Radiomorphometric analysis of mandibular lingula and evaluation of its relationship with anatomical structures

The mandibular lingula (ML) is a small bony prominence on the medial surface of the mandibular ramus above the anatomical opening called the mandibular foramen (MF) through which the inferior alveolar nerve, artery and vein pass. This structure is used as a reference point in anaesthetic procedures such as inferior alveolar nerve block (IASB) and is a critical anatomical point for the protection of nerves and vessels in ramus osteotomies. The aim of our study was to retrospectively evaluate the shape and position of the ML and its relationship with the surrounding anatomical structures in individuals with different skeletal classes and mandibular arch shapes using cone beam computed tomography (CBCT) images and to contribute to clinical practice for successful IASB and ramus surgery. This retrospective study was performed on 216 KIBT images obtained between 2013 and 2023 at Süleyman Demirel University Faculty of Dentistry. The study included 118 female and 98 male patients with a mean age of 25.29±7.94 years. Patients were divided into groups according to right-left side, gender, skeletal class and mandibular arch shape. Analyses were performed by a single observer using Planmeca Romexis and Quick Vision 3D software. The shape of the ML and Antilingula (AL) were determined and the distances of the ML and MF from the surrounding anatomical structures were measured. The most common form of ML was nodular (35.3%) and the least common forms were truncated and assimilated (17.1%). The most common form of AL was hill-shaped (34.4%) and the least common form was plain (17.1%). The positions of the ML and MF were largely similar between the right and left sides. In males, the distances of the ML and MF to the surrounding anatomical structures were often significantly greater than in females. In skeletal class 3, the position of the ML and MF relative to the occlusal plane was significantly higher than in the other skeletal classes. The distance of the ML to the sigmoid notch (SN) was significantly higher in skeletal class 3 than in other skeletal classes, and the distance of the MF to the SN was also significantly higher in skeletal class 3 than in skeletal class 2. There was no significant difference in the position of the ML relative to the anterior and posterior ramus, but the distance of the MF to the anterior ramus was significantly higher in skeletal class 2 than in skeletal class 3. The distance of the ML to the mandibular canines on the same and opposite sides was significantly higher in the square-shaped mandibular arches than in the other mandibular arch shapes, and in the oval-shaped mandibular arches than in the conical shape. The distances of ML and MF to the gonion were significantly higher in the square-shaped mandibular arches than in the conical shape. In our study, it was observed that the morphological variations and positional characteristics of ML and MF may vary according to right-left side, gender, skeletal class and mandibular arch shapes. The results of our study provided information to guide clinical practice to preserve anatomical structures and increase the success rate in IASB applications and mandibular ramus surgeries.