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Types of Malocclusion and How to Fix Crooked Teeth

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Malocclusion‘ is a term that dentists and orthodontists used to refer to a misaligned bite. In other words, one or more crooked teeth prevent the upper and lower teeth from coming together in a normal position.

child with wonky teeth
Do you or your child have crooked teeth?

This can lead to:

  • Self-consciousness about the appearance of the teeth
  • Difficulty chewing and eating
  • Problems maintaining good oral health
  • Extra pressure on certain teeth and muscles, causing strains or breakages

Fortunately, there are various malocclusion treatments that can realign wonky teeth into a healthier position. In this article you'll find information about the types of malocclusion, what causes crooked teeth, and how to fix crooked teeth with braces, veneers, or other treatments. 

What causes crooked teeth?

Malocclusion of teeth can occur for a number of reasons. Sometime it's down to genetics, but certain behaviours or habits can also cause crooked teeth. Possible causes include:

child with crooked teeth
Baby and adult teeth can come in crooked

Should I worry about crooked baby teeth?

Baby teeth coming in crooked shouldn't be an immediate cause for concern. There are various factors that can make baby teeth crooked, and it doesn't necessarily mean that the permanent teeth will follow suit. 

Ask a dentist: Do crooked teeth get worse over time?

Research shows that the crowding of teeth can get worse as we age, just like other age-related changes — wrinkling of the skin and hair turning grey. So you may find that as you grow older, you have crowded teeth when once it wasn’t a problem. 

One of the tools orthodontists have to ensure that crowding doesn’t get worse is orthodontic retainers, usually worn after orthodontic treatment with braces. These are often permanent or fixed to the backs of the teeth, so they aren’t visible, but work to keep teeth in line.

Orthodontic treatment can be a significant advance towards enhancing your dental wellbeing. Visit your orthodontist for a consultation if you or your child has crowded teeth.

Dr Yusupov, Amazing Smiles Orthodontics

However, if baby teeth are growing in crooked because the child has inherited a small jaw from one parent and large teeth from the other, resulting in overcrowding, it's likely they will need orthodontic work later on. If a child has gaps between their baby teeth, this is usually a good indication that they won't suffer from overcrowding with their adult teeth.

Crooked teeth are harder to clean than straight teeth, so you'll need to pay special attention to your child's oral health.

You should start taking your child to dentist as soon as their first tooth erupts. This not only lets the dentist monitor the growth of their teeth; it also gets the child used to having dental checkups.

What to do if permanent teeth are coming in crooked

Don't panic if your child's permanent teeth are coming in crooked; they may well straighten themselves out as they find space to grow. However, it's a good idea to take your child for regular dental checkups. If the dentist thinks your child may need braces, they will refer to you an orthodontist for further assessment.

Our article on braces for kids has more information on how cases are assessed for NHS treatment eligibility according to the IOTN.

Crooked teeth in adults

braces on crooked teeth
Adults can choose clear or invisible braces

Many adults live their lives with wonky teeth and think nothing of it. Unless your malocclusion is severe enough to affect your eating or speech, or it's causing you pain of some kind, there may not be any medical need to fix it.

But of course, it's natural to be self-conscious about a less-than-perfect smile. Teeth can become more crooked over time, and it's quite common for adults to fix their crooked teeth later in life for purely cosmetic reasons.

Types of dental malocclusion

Ask a dentist: Do removable clear aligners work as well as braces?

Clear aligners like Invisalign are an increasingly popular alternative to traditional metal braces. There are no brackets or wires and they should require fewer repairs and adjustments during the course of treatment than braces.

The obvious advantages to patients – especially adults – are that they are removable and less noticeable. Those perks also mean aligners are easier to clean and maintain.

Aligners may not be the best teeth-straightening solution for all orthodontic patients, however. Braces are favoured in more complex situations involving severe crowding, impacted teeth, or jaw relationship correction.

Typically, the cost for aligners and braces are comparable. As with all healthcare decisions, it’s important to begin with a thorough examination and consultation with your orthodontist so that the two of you can come up with a treatment plan that makes the most sense for your individual case.

