A normal bite means that when you close your mouth, the upper and lower teeth fit together harmoniously, the jaws are positioned in balance, and chewing and speaking can be done comfortably. The framework used in orthodontics for an ideal bite is known as the six keys, first described by Lawrence Andrews. However, most mouths do not match this description exactly; a deviation from the bite is not, by itself, considered a disease that needs treatment. On this page, we explain in plain terms what a normal bite is, when deviations become important and how the decision process works.
This information is general; the decision for you is made after an examination.
What is a normal bite, and is it the same as an ideal bite?
The bite (occlusion) is the way the lower and upper teeth contact each other. Doctors distinguish between two concepts. A normal bite covers a wide range of situations that do not impair function and do not cause a major problem. An ideal bite is the idealized example from textbooks and is rarely seen in natural mouths. In other words, your teeth not matching the ideal description does not mean your bite is abnormal.
To consider a bite healthy, doctors generally look at the following: does the mouth close comfortably, do the teeth work together when chewing, are the jaw joint and muscles not strained, and are the teeth and gums not exposed to excessive load? Aesthetics is a separate dimension; people whose function is good but who are unhappy with the appearance also come for an orthodontic examination.
What are Andrews' six keys?
Andrews examined mouths with a well-balanced bite and grouped their common features under six headings. These headings are still used today as a guide in orthodontic assessment and in setting treatment goals.
- Molar relationship: The front cheek-side cusp of the upper first molar sits in the groove between the two cusps of the lower first molar. This is known as an Angle Class I relationship (for details, see the bite classes page).
- Crown angulation (tip): The crown axis of the teeth is arranged at a certain angle with the root axis; teeth do not stand fully upright and parallel side by side but carry a slight tilt.
- Crown inclination (torque): The front-to-back tilt of the teeth is appropriate; the upper front teeth do not lean too far forward or backward.
- No rotations: The teeth are not rotated around their own axis; a rotated molar at the back can disturb the bite.
- Tight contacts: There are no gaps between neighboring teeth, and the teeth are not crowded either.
- Flat occlusal plane: The line along which the teeth are arranged on the chewing surfaces is flat or only very slightly curved (the curve of Spee).
These six keys are a kind of checklist; it is not expected that all of them will be met in full. The doctor evaluates them on a panoramic film, an intraoral scan or a model, together with the facial and jaw structure.
Which measurements describe the bite?
There are three terms you will often hear at the examination:
- Overjet: The amount by which the upper front teeth project in front of the lower front teeth (horizontal distance). Normally it is a few millimeters.
- Overbite: The amount by which the upper front teeth cover the lower front teeth vertically. Normally part of the lower teeth is covered, but not all of it.
- Midline: The imaginary line passing through the middle of the upper and lower front teeth. Ideally it lines up with the middle of the face; small shifts are common and often do not cause a problem (see midline shift).
When do deviations from normal need treatment?
Not every deviation needs treatment. The decision is usually based on three questions: Is function affected? Are the teeth, gums or joint being harmed? Is the person bothered aesthetically? The table below offers a general framework for common deviations.
| Situation | What it means | When to see a doctor |
|---|---|---|
| Open bite | A gap remains between the front teeth when the back teeth close | If biting and speaking are difficult, or if a thumb-sucking or tongue-thrusting habit continues in children |
| Deep bite | The upper teeth cover the lower teeth too much | If the lower front teeth touch the palate or the back of the upper teeth and cause wear |
| Crossbite | Some upper teeth close inside the lower teeth | If the jaw is forced to shift, especially if facial and jaw development is being monitored in children |
| Crowding | The teeth are arranged crowded because of a lack of space | If cleaning is difficult, the gums bleed or there is aesthetic discomfort |
| Protruding upper teeth | The overjet is markedly increased | If the teeth are exposed to impact or there is difficulty closing the lips |
| Mild midline shift | The lower and upper midlines do not line up exactly | Usually assessed only if a bite mismatch at the back accompanies it |
For more detail, you can look at the open bite, deep bite and crossbite pages, or the blog article on deep bite.
Function or aesthetics?
Functional reasons include difficulty chewing, certain teeth being under excessive load, tooth wear, contact problems that set the stage for gum recession, and shifting that strains the jaw joint. These problems are not seen with every bite deviation, so the presence of a deviation is not automatically a reason for treatment.
Aesthetic reasons are based on a person's dissatisfaction with their smile and are entirely legitimate. For a balanced and sound decision, it helps to discuss the two dimensions separately: Do I want this for my function or for my appearance? The answer affects the treatment goal, the duration and the method chosen.
Which methods are used to correct the bite?
For mild and moderate dental deviations, traditional braces (brackets and wire) or clear aligners can be used. In children, jaw expansion appliances and functional appliances may come into question to guide jaw growth. When the mismatch between the jaw bones is marked, approaches in which orthodontics and surgery are planned together are considered in adults. For the general framework, you can take a look at the orthodontic treatments page.
Can the bite be corrected with clear aligners?
In most people, clear aligners can be used for a large share of bite deviations of dental origin; crowding, gaps between the teeth, and mild to moderate open, deep or crossbites are among them. Along with the aligners, helpers such as attachments (small tooth-colored bumps for grip), elastics and IPR (interproximal reduction) can be added to the plan.
On the other hand, there are limits. Marked mismatches that originate in the jaw bone may not be corrected with clear aligners alone; surgery or a different approach may be needed in these cases (see do clear aligners correct the jaw structure?). How effective the aligners will be also depends on the type of deviation, the doctor's plan and regular wear. You can read the question of suitability more broadly on the page who are clear aligners suitable for. The blog also has an article on open bite.
How can you assess your own bite?
A quick look in the mirror is not a substitute for a diagnosis, but while preparing for an examination you can note the following: When you close your mouth, do your back teeth sit comfortably? Do you prefer to chew on one side? Is there clicking or pain when the jaw opens and closes? Have you noticed findings such as uneven wear on your teeth or gum recession? Does your child have a horizontal or vertical gap, a crossed tooth or mouth breathing that catches your attention?
In addition to these questions, an intraoral scan or impression, photographs and, when necessary, panoramic or cephalometric films are taken at the examination. Preparing a list of questions before the appointment is also a good idea; the orthodontic examination question list page can help with this. At the examination, your bite is assessed by looking not only at the teeth but also at the facial profile, lip and tongue habits, breathing pattern and jaw movements, because the bite is the result of a whole system rather than of a single row of teeth. The what is orthodontics page and the orthodontics article on the blog may also be of interest for the general framework of orthodontics.
Where can you go for an examination?
At the Funda Sarıkaya Oral and Dental Health Polyclinic, Funda Pekyılmaz Sarıkaya, specialist orthodontist (Uzm. Dt.), carries out bite assessments; the Invisalign system is also used at the clinic. The clinic is located at Park Oran Ofis Dükkan No:70, Kudüs Cd., Oran Mah., Çankaya/Ankara (next to Panora Mall, opposite One Tower Mall). Service languages are Turkish, English, German and Russian. You can make an appointment by phone or WhatsApp on 0312 911 60 36, Monday–Saturday between 09:00 and 20:00.
This information is general; the decision for you is made after an examination.