Overbite, open bite or crossbite: what does it mean?

Quick answer: These are names for the way your upper and lower teeth close together. With an overbite, the upper front teeth stick out well past the lower teeth, with a deep bite they cover the lower teeth too much, with an open bite the front teeth do not touch, and with a crossbite upper teeth close inside the lower teeth. Not every irregularity needs to be treated.

Usually you hear a word like this in passing. The dentist mentions an open bite or a crossbite, and you are back at the reception desk before you have worked out what it means.

Below, for each type of bite problem, you can read what the word means, what you can see of it in the mirror and why it is about more than appearance. One note up front: this article explains words, it does not diagnose anything. What is actually going on becomes clear from examining and measuring in the chair.

Practitioners measure your bite in two directions:

• The forward distance between the upper and lower front teeth is known technically as the overjet.
• The downward overlap, meaning how far the upper teeth cover the lower teeth, is called the overbite.

In everyday language, the word "overbite" is used for both, and that is often where the confusion starts. So feel free to ask what is meant.

What it is. The upper front teeth sit some distance in front of the lower front teeth. Often the upper jaw is slightly further forward, or the upper teeth tilt outwards.

What you can see yourself. Bite down on your back teeth and look in the mirror from the side. Do your upper front teeth clearly stick out in front of your lower teeth? Do your lips close naturally at rest?

Why it is about more than looks. This is the bite problem with the best research behind it, and that research is about accidents. Front teeth that stick out a long way and are not properly covered by the lip take the first impact in a fall or when a ball hits the face. Lip coverage probably even matters more than the distance itself. In a large international research review (Cochrane, 2018), new injuries to the front teeth occurred in about 19 per cent of children treated early, compared with about 30 per cent of children who were treated later. The researchers themselves rate the strength of that evidence as low to moderate, and it is about probabilities across a group, not a guarantee for any one child.

What it is. Everyone has a little overlap, and that is how it should be. With a deep bite, the downward overlap is so large that the lower front teeth largely or completely disappear behind the upper teeth.

What you can see yourself. Bite down on your back teeth and look straight into the mirror. Can you still see part of your lower front teeth, or have they disappeared?

Why it is about more than looks. Teeth that rub against each other with every movement can wear down faster, and in the deepest cases the lower front teeth touch the gum behind the upper teeth. To be honest about the evidence: this is based mainly on clinical experience and smaller studies. Wear also has more causes than the bite alone, such as acidic food and stomach acid coming back up.

British healthcare classifies it like this: a deep bite without functional problems normally does not need treatment for medical reasons, a deep bite with functional problems does.

What it is. Your back teeth meet, but a gap remains between your upper and lower front teeth. This is called an open bite at the front. It also occurs further back: the front teeth then do touch, but the back teeth do not.

What you can see yourself. Bite down on your back teeth and see whether light shows through between your front teeth. Are you unable to bite a piece off a sandwich or an apple with your front teeth?

Why it is about more than looks. The biting you would normally do with your front teeth has to happen somewhere else. In small comparative studies, children with an open bite chew less efficiently than children without one. An open bite also occurs more often together with distorted hissing sounds, especially the s. Bear in mind: that is an association, not a proven causal link. Correcting the bite does not make a speech problem disappear by itself, that usually requires speech therapy.

We are cautious about how it develops. Thumb sucking and long-term dummy use are consistently linked with an open bite, and the longer the habit lasts, the stronger that link. There is no strict proof that one causes the other. In young children, the bite often largely corrects itself once the habit stops.

What it is. Normally your upper teeth close around your lower teeth like a lid. With a crossbite, this is reversed in one spot or on one side: there, the upper teeth bite inside the lower teeth. Often the upper jaw is then somewhat narrow.

What you can see yourself. As you bite together, look at the back teeth on both sides. Does the upper row fall inwards on one side? Does your lower jaw shift slightly to one side?

Why it is about more than looks. That sideways shift is what practitioners look out for. The technical term for it is a functional shift (also called a forced bite): your jaw first makes contact somewhere and then slides sideways into a position where the teeth fit together. Dutch professional literature states that an untreated one-sided crossbite with a functional shift can give rise to asymmetrical development of the jaw joints and teeth. Note the word "can". Whether a crossbite leads to jaw joint problems later on has not been proven: the studies contradict each other.

This is the most important part of this article. Having a name for something does not mean something needs to be done about it. The international dental federation FDI puts it briefly and clearly: not every bite problem needs to be treated.

What determines the decision is not the word, but this:

1. Are there any problems? Difficulty biting or chewing, pain, teeth that break or gums that get damaged.
2. Is there a risk of damage? For example, front teeth that stick out a long way in a child who does a lot of sport, or a functional shift that persists.
3. How big is the deviation? A slight difference is not the same as a clear one.
4. What do you want yourself? For adults, appearance often plays a part, and that is a valid reason. But then it is a choice, not a medical necessity. See braces for adults.

Many mild bite problems never cause any trouble and stay as they are. Leaving them that way is not negligence, it is a sensible judgement.

In short: if you are unsure, if there are problems, or if your dentist brings it up. Do not try to measure it yourself: you cannot reliably judge the position of your teeth and jaws in the mirror.

With children, there is also the question of when the right moment is. That depends on the change from baby teeth to adult teeth and on growth, and we have a separate page on that: when should my child see an orthodontist. You can read what happens at a first appointment under our consultations.

Our practice is in central Amsterdam, on Teniersstraat close to Museumplein. Lotte Meereboer is a dentist specialising in orthodontics (Drs. MSc Orthodontics) and treats children, teenagers and adults.

At a first appointment we look at the position of the teeth and also at how the jaws work together: how you bite, whether there is a functional shift and whether there is any wear. Afterwards we tell you what we see and whether anything needs to be done. Sometimes the answer is that it is perfectly fine as it is. If treatment does turn out to be worthwhile, we discuss which types of braces are suitable.

What is the difference between overbite and overjet?

Overjet is the technical term for the forward distance between the upper and lower front teeth, overbite for the downward overlap. In everyday language the word "overbite" is used for both, so ask what is meant.

Is an overbite serious?

That depends on how pronounced it is. A slight overbite often never causes problems. If the front teeth stick out a long way and are poorly covered by the lip, the risk of damage in a fall is greater. That is a reason to have it assessed, not a reason to be alarmed.

Can an open bite go away on its own?

In young children who stop a sucking habit, the bite often largely corrects itself. Once the permanent teeth are in, this generally no longer happens.

Does a crossbite always need to be treated?

No, not automatically. Practitioners mainly look at whether the lower jaw shifts to the side when you bite together and whether there is damage or there are problems. If not, monitoring and waiting can be a good choice.

Can I work out for myself which bite problem I have?

No, and that is not the purpose of this article either. You may well notice something that stands out, and that is a perfectly good reason to ask your dentist or us. The assessment involves looking, measuring and usually an X-ray.

Would you like to know more or request a no-obligation consultation? Contact our practice in Amsterdam.