A comprehensive in vitro study of image accuracy and quality for periodontal diagnosis. Part 2: the influence of intra-oral image receptor on periodontal measurements.

The aim of the study was to determine the image receptors' influence on exposure levels, image accuracy, and quality for periodontal diagnosis. Periodontal defects from cadaver specimens were imaged using two intra-oral conventional films (E-, F/E-speed), four indirect receptors (Digora 8 bit, Vistascan 12 bit with/without filter, Vistascan 16 bit), and two solid-state sensors (Sigma 12 bit, VistaRay 14 bit) at rising exposure (20-160 ms). Three observers assessed the standardized radiographs for alveolar bone measurements (1,732, 31 sites) and for subjective rating of lamina dura, contrast, trabecularization, crater, and furcation involvements. The measurements were compared to the gold standard. For the imaging plates, highest measurement accuracy was found with Vistascan 16 bit (100% within 0.5 mm) and for solid-state sensors with VistaRay 14 bit (100%, 0.5 mm), although the latter are mostly not significantly different. Higher contrast resolution imaging plates require up to 50% less exposure time, but for solid-state sensors, the dose remains unchanged. For the latter, a higher bit depth does seem to provide more accurate depiction of the alveolar crest, counteracting blooming artifacts. The use of a dedicated periodontal filter contributes to higher accuracy at all exposure times (p < 0.05-0.0001). Accuracy of periodontal diagnosis increases with higher contrast resolution. Digital exposure levels are thus dependent of image receptor as well as X-ray generator.