Comparison of cone-beam volumetric imaging and combined plain radiographs for localization of the mandibular canal before removal of impacted lower third molars

Objective. The removal of third molars requires information about the relative position of the root tips and the mandibular nerve. The diagnostic value of conventional radiologic procedures using a panoramic radiograph and symmetrical PA cephalometric radiograph (PAN&PA) was compared with that of a cone-beam volumetric imaging (CBVI) device (Galileos; Sirona, Bensheim, Germany). Study design. Six observers evaluated 30 PAN&PA and 30 CBVI for the position of root tips. Diagnostic information was rated from 1 to 5 (excellent to poor). Results. With PAN&PA, 3 times more scans showed nondetectable information for horizontal position compared with CBVI. The diagnostic information in the vertical dimension received a median rating of 2 (good) for CBVI and for PAN & PA; for the horizontal dimension, CBVI received a median rating of 2 (good), compared with a significantly worse median rating of 3 (sufficient) for PAN&PA (P =.000). The variance was highest for the horizontal dimension with PAN&PA (1.27). Conclusion. These findings indicate that cone-beam technology improves the localization of third molar for presurgical planning.