Impaction In The Following Order Of Frequency

1. Mandibular third molars.
2. Maxillary thirds molars.
3. Maxillary cuspids.
4. Mandibular bicuspids.
5. Maxillary bicuspids.
6. Upper central incisors.
7. Upper lateral incisors.

Complications From Retained Impacted Teeth

1. Infection

• Pericoronal infections.
• Acute or chronic alveolar abscess.
• Chronic suppurative osteitis.
• Necrosis.
• Osteomyelitis.

2. Pain

• Pain may be reflected not only to the areas of distribution of the nerve but the associated areas too. Pain may be slight and localized.
• Severe and excruciating involving the entire upper and lower teeth.
• Intermittent, constant or periodical.

3. Fractures : Frequency with which fractures of the mandible occur through areas occupied by the tooth, proves to be a factor.

Classification Of Impacted Mandibular Third Molar

A. Relation of the tooth to the ramus of the mandible and second molar.

CLASS I : There is sufficient space between the ramus of the mandible and the distal of the second molar to accommodate the mesiodistalwidth of the third molar. Still it fails to erupt.

CLASS II : Space between the ramus and distal of the second molar is less than the mesiodistal diameter.

CLASS III : All or most of the third molar located within the ramus.

B. Relative depth of the third molar bone.

Position A : Highest portion of the tooth is on a level with or above the actual line.

Position B : Highest portion of the tooth is below the actual plane but above the cervical line of the second molar.

Position C : Highest portion of the tooth is below the cervical line of the second molar.

C. Relationship of the long Axis of the impacted third molar in relation to the long axis of the second molar

i. Vertical
ii. Horizontal
iii. Inverted
iv. Mesioangular
v. Distoangular
vi. Buccoversion
vii. Linguoversion