issue 1, March 2020


Dr Arosha Weerakoon, School of Dentistry, University of Queensland

Our mouths are important parts of our body – we need them to taste, eat, speak and show emotions. And your smile is the first thing people notice. After the baby teeth fall out, we only get one set of teeth to smile with, so it’s important to take care of them for the rest of your life.

If we don’t take care of our teeth and mouth, we can end up with bad breath, brown/black coloured teeth, pain or infection and even lose teeth. So how can you protect your teeth and make your smile dazzle?

Figure 1: Our smile is more important that we realise.

In this article, you will learn how to protect your teeth and gums by:

  • Understanding what causes holes in teeth as well as gum disease

  • How to change habits and keep smiling confidently.

First, let’s learn a little bit about the mouth.

What do we find in our mouth?

The basic structures in the mouth include the tongue, salivary glands (little pouches that fill like water balloons and empty into the mouth), taste buds, mucosa (skin) and teeth. Teeth are uniquely designed structures. Looking into the mouth, we only see the crowns of the teeth because the roots are embedded in the jaw bone.

A tooth crown is a bit like an egg; the enamel is the hard shell that sits on the outside which protects the softer dentine. Both enamel and dentine surround a softer structure called the pulp which is full of nerves and blood vessels that are connected to the jaw bone and to the rest of the body.

Figure 2: Human mouth anatomy: our mouth contains many complex structures that play different roles

How can things go wrong with our teeth?

The two main problems that arise with teeth are related to holes (decay, or cavities) in the teeth and problems with the gum tissue that surround them. Cavities arise when the hard outer enamel shell is breached to expose the softer dentine. When the soft dentine opens, it is very sensitive and sends signals to the nerves when we eat sweet, cold or even hot things. This is called toothache. If the decay gets large enough, it eventually damages the pulp and causes infection, known as an abscess. An abscess can be very painful, giving you a swollen face and making you feel unwell.

Figure 3: Tooth decay and infected pulp.

What about the gums?

Gums love to be brushed and flossed regularly. If we don’t clean them often enough, we can get a condition called gingivitis which is the early stage of gum disease. Gingivitis is caused by the reaction of the body (gums in this case) to extra bugs (bacteria) that grow on teeth and gums. This reaction is like when we get a splinter under the skin, except gingivitis doesn’t hurt.

All healthy mouths have hundreds of different bugs (bacteria) living together. We call these bacteria dental plaque. Many types of bacteria can live in the mouth. While most are generally harmless, some types are known to cause gum problems and also play a role in creating holes in the teeth. In a healthy mouth, the number of the bad compared to the good bacteria is minimal.

Figure 4: Tooth decay and infected pulp.

How do bad bacteria grow in my mouth?

Three main factors can cause bad bacteria to grow in the mouth, and these are related to

  • How often and well you clean your teeth and gums

  • What and how frequently you eat and drink food, especially those containing a lot of sugar

  • Habits such as playing sport

Just like plants and trees, bacteria in the mouth will thrive or die in different conditions.

Why is it important to clean your teeth and gums?

Cleaning our teeth and gums destroys the city-like structures that bacteria form in plaque. The longer you leave your teeth and gums dirty, the more different types of bacteria grow in your dental plaque. When left long enough, the plaque starts to

  • irritate the gums to make them swell-up and bleed (gingivitis)

  • produce acid as a by-product (bacterial poo) that lead to holes forming in the teeth


The good news is that gingivitis is the very early stage of gum disease, and is reversible. Once you get gingivitis, and if you leave the plaque on your teeth and gums uncleaned for long enough, the body starts fighting harder and longer. But by then, the bacterial plaque is well-established enough to create its own protective forcefield, so much so that whatever fighter cells your body throws at the plaque just bounce off.

Unfortunately, when this happens, instead of destroying the bacteria, the fighter cells start to destroy the structures that hold your teeth in your head, particularly the jaw bone. Over time, you can develop advanced periodontitis where the bone that holds your teeth in the jaw shrinks away, teeth get loose and sometimes even fall out. Not to mention, people with advanced gum disease aka periodontal disease suffer from very bad breathe because of all the infection and smell-forming bacteria growing in their mouth.

Figure 5: Tooth decay and infected pulp.

What causes holes in my teeth?

If your mouth has lots of good saliva rich in alkaline mineral salts, those salts will neutralise the acids by binding to them. However, if there isn’t enough saliva or minerals, or your saliva can’t keep up production to match what and how much you’re eating, then your teeth turn into a sacrificial anode. Basically, the minerals will dissolve to balance the mouth’s pH. Dentists call this the ‘critical pH’ which sits around 5.5.

If you don’t clean the plaque or give your mouth a break from eating, then the minerals in your teeth will continue to dissolve, leaving only a soft mushy structure that we call a hole, caries or a cavity.

