Detection of secondary caries is difficult in proximal areas. Enamel translucency, cavitation, or change in hardness and color of the enamel and dentin are among the clinical signs and symptoms of Abstract Objectives: To assess the effects of denoising and sharpening on detection of secondary caries under proximal amalgam and composite restorations on digital periapical radiographs. Methods: After preparing a single box in proximal surfaces of 144 proximal surfaces of extracted premolars, the

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... vities were restored with amalgam and composite resin. Next, artificial carious lesions were randomly induced on 72 surfaces by the acid challenge. The teeth then underwent photostimulable phosphor plate (PSP) digital radiography with the parallel technique. Images were enhanced using sharpening and denoising filters of the Scanora software. The images were evaluated by a restorative dentist and an oral and maxillofacial radiologist blindly. The sensitivity and specificity of denoised and sharpened images were calculated by the modified Wilson method via SPSS. The inter-observer agreement was assessed by the kappa analysis. Results: Maximum sensitivity was noted for detection of caries under amalgam restorations on imagesenhanced with sharpness 3 with/without denoising (100%). Minimum sensitivity belonged to original images of amalgam restorations (36.1%). Maximum specificity belonged to original images of amalgam restorations and those enhanced by sharpness 1 (94.4%). Minimum specificity belonged to images of composite restorations enhanced by sharpness 3 (8.3%). Conclusion: Increasing the sharpness increased the sensitivity for both restoration types but decreased the specificity. Denoising decreased the sensitivity for both restoration types. It also decreased the specificity of caries detection under amalgam restorationsand increased the specificity of caries detection under composite restorations. The sensitivity and specificity of caries detection were higher for amalgam than composite restorations.