Anterior buccal mandibular depression: A descriptive study of CT findings

OBJECTIVE: This study aims to report the concurrence of the radiographic features of anterior buccal mandibular depressions (ABMDs) and anterior lingual mandibular depressions (ALMDs) by conventional computed tomography (CT) and cone beam CT scans. We also assess the effect of ABMDs and ALMDs on dental implant sites. METHODS: A retrospective review of CT scans of the mandibles with ABMDs was conducted to assess the morphology, site, presence of foramina, ALMDs, and the integrity of the cortical plate. The superoinferior width of ABMD, the buccolingual depth, and mesiodistal length were measured and compared with the thickness of the cortical plate at the depression to the area superior to it. RESULTS: Thirty-seven patients with 74 ABMDs were included in this study. All observed ABMDs occurred bilaterally, and ALMDs with ABMDs occurred in 13 sites (17.56%). In 20 (54%) cases, at least one foramen was noted. The buccal cortical bone was intact in all cases. The contents of ABMDs were found to be fatty. On an average, their superoinferior width was 7.1 mm, buccolingual depth 1.67 mm, and mesiodistal length 18.8 mm. The average buccal cortical bone plate thickness at the ABMD was 1.23 mm (range 0.4–1.9 mm), while the average buccal cortical bone plate thickness coronal to the ABMD was 1.34 mm (range 0.7–2.2 mm). The average buccolingual dimension of the mandible was 8.72 mm (range 4.15–13.4 mm) at ABMD sites without ALMD and 4.6 mm with ALMD (range 1.8–8 mm). CONCLUSION: When ALMD occurs in the presence of ABMD, the amount of bone available for implant placement is greatly reduced.