Radiographic simulation of a periapical lesion comparing the paralleling and the bisecting-angle techniques.
Sixty apical areas of single-rooted teeth were examined in this study. A simulated periapical lesion was produced using an acrylic sphere (diameter 2.0 mm), the surface of which was covered with a thin layer of zinc cement. The sphere was placed in close contact with the apical foramen using a thin orthodontic wire inserted into the apical portion of the root canal. The correctly adjusted parallel projection depicted the simulated lesion with a very low degree of error. Overangulation of the central beam with maintenance of parallelism between tooth and film resulted in a moderate degree of magnification. When correctly adjusted, the bisecting-angle technique produced images with almost the same accuracy as the paralleling technique. Over-angulation resulted in most images showing a reduced size of the simulated lesion. Moderate under-angulation most often recorded the correct dimension of the globe. In some cases a magnified image of the sphere was produced. Generally, this was associated with a palatally curved root. The investigation thus clearly indicated that the paralleling technique provides the most reliable information about the extent of a pathological process.
Forsberg
J
J
Department of Oral Radiology, School of Dentistry, University of Bergen, Norway.
Halse
A
A
D006801:Humans; D010483:Periapical Diseases / Q000000981:diagnostic imaging*; D011861:Radiography, Dental / Q000379:methods*