Masseter Muscle Thickness and Craniofacial Skeletal Patterns

Facial morphology is influenced by hard and soft tissues, including bone and muscle. While numerous factors can lead to changes in bone tissue, soft tissues such as muscle also have an important influence. It is widely acknowledged that the function, shape and thickness of masticatory muscles have substantial effects on facial morphology and skeletal development, and are correlate with other anthropometric variables. Furthermore, a correlation has been observed between masseter muscle thickness and various characteristics of the dental arches, such as alveolar process thickness and intermaxillary width. The evaluation of soft tissue in the region of the face is a more challenging process in comparison to that of hard tissue.The recent development of cone beam computed tomography has improved the analysis of three-dimensional skeletal morphology and jaw. However, the radiographic assessment of soft tissue remains more difficult.The thickness of masticatory muscles can be measured using computerised tomography; however, this has the disadvantage of exposing the patient to radiation. Magnetic resonance imaging (MRI) is an imaging technique that can be used to assess soft tissues. However, this technique is expensive and time-consuming. Furthermore, MRI is a static rather than a dynamic imaging technique, which makes it difficult to analyse during muscle contraction and relaxation. Ultrasound is a technique that provides dynamic imaging that can assess the masticatory muscles without the use of ionising radiation. There are many publications in the literature that indicate that malocclusions in the vertical and sagittal dimensions can be assessed with measurements from lateral cephalometric radiographs.