Panoramic radiographs underestimate extensions of the anterior loop and mandibular incisive canal.
OBJECTIVE
The purpose of this study was to detect the anterior loop of the mental nerve and the mandibular incisive canal in panoramic radiographs (PAN) and cone-beam computed tomography (CBCT) images, as well as to determine the anterior/mesial extension of these structures in panoramic and cross-sectional reconstructions using PAN and CBCT images.


METHODS
Images (both PAN and CBCT) from 90 patients were evaluated by 2 independent observers. Detection of the anterior loop and the incisive canal were compared between PAN and CBCT. The anterior/mesial extension of these structures was compared between PAN and both cross-sectional and panoramic CBCT reconstructions.


RESULTS
In CBCT, the anterior loop and the incisive canal were observed in 7.7% and 24.4% of the hemimandibles, respectively. In PAN, the anterior loop and the incisive canal were detected in 15% and 5.5% of cases, respectively. PAN presented more difficulties in the visualization of structures. The anterior/mesial extensions ranged from 0.0 mm to 19.0 mm on CBCT. PAN underestimated the measurements by approximately 2.0 mm.


CONCLUSIONS
CBCT appears to be a more reliable imaging modality than PAN for preoperative workups of the anterior mandible. Individual variations in the anterior/mesial extensions of the anterior loop of the mental nerve and the mandibular incisive canal mean that is not prudent to rely on a general safe zone for implant placement or bone surgery in the interforaminal region.
Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
Ana Caroline Ramos
AC
de Brito
Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
Yuri
Y
Nejaim
Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
Deborah Queiroz
DQ
de Freitas
Department of Stomatology, Public Oral Health and Forensic Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
Christiano
C
de Oliveira Santos
Anatomic Variation; Cone-Beam Computed Tomography; Mandible; Radiography, Panoramic
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