Twin Blocks: Your Essential Guide

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A dentist explains the benefits of a twin block functional appliance to correct class II bite issues.

Your orthodontist has recommended that you wear a twin block, but what is it?

A twin block is a removable appliance that is sometimes prescribed before traditional fixed braces. It is designed to help straighten your teeth and encourage your jaws to grow. It’s usually worn by growing patients with class II bites: where the upper teeth sit further forwards compared to the lower teeth.

A twin block is made up of 2 separate parts: one for the upper jaw and one for the lower. These parts interlock, encouraging your lower jaw to sit forward whenever you bite, chew, or speak. The constant, gentle pressure applied by the twin block can help your jaw grow into a more favourable position naturally, providing both a functional and aesthetic improvement over time.

You should wear the appliance as much as possible. This means day and night: remembering to take it out for any sports, and cleaning. Over 9 to 12 months of consistent wear, you could see significant changes to the position of your teeth, helping to align your smile without the need for more invasive procedures.

Key Takeaways

  • A twin block appliance corrects Class II bites; where top teeth bite in front of the lower teeth .
  • For best results, it needs to be worn full time including sleeping, and removed only for sports and cleaning.
  • Treatment typically lasts 9 to 12 months.
  • It can be a bit uncomfortable at first, but this settles quickly
  • Be sure to visit your orthodontist regularly for review.

How Does a Twin Block Work?

Twin blocks are designed to correct class II bite issues. This is a situation in which you may have:

  • an increased overjet: Front teeth sit further in front of lower teeth
  • an increased overbite: Your upper teeth cover much of your lower teeth when you bite together.

Twin blocks work by gently repositioning the lower jaw forwards.

They are made up of two removable parts: an upper and a lower acrylic block, with clasps that fit over your back teeth. The two parts are designed to work together. When worn, your jaw can only close in the desired position- with the twin block gently stretching the lower jaw more forwards. This encourages forward growth of the lower jaw, and helps to gradually align your bite.

Twin blocks help to reposition lower jaw and teeth forwards

Imagine wearing both upper and lower braces; your jaws will only close in the new, improved position that the twin blocks create. Over time, this persistent pressure encourages your jaw to grow into that corrected position naturally. Not only does this treatment align your bite, but it also improves your overall jaw profile.

Twin blocks are particularly effective during the adolescent growth spurt. For boys, this typically happens between ages 11-14, and for girls, it’s between 10-13.

They’re removable, but they need to be worn consistently (ideally 20 hours a day) to be effective. Missing wear time can delay progress and impact results.

How Do You Wear a Twin Block?

Wearing a twin block brace can seem a bit tricky at first, but you’ll get the hang of it in no time.

  1. Inserting your twin blocks: Gently push your twin blocks into place. Avoid forcing them, as this can lead to damage. Use a mirror to make sure they are seated correctly and comfortably. Each block has 4 clasps which should clip over your back teeth, to keep them secure.
  2. Keep the blocks together: Bite together on the appliance at all times, keeping the blocks together- even when speaking. This helps to keep constant forward pressure on the bottom jaw and makes the twin blocks work quicker.
  3. Removing: To remove, start by loosening the clasps with your fingers. Work evenly from both sides to avoid bending or breaking.


  • Try to wear the twin blocks as much as possible, aiming for 22 hours a day. This means keeping them in while you sleep. The more consistently you wear the appliance, the quicker and more effective the treatment will be. If you only wear the braces sporadically, you may not see progress.
  • Eating and speaking might feel unusual at the start, but don’t worry, you’ll adjust. Keep the braces in while eating if you can. If you’re struggling when eating, take them out during meals.
  • It’s recommended to consult your orthodontist for specific instructions. You should follow their advice closely to ensure the best outcome.

Staying diligent with your twin block brace can make a huge difference in the results you’ll see. Remember that discomfort is usually temporary and can be managed with mild painkillers if necessary.

How Long Do You Need to Wear a Twin Block for?

Most patients wear twin block braces full-time for around 9 to 12 months. The exact time depends on how well its worn, the amount of correction needed and the patient’s age.

Keep up with regular orthodontist appointments and to track progress.

After the initial phase, you might need additional fixed braces for 18 to 24 months to refine the alignment.

What To Expect When You First Get Your Twin Block

  • Initial Discomfort: You might feel some discomfort or soreness in the first few days. This is normal and usually lasts a few days, as you get used to wearing them.
  • Speech Adjustments: Talking might feel awkward, and you’ll notice more saliva in your mouth at first, but with practice, it improves.
  • Eating Habits: Stick to soft foods initially and avoid hard, sticky, or sugary foods that can damage the appliance.

