Pathological changes related to long-term impaction of third molars. A radiographic study.

Pathological changes related to impacted 3rd molars (ITM) were studied in a radiographic investigation of 2128 randomly selected patients. In radiographs from 644 patients, 1211 ITM were noted. Pathological changes were observed in 25 of 477 (5.2%) maxillary ITM and in 59 of 734 (8%) mandibular ITM. A pathologically widened pericoronal space (indicating a dentigerous cyst) was observed in 5 of 477 maxillary and 43 of 734 mandibular ITM (p less than 0.001). Other pathologic changes observed were resorption of the 2nd molars (1% in the maxilla, 1.5% in the mandible) or loss of marginal bone on the distal aspect of the second molars (4% in the maxilla, 1% in the mandible). The risk of pathological sequelae because of ITM, apparently, is low. Prophylactic surgical removal should, therefore, be regarded with some reserve, particularly in view of the high frequency of deep impactions, with greater risk for surgical complications.