Abstract

From the Department of Dental Radiography (Head: Professor G. HERULF), the Royal School of Dentistry, Stockholm. A n 'anat o 111 ic' p r0.j ec t i on iiie tl I od for dent a1 rad i ogrn 11 h y . BY G. HERULF. Two factors commonly recognized as being responsible for distortion in dental radiographs are the divergence of the X-ray bundle and the difficulty of keeping the root of the tooth and the film plane parallel. For the production of radiographs that are correct in at least some respects, it has long been the practice to follow as closely as practicable some predetermined geometrical rules for the mutual positioning of the X-ray coniponents and the cranium. The disadvantages inherent in this approach lie in its essentially theoretical nature in virtue of which it is impossible to judge with any confidence how near the actual setting is to the ideal. Neither is the final radiograph of any assistance in this respect. Kot only will it give no indication whether or no an accurate setting has been accomplished; in many cases it will be impossible to observe how large a deviation has been incurred. The practised dentist, in