Causes of Masseter Hypertrophy

If the masseter muscle becomes enlarged, it will have a huge impact on the entire face shape. There are many reasons that lead to masseter muscle hypertrophy, such as congenital, using only one side of the teeth to chew, overdevelopment, etc. These reasons are relatively common and can lead to masseter muscle hypertrophy. If you want to treat it, you can usually adjust it through surgery.

Common causes

The masseter muscle is located lateral to the ascending ramus of the mandible at the angle of the mandible, in front of the parotid gland, and is partially covered by the parotid gland. The size, function, and shape of the masseter muscle are clearly related to facial contour. The masseter muscle, as the power source of mandibular movement, is an extremely important component in achieving chewing activities that are complex, multi-directional and require endurance. Through the study of the distribution of masseter muscle spindles, the masseter muscle's ability to control strong occlusal force, maintain mandibular posture, and regulate fine mandibular movements has been demonstrated.

Benign hypertrophy of the masseter muscle (often accompanied by hypertrophy of the mandibular angle) can be congenital or acquired, and can be unilateral or bilateral. Frequent chewing of food with only one side of the teeth causes benign hypertrophy of the masseter muscle on one side. During adolescence, the mandibular bone is highly plastic and the muscles are also in the development stage. The masseter muscles on both sides are overdeveloped, resulting in hypertrophy and eversion of the mandibular angle, resulting in a square face in adulthood.

Preoperative examination

1. Preoperative examination First of all, from the appearance point of view, the face shape of patients with masseter hypertrophy is generally nearly square, so it is also called "square face". During the examination, ask the patient to close his mouth and clench his teeth while touching the masseter muscles on both sides at the mandibular angle to feel the contraction range and thickness of the masseter muscles. When the masseter muscle of patients with masseter hypertrophy contracts, it can be clearly felt that the masseter muscle is larger and thicker. When checking the masseter muscles, attention should be paid to the degree of mandibular angle hypertrophy and whether there is eversion of the mandibular angle.

2. X-ray and CT examinations mainly check the hypertrophy of the mandible and mandibular angle, but the development of the masseter muscle cannot be shown on X-rays. X-ray examination can take "surface section" and "lateral skull" films to determine the degree of hypertrophy of the mandibular body. However, X-rays are not required as routine preoperative examinations. CT reconstruction can intuitively display the three-dimensional image of the jaw and the thickness of the masseter muscle.

3. Other routine preoperative examinations include routine blood test, routine urine test, chest X-ray and electrocardiogram.