Chewing food on one side of your mouth is called habitual chewing side syndrome. One-sided chewing can be detrimental to your health leading to jaw problems including TMJ pain, TMJ headaches and TMJ ear pain. TMJ stands for temporomandibular joint. You have two of them on each side of our face. The TMJs connect the skull to the jawbone and are necessary for chewing, along with the surrounding muscles in the lower face.