The Chemistry of Orthodontics

You can’t be a pharmacist, doctor, vet or orthodontist without understanding chemistry.

Here are four ways that molecules matter to orthodontists and their patients when using braces to straighten teeth.

A taste of the ocean

If you’ve had braces fitted you will have had “impressions” taken of your teeth.

The gunk that is squidged into your mouth is called “alginate” (pronounced al-jin-ate). It’s extracted on an industrial scale from brown seaweed such as giant kelp.

When sodium alginate powder is mixed with water, it sets to form a stiff gel. You will have noticed yourself that the stuff is gooey when it goes in but is quite stiff when your dentist takes it out.

The “setting time” depends on temperature. So on a hot  day, the alginate may set too quickly before your dentist can get it in your mouth… so may need a second attempt!

Watch this clip to see how we use your impressions to make models of your teeth.

How is your apatite?

Why do dentists keep banging on about fluoride?

The outer layer of your teeth is called enamel and is made mostly from tightly-packed crystals called “hydroxyapatite”. Tooth decay occurs when plaque acid from bacteria dissolves the crystals away.

In orthodontic treatment, there is a risk of “demineralisation”  due to the same process. This appears as permanent white or brown marks on the teeth.

Fluoride works by altering these crystals to “fluorapatite” which makes enamel much more resistant to acid attack.

Daily fluoride mouthwash during orthodontic treatment is one of the ways you can keep lots of strong fluorapatite crystals in your enamel.

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A kind of blue

Fitting braces requires a type of plastic glue called “composite resin”. It’s similar to the plastic used for acrylic nails (I’m told).

The glue is set by shining a blue light onto it. This causes the smaller molecules to link up into chains, causing the plastic to set hard. This is a process called “polymerisation”.

You may have heard some annoying beeping while your brace is being fitted. The beep tells the orthodontist how long the blue light needs to be on for.

(Note : it’s not ultraviolet light as many people think. UV light is not visible. Unless you are a bee).

Mixing up your metals

We use different types of wires during a course of orthodontic treatment. At the start they have to be very elastic and bendy; towards the end they have to be very stiff.

So the wires need to be made from different combinations of metals to give us those different properties.

The starting wires are made of nickel and titanium. This material was initially developed in the Apollo space program, which is probably the most exciting fact that the world of orthodontics can boast of.

The thicker wires are made of stainless steel, which is an alloy of carbon, iron and chromium. They are very stiff, which is why they feel very tight when they are fitted.

Read more about the wires we use and how we choose them.

About Cleveland Orthodontics

Our specialist-led practice has been established since 1996 and provides brace treatment to people of all ages from across the North East, including Middlesbrough, Yarm, Stockton-on-Tees, Billingham and Redcar.

We offer NHS orthodontic treatment for children and a range of modern white and “invisible” braces for adults of all ages such as Invisalign. FREE consultations are available… you can either telephone for an appointment on 01642 243 020 or book through our website.

Images

By Stef Maruch (kelp-forest.jpg) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

“Dental braces” by Originally uploaded by Sputnikcccp (Transferred by Vinne2) – Originally uploaded on en.wikipedia. Licensed under CC BY-SA 3.0 via Wikimedia Commons

“NaCl-Ionengitter” by H. Hoffmeister – first upload in de wikipedia on 17:21, 14. Okt 2005 by Lanzi. Licensed under CC BY-SA 3.0 via Wikimedia Commons

“Blaulicht (10584791706)” by Dirk Vorderstraße – Blaulicht. Licensed under CC BY 2.0 via Wikimedia Commons