How Sleep-Related Bruxism Affects the Jaws

The masseter and temporalis muscles are the two main muscles that are involved in SRB.

Antigonial Notching of the Mandible:

The animation above shows the masseter and temporalis muscles contracting. The masseter is the lower, located in your cheeks. This is a very powerful muscle that originates at the cheekbone, or symptomatic arch, and attaches to the mandible in the region of the molars. Excessive pressure on the mandible over time can result in irreversible bending of the lower jaw.

Antigonial notching can be felt by toughing under the jaw. The bend can be felt in patients suffering from SRB.

Coronoid Process Elongation:

In the above animation, the temporalis muscle (the upper fan-shaped muscle) originates on the side of the head and temple region extending under the cheek-bone, attaching to the coronoid process of the mandible. The excessive forces of SRB result in the coronoid process being stretched or lengthened, extending too high.

When elongated significantly, this can restrict the jaw movement side to side as the coronoid process collides with the check bone that overlies it.

Formation of Tori:

Tori is the term given to bone outgrowths that commonly occur in the inside of the lower jaw, in the region of the first bicuspids to the molars on both sides. This has been shown to be caused by the excessive forces of SRB. In the palate, a single torus can form in the midline of the palate. These can be quite large, crowding the tongue.

Abnormal Tooth Wear:

With the excessive forces of SRB on the teeth, tooth wear can occur. The wearing of the enamel shortens and disfigures the teeth. This can also result in hypersensitivity to temperatures.