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Growth Modifying Appliances


Functional appliances are used when a patient has an incorrect bite caused by a small or underdeveloped lower jaw. This can often appear as if the patient has protrusive or ‘buck’ front teeth.

Functional appliances work by holding the lower jaw forward. This changes the muscle function and improves the jaw position. By doing this, not only is the bite corrected, but the facial profile is also enhanced. As they are a type of growth-modifying appliance, they are only effective in growing patients and are ideally fitted prior to the pubertal growth spurt.

These appliances come in many different designs, and can be removable or glued to the teeth.  At Pure Orthodontics, the functional appliances we most commonly use are Twin Blocks and Cantilever Bite Jumpers (CBJ).


Twin Block


A Twin Block appliance is a removable, functional appliance. It is made up of an upper plate and a lower plate. The two plates fit together in the mouth in a way which encourages the lower jaw be held forward as the teeth come together.  An expansion screw may also be incorporated into the upper plate to expand the upper jaw. A Twin Block needs to be worn as close to full time as possible. Click here to find out more about the Twin Block.


Cantilever Bite Jumper


A Cantilever Bite Jumper (or CBJ for short) consists of upper and lower frames, which are glued to the teeth. These frames are joined together by “arms”, which act to hold the lower jaw forward. The upper frame usually contains an expander, which will widen the upper jaw.

CBJ’s are particularly effective because they cannot be removed by the patient,  and are therefore working 24 hours a day, 7 days a week. Since there is less need for patient co-operation, they are a great option for many children and treatment is often finished sooner than with a removable appliance.

Click here to find out more about Cantilever bite Jumpers.




Headgear is an orthodontic appliance with parts worn both inside and outside of the mouth.   These devices are used when braces on their own are not capable of fixing the bite problem.  They come in a variety of designs, depending on the type of growth guidance and tooth movement required.

Click here to find out more about Headgear.