Maxillary 3rd Molar or Wisdom tooth Impaction Classification – Archer

Maxillary 3rd molar is not as commonly impacted as the Mandibular but the frequency of Impaction rate is high. Maxilalry 3rd moalr impaction is considerably difficult because of many factors which are favorable when compared to Mandibular 3rd molar like the Visibility factor, Reach, Tuberosity and its Proximity to the Maxillary Sinus. These are the many factors which make  Maxillary Impaction a Challenge to Dentists.

The various types of Impactions in Maxillary 3rd Molars is similar to that of the Mandibular 3rd Molars based on the Orientation and location of the tooth in relation to the 2nd molar. Archer (1975) classified them into 7 types:

1. Mesioangular: The Impacted tooth is positioned with the Crown pointing in the Mesial direction towards the 2nd Molar and the Roots pointed Distally.
2. Distoangular: The Impacted tooth is positioned with the Crown pointing in the Distal direction towards the 2nd Molar and the Roots pointed Mesially.
3. Vertical: The tooth has not erupted completely and the crown of the 3rd molar lies near the root of the 2nd molar.
4. Horizontal: The impacted 3rd molar lies horizontally in the alveolar bone, with the crown towards the 2nd molar and the root tips towards the Distal side
5. Buccoangular: The Impacted Tooth is positioned in such a way in the alveolar bone that the Occlusal surface of the crown is towards the Buccal aspect
6. Linguoangular: The Impacted tooth is positioned  in such a way in the alveolar bone that the Occlusal surface of the crown is towards the Lingual aspect
7. Inverted: This is a very rare scenario but has been documented in the past, the impacted tooth is completely inverted with the root tip towards the occlusal surface and the Crown of the tooth towards the root of the 2nd Molar.

Note: The image is taken from the book: Textbook of Oral Surgery by Fragiskos D. Fragiskos 

Archer has classified Maxillary 3rd Molar or Wisdom tooth Impaction depending on the depth of Impaction in relation to the adjacent normally erupted 2nd Molar into 4 types:

The Impaction is classified into 5 types depending on the increase in depth at which the tooth is placed at. The difficulty of removal of the tooth increases with the increase in the depth of the Impacted tooth. Impacted tooth seen in the figure. a is easier to extract when compared to the impacted tooth seen in fig. e.