Evaluation of the Relationship between the Dimensions of Masseter Muscle and the Vertical Dimensions of the Face and Mandible Using the CT Scan Technique

Since the matrix functional theory is critically important in explaining craniofacial growth and development, it is necessary to evaluate the relationship between the function of masticatory muscles, including the masseter muscle, and craniofacial growth and development, especially in the vertical dimension. This study aimed to evaluate the relationship between the masseter muscle size and the vertical dimensions of the face and mandible using computed tomography scanning.

In this analytical-descriptive study, three-dimensional CT scan facial images of 190 patients (men and women) were evaluated. Then measurements were made on two sides (left and right) with Workstation software. The width of masseter muscle was measured on the axial view, and its length and thickness were measured on the coronal view. The ramus height was measured on both sides, and the face vertical dimension was measured in the anterior and posterior areas. At the end of the measurements, no significant difference was observed between the two sides of the face. The data were analyzed with t-test and Pearson’s correlation coefficient using SPSS 22 (p value < 0.05).

The mandibular ramus length showed a significant difference between the two genders (p value < 0.0001), with males exhibiting a longer ramus compared to women. There was a direct and significant correlation between mandibular ramus length and the masseter muscle width, length, and thickness, in all the subjects (p value < 0.0001). Investigation of the correlation between the vertical dimension of the face and masseter muscle dimensions and the palatal and mandibular plane angles (p value = 0.676 (and the inclination of the mandibular plane in all the patients showed a direct but non-significant correlation (p value = 0.993).

Changes in the masseter muscle dimensions affects the skeletal size, craniofacial morphology, and skeletal angles.