A CBCT Study of the Anterior Loop of the Mental Canal in Thais
Background: Injuries to neurovascular bundles in the anterior loop of the mental canal in the interforaminal areas from dental implant installation may cause neurosensory disturbances of the lower lip and chin. Studies regarding the prevalence and length of the anterior loop in Thai populations are scarce.
Objectives: To investigate the prevalence and length of the anterior loop in Thai populations using cone-beam computed tomography (CBCT).
Materials and methods: CBCT images obtained during 2010-2013 using a Promax 3D® (Planmeca, Helsinki, Finland) CBCT machine at the Dental X-ray Center, Faculty of Dentistry, Chiang Mai University, Thailand, were collected. With inclusion criteria, CBCT images of 102 patients were included in this study. Three calibrated observers evaluated the presence of the anterior loop and measured its length using the multiplanar planes of the CBCT images.
Results: Ninety-three per cent of our samples showed the anterior loop on both sides of the mandible, whereas 4% showed the anterior loop only on one side. Three per cent had no anterior loop. The anterior loop length ranged from 0.90-7.20 mm. The average length of the anterior loop on left and right sides of the mandible were 3.62±1.23 mm and 3.42±1.19 mm, respectively. There were no significant differences between the anterior loop length on either side (P-value = 0.064) or gender (P-value = 0.168), or between different age groups (P-value = 0.403). More than 99% of the samples had anterior loop lengths ≤ 6.30 mm.
Conclusions: The Thai population in our study had a high prevalence of the anterior loop (93%). Surgeons should be concerned about the presence of this structure when placing implants in the interforaminal area of the mandible. It can be suggested that the safety margin in 99% of Thais for implant installation is >6.30 mm anterior to the mental foramen.
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