Figure 6: The saliva we produce is more important than some of us realise.

Getting a hole in your tooth can cause a lot of problems.

  • Food will get stuck in the hole every time you eat

  • Your tooth may get sore when you eat or drink sweet, hot or cold things

  • If the cavity gets too big, some of the tooth will break and collapse

  • If left too long, the nerve in the tooth will die and the tooth may get infected or need to be removed or receive special treatment so you can still keep it.

Figure 7:  Tooth decay results from a build up of acid if teeth aren’t cleaned regularly or given a break from food.


I don’t want cavities or gum disease, what can I do?

You can stop yourself from getting cavities and gum disease by understanding the information below.

Figure 8: Credit: Arosha Weerakoon.

Brush and floss

Brushing your teeth and gums in the morning after breakfast and before going to bed will help reduce the amount of plaque in your mouth. This means that the plaque doesn’t last long enough to mature and cause gingivitis or cavities. Because we can’t get to all surfaces of our teeth and gums with a toothbrush, it’s also good to floss between them. 

Choose tooth-friendly foods and drinks

Figure 9: Cavity-causing bacteria thrive on sugary foods and drinks. Credit: Arosha Weerakoon

Cavity-causing bacteria love food and drinks with lots of sugar and acid.This is partly to do with how we digest food. As it passes through the body, food is broken down into its basic building blocks. The first part of this digestion happens in the mouth, when we eat carbohydrates such as rice and pasta (good food) as well as biscuits and soft drinks (not so good food). Special ingredients in the saliva help break these foods down which in turn increases the amount of acid in our mouth. When this happens, the saliva and glands work go on overdrive trying to remove or reduce the acid.

Good carbohydrates such as rice or pasta produce less acid than sugary foods. It takes the mouth and saliva about 20 minutes to clear the acid, which means the next issue occurs if we don’t give our mouth a break. Therefore, although it is important to enjoy meals and eat slowly, try to eat your food in one go and not snack constantly.

Things that ruin smiles

While it is important to be able to express free will and individuality, sometimes we may pick up habits and activities that affect our oral health (Table 1).

Table 1: How the habits & choices we make affect our smile.

ActionHow it affects our mouth
SmokingCoats your teeth with yellow/brown stain
Reduces amount of saliva in your mouth
Causes bad breath
Makes gum disease worse
Increases risk of mouth cancer
VapingIncreases risk of developing gum disease
May increase risk of developing mouth cancer
Drinking AlcoholSugar and acids dissolve teeth
Dehydrates your body – reduces saliva
Taking illegal drugsSmashing teeth together – cracks and fractures teeth
Creates sugary food cravings
Piercings in your mouthCutting through the mouth’s protective barriers can lead to swelling, pain and infections
Metal rubs against gums cause them to shrink and crack or fracture teeth by banging against them
StressCan cause painful ulcers in your mouth
Grinding and clenching your jaw can cause headaches and pain
May stop you from taking care of yourself properly

The importance of dental check-ups

When you visit your dentist or therapist for a check-up you may have the following things done:

  • Have your mouth and teeth checked for

    • How many teeth you have

    • Whether your teeth have come through in the correct order (if you have baby teeth and adult teeth)

    • What your saliva quantity and quality looks like

    • Cavities

    • Gingivitis

    • How your existing fillings (should you have any) are fairing

    • Any unusual lumps and bumps in your mouth that shouldn’t be there

  • Have x-rays taken. X-rays are like photos that allow us to see through the outer hard surface of the tooth to check for cavities that are hard to see just by looking. They are also handy to see your adult teeth that may still be growing in your jaw, such as wisdom teeth.

  • Have your teeth cleaned using a special buzzy tool, a plaque scraper and a polisher that can sometimes feel like a water pistol with powder, or an electric toothbrush. This allows us to clean the plaque that you may have difficulty getting to.

  • A fluoride treatment which helps harden your teeth and protect them from getting holes. This could come in the form of a gel, a sticky gooey varnish that is painted on your teeth or a white cream.

At a check-up appointment, your dental professional may ask you about all the things we have discussed in this article such as your teeth and gum cleaning habits, what you eat and drink and lifestyle habits.

No matter how old you are, it is important to keep you smiling for life. Good oral health means having nice breath, clean white strong teeth that can help you chew and enjoy many different types of foods. And most importantly, it lets you keep smiling.

Figure 10: Try to see a dental professional at least once per year for a check-up

So where can I find someone to help me with my teeth?

Some of us may have access to a dentist or therapist through schools or privately. For those who aren’t sure, here is list to help you get started.

Accessing dental services


Government Services

Young people usually up to the age of 15 can access free dental services through the school government system. The following links will take you to your local oral health centres.


