Roadway House
35 Monument Hill, Weybridge, Surrey KT13 8RN
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Functional Appliances

Functional Appliances

What is a functional appliance?

A functional appliance is a removable brace that works on the upper and lower teeth at the same time. There are a number of functional appliances that can be used. We mainly use the Twin Block appliance.

  • Twin Block appliances are used in the growth phase to treat an underdeveloped lower jaw. It is usually a ‘phase 1’ type appliance and is followed by fixed braces (phase 2) or a retainer.
  • The Twin Block appliances are made from acrylic using two plastic blocks on the top jaw and two on the bottom jaw. The appliance postures a patient’s lower jaw into a forward position on closing their mouth. The forces of occlusion are used as the functional mechanism to correct the malocclusion and aid lower jaw growth.
  • The Twin Block is a removable functional appliance worn full-time for 9-12 months.
  • Mainly the upper and occasionally the lower plate may include an expansion screw to widen the arch.

What are Twin-Blocks?

Twin-Blocks are jaw aligning braces. They are powerful braces, which can reduce an overjet in a young teenager for example from 10mm to the ideal standard of 4mm in six to nine months.

What is an Overjet?

Your top teeth should be in front of your bottom teeth by 2-4mm. This is the ideal overjet.

When should the Twin-Blocks be worn?

As Twin-Blocks work by harnessing the power of the chewing muscles they should be worn all the time. However, if you find your jaw tiring, simply leave the brace out for a short period to rest your jaw.

Should I eat whilst wearing Twin-Blocks?

Twin-Blocks are designed to allow you to eat with the braces in. If you find this too difficult at first, you can take it out for meals.

Will taking my braces out to eat and rest my jaw at the start of treatment delay my treatment?

Try to wear your braces all the time. Taking them out to eat until you get used to them will not harm your treatment and your bite will still improve but treatment will be delayed.

How do I clean my teeth?

Remove the brace and clean your teeth as normal.

How do I clean my brace?

You can clean your brace with a soft toothbrush and toothpaste. The brace also needs to be cleaned with Retainer Brite solution 4-5 times a week.

Do I turn the expansion screw?

The upper block usually has an expansion screw fitted which you will need to turn. This should be turned in the direction of the arrow as directed by your orthodontist.

What about sports?

It is best to take the braces out when playing sports. You can keep the brace safe by placing it in a brace box. Remember to put your name on your brace box.

What about playing musical instruments?

It is best to remove your brace when playing wind instruments.

What happens if the functional appliance breaks?

The plastic or the wire parts of the appliance can break. If you are still able to wear the appliance please continue doing so. If the appliance is unwearable then please telephone the Orthodontic Practice and the receptionist will schedule the next available appointment for you. Please bring both twin block appliances to the appointment.

Dr Stubbs Reviewed by Helen Tedeschi on

I have been thoroughly impressed with the service and treatment Megan has received at WO with her functional appliance. The staff have been very friendly and courteous, the facilities are excellent and the surgeries are very clean. Very impressed!

Helen Tedeschi
Rating: 4.5
Dr Stubbs Reviewed by Emily Williams on

The team are very supportive people, encouraging, and positive when my teeth were improving. Helpful and friendly service. My experience with my functional appliance was really good.

Emily Williams
Rating: 4.5
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