Chewing with the left teeth and having pain in the right cheek can be caused by mumps, jaw joint abnormality, muscle strain and so on. 1. Mumps: Mumps is caused by the mumps virus, and when you chew with your teeth, your cheek on one side will have pain. 2. Abnormal jaw joints: Excessive chewing or disorders of the bite relationship can lead to pain and discomfort in the jaw joints, and the pain will worsen when chewing with the teeth. If the left side of the teeth chewing on the right side of the cheek pain, and the symptoms do not ease, it is recommended to seek early medical care, a clear diagnosis, for treatment.