Intra-oral storage phosphor and conventional radiography in the assessment of alveolar bone structures

To compare storage phosphor (SP) with conventional film radiography for accuracy of linear measurements of the marginal alveolar bone and visibility of anatomical structures.

Linear measurements were made in paired SP and conventional images of dried human mandibles with a metal pin fixed 10 mm below the alveolar crest. One observer measured the distance from the alveolar crest to the reference point on the radiographs. The difference between the measured and the true distance was calculated. Two observers rated the visibility of bony structures (periodontal ligament space, periapical bone tissue, alveolar crest) in 51 paired digital and conventional images of 21 patients on a 3-point scale. Overall agreement and Kappa index were calculated.

Accuracy of linear measurements was higher in digital radiography (mean difference 0.17 mm) than in conventional radiography (mean difference 0.59 mm). Overall, the two observers rated visibility higher in conventional radiographs. The Kappa indices for the periodontal ligament space and periapical bone indicated fair to almost perfect agreement (kappa = 0.38 and 0.5; kappa = 0.39 and 0.84) while for the alveolar crest there was only poor or moderate agreement (kappa = 0.2 and 0.5).

The small differences in linear measurements indicate that the Digora system is suitable for clinical assessment of periodontal and peri-implant bone loss. The visibility of dental structures depends as much on the individual features assessed, as the radiographic system.