Lingual foramina on cone beam computed tomography: A retrospective radiographic study

Dental surgeons commonly believed that the mandibular site between the mental foramina is the safest for surgical procedures, but there have been numerous reports of significant bleeding accidents in this area. Adequate knowledge about the presence and variation in the morphology of anterior lingual foramina is necessary before starting surgical procedures such as implant placement and ridge augmentation.

The aim of this study was to analyse the presence, frequency, location and relationship of lingual foramen with the inferior border of mandible on Cone Beam Computed Tomography scans (CBCT).

This retrospective radiographic study was designed and conducted at Maharashtra Institute of Dental Sciences & Research, Latur, India in the Department of Periodontology after approval from the Institutional Ethical Committee.

100 CBCT scans of dentulous and partially edentulous mandible were randomly acquired and assessed in coronal, sagittal, transverse and cross-sectional views. The CBCT scans made for diagnostic purposes under field of view 15 × 5 cm, 200 μm voxel size, of patients >20 and < 70 years of age of both the genders were included. Presence of cysts, tumours, systemic diseases affecting bone, fractures, previous surgery in the inter-foraminal region and poor quality of CBCT scans were excluded. Total number of foramina, their location and vertical distance between them to inferior border of mandible were recorded.

Data were entered in data sheets and analysed by using descriptive and inferential statistics. Qualitative data were expressed in terms of proportions while quantitative data were expressed in terms of means and standard deviation. Potential significance was evaluated with Chi square tests.

100 CBCT scans (47 male and 53 females) were randomly analysed. All participants had at least 1 lingual foramen (LF). Total 172 LF were detected on 100 CBCT scans, including 154 (89.5 %) medial LF (MLF) and 18 lateral LF (LLF) (10.4 %). Out of 154 MLF, 63.6 % were present superior and 36.4 % inferior to genial tubercles. Out of 100 subjects, single LF in 44, two in 43, three in 11, four in 1 and five in 1 patient were observed. 94.44 % LLF were observed in canine and 1st premolar region. The mean distance from the MLF and inferior border of mandible was 10.87 ± 2.99 mm, while the same for LLF was 7.1 ± 4.76 mm. About one third of the foramina were in between 13.1 and 16 mm distance from inferior border.

Considering the limitations of the study, the midline lingual foramen can be considered as normal regular anatomic feature with 99 % prevalence while the lateral lingual foramina occur infrequently with a lot of variability in numbers and present commonly in the canine-first premolar zone. Almost 1/3rd of midline foramina are present superior to the genial tubercles.