Comparison of intra-oral long-cone paralleling radiographic surveys and orthopantomographs with special reference to the bone height

A comparison between bone height scores from long-cone paralleling radiographic surveys and orthopantomographs (Panex-EC) of forty-one patients was made. Intra-examiner reliability and inter-examiner objectivity of the measuring method (Schei ruler) proved to be very good (r = 0.954 and r = 0.923 respectively for the intra-oral surveys; r = 0.928 and r = 0.916 respectively for the orthopantomographs). Distribution and frequency of the non-measurable surfaces were evaluated. In each technique an attempt was made to discern the main cause of non-measurability: overlapping of adjacent structures, absence of the surface and absence of the apical region on the image. For twenty of the thirty-six surfaces significant differences were found between bone height scores for corresponding surfaces in the long-cone survey and in the orthopantomograph. In periodontal, prosthetic and conservative dentistry the long-cone paralleling technique should be considered as the best radiographic technique.