A tooth which fails to erupt in normal anatomical position either due to lack of space or due to obstruction from tooth, bone or soft tissue.
1. Causes :
» Irregularity in the position and pressure of an adjacent tooth.
» Density of the overlying or surrounding bone.
» Chronic inflammation with resultant fibrosis of the overlying mucosa.
» Lock of space due to under developed jaws. Unduly over retention of the deciduous teeth.
» Premature loss of deciduous teeth.
» Acquired disease such as necrosis due to infection.
» Inflammatory changes in the bone due to exanthematous diseases in children, like, Chicken pox, Parotitis.
b. Post Natal
» Endocrine dysfunctions.
» Diseases of jaw and surrounding tissue
3. Rare Conditions
» Cleidocranial dysostosis
» Cleft palate
2. Impaction In The Following Order Of Frequency
» Mandibular third molars.
» Maxillary thirds molars.
» Maxillary cuspids.
» Mandibular bicuspids.
» Maxillary bicuspids.
» Upper central incisors.
» Upper lateral incisors.
3. Complications From Retained Impacted Teeth
» Pericoronal infections.
» Acute or chronic alveolar abscess.
» Chronic suppurative osteitis.
» 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.
Frequency with which fractures of the mandible occur through areas occupied by the tooth, proves to be a factor.
4. Classification Of Impacted Mandibular Third Molar
A. Relation of the tooth to the ramus of the mandible and second molar.
There is sufficient space between the ramus of the mandible and the distal of the second molar to accommodate the mesiodistal width of the third molar. Still it fails to erupt.
Space between the ramus and distal of the second molar is less than the mesiodistal diameter.
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
5. Factors Complicating the Operative Procedure
» Abnormal root curvature.
» Proximity of mandibular canal.
» Extreme bone density especially in elderly patients.
» Follicular space filled with cementum or bone.
» Small orbicular oris.
» Inability to open the mouth.
» Large and uncontrollable tongue.