Background and Objective: The infraorbital canal (IOC) is located in the floor of the orbit and terminates at the infraorbital foramen below the orbital rim. The IOC is a crucial anatomical landmark for successful anesthesia in dentistry and oral and maxillofacial surgery. This study aimed to evaluate the position and dimensions of the IOC based on cone-beam computed tomography (CBCT).
Methods: This descriptive-analytical study was conducted on CBCT images of 250 individuals (105 males and 145 females) (mean age = 36.14±17.7 years) referring to a specialized oral and maxillofacial radiology clinic in Babol, Iran, during 2021-22. Three different types of IOC pathways from the sinus roof were measured: Completely located within the maxillary sinus roof (Type 1), located below the maxillary sinus roof (Type 2), and suspended from the maxillary sinus roof within the septum or lamella of the infraorbital ethmoid cell (Type 3). Additionally, the angles between the IOC and the infraorbital groove with the maxillary sinus roof, the angles between the IOC and the infraorbital groove, the lengths of the IOC and the infraorbital groove, and the distances of the IOC from various anatomical landmarks were measured. Distances of the IOC (mm) were evaluated from other anatomical landmarks according to gender and age groups.
Results: Overall, various pathways of the IOC from the sinus roof were 39.4% in Type 1, 53% in Type 2, and 7.6% in Type 3; the mean distance of the IOC to the infraorbital rim was 8.58±1.30 mm, and to the midpoint of the canine root was 10.16±0.81 mm. The mean length of the canal was 25.89±2.47 mm, and the infraorbital groove was 5.06±0.58 mm; and the mean angle between the IOC and the infraorbital groove was 153.20±3.28 degrees. In general, the distance of the IOC to the midpoint of the canine root on both the left and right sides was greater in males than in females, which was statistically significant on the left side (P<0.05). It was found that the length of the IOC and the angle between the IOC and the infraorbital groove on the left side had statistically significant correlations with age groups (P<0.05). The mean distance from the foramen to the infraorbital rim and the length of the IOC were proportional to the degree of nerve protrusion into the maxillary sinus; however, no significant correlation was found between the types of canals (degree of nerve protrusion) and gender.
Conclusion: Type 2 was the most common pathway of the IOC from the sinus roof. Although Type 3 was less common, due to the high risk associated with this type of canal, surgeons should be fully aware of the morphology and anatomical position of the IOC during sinus and orbital surgeries to reduce probable injuries.