Comparison of Orthodontic Methods The fixed appliance of movable appliance can be taken out and put on the teeth by the patient himself, but it cannot be taken off by himself. Widely used in simple orthodontics, but also can be used in complex orthodontics. At present, the commonly used orthodontic methods are divided into active orthodontics and fixed orthodontics. Some serious skeletal deformities may need surgical correction and must be studied by oral and maxillofacial surgeons and orthodontists.