Teeth

Hey! Look, I lotht a tooth. - Pretty gap! Can you say ‘s’? - Eth. What!? - Haha! Nithe, Thothia! - Yes, without teeth it can be difficult to speak properly.

And difficult to chew food. When Sofia bites an apple she uses her incisors. These are mostly used to bite off pieces of food. Then she chews the fruit, using the teeth further back in the mouth: the premolars and molars. These chew and mash up the food before Sofia swallows it.

This is one of the teeth’s most important jobs, reducing the food into smaller pieces. This is the first stage of digestion. In the mouth, there are also some longer, sharper teeth: the canines. Many mammals, including human beings, have canines to grip and tear food apart. A tooth has four separate parts.

The outer part is a protective layer. This is white, and it’s the hardest tissue in the body: the enamel. The enamel is durable and hard-wearing, so that the teeth don’t break when biting and chewing. Inside the enamel, is the dentine. This forms the biggest part of the tooth.

Dentine is not as hard as enamel, but it’s harder than ordinary bone tissue. This is the main part of the tooth. Deep inside the tooth there is soft tissue containing lots of blood vessels and nerves - the pulp. The nerves in the pulp are what make the teeth sensitive. When you bite off a piece of really cold ice-cream, the nerves feel the cold.

Too much cold can damage the teeth, so the nerves send a warning to the brain. The result is a sharp sensation or pain in the teeth. The teeth stay firmly attached in the mouth, even when biting hard or doughy things. They have roots, which are firmly fixed in the upper and lower jaws. The roots of the teeth consist of dentine, and cementum.

Human teeth are living tissue. To live and grow they need nutrients and oxygen. These come via the root canal and the pulp. Babies are most often born without teeth. The first teeth usually appear before the age of one, and these are called milk teeth.

Between the ages of five to seven, the milk teeth get loose. They fall out eventually, and that’s what happened to Sofia when she bit the apple. But under the milk teeth, there are new teeth ready to develop, permanent teeth. These teeth, Sofia will have for the rest of her life. So it’s important to take care of them, and brush them with toothpaste.

Otherwise bacteria can attach and form a coating called plaque on the teeth. The bacteria decompose food remains, and this creates acid. The acid corrodes the teeth. Saliva, or ‘spit’ in the mouth inhibits this corrosion. But if there is too much acid, the saliva can’t counterbalance it.

The acids can corrode the enamel. The teeth get cavities: caries. It’s good to take regular pauses between mealtimes, so that the saliva has a chance to counterbalance the acid. Snacking increases the risk of caries. On top of this, bacteria thrive best on sugar from candy or ice cream.

So, if you want to reduce the risk of caries, it’s good to eat less sugar. What!? No thugar? No thweet-th? It’s ok.

You can have some. And soon enough, you’ll have a new tooth, so we can understand you again.