What is the Angle classification?
The terms “Class I”, “Class II” and “Class III” that often appear in orthodontic examination notes are based on a descriptive system known as the Angle classification. This system mainly looks at the position of the upper and lower first permanent molars (the six-year molars) relative to each other. With the mouth closed, how far forward or back the upper molar sits relative to the lower molar shows which class the bite belongs to.
The classification is less a diagnostic tool than a starting point that gives clinicians a shared language for describing the bite. The treatment plan is built from the class together with many other details, such as crowding, a deep bite or open bite, the facial profile, age and growth status.
The classes in brief
| Class | Molar relationship | Commonly associated findings | Related page |
|---|---|---|---|
| Class I | Upper and lower molars in a normal relationship | Crowding, gaps between teeth, deep bite or open bite may be present | Crowded teeth |
| Class II, division 1 | Lower molar sits back relative to the upper molar | Upper front teeth tilted forward, marked distance between the front teeth (overjet) | Retruded lower jaw |
| Class II, division 2 | Lower molar sits back relative to the upper molar | Upper front teeth tilted inward, often a deep bite | Deep bite |
| Class III | Lower molar sits forward relative to the upper molar | Lower front teeth in front of the upper ones or edge to edge, anterior crossbite | Protruding lower jaw |
Class I
The relationship between the molars is considered normal; that is, the front-to-back fit of the jaws is usually balanced. However, this does not mean the teeth are straight. A Class I bite can still include problems such as crowding, gaps, an open bite or a crossbite.
Class II
The lower teeth bite further back relative to the upper teeth. It is described in two divisions:
- Division 1: The upper front teeth are tilted forward; the appearance often described as “buck teeth” frequently goes with it. See protruding teeth.
- Division 2: The upper central incisors are tilted inward, the lateral incisors are sometimes tilted forward, and the front teeth usually have a deep bite.
Class III
The lower teeth bite further forward relative to the upper teeth. The front teeth may meet edge to edge, or the lower front teeth may sit in front of the upper ones. The reason may be a forward lower jaw, an upper jaw that has stayed back, or both; see retruded upper jaw.
Skeletal or dental?
The same class can arise from different causes. For example, a Class II bite:
- May be dental: the jaws fit well, but the teeth are positioned forward or back on the jawbone.
- May be skeletal: the lower jaw has developed further back or the upper jaw further forward, and the teeth reflect this difference.
- In most cases both factors are present together.
To tell them apart, your orthodontist examines the facial profile and, if necessary, assesses the position of the jawbones relative to each other with records such as a lateral cephalometric X-ray. The distinction matters, because dental problems can usually be addressed by moving the teeth, while marked skeletal differences may call for growth guidance or, in adults, surgical support. More information: skeletal jaw problems.
Approach in children and adults
| Growing children and teenagers | Adults who have finished growing | |
|---|---|---|
| Class II | Functional appliances that support lower jaw growth may be considered (e.g. twin block, mandibular advancement with clear aligners) | Dental camouflage (improving the bite by adjusting the position of the teeth) or, in a marked skeletal case, surgical options together with orthodontics |
| Class III | Approaches that support upper jaw growth may be considered (e.g. face mask, palatal expansion); monitoring during growth is important | Dental correction in mild cases; planning together with orthognathic surgery in a marked skeletal difference |
| Class I | Lack of space, habits and the order in which teeth erupt are monitored | Tooth alignment is corrected with clear aligners or fixed braces |
The aim of treatments started during growth is to help the jaws develop in as harmonious a way as possible; however, the direction and amount of growth vary from person to person and the outcome cannot be known for certain in advance. On when an examination is needed: early orthodontic treatment. On whether surgery is needed in adults: When is orthognathic surgery needed?
Clear aligners or fixed braces?
For many Class I, II and III bites, both clear aligners and fixed braces can be considered; the choice depends less on the class itself than on the tooth movements needed, the skeletal component and how consistently the patient will wear the appliance. General comparison: clear aligners or braces?
Frequently asked questions
Does a Class I bite mean my teeth are straight?
No. Class I only describes a normal front-to-back relationship between the molars. Crowding, gaps or vertical bite problems may still be present.
Do Class II or Class III always require surgery?
No. Many dental and mild to moderate cases can be addressed with orthodontic treatment. Surgery is usually considered for marked skeletal differences in people who have finished growing; the decision is made after a detailed examination.
Can my bite class change?
During growth, jaw development can affect the bite. The molar relationship can also be changed with treatment. After treatment, retention is important for keeping the result.
My examination notes say “Class II, division 2”. What does that mean?
It means the lower teeth bite further back relative to the upper teeth and the upper front teeth are tilted inward; a deep bite usually goes with it. For terms, see our orthodontic glossary.
For questions, you can call 0312 911 60 36 or use the form on the contact page.
This page is for general information only; diagnosis and the treatment plan are determined by an examination and your orthodontist's assessment.
