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A Science Lesson on Teeth


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Calling all adults who are home schooling! Or adults who are bored at home for that matter.

How about a science lesson on teeth and decay??

We all have them, and we all use them on a daily basis. So shall we learn a bit about them?

What are teeth?

Teeth are small, calcified, white structures found along the jaws of most humans and animals.

Human teeth start forming before you’re even born, and we get two sets of teeth.

Children have 20 teeth, and adults have 32 teeth. Usually, your baby teeth (or deciduous teeth to give them their proper name) have all been replaced with adult teeth by the time you reach teenager-dom, although everyone is different. I know some 60 year olds who still have one baby tooth hanging on in there!

There’s a rough guide below as to when you can expect your teeth to errupt. This is the term used for when the tooth cuts through the gum.

What is the function of each tooth?

The main function of teeth is to chew food, and you’d also look a bit strange trying to smile with no teeth! They are also used for defense or protection (more so in animals than humans, I’d hope!). Each tooth has a different function. The shape of teeth is often determined by diet. Mammals that only eat plants (herbivores) may have more molars for grinding. Animals that only eat meat (carnivores) may have more incisors for cutting or tearing flesh. There are four types of permanent (second) teeth in a human.

What are the types of teeth?

Incisors: which are used to cut food

Canines: which are used to tear food

Premolars: used to grind food.

Molars: also used to grind food.


What is a tooth made of?

The tissue that seals the side of the tooth to prevent infection is called the gum. Teeth are fixed into jaw bones and are held in place by cement. The three main layers of a tooth are called enamel, dentine and the living layer is called the pulp. Enamel is the hardest material in the body (which is a fact that shocks a lot of people, given it’s so suseptible to decay). This hard mineralized coating covers an exposed tooth. It is normally grayish or white in color and is a very tough material.

The cementum is a layer of tough, yellowish, bone-like tissue that covers the root of the tooth.

The crown is the visible part of the tooth.

Nerve: This is what allows us to feel hot and cold. Sometimes when this root becomes too sensitive to hot and cold the dentist will kill this nerve. This procedure is called root canal.

Periodontal Ligament: is fleshy tissue between tooth and the tooth socket; it holds the tooth in place.


What is a decay?

Decay is the arch nemesis of any tooth. The mouth has colonies of bacteria (living organisms) on our teeth, tongue, lips and gums. Some of the bacteria is good and helps us break down food particles. However, some of these bacteria are bad especially when it attaches itself to hard surfaces like enamel and doesn’t get brushed away. This bad bacteria usually appears when you eat, as the food you chew reacts with the bacteria in your mouth. When this happens this yellowish film is called plaque. Yuck! That’s way it’s so important to brush your teeth and not to eat too many sweets, as brushing is the only way to get rid of it. Once it becomes hard, you won’t be able to get rid of it with a brush, and that’s when you need to come to the dentist to have it cleaned off.

Why do some kids have braces?

Sometimes when kids are growing, their teeth come through a bit wonky. Braces are used to correct such things as underbites, overbites, cross bite and open bites, deep bites, or crooked teeth and various other flaws of teeth and jaws, whether cosmetic or structural. But adults can have braces too, and we have many who come to us for cosmetic reasons for a nicer smile) rather than functional reasons (to eat or chew properly)

How do we keep our teeth healthy?

Our teeth have to last us a long time. So, it’s important to brush your teeth twice a day with a fluroide toothpaste. Once in the morning and then at night. Otherwise the plaque will eventually build up, corrode and rot your teeth.

It’s also important to snack on the right foods between meals, or not snack at all if possible and keep sweet treats to meal times. Avoid sticky foods that will get stuck on your teeth and cause tooth decay, and try to stick to water inbetween meals too.

This is because you have a natural acidic level on your mouth. Every time you eat or drink something, that level drops, and your teeth are not protected against decay anymore. It can then take up to an hour for this level to normalise.

If you imagine that you keep snacking every 10 minutes, then that acidic level is dropped over a long period of time, leaving your teeth suseptible to decay. However, if you eat everything within a 10 minute window, then your mouth has time to restore it’s natural balance and carry on protecting your teeth.

The chart below shows this in action over a 24 hour period. The blue line represents your natural acidic level, and the red line represents the level at which it has to drop below before it’s no longer protecting your teeth.

So, when you ask your mom or dad for yet another biscuit, and they say no, this is why! You don’t want to have a filling, trust me!


I hope this little lesson has been instructive to you all, and has helped you learn a bit more about teeth during this time of isolation.

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