Dr. Greg Nalchajian, Nalchajian Orthodontics

Malocclusion classes

Orthodontists use the following classifications to define malocclusions:

  • Normal occlusion: The upper and lower first molars come together normally.
  • Class 1 malocclusion: The upper and lower first molars come together normally but other teeth have some crowding, rotation or other irregularities.
  • Class 2 malocclusion: The upper first molar is positioned too far forwards in relation to the lower first molar (resulting in an overbite).
  • Class 3 malocclusion: The upper first molar is positioned too far back in relation to the lower first molar (resulting in an underbite).

Don't worry if these are a bit difficult to understand. There are other ways to categorise malocclusions and crooked teeth using more familiar terms. We have written detailed articles about each of these problems; click through on the links below to read more.

Whatever position your teeth are in right now, would you like to know what they could look like after orthodontic work? Use this SmileView tool from Invisalign to get a free preview in under two minutes!

smile view invisalign test


With an underbite, the lower front teeth stick out further than the upper teeth. Around 5-10% of the population have an underbite, and correction is usually recommended.

Read more about underbite treatments.

Overbite/deep bite/overjet

overbite teeth with braces
An overbite malocclusion being treated with braces

An overbite occurs when the upper front teeth overlap the bottom teeth too far horizontally (a deep bite) or when they stick out too far vertically (an overjet). This is a common dental problem which can usually be corrected with braces.

Read more about overbite treatments.


A crossbite occurs when the upper teeth sit inside the lower teeth. It may affect just one tooth or a whole row of teeth anywhere in the mouth. Surgery may be necessary if the jaw is misaligned.

Read more about crossbite treatments.

Open bite

With an open bite, a gap remains between the upper and lower front teeth while the back teeth make contact when biting. This is usually caused by habits like thumb sucking and tongue thrusting. 

Read more about open bite treatments.


Overcrowding is a common cause of crooked teeth. If there isn't enough space in the jaw for teeth to erupt in the proper position, they end up rotating or overlapping. This can happen in either jaw, so you may end up with only crooked bottom teeth or crooked top teeth. 

It's sometimes necessary to remove one or more teeth to create enough space in the jaw.

Read more about treatments for overcrowding.

Gaps between teeth

Even if teeth come in perfectly straight, there may be noticeable gaps between them. The technical term for a gap between two teeth is a diastema. It most commonly occurs between the two front top teeth. 

Gaps between teeth can affect the aesthetics of a smile, and also make it easier for food to get stuck. 

Read more about diastema treatment options.

How to fix crooked teeth

The most common crooked teeth treatment is braces. There are various types of braces for adults and for children, but they all work by gradually shifting the teeth into a better alignment.

crooked front teeth before and after braces
Crooked front teeth before and after braces

Treatment with braces on crooked teeth usually takes 12-18 months, but more severe cases can take longer. Sometimes it's necessary to do teeth filing to create more space between teeth or to even up the edges. And some patients will need spacers before braces to make room for the braces themselves to be fitted properly.

If you have slightly crooked teeth, or it's only your front teeth which need to be straightened, treatment may be quicker and cheaper. Certain brands of braces offer special crooked front teeth solutions designed just for this purpose.

On the other hand, if you have a severe malocclusion because of a misaligned jaw, you may need surgery in addition to braces to straighten your crooked teeth.

How to fix crooked teeth without braces

If you'd prefer to avoid having metal braces fixed to your teeth, you might consider treatment with removable aligner braces. Using this style of brace, which includes the popular brand Invisalign, crooked teeth can be shifted into proper alignment without it being obvious you're undergoing orthodontic work. Many patients, especially adults, appreciate being able to remove their braces for several hours per day, too.

It's quick and easy to check whether you're a suitable candidate for treatment with Invisalign clear aligners. Take a free Smile Assessment on Invisalign's website and submit your details to get an answer in just a couple of minutes. 

If you'd prefer to discuss your treatment in person, you can find your nearest Invisalign provider here and book an appointment online.

