Aims: To compare the estimated values of remaining dentin thickness (RDT) recorded by a newly introduced electrical device (Preprometer) with cone beam computed tomography (CBCT) and histological method. Material and Methods:A total number of thirty human molars were used in this study. A standardized class I cavity prepared. The RDT for each cavity was measured with Preprometer in three different points (mesial, middle and distal). Same specimens were imaged with high resolution Cone Beam Computed Tomography CBCT (0.1 mm voxel size) using I CAT next Generation Machine (Imaging Science International, Hatfield, PA, USA), to provide the highest possible accuracy of linear measurements. Finally, the specimens were vertically sectioned parallel to the long axis of the tooth in a mesiodistal direction splitting the cavity into two halves through its center. Then the actual RDT of each half measured in the same three points using a digital caliper. Results:The outcome of one-way ANOVA revealed that there was no significant difference in RDT values measured by prepometer device, CBCT or histological sectioning methods. (P> 0.05). Conclusions:Within the limitations of this laboratory study, prepometer seems to be a potentional noninvasive accurate measuring tool for RDT. Key words:CBCT,RDT,Prepometer