Incidence and classification of bifid mandibular canals using cone beam computed tomography

Abstract

Aim: To determine the prevalence and classification of bifid mandibular canals using cone beam computed tomography (CBCT). Methods: The sample comprised 300 CBCT scans obtained from the Radiology and Imaging Department database at São Leopoldo Mandic Dental School, Campinas, SP, Brazil. All images were performed on Classic I-Cat® CBCT scanner, with standardized voxel at 0.25 mm and 13 cm FOV (field of view). From an axial slice (0.25 mm) a guiding plane was drawn along the alveolar ridge in order to obtain a cross-section. Results: Among 300 patients, 188 (62.7%) were female and 112 (37.3%) were male, aged between 13 to 87 years. Changes in the mandibular canal were observed in 90 patients, 30.0% of the sample, 51 women (56.7%) and 39 men (43.3%). Regarding affected sides, 32.2% were on the right and 24.5% on the left, with 43.3% bilateral cases. Conclusions: According to the results obtained in this study, a prevalence of 30% of bifid mandibular canals was found, with the most prevalent types classified as B (mesial direction) and bilateral.

Prevalence evaluation and classification of bifid mandibular canals in CBCT exams in different facial types

“…The relative frequency of mandibular canal bifurcation according to the classification suggested by Freitas et al 9 , Class D, was the commonest (retromolar direction), since it occurred in 9 of the 23 cases (39.1%). The second most prevalent classification was "C" (alveolar direction), which occurred in 5 of the 23 cases (21.7%).…”

“…The literature points to the importance of knowing the anatomy of the mandibular canal and its possible variations for the success of many dental procedures performed on the mandible, such as anesthesia, endodontics, periodontics, pediatric dentistry and more invasive procedures such as surgical exodontia, orthognathic surgeries, implant placement, among others 9,16,[19][20][21] .…”

“…The dentist should be aware that the mandibular canal may undergo anatomical variations in shape, size, number, as well as in vertical and horizontal positions. For these reasons, several authors have emphasized the importance of studying the precise location of such landmarks and possible anatomical variations therein using CT scans 3,5,8,9 . In most cases, the mandibular canal presents as a single structure, though canal duplications, also known as bifid canals, are among the commonest anatomical variations of the mandibular canal and can be grouped in different classifications, as proposed by several authors 6,9,19 . Chávez-Lomeli et al 20 questioned the definition of the term bifid attributed to the mandibular canal, as the authors state that there is no division of the mandibular canal into two or more canals as such, but the persistence or non-fusion of the embryologically defined branches of the mandibular canal.…”

“…To evaluate the frequency of bifid mandibular canals in the different facial types, as well as gender, age and affected side, the percentage frequency was used, with a descriptive analysis of the results. In cases where bifid canals were present, these were classified according to the study by Freitas et al 9 . According to this study, bifid mandibular canals are classified according to the direction they follow into Class A -buccal direction, Class B -mesial direction, towards the mesial or anterior aspects, Class C -alveolar direction, towards the alveolar or upper directions, Class D -retromolar direction (according to Figure 2), Class E -lingual direction and Class F -towards the base of the mandible.…”

“…Many dental surgeons are unaware of the existence of anatomical variants of this canal and thus may not be able to visualize them in conventional panoramic and tomographic images 8 . As a consequence, trans and postoperative surgical complications, anesthetic failures and implant placement failures may occur 9 .…”