TACT IMAGING OF PRIMARY CARIES

Objective. Tuned-aperture computed tomography, a new method for creati ng 3-D radiographic information based on optical aperture theory, was evaluated for diagnostic efficacy in primary caries detection. Study d esign, Sixty-four extracted teeth with 89 carious lesions were imaged with D-speed film, direct digital, And TACT modalities. A commercially available, 8-bit, charge-coupled device was used in the later two mod alities. Six trained observers were asked to identify the presence or absence and depth oi interproximal and occlusal lesions for all three modalities. The teeth were sectioned and examined microscopically to d etermine ground truth. Logistic regression analysis was performed for all three imaging systems for the detection task. Analysis of variance was used for depth determination. Detection of lesion, depth of lesio n accuracy, and time for diagnosis were also examined. Results, For ca ries detection TACT and film were not different (p = 0.2216) with the Wald statistic, Film and TACT were significantly more accurate than th e digital system (p = 0.0001). Scheffe's post hoc test revealed that T ACT and film were more accurate than the direct digital system for det ermining lesion depth (p = 0.05) but not statistically different when compared with each other. The detection data were substantiated furthe r by receiver operating characteristic analysis that demonstrated simi lar statistical relationships. Time required per diagnosis was not sho wn to be statistically different among the three imaging modalities. C onclusions, We conclude for caries detection and depth determination t hat TACT could not be distinguished from film despite the significant relative loss of information capacity in the charge-coupled device rec eptor. The relatively poorer performance yielded by the digital contro l images suggests that increased information capacity associated with more modern charge-coupled device detectors may improve diagnostic per formance for both direct digital and TACT displays over that demonstra ted in this investigation.