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Risk of lingual concavity in implantology: CBCT correlates with inferior alveolar nerve canal

Researchers use cone beam computed tomography to correlate the deepest lingual concavity depth with inferior alveolar canal and its association with gender, age, and race. (Image: Dr. Tanay Chaubal and Canva)

Fri. 2 February 2024


KUALA LUMPUR, MALAYSIA: A cross-sectional study conducted by Dr. Tanay Vijaykumar Chaubal and his team at the School of Dentistry, International Medical University, Kuala Lumpur, Malaysia, has found a correlation between the deepest lingual concavity and the level of the inferior alveolar canal, with variations across age groups, genders, and races. To account for depth variations and penetration risks, the study recommends assessing the implant fixture site on a case-by-case basis.

Successful integration of implants requires comprehensive investigation and treatment planning, especially on important anatomical landmarks, such as lingual concavity and position of the inferior alveolar canal, where the inferior alveolar nerve passes through the mandibular foramen into the mandibular bone and exits at the mental foramen. 

Clinical experience and research have shown that lingual concavity is a risk factor and errors made during surgical placement of dental implants could lead to lingual plate perforation, resulting in complications ranging from local edema to life-threatening events. The lingual nerve injury could cause loss of general sensation at the anterior 2/3rd of the tongue. Injury to the inferior alveolar canal may cause irreversible neurosensory disturbances, such as loss of vitality of teeth and numbness of the chin in the affected quadrant. Bleeding and infection can also occur due to perforation of sub-mylohyoid space, or even parapharyngeal spaces, leading to upper airway obstruction.

Principal investigator Dr Tanay Vijaykumar Chaubal. (Image: International Medical University, Malaysia)

In the study led by Dr. Tanay Chaubal, the researchers evaluated 384 CBCT scan records via eXamVision software from 2011 to 2019. Panoramic, sagittal, axial, and cross-sectional images were reconstructed for the mandible, and the inferior alveolar canal was identified, and color-marked for each scan. Measurements were performed in every cross-sectional image between the 1st premolar to 2nd molar region. The scan that portrayed the deepest lingual concavity was measured in cross-sections at 1 mm intervals, with 1 mm thickness from mesial of 1st premolar to distal of 2nd molar. The deepest lingual concavity was compared with the color-marked inferior alveolar canal to evaluate its position: above, at, or below the inferior alveolar canal.

The mean lingual concavity depth was 2.23 ± 0.76 mm in male subjects and 1.74 ± 0.61 mm in female subjects. The mean lingual concavity depth was highest in Indian (2.20 ± 0.73 mm), followed by Malay (2.00 ± 0.73 mm), and Chinese (1.80 ± 0.69 mm) populations. The deepest lingual concavity was located above the inferior alveolar canal on both sides of the mandible with the deepest concavity noticed in the second molar area in most of the scans. There was no statistically significant difference in the level of the inferior alveolar canal among different age groups and genders for each side of the mandible.

The lingual concavity depth of the posterior mandible was significantly influenced by race (p<0.05). The concavity was the deepest in Indians, followed by Malays and Chinese for both sides of the mandible. This indicates that the width and thickness of the posterior mandibular bone are less in Indians, followed by Malays and Chinese. It could also mean that Indians have the biggest submandibular gland, which is situated in that fossa, Dr Chaubal stated.

“Different races have discrete structural variations or facial morphology leading to divergent anatomy of the posterior mandible and its vital structures.” —Dr Tanay Vijaykumar Chaubal, International Medical University, Malaysia

“In the future, studies must be conducted to perform concavity measurements in patients with a history of systemic diseases, such as diabetes mellitus and osteoporosis to measure their impact. Additionally, difference in concavity measurements of edentulous and dentulous patients could be considered as a future point of research,” Dr Chaubal, stated.

The study, titled “Evaluation of lingual mandibular depression of submandibular salivary glands and its relation to inferior alveolar canal using cone beam computed tomography in Malaysian population: a cross-sectional study,” https://doi.org/10.5114/jos.2023.133635 is published in Journal of Stomatology.

Read more about Dr. Tanay Chaubal here

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