An analysis of anterior mandibular anatomy by using cone beam computed tomography: A study of 225 mandibular images.

STATEMENT OF PROBLEM

The anterior mandible has conventionally been deemed as a safe zone for dental implants. However, with the evolution of cone beam computed tomography (CBCT), several anatomic challenges have been identified that, if violated, can lead to surgical complications, including life-threatening hemorrhage.

PURPOSE

The purpose of this observational clinical study was to obtain standardized average values for the location of the sublingual artery (SLA), submental artery (SMA), and mandibular incisive canal (MIC) and to determine whether differences exist between dentate and edentulous individuals. In addition, the prevalence of these anatomic landmarks on CBCT images was determined. An additional objective was to study the cross-sectional morphology of the anterior mandible.

MATERIAL AND METHODS

CBCT images of 125 edentulous and 100 dentate patients were studied at the anterior mandible for the prevalence of SLA, SMA, and MIC. Measurements of these 3 structures were then made from the inferior cortical border of the mandible to the superior border of each structure to obtain average anatomic measurements. The cross-sectional shapes of anterior mandibles were then categorized, and the prevalence of each shape in this sample was calculated.

RESULTS

The prevalence of SLA across all 225 CBCT images was 100% for edentulous patients and 98% for dentate patients. The SLA was located approximately 15 mm above the inferior border of the mandible. The prevalence of SMA was 94% for edentulous patients and 88% for dentate patients. The SMA was located approximately 5 mm above the inferior border of the mandible. The prevalence of MIC was 61% for edentulous patients and 59% for dentate patients. The MIC was located approximately 11 mm above the inferior border of the mandible in edentulous patients and approximately 14 mm above the inferior border of the mandible in dentate patients. Five distinct shapes were observed for the cross-sectional morphology of the anterior mandible: hourglass (1%), pear (53%), sickle (4%), ovoid (26%), and triangular (17%). The distance from the crest of the residual ridge to a minimum 6-mm width in the anterior mandible was approximately 4 mm.

CONCLUSIONS

The SLA and SMA vascular structures were consistently identified in the anterior mandible on CBCT images, both in dentate and edentulous patients, whereas the mandibular incisive canal was not consistently visualized. Average values from the inferior border of the mandible to the SLA, SMA, and MIC were computable. The cross-sectional morphology of the anterior mandible is diverse in dentate and edentulous mandibles, with pear shaped being the most common in both. These findings should be taken into consideration when dental implants are planned in the anterior mandible.