The Science Behind the Bite

Most of us chew our foodwithout ever thinking about the complex processes required to perform thisvital action. It may seem a simple taskto raise and lower our jaw, but the process of mastication (chewing) requiresseveral components to work together: nerves, muscles, joints, bones, andteeth. A problem with any one componentcan lead to real medical issues like TMD (temporomandibular joint disorder),which causes chronic pain and other symptoms.

Mastication Mechanics

In order to raise thelower jaw (mandible)into contact with the upper dental arch (maxilla),your brain sends a signal to a collection of four muscles, the tensor tympani, tensor veli palatini, mylohyoid, andthe digastric. These muscles pullthe mandible up and back, flexing the temporomandibular joint, often called the TMJ.

There are two TMJs, one on either side, working in unison. The name is derivedfrom the two bones which form the joint: the upper temporal bone whichis part of the cranium (skull), andthe mandible.The TMJ is one of the most complexjoints in our body. The unique feature of the TMJ is the articular disc, composed of tissue likethe firm and flexible elastic cartilage of the ear. The articular disc ispositioned between the two bones that form the joint.

After the muscles pull and the TMJflexes, the top and bottom rows of teeth come together. Ideally, these two rows should match upperfectly. However, most people havesome degree of malocclusion, whichis a misalignment of the teeth. Malocclusion is commonly described as an overbite or underbite,and in serious cases is fixed for aesthetic or medical reasons through the useof orthodontics.

Problems May Be Painful

A majority of thepopulation experiences malocclusion,but most do not consider it a serious problem. However, when the teeth are misaligned, they cannot support the musclesin the face needed for chewing and swallowing. These muscles are then forcedinto a strained position, which over time can cause TMD (temporomandibular joint disorder). Most often with TMD, the articular disc has become displaced, allowing painfulbone-to-bone contact.

TMD can lead to chronicpain, as well as a wide variety of other symptoms. Though the problem starts with the teeth andjaw, pain can spread all over the neck and shoulders. This is because the trigeminalnerve, which controls facial movements like chewing, also transmits painsignals from all parts of the face and head.