Five common bite patterns an orthodontist looks for in a growing child are overjet, deep overbite, underbite, open bite and crossbite. Spotting one is a reason for a check, not proof that treatment is needed.
- Overjet. Upper front teeth sit well forward of the lower front teeth.
- Deep overbite. The upper front teeth cover much more of the lower ones.
- Reverse Overjet (Underbite). The lower front teeth sit in front of the upper ones.
- Open bite. Some teeth do not touch when the child bites together.
- Crossbite. One or more upper teeth sit behind or inside the lower teeth.
What Does Each Bite Problem Look Like?
Each pattern describes how the upper and lower teeth meet, and each is easier to picture than the terms suggest. Our bite problems page sets out each term in more detail.
Overjet means the upper front teeth sit too far ahead of the lower front teeth, the pattern many people call buck teeth. Picture the child’s smile from the side and look at the forward gap.
A deep overbite means the vertical overlap between the upper and lower front teeth is more than usual. Seen from the front, much of the lower front teeth may be hidden behind the upper ones.
An underbite, which our page calls a reverse overjet, means the lower front teeth sit in front of the upper ones. Our page says this is more often due to the jaws being out of step with each other. It is less often about tooth position alone.
An open bite means some teeth do not touch when the child bites down. It is usually the front teeth, though the back teeth can be involved as well.
A crossbite means the upper teeth sit on the wrong side of the lower ones. At the front, an upper tooth sits behind a lower one. At the back, an upper tooth sits inside a lower one, where it would usually sit outside.
What Is the Difference Between an Overjet and an Overbite?
Overjet and overbite measure two different things, even though people often use the words interchangeably. Overjet is the forward gap between the front teeth, seen from the side. Overbite is the vertical overlap, seen from the front.
| Term | What it measures | Easiest to see from |
| Overjet | The forward gap between the upper and lower front teeth | The side |
| Overbite | How far the upper front teeth cover the lower ones | The front |
Our bite problems page notes that an overjet is often called an overbite by mistake. The two measure different things, so a child can have one without the other. Only an examination can say which applies.
Why Do Some Bite Problems Matter?
Some bite patterns may make the teeth or gums more prone to wear or injury, which is why they are worth a look. None of these effects is certain for any one child.
A larger overjet is the clearest example. A 2019 review pooled many studies. It found that a larger overjet was linked with more injuries to the teeth across the age groups studied.
Children with prominent upper front teeth may be more likely to knock or chip one.
Our page also notes that a deep overbite may contribute to tooth wear and gum recession over time.
It says a reverse overjet may make chewing harder and add to tooth wear, and that an open bite may affect chewing and speech. It adds that a crossbite can sometimes affect wear and jaw growth. These are possibilities to discuss at a check, not predictions.
Can Thumb or Dummy Sucking Affect a Child’s Bite?
Sucking habits are one of several things that may shape how a bite develops. One 2025 review of 33 studies linked them with open bite. It found that prolonged, daily thumb and dummy sucking went with a higher risk of anterior open bite in children.
This is an association seen across groups of children. It does not mean a habit caused a bite problem in any one child, or that every child with a habit will develop one.
The American Association of Orthodontists says most orthodontic problems are inherited. In its view some develop over time, and it lists habits such as thumb or finger sucking and mouth breathing among the possible factors.
Habits are common and understandable in young children, and nothing here is a judgement on parents. Orthodontics Australia lists thumb or finger sucking that continues past age five among the reasons to see a specialist.
What Is a Crossbite, and Why Might a Bite Shift to One Side?
A crossbite is one of the few bite patterns with a pooled figure behind it. A 2022 review of 123 studies pooled results from children and teenagers aged 18 or under in many countries.
On average about 9% had a posterior crossbite, though results varied widely between studies. It is an international average, not a figure for Canberra or Australia.
In some crossbites the lower jaw closes to one side, which is called a functional shift, and an orthodontist checks for this. A parent may notice the bite seeming to move to one side when the child closes. Orthodontics Australia lists a jaw that shifts when opening or closing among the reasons to see a specialist.
What Happens at a Bite Check?
A bite check is a conversation and an examination, not a commitment to treatment. Orthodontics Australia says an orthodontist will typically examine a child’s baby and adult teeth, as well as the face, lips, jaws and bite.
That examination can pick up crowding, deep bites, crossbites, open bites and underbites. The orthodontist then explains what they see and answers a parent’s questions. Parents can bring up anything they have noticed, even if it seems small.
Why Are Some Bite Issues Monitored First?
Noticing a bite problem does not always lead to treatment straight away. The American Association of Orthodontists states that not all early visits result in treatment. Some children are simply followed periodically while the face and jaws keep developing.
Orthodontics Australia says an underbite in a very young child can sometimes self-correct as the baby teeth are replaced by adult teeth. It also notes that more severe cases may need some care from as young as 6. Timing varies from child to child, and the orthodontist decides it after an examination.
An assessment therefore gives a baseline. The orthodontist may suggest one of three paths.
- Review over time. The bite is checked again as the face and jaws keep developing.
- Start care now. Treatment begins where the orthodontist thinks it is suitable.
- Leave things as they are. No treatment is suggested.
Our earlier article on early orthodontic treatment explains when early care is used and when it is not.
When Should a Parent Arrange a Bite Check?
Guidance on timing differs a little between countries. Orthodontics Australia recommends a first assessment between about 8 and 10 years old, once the front adult teeth have come through. The American association suggests a first check-up by age 7.
Our children’s page notes that most children have a mix of baby and adult teeth between 7 and 10.
Whatever your child’s age, if you have noticed something you can raise it with an orthodontist. Healthdirect also notes that no referral is needed to see an orthodontist.
We cover the early signs of a bite or jaw concern in signs your child may need braces. That list is not repeated here. A bite problem can only be assessed properly by a clinician after an examination, and a parent cannot do so from an article.
How Do I Book a Bite Check?
If something about your child’s bite has caught your eye, an orthodontist can explain what it means. At a check, the orthodontist examines the teeth, face, lips, jaws and bite.
They explain what they see in everyday words and talk through whether to monitor or act. If an appliance is ever suggested, our appliances page explains how the common appliances work.
To read the full description of each bite pattern, visit our bite problems page. To arrange a check, contact the Capital Smiles team in Deakin and we will be glad to help. Our first visit page explains what to bring and how to get here.