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Teeth and Face Classifications

Classification of Teeth

The classification of bites is broken up into three main categories: Class I, II, and III.

Class I: Class I is a normal relationship between the upper teeth, lower teeth, and jaws or balanced bite.

Class I Normal
Normal

Class I Crowding
Crowding

Class I Spacing
Spacing

Class II: Class II is when the lower first molar is posterior (or more towards the back of the mouth) than the upper first molar. In this abnormal relationship, the upper front teeth and jaw project further forward than the lower teeth and jaw. There is a convex appearance in profile with a receding chin and lower lip. Class II problems can be due to insufficient growth of the lower jaw, an overgrowth of the upper jaw, or a combination of the two. In many cases, Class II problems are genetically inherited and can be aggravated by environmental factors such as digit sucking. Class II problems are treated via growth redirection to bring the upper teeth, lower teeth, and jaws into harmony.

Class II Division I
Division 1

Class II Division II
Division 2

Class III: Class III is when the lower first molar is anterior (or more towards the front of the mouth) than the upper first molar. In this abnormal relationship, the lower teeth and jaw project further forward than the upper teeth and jaws. There is a concave appearance in profile with a prominent chin. Class III problems are usually due to an overgrowth in the lower jaw, undergrowth of the upper jaw or a combination of the two. Like Class II problems, they can be genetically inherited.

Class III Skeleton
Skeleton

Class III Dental
Dental

Classificaiton of Face

It is not sufficient to categorize orthodontic malocclusions on the basis of a classification of the teeth alone. The relationship with other craniofacial structures must also be taken into consideration.

Class I

Maxillary-Mandibular Dental Protrusion — teeth
Maxillary-Mandibular
Dental Protrusion — Teeth:
This is an example of a dental malocclusion that may require the removal of teeth for correction.

Maxillary-Mandibular Dental Retrusion — teeth
Maxillary-Mandibular
Dental Retrusion — Teeth:
This is an example of a dental malocclusion that may be treated with expansion rather than removing teeth.

Class II

Maxillary Dental Protrusion — teeth
Maxillary Dental
Protrusion — Teeth:
This malocclusion may require the removal of teeth.

Mandibular Retrognathism — jaws
Mandibular
Retrognathism — jaws:
The lower jawbone has not grown as much as the upper jaw. This example of a Class II malocclusion demonstrates the need for early growth guidance.

Maxillary Dental Protrusion — teeth & Mandibular Retrognathism — jaws
Maxillary
Dental Protrusion — teeth & Mandibular
Retrognathism — jaws:
These Class II malocclusions are more difficult to treat due to the skeletal disharmony and may require orthognathic surgery in conjunction with orthodontic treatment.

Class III

Mandibular Dental Protrusion — teeth:
The lower teeth are too far in front of the upper teeth. This malocclusion is treated with orthodontic procedures which may require the extraction of teeth due to the dental protrusion.

Mandibular Prognathism — jaws:
The lower jaw bone has outgrown the upper jaw. This malocclusion is more difficult to treat due to the skeletal disharmony and may require orthognathic surgery in conjunction with orthodontic treatment.