Angle’s Classification

There are a number of methods that can be used to classify malocclusions and one of these in Angle’s Classification. This was developed by Edward Angle in 1850 and is the first method that was developed to describe malocclusions.

Definition
The classification is based on the relationship between the mesiobuccal cusp of the maxillary first permanent molar and the buccal groove of the mandibular first permanent molar.

Class 1

A Class 1 molar relationship is described as:

  • The mesiobuccal cusp of the maxillary first molar occluding in line with the buccal groove of the mandibular first molar i.e. the maxillary first molar is slightly posteriorly positioned relative to the mandibular first molar.
Class 1 Molars

Class 1 Molars

Class 2

This most commonly causes a retrognathic facial profile. A Class 2 molar relationship is described as:

  • The mesiobuccal cusp of the maxillary first molar occluding anterior to the buccal groove of the mandibular first molar i.e. the maxillary first molar is inline with or anteriorly positioned relative to the mandibular first molar.
Class 2 Molars

Class 2 Molars

The Class 2 molar relationship can be divided into 2 further parts:

  • Class 2 Division 1 – Class 2 molars with normally inclined or proclined maxillary central incisors
  • Class 2 Division 2 – Class 2 molars with retroclined maxillary central incisors
Class 2 Div 1

Class 2 Div 1

Class 2 Div 2

Class 2 Div 2

Class 3

This causes a prognathic facial profile. A Class 3 molar relationship is described as:

  • The mesiobuccal cusp of the maxillary first molar occluding posterior to the buccal groove of the mandibular first molar i.e. the maxillary first molar is severely posteriorly positioned relative to the mandibular first molar.
Angle's Classification - Class 3 Malocclusion

Class 3 Malocclusion

Each class can also become more specific by being described as half-unit or full-unit classes, where a ‘unit’ is essentially an entire tooth position. For example, a half unit class 2 relationship is where the mesiobuccal cusp of the maxillary first molar occludes with the mesiobuccal cusp of the mandibular first molar. Whereas, a full unit class 2 is where the mesiobuccal cusp of the maxillary first molar occludes at the embrasure space between the mandibular second premolar and first molar.

A good summary of the variable positions of the molars is demonstrated in the image below:

Angle's Classification

Quiz

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References and Recommended Reading

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About the author

Prateek Biyani

BDS (Hons.) MFDS RCPS (Glasg.)
Currently working as a Dental Core Trainee in OMFS

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