Orthodontic radiology: a review.

Before starting orthodontic treatment it is important to have status radiographs to ascertain the state of the patient's general dental health. A dental panoramic tomogram is very suitable in this respect, but right and left bimolar projections together with upper and lower occlusal films provide an appropriate alternative. Unerupted upper cuspids can be localized by means of parallax shift or by using the vertex occlusal projection. The cephalometric radiograph is an invaluable adjunct to the clinical examination and models of the dentition, which together form the basis for orthodontic diagnosis and treatment planning. However, the user should be aware of the various errors which can detract from the reliability of this technique. Cephalometric landmarks are identified and tracings of the radiograph are made. Angular measurements taken from the tracing enable the maxillary and mandibular bases to be related to each other and to the cranial base. Recent developments in computer science and information transfer offer the possibility that in the future cephalometric radiographs will be analysed with the aid of a computer at sites which may be remote from the dental office.