[Topographic evaluation of the impacted mandibular third molar. Radiographic study].

Preoperative planning of surgical extraction of a wisdom tooth is always necessary. Accurate evaluation of its position and relation to the other surrounding anatomical structures is facilitated by radiographic examination. Nine hundred sixty one radiographs of patients who came to the clinic of Exodontia and Radiology were used. Of these radiographs one thousand hundred thirty six impacted and partially impacted mandibular third molars and its relation to the second molar and the anterior border of the ramus were studied. The distance between the anterior border of the ramus and the posterior surface of the second molar in comparison to the crown diameter of the studied wisdom tooth was equal in 12.68 percent, smaller in 66.55 percent (P less than 0.0001) and larger in 20.77 percent. Most of the impacted third molars were located mesio angularly (42.34%, P less than 0.0001), 21.13% were vertical, 20.60% horizontal and 2.73% lingo-angular.