Extraoral radiographic imaging of primary caries

To evaluate three extra-oral radiographic imaging modalities as alternatives to conventional intra-oral film for the detection of primary caries.

Sixty-four extracted primary molar teeth with eighty-five carious lesions were radiographed using D-speed film (N = 8), panoramic imaging (N = 8), multidirectional tomography (N = 8), and linear tomography (N = 8). Eight trained observers were asked to identify the presence or absence of caries on each surface using a five point scale. Ground sections were viewed microscopically to determine truth. ROC curve areas (Az) were generated from observer responses and assessed with ANOVA.

Average of Az for the detection of combined results for proximal and occlusal lesions were 0.70 for D-speed, film, 0.58 for linear tomography, 0.64 for both multidirectional tomography, and panoramic film. Turkey's pairwise comparisons of Az revealed that D-speed film was significantly better than linear tomography (P = 0.0039). When data were divided into proximal and occlusal surfaces the variability due to modality remained significant (P = 0.0003 and P = 0.0024 respectively). Turkey's comparisons for proximal surfaces revealed that D-speed film was significantly better than linear tomography (P = 0.0007), multidirectional tomography (P = 0.0010) and panoramic radiography (P = 0.0100). For detection of occlusal lesions, multidirectional tomography was significantly better than linear tomography (P = 0.0075) and panoramic radiography (P = 0.0034), but not significantly different from D-speed film (P = 0.2337).

Multidirectional tomography and panoramic radiography performed as well as intra-oral D-speed film for the combined assessment of proximal and occlusal caries in the model used. when proximal surfaces were evaluated alone, D-speed film was significantly better. For occlusal caries there was no statistically significant difference between multidirectional tomography and D-speed film.