Assessment of Anatomical Variations of Median Lingual Canals: A CBCT study

Objectives: To investigate the presence, the number, the anatomic location, the course and morphology of median lingual canals in edentulous patients using cone beam computed tomography (CBCT).
Subjects and methods: Fifty completely edentulous patients were recruited from the outpatient clinic of the Prosthodontics Department, Faculty of Dentistry, Cairo University. All patients in this study were seeking to improve the retention of their mandibular complete dentures through dental implants. Patients were of age ranging from 50 to 70 years. A CBCT scan was performed for all patients to evaluate the edentulous area prior to implant placement. The number, the anatomical location and morphology of the median lingual canals were assessed by two Oral and Maxillofacial Radiologists. Additionally, the slope of the canals, the distance between the alveolar crest and the terminal ends of the median lingual canals; the length and the diameter of the median lingual canals were also assessed.
Results: All patients had at least one median lingual canal. Supra-spinosum canals were more frequent than infra-spinosum canals. Regarding the anatomical lingual canal morphology, Type E, A and D showed the greatest frequency. Most of the supra-spinosum canals sloped downward toward the labial surface, while most of the infra-spinosum canals sloped upward toward the labial surface. The distance between the buccal terminal end of the canal and the alveolar crest ranged between (3.6 - 21.2 mm) for supra-spinosum canals and (9.4 - 24.8 mm) for infra-spinosum canals. The distance between the lingual terminal end of the canal and the alveolar crest ranged between (2.7 - 19.4 mm) for supra-spinosum canals and (10.8 - 30.4 mm) for infra-spinosum canals. The canal length was found to be (3.5-15.3 mm) for supra-spinosum canals and (2.4 - 10.2 mm) for infra-spinosum canals. The average diameter of all canals ranged between (0.4 - 1.2 mm).
Conclusions: Determination of the number, the position as well as the diameter of median lingual canals before mandibular midline implant surgery in edentulous patient is important as these canals are constant anatomical landmark which have both vascular and neurosensory components.