Many universities around Australia have dental schools, where our future home-grown dentists come from. Many of these schools provide free or subsidised treatment to patients that can include treatments such as braces, root canals and wisdom teeth extraction.

Student activities

1. Look up three features that are found in your mouth and describe their functions.

2. Rearrange these foods/drinks from most acid-containing to least acid-containing. Apple juice, bananas, lollies, broccoli, butter, tofu, lime juice.

3. Find a song that lasts for approximately two minutes that you can listen to while brushing your teeth. For instance – Blur’s ‘Song 2’ plays for approximately 2 minutes, which is how long it should take you to brush your teeth!

4. Watch the short video on tips to brush your teeth here: and answer the following questions.

  • What kind of tooth brush should you use and why?

  • How much toothpaste should you use?

  • What angle should you title your brush

  • How do you brush if you have electric tooth brush?

  • How many segments do we have in our mouth? Name them.

  • Why do you brush your tongue?

  • What do you do with the paste in your mouth?

  • How many times should you brush and floss per day?

5. Watch the short video on tips to floss your teeth at and answer the following questions

  • What are the four flossing tools available?

  • Should you floss before or after brushing?

  • How long should your piece of floss be?

  • What should you do if your gums bleed?

  • How much of your tooth surface does brushing reach?

6. How much sugar is in that? You will need

Step 1

Look up your favourite or popular food or snack on the calorie king website. In my example, I have searched for Snickers Chocolate.

Step 2

Ensure you find the correct serving in the drop-down menu. For instance, in this example, I am looking for a standard 50g bar.

Step 3

Look at the nutritional panel and record the amount of sugar, which in this instance will be 23.5g.

Step 4

Place the empty ziplock bag on the weighing scale and zero it. Fill the bag with 23.5g of sugar.

Step 5

Attach ziplock bag to wall space next to an image of the food you searched for.

Step 6

Repeat steps 1-5 with other food or drinks.

7. How much sugar do you eat in a day?

  • Record what you eat for a day

  • Use the Calorie King website to calculate the total amount of sugar you consume in one day. How does your sugar consumption compare to your class mates?

8. How acidic are my drinks?

The following link provides instructions about conducting an experiment to show how the acids in our beverages affect our teeth.

The first resource may suit older students

The following resource will suit younger students



American Dental Association, Mouth Health Teens {online}, available at <> accessed March 2020.

Australian Dental Association, Teens 12-17, {online}, available at <> accessed March 2020.

British Columbia Dental Association, Your dental health {online}, available at <> accessed March 2020.’

pH values of common foods and ingredients, {online}, available at <> accessed March 2020.

Nejad AR, Emami E, Chandad F etal. ‘The correlation between caries and periodontal disease’, Conference paper from IADR General Session 2012. {online}, available at

Food Standards Australia New Zealand, {online}, available at <> accessed March 2020.

Dieticians Association of Australia, Teens, {online}, available at <

Australian Bureau of Statistics, Australian Health Survey: Consumption of added sugars, 2011-12, {online}, available at <>

Articles written by author for the general population

Weerakoon AT, Curious Kids: Why do we make saliva? {online},. 2020 Feb. The Conversation Media Group Australia. available at

Weerakoon AT, How to avoid the dentist this holiday (and what to do if you need one in an emergency) {online},. 2020 Jan.The Conversation Media Group Australia.available at:

Weerakoon AT, Can we heal teeth? The quest to repair tooth enamel, nature’s crystal coat. {online}, 2019 Sep. The Conversation Media Group Australia.available at:

Weerakoon AT, How often should I get my teeth cleaned? {online}, 2019 Aug. The Conversation Media Group Australia.available at:

Featherstone, J.D., Domejean-Orliaguet, S., Jenson, L., Wolff, M. and Young, D.A., 2007. Caries risk assessment in practice for age 6 through adult. CDA, 35(10), p.703.

Cronin, A.J., Claffey, N. and Stassen, L.F., 2008. Who is at risk? Periodontal disease risk analysis made accessible for the general dental practitioner. British dental journal, 205(3), p.131. Available at:

Sirimaharaj, V., Messer, L.B. and Morgan, M.V., 2002. Acidic diet and dental erosion among athletes. Australian dental journal, 47(3), pp.228-236.

Bertrand Dautzenberg, 2017. The use of e-cigarettes in adolescents: public health consequences. Tobacco Prevention and Cessation, 3(May Supplement), pp.Tobacco Prevention and Cessation, 01 May 2017, Vol.3(May Supplement).

Sundar, I. K., Javed, F., Romanos, G. E., & Rahman, I. (2016). E-cigarettes and flavorings induce inflammatory and pro-senescence responses in oral epithelial cells and periodontal fibroblasts. Oncotarget, 7(47), 77196–77204.