Imaging and Facial Asymmetry

Facial asymmetry may occur due to multiple etiologies, including developmental, pathologic, and traumatic conditions or a variable combination of these. Facial asymmetry is a radiographic or clinical sign, and not a diagnosis. The diagnostic category or etiology of a facial asymmetry can be determined by integrating three-dimensional (3D) imaging with the clinical findings and the patient’s history. A large field of view such as seen with computerized tomography (CT) or cone beam CT (CBCT) scans is ideal for imaging the maxillofacial skeleton to identify or rule out the presence of a skeletal asymmetry. In the case of a skeletal asymmetry, a CBCT enables an anatomic component analysis to determine which skeletal elements are demonstrating deviant form and growth. The component analysis results are used to identify the etiology and activity status of the maxillofacial asymmetry. It is well recognized that facial asymmetry due to mandibular asymmetry is frequently associated with an underlying temporomandibular joint (TMJ) anomaly. This chapter discusses the biomechanics and morphologic alterations involved in the development of an asymmetry along with a focus on imaging characteristics associated with TMJ-related conditions contributing to a mandibular asymmetry.