Two- and three-dimensional imaging modalities for the detection of caries. A comparison between film, digital radiography and tuned aperture computed tomography (TACT)

To compare the diagnostic performance provided by two- (film and digital radiography) and three-dimensional imaging modalities (TACT slices and TACT pseudoholograms) in the detection of primary caries.

Forty-two extracted human posterior teeth were mounted and imaged with conventional film and direct digital radiography. Free-hand positioning of a dental X-ray source was used for all exposures. From the digital images, iteratively restored TACT slices and TACT pseudoholograms were generated. Film images were viewed on a viewbox. Digital format images were viewed on a high-resolution monitor. Eight observers used a five-point scale to score the presence or absence of occlusal and proximal caries using the four image modalities. Observers' assessments were compared with the histological examination of tooth sections. Possible differences in ROC curve areas among image modalities, observers, and surfaces were assessed by ANOVA. Intra- and interobserver reliability as indicated by intraclass correlation was also calculated.

There were no statistically significant differences between the diagnostic performances of film, digital radiography, TACT slices and TACT pseudoholograms in the detection of caries (P = 0.310). Intraclass correlation indicated the highest concordance both within and between observers when film was used for the evaluation.

Under the experimental conditions of this study, three-dimensional TACT images did not improve caries detection over film or digital radiography. Further research should investigate the effects of imaging variables on TACT's diagnostic efficacy.