Liedke, G.S., Spin-Neto, R., Boessio Vizzotto, M., Da Silveira, P.F., Dias Silveira, H.E., Wenzel, A.

Statement of problem: Although the postprocessing of digital images with enhancement filters could lead to the presence of artifacts and result in false positive diagnoses, no study has analysed whether the use of digital radiographs and/or postprocessing of digital images interferes with the diagnosis of marginal adaptation in metal-restored teeth.
Purpose: The purpose of this study was to compare the diagnostic accuracy of conventional and digital radiographic images with and without filters for detecting a misfit between the tooth and restoration in metal-restored teeth.
Material and methods: Forty teeth with mesial-occlusal-distal inlays and 40 with complete crowns (each with a perfect fit, 20 with a 0.2mm gap and 20 with a 0.4mm gap) were imaged with conventional film and digital phosphor plate systems. Digital radiographs were exported as original images and with edge enhancement (high and low), inversion, and pseudo-three-dimensional filters. Four examiners assessed the presence of gaps by using a categorical scale (fit, misfit, cannot decide). Sensitivity, specificity and overall accuracy were calculated for each variable. In addition, time spent scoring the images was recorded. A multivariate logistic regression was performed with accuracy as the dependent variable.
Results: Of the images, 6.2% received the score “cannot decide”, most of them with a high edge enhancement filter and in the crown group. A tendency for higher sensitivity (range 0.67-0.83), specificity (range 0.81-0.92) and accuracy (range 0.73-0.86) values was found in conventional and digital original images. Results of a logistic regression found that restoration type, gap size, and high enhancement and inversion filters had a statistically significant impact on accuracy (P < 0.05).
Conclusions: Original non-filtered images should be used to assess teeth with metal restorations. High enhancement filters and image inversion should be avoided, especially when metal crowns are present.

J Prosthet Dent 2015; 113: 39-47.