Bite Classifications

For information regarding types of malocclusions, refer to the following:

Bite classification is based on the relation of the first permanent molars in centric occlusion. It is conditioned by the skeletal position of the maxilla and the mandible as related to each other and with the cranial base. Assessing the dental as well as the skeletal condition of a patient, in all planes of space, is fundamental for a proper and comprehensive diagnosis and treatment planning.

Born in 1855, Dr. Edward Angle is considered the father of modern orthodontics. He invented ingenious mechanical appliances for moving teeth and created the classification of malocclusions that orthodontists still use today. Dr. Angle's bite classifications are divided into three main categories:

• Class I
• Class II
• Class III

Class I:

Dr. Angle came to the conclusion that the fundamental reference of ideal occlusion is the position of the first molars. He found that in patients with healthy bites, the mesio-buccal cusp of the upper first molar occludes in the buccal groove of the lower first molar.

A class I is described as the ideal occlusion with a proper molar relationship.  This occurs when the mesio-buccal cusp of the maxillary first permanent molar occludes with the buccal groove of the mandibular first permanent molar.

A Class I canine relationship is defined as when the cusp of the upper canine rests in the embrasure between the lower canine and first premolar.

Class II:

If the mesio-buccal cusp of the upper first molar is anterior to the buccal groove of the lower first molar, it’s considered a Class II molar relationship.

The molar relationship shows the buccal groove of the mandibular first molar is distally (posteriorly) positioned when in occlusion with respect to the mesio-buccal cusp.

Usually, the mesio-buccal cusp of maxillary first molar rests in between the first mandibular molar and second premolar. 

If the cusp of the upper canine is anterior to the embrasure between the lower canine and first premolar, we are also facing a Class II canine relationship.

Class II malocclusions can be divided into two types according to position of the incisors:

• Division 1: A Class II molar relationship with the anterior teeth protruded. Maxillary teeth are proclined and a large overjet is present.
• Division 2: A Class II molar relationship with the upper anterior teeth retroclined. The maxillary lateral incisor teeth may be proclined or normally inclined and a deep overbite is present.

Class II malocclusions of up to 3 mm can be treated with aligners using sequential distalization and Class II elastics to preserve anchorage.

Class III:

In a Class III malocclusion, the mesio-buccal cusp of the upper first molar is distally positioned with respect to the buccal groove of the lower first molar.

The cusp of the upper canine is also distally positioned with respect to the embrasure between the lower canine and lower first premolar.

Treatment approaches are based in diagnosing if there is also a skeletal component in the Class III malocclusion. If there is no skeletal component, the treatment usually considers IPR and retroclination of the lower incisors, proclination of the upper incisors and use of Class III elastics.