During the OPG the arm of the machine will rotate slowly around the head but will not come into contact with the patient. The Radiographer (a technologist trained in medical and dental imaging) will instruct the patient to bite on a small plastic mouthpiece attached to the machine, which keeps the top and bottom teeth separated and helps position the mouth properly in the machine.
For a Lateral Cephalogram you are required to hold still and bite together on the back teeth. Lips should be relaxed. The Radiographer will help ensure that patients are in the correct position before taking the x-ray.