An alternative to Invisalign which is suitable for mild to moderate straightening is Straight My Teeth. These aligners work in much the same way as Invisalign and are just as hard to spot. The big difference is that Straight My Teeth is a ‘remote orthodontics' company, meaning you do everything from home. Their full treatment costs just £999.

You begin by taking your own teeth impressions, then after they have confirmed you are a suitable candidate, they will post your aligners to your home. You change them out as instructed, and in 9-12 months your treatment will be complete. Meanwhile, a dentist or orthodontist monitors your progress using an app.

Not everyone is a suitable candidate for at-home aligners, but you can visit the Straight My Teeth website to take a quick online assessment to check your eligibility. We also have a full review of them here.

Veneers for crooked teeth in adults

Veneers are a cosmetic treatment which can be used in mild cases of misalignment to improve the appearance of the teeth. Rather than changing the position of the teeth, a dentist can place veneers on crooked teeth to make them look straighter.

porcelain veneers
Veneers can fix crooked teeth in some cases

These tooth coverings can be applied directly using composite material or made to measure from porcelain. Composite veneers for crooked teeth cost £100 – £400 per tooth while porcelain veneers cost £400 – £1,000 each. You can read more about this treatment and see images of crooked teeth before and after veneers here.

Bear in mind that you can only use veneers for crooked front teeth, and they aren't suitable for all malocclusion cases. The original teeth will need to be filed down slightly, meaning you can't simply remove the veneers when they fail. You'll need to get new veneers or crowns to cover the teeth again.

Can you fix crooked teeth at home?

You may have heard of or seen people describing ways to fix crooked teeth at home, without seeing a dentist, for example by using elastic bands. Although the cost savings may be appealing, you should always seek treatment from a professional. DIY treatments or fake braces risk doing permanent damage to your teeth. Plus, without a retainer, any results are likely to be temporary.

There is also the option of home teeth straightening kits, like Straight My Teeth, which are like mail-order braces. The clear aligners are similar to Invisalign but with a dentist checking your progress remotely. You can read more about these and other teeth straightening options in our separate guide.

Summary of malocclusion treatments

The table below shows the possible ways to fix crooked teeth, according to the type of malocclusion. The most suitable treatment for you will depend on a number of factors, so follow your dentist's advice.

Braces (including invisible aligners)? Surgery (in severe cases)? Veneers?
Overbite Yes Yes No
Underbite Yes Yes No
Crossbite Yes Yes No
Open bite Yes Yes (more likely for adults) Yes
Overcrowding Yes No Yes
Gaps between teeth Yes No Yes


Whatever type of malocclusion you have, the good news is that you don't have to live with wonky teeth and all the problems they bring. There are various treatments that can improve your bite, the appearance of your teeth, or both. Options include braces, veneers and surgery, depending on the severity of the misalignment.

You'll need to visit a dentist for a consultation to discuss your options. If you're considering invisible braces, search for Invisalign dentists near you so you can book an appointment to get a personalised treatment plan. And if you haven't already, quickly check your eligibility now with Invisalign's Smile Assessment tool.

Types of Malocclusion and How to Fix Crooked Teeth
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Amanda specialises in writing informative content about dentistry. She has been a regular contributor to since 2017, and collaborates with dozens of dentists to keep this content accurate and up-to-date.
Dr. Nalchajian received a degree in engineering and worked as an aerospace engineer before earning his dental degree at USC and his certificate in orthodontics from the Eastman Dental Center in Rochester, NY. He frequently travels internationally to give lectures to orthodontists on practice management and treatment for the Invisalign system, helping hundreds of orthodontists improve their practices along the way.
Dr. Yusupov is one of the leading professional orthodontists that have extensive three-year post-doctoral training in the latest techniques such as Temporary Anchorage devices, Invisalign, Innovation Clear braces, Damon and Speed Systems.
SlideShare: Classification of malocclusion. Consulted 1st June 2019. British Orthodontic Society: What is the IOTN? Consulted 1st June 2019.