PERIAPICAL RADIOLUCENCIES AS EVALUATED BY BISECTING-ANGLE AND PARALLELING RADIOGRAPHIC TECHNIQUES

Two groups of patients were included in the study. The first group con sisted of patients who received root canal treatment of single-rooted teeth (n=63), The completed roof fillings were exposed to two differen t radiographic techniques, the paralleling and the bisecting-angle tec hnique, The second group consisted of 1-year review radiographs of pat ients who had received apicectomies of single-rooted teeth (n=105), Th ree observers examined the radiographic images. First, they were asked to identify teeth with a normal apical condition and those with an ap ical radiolucency. Thereafter pairs of radiographs were compared; case s judged as normal by all observers were excluded. The observers were now asked to ascertain whether the apical radiolucency was largest in the first image, the apical radiolucency was largest in the second pic ture or both radiolucencies were the same size, Both intraobserver and interobserver agreement, calculated as Cohen's kappa, was high with r espect to the presence of lesions within both samples and it was at th e same level for both radiographic techniques. The evaluation of the s ize of the lesions proved to be more inconsistent, Kappa values were i n the range 0.38-0.71 for intraobserver comparisons and in the range 0 .25-0.48 for interobserver comparisons. No significant difference was found between the size of lesions as recorded by the two techniques (P > 0.05), It is concluded that, when correctly adjusted the bisecting- angle technique and the paralleling technique provide similar diagnost ic results.