Comparison of Orthopantomographs and Conventional Tomography Images for Assessing the Relationship Between Impacted Lower Third Molars and the Mandibular Canal

A comparative analysis was made of the relationship between impacted lower third molars and the mandibular canal by means of orthopantomography and conventional mandibular tomography. Consideration was given to the association between the existence or absence of a close relationship according to gender, age, and tooth involved, as well as the resolution of the mandibular canal tomograph of the mesial and distal roots. The sample consisted of 19 patients of both genders with impacted third molars that exhibited a close relationship between impacted lower third molars and the mandibular canal on the orthopantomograph. Thirty-one relationships were assessed, for each of which a conventional mandibular tomograph was requested. Cases were verified for a true relationship. All cases were appraised by the same radiologist. A close relationship with the mandibular canal was found on the tomograph in 77.4% of cases. The reported data showed that the most common relationship criterion was darkening of the roots (14 cases; 45.2%). A true relationship was confirmed on the tomograph in 92.1% of these cases. The presence of the radiographic sign of a close relationship found on the orthopantomograph represents, in most cases, a true relationship, requiring the classification of the type of radiographic sign to prevent injury to the nerve.