One of the most important things in orthodontry is trying to get the force of the archwire transferred to the tooth surfaces. This is done via the brackets, but sometimes the tooth has to be turned at an angle, or must have the pressure distributed in a different way than that of the main pull of the archwire. In these cases, tiny “rubber bands”, or orthodontic elastics are used to align the teeth. These elastic rings tend to confound people, so we are going to write a few words in this article to try to clear up when and why these are used and what they are used for.
These rings are made of clear or coloured medical grade plastic that is absolutely bio-compatible and hypoallergenic. It is hooked unto tiny little arms that are on the brackets, and by hooking them to each other, you can exert pressure in pretty much any direction, and this will allow the teeth to be moved in pretty much any direction. The reason that elastics are used in orthodontics is because of a little something called ligation.
These elastics are sometimes called ligatures, because they are responsible for ligation. A ligature is a suture that is tied around some kind of anatomical part. In this case, that part is the bracket on your tooth, and the ligature ties the wire to the bracket. These ligatures are usually changed at each activation session, which is one more reason that it is so important to make it to all of your orthodontists’ appointments. Ligature can be made of plastics or form a power chain, which is literally a piece of chain link that is made from surgical steel, also quite hypoallergenic.
The technology of using elastics or chains to bind the wire and to direct its force into the bracket is now completely obsolete, although still used. Damon and other orthodontic systems have become self-ligating. This means that the brackets are now equipped with a special kind of device that is essentially a miniature trap door that holds the wire and makes sure that the force is transferred properly to the tooth surfaces. These orthodontic devices can shorten treatment times greatly. This is because the elastics used in orthodontry stretch out and exert less and less force over time, while the bracket continues to exert the same amount constantly. They are also reportedly more comfortable, although opinions do differ on this point.