Quantitative comparison of enamel–dentin and dentin–pulp distances between cone-beam computed tomography and histological sections: An ex vivo study

Cone-beam computed tomography (CBCT) has become an essential imaging tool in dentistry for evaluating internal tooth morphology. However, its quantitative accuracy in representing true enamel–dentin (E–D) and dentin–pulp (D–P) distances remains uncertain. This study aimed to compare CBCT-derived measurements with histological references and to assess depth-dependent discrepancies across tooth sections. A total of 18 extracted human teeth were sectioned bucco–lingually and analyzed using both CBCT and histological microscopy. For each tooth, three representative slices were selected: the first and last slices containing pulp tissue, and one at the midpoint. E–D and D–P distances were measured digitally and compared between modalities using paired t -tests, correlation analysis, and Bland–Altman plots. CBCT consistently overestimated E–D distances compared with histology, particularly near the pulp chamber, whereas D–P differences showed greater variability. Weak to moderate linear correlations were observed between