Rubber bands, or elastics, are generally used to help improve how teeth fit together. They are also often used to help close spaces, or make sure spaces are closing in the right direction, and improve cross-bites and midlines.
They are simply small rubber bands that are attached to the braces. They are attached by the patient to little hooks that are a part of the braces. Since they need to be placed by the patient, cooperation with instructions for wear is critical to make progress and achieve a good outcome.
There are many different types and sizes of elastics. They are generally classified by the problem that is to be corrected. For example, Class II elastics are worn in such a way to help correct a Class II malocclusion. Illustrations of the different ways elastics can be worn are shown below.
In addition to the shape and direction, there are also differences in the sizes of the elastics. The size differences are necessary since adequate force levels are needed for various positions on the teeth. For example, if a patient is wearing a long Class II elastic, a very small, tight elastic may not allow the patient to open their mouth very well. It may also place too much force on the teeth. Therefore, the orthodontist will advise each patient to wear properly sized elastics. This may vary depending on the configuration and circumstances.
Elastic wear instructions are generally either recommended as full-time or night-time wear. Full-time wear is usually prescribed in those situations when tooth and bite movement is desired. Whereas night-time wear is effective for holding a correction. The difference between full-time and night-time wear is significant, since the teeth and bite will only move if pressure is constant. Therefore, if instructions are not followed, and a patient wears the elastics less than required, the teeth and bite will not move properly. This can slow down the treatment progress and may result in a compromised final result.
Some patients try to compensate for poor rubber band wear by wearing double elastics. This tends to be ineffective for movement, since the length of time a force is present is more important than the amount of force. Double elastics also tend to increase soreness. The best advice for effective movement is to follow the instructions of the orthodontist.
Be aware that some patients may have a latex allergy. Since rubber bands are usually made from latex, ask the orthodontist for an alternate rubber band material. There are rubber bands manufactured from vinyl rather than latex, which will still provide effective movement without a potential reaction.
Besides the larger rubber bands just described to help move the bite, smaller elastics are also used for braces. These tiny rubber bands are used to hold the wire into the brackets (as shown below) and are what most people talk about when they choose colours for their braces. These rubber ties get changed every visit since they will stretch and weaken over time. This also allows for changing up different colour combinations throughout the braces treatment. Special instruments are used to place and remove each tie at the orthodontic adjustment appointments. There are also ties that are all linked together. These "chains" are used to help hold the wire in, but they also pull between the teeth to close spaces.