It’s important to remember, that this discomfort will soon settle. When you first get your twin block try to wear it, and practice speaking with it in, as much as possible. This will help you to get used to the appliance quickly.

If the blocks cause persistent pain or sore spots, consult your orthodontist for adjustments.

What Happens If I Don’t Wear My Twin Block?

Not wearing your twin block can lead to setbacks in your treatment. If it’s not worn consistently, the process may take longer, and you might not achieve the desired results. Traditional fixed braces alone will not achieve the same results as a twin block to improve class II teeth and jaw position. It’s important to follow your orthodontist’s instructions, and wear the twin block well for good results.

Twin blocks are most effective if worn full time, during the active teenage growth spurt, so try to wear them as much as you can. If it’s not worn, you are unlikely to see a significant improvement in your class II bite.

If you have severe class II bite issues, your orthodontist may advise a surgical procedure (orthognathic surgery) to correct your bite, when you’re an adult.

Do Twin Blocks Hurt?

Twin block braces are generally comfortable, but they do take a few days to get used to. You may experience some soreness in the jaw or difficulty speaking. As you wear the appliance, you should quickly adapt and wear them with ease.To manage this discomfort:

  1. Eat Soft Foods: Stick to soft foods like mashed potatoes, yoghurt, or soup initially.
  2. Pain Relief: Over-the-counter pain relievers, like paracetamol. can help ease the discomfort. Always follow the dosage instructions.
  3. Warm Salt Water Rinses: Rinsing your mouth with warm salt water can soothe soreness and help keep your mouth clean.

If your pain persists or becomes severe, it’s important to contact your orthodontist. Your orthodontist can adjust your braces if necessary to ensure a more comfortable fit. Regular check-ups are also crucial to monitor your progress and address any concerns.

Remember, experiencing some discomfort often means the twin blocks are working!

Follow these tips and give it some time. Soon enough, your twin block braces will feel like a natural part of your day. If you have any concerns, never hesitate to reach out to your orthodontist for advice.

Looking After Your Twin Blocks

Cleaning: Clean your teeth and twin blocks regularly: this means every morning, evening and after meals. An electric toothbrush and daily fluoride mouthwash for braces is useful to keep your teeth healthy. Use a soft toothbrush and soap to clean your twin blocks between meals. Mild soap can be used, but skip toothpaste—it’s too abrasive. To keep your twin blocks hygienically clean, I would recommend using dissolvable tablets and an ultrasonic cleaner, like the Zima dental pod for a daily disinfection. Avoid hot water as it can warp the plastic. .

Storage: When not in use, store your twin blocks in a protective case. This keeps them safe from damage and reduces the risk of losing them.

Meals: Your orthodontist may advise you try to wear the twin block when eating. Avoid sticky foods that can damage the appliance, and fizzy drinks. If it’s more comfortable to remove your twin block during meals, make sure you brush your teeth and appliance well before reinserting them.

Sports: For contact sports or swimming, and activities like playing wind instruments, you should remove your twin blocks. This ensures you avoid any accidental damage.

Breakages: If a breakage occurs, don’t attempt to fix it yourself. Contact your orthodontist immediately.

Frequently Asked Questions

What Happens If You Don’t Wear Your Twin Block?

Not wearing your twin block can lead to setbacks in your treatment. The process may take longer, and you might not achieve the desired results. It’s important to follow your orthodontist’s instructions, and wear the twin block well for good results.

Does Wearing Twin Blocks Hurt?

Twin block braces are generally comfortable, but some people might experience mild discomfort initially. This can include some soreness in the jaw or difficulty speaking. As you wear the appliance, you should quickly adapt and wear them with ease.

How Effective Are Twin Blocks In Orthodontic Treatments?

If worn consistently, twin blocks work really well to correcting discrepancies between the upper and lower jaws in actively growing teens. They can help to improve increased overbite and overjets and facial profile.

How Do Twin Block Braces Compare To Herbst Appliances?

Both twin blocks and Herbst appliances are used to help correct jaw and teeth alignment. They both work well, but are different in design and functionality. The main difference is that twin blocks are removable, while Herbst appliances are fixed. Some patients may find twin blocks more comfortable and easier to manage daily. The choice between them should be based on individual needs and orthodontist recommendations.

Picture of Dr Ambika Amini

Dr Ambika Amini

BDS (Honours) London 2014, BSc Neuroscience (Hons) 2010. Dr Ambika Amini is a private dentist who has worked in 4 practices across West Yorkshire. She has an interest in Fixed Orthodontics and Clear Aligners.

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