Radiographic detection of cavitation in approximal surfaces of primary teeth using a digital storage phosphor system and conventional film, and the relationship between cavitation and radiographic lesion depth: an in vitro study.

The need for operative treatment of approximal carious lesions may depend on whether or not the surface is cavitated. The aims of this in vitro study were to compare the accuracy of cavity detection in approximal surfaces of primary molars using a storage phosphor system (Digora) and Ektaspeed Plus film, and to relate radiographic lesion depth to the presence or absence of cavitation in the tooth surface. The material consisted of 72 approximal surfaces in 46 exfoliated/extracted primary molars. The teeth were radiographed using Ektaspeed Plus film and then the Digora system with 10% of the film exposure dose. Three examiners independently scored the radiographs for the presence or absence of cavitation on a 5-point confidence scale and for lesion depth on a four-category disease severity scale. Validation of the radiographic diagnosis of cavitation was done by inspecting the dried and cleaned surfaces in direct light using a sharp probe. The surfaces were scored: 0 = sound, 1 = discoloration without cavitation, 2 = cavitation. Diagnostic accuracy of the two radiographic methods was evaluated by ROC curve analysis. There was no statistically significant difference between the accuracy of the two methods for detection of cavitation. There was also no significant difference in the proportion of lesions in outer enamel, inner enamel and dentine detected by the two methods. The majority of lesions diagnosed radiographically to be in dentine were cavitated.