EXTRAORAL RADIOGRAPHIC IMAGING OF PRIMARY CARIES

Objective: To evaluate three extra-oral radiographic imaging modalitie s as alternatives to conventional intra-oral film for the detection of primary caries.Methods: 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 lin ear tomography (N=8). Eight trained observers were asked to identify t he presence or absence of caries on each surface using a five point sc ale. Ground sections were viewed microscopically to determine truth. R OC curve areas (A(z)) were generated from observer responses and asses sed with ANOVA. Results: Averages of A(z) for the detection of combine d results for proximal and occlusal lesions were 0.70 for D-speed film , 0.58 for linear tomography, 0.64 for both multidirectional tomograph y, and panoramic film. Tukey's pairwise comparisons of A(z) revealed t hat 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=0.002 4 respectively). Tukey's comparisons for proximal surfaces revealed th at D-speed film was significantly better than linear tomography (P=0.0 007), multidirectional tomography (P=0.0010) and panoramic radiography (P=0.0100). For detection of occlusal lesions, multidirectional tomog raphy was significantly better than linear tomography (P=0.0075) and p anoramic radiography (P=0.0034), but not significantly different from D-speed film (P=0.2337). Conclusions: 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 si gnificantly better. For occlusal caries there was no statistically sig nificant difference between multidirectional tomography and D-speed fi lm.