Morphological variability of inferior alveolar nerve in low-grade craniofacial microsomia.

Craniofacial microsomia (CFM) involves asymmetric hypoplasia and dysmorphogenesis of the facial skeleton. Certain aspects of CFM may be treated by surgical osteotomy and distraction osteogenesis (DO). Mandibular osteotomy places the inferior alveolar nerve at risk. The aim of this study was to investigate radiological landmark relationships to the anatomy of the inferior alveolar nerve in CFM. Application of this understanding will aid intraoperative protection of the inferior alveolar nerve. Six subjects with similar presentations of hemifacial microsomia were selected. Three-dimensional reconstruction CT images was used to locate bony structures that held important relationships with the inferior alveolar nerve. Measurements (of the normal and microsomic sides) were made between fixed landmarks: mandibular notch, mandibular foramen, condyle, back of second and third molar tooth, and mental foramen. The unaffected sides acted as controls. The distance between the normal and the microsomic sides from condyle to mandibular foramen was significantly different. The sizes of condyles differed significantly between the normal and microsomic sides. Most of the remainder of the vertical distance of the ramus and most of the horizontal distance of the body were similar. In conclusion, the inferior alveolar nerve should be found in very similar locations on both normal and microsomic sides in low-grade hemifacial microsomic patients.