Studies on the use of digital radiography for the assessment of periapical bone lesions.

The aim was to study digital radiography and to evaluate the influence of image processing on digital dental radiographs for the assessment of periapical lesions. In four studies, artificial bone lesions were made periapically and interradicularly in the mandibular premolar and molar regions. In a clinical study, direct digital radiographic images depicting the periapical bone tissue of different regions were assessed. Digital subtraction was performed on digitised conventional periapical radiographs. The observer performance was significantly better for the subtraction images than for the conventional radiographs, in particular for the detection of shallow lesions. Periapical bone lesions were easier to detect than interradicular lesions. Direct digtal radiography was performed with a CCD sensor based imaging system, Visualix/VIXA. The high-contrast resolution and the low-contrast resolution of the digital imaging system and of conventional radiographic E-speed film was evaluated. The high-contrast resolution was superior for E-speed film, whereas the low-contrast resolution was comparable for the two imaging systems. The properties of phantom material are discussed. When two different kinds of detectors, as a radiographic film and a sensor, are compared, a plexiglass phantom is to be preferred. Observer performance was comparable for direct digital radiography and E-speed film when assessing the artificial periapical bone lesions. In the clinical study, E-speed film performed slightly better. Image processing did not improve the observer performance.