Aim:The purpose of this laboratory research was to compare the accuracy of digital and conventional bitewing radiographs in the diagnosis of recurrent caries under class II amalgam restorations. Methods and Materials:This study involved 82 posterior intact teeth in which class II amalgam boxes were prepared. Carious lesions were simulated in half of the proximal boxes in the intersection between the facial or lingual wall and the gingival floor or midway between the facial and lingual walls. The other half of each tooth specimen served as a control. The prepared boxes were then restored with a Tytin FC (Kerr, USA) amalgam. The teeth were radiographed in the bucco-lingual direction to obtain images comparable to bitewing. Digital radiographs made with an intraoral CCD sensor and conventional radiography with dental E film were used. Three expert observers evaluated both types of images for the diagnosis of recurrent caries.Results: Sensitivity and specificity values for direct digital radiography were 73 and 95 percent at the buccal and lingual line angles, respectively, and 29 and 90 percent at the mid-gingival floor, respectively. These corresponding values for conventional radiography were respectively 63 and 93 percent at the buccal line angle, 61 and 93 percent at the lingual line angle, and 44 and 95 percent at the mid-gingival floor. The total sensitivity and specificity values were 58 and 93 percent for digital radiography and 56 and 93 percent for conventional radiography. The overall accuracy was 76 percent for digital and 75 percent for conventional radiography. No significant difference in specificity or sensitivity was found between the digital and conventional radiography (p=0.104). Separately, no significant difference was seen between the buccal line angle and the mid-gingival floor, but a significant difference was seen between the two methods in the lingual line angle (p=0.004). Conclusion:The digital and conventional bitewing radiographs had similar diagnostic accuracy for the diagnosis of recurrent caries. Lesions located at the buccal or lingual line angle were more easily detected than those at the mid-gingival region.Clinical Significance: Although there was no significant difference between digital and conventional radiography in the diagnosis of recurrent caries, digital radiography requires less ionizing radiation, making this method of imaging suggested for routine dental practice.