Background: Evaluation of the vascular anatomy of the rat mandible is of great interest to researchers in cranofacial surgery that utilize a murine surgical model. Previous anatomical studies of the rat mandible utilized two-dimensional contrast micro-radiography of an injected opaque material to identify vascular supply. Histologic specimens and staining of angiogenic proteins have heretofore been primary means of evaluating vascular anatomy. These methodologies are painstaking, laborious, and limited in their ability to visualize three-dimensional attributes. Microcomputed tomographic vascular mapping overcomes such limitations and provides a modality with which to examine the three-dimensional vascular architecture within the intact mandible of the rat.

Material & Methods: Six adult male Sprague-Dawly rats were used for the study. The animals were anesthetized and perfused through the left ventricle with 15ml of a radiopaque silicone compound. Mandibles were dissected and decalcified, and contrast-enhanced micro-CT scans of the entire left hemimandible were taken at 18-µm voxel size in order to resolve small vascular structures. MicroView imaging software was used to reconstruct the images and analyze the macro-vascular pattern. A brightness threshold of 1000 was used for visualizing and isolating vessels with contrast from the surrounding tissue. The vessels were then systematically identified and compared to previously published anatomical analyses.

Results: The posterior regional blood supply of the coronoid, condylar, and angular processes was evident in the three-dimensional reconstruction. The condylar artery and its penetrating vessels were visualized at the condylar neck. A vascular bridge and radiating branches linked the condyle and the coronoid process. The blood supply to the angle of the mandible distributed its arterioles across the angle, as the venous drainage formed an arch along the lower border of the angle. In the molar region, much of the blood supply came from the inferior alveolar artery entering through the mandibular canal. This vessel then split into a superior branch that continued anteriorly and emitted branches to the periodontium, molars, and upper bone border. The inferior branch turned to the apex of the root of the incisor, and supplied multiple anterior branches to its pulp and periodontium. Entering through a foramen posterior and inferior to the incisor, was the supplementary mandibular artery. This artery helped to supply the posterior border of the ramus and periodontal vascular network as it ran anteriorly. Also clearly visualized were the artery of the incisor tooth pulp, molar pulp branches, and large gingival perforating arteries.

Conclusions: This study demonstrated the utility of micro-CT vascular mapping as an imaging modality capable of generating a three-dimensional anatomic map of the murine mandible. The reconstructed images allowed discrimination and confirmation of the vasculature previously only identified through labor-intensive methodology. In addition, however, the vascular mapping utilized in this novel technique allowed rapid imaging of vessels' paths within the mandible. This study has validated vascular anatomic mapping utilizing micro-CT as an innovative, rapid, and reproducible technique that can be employed for future studies involving analyzing vascular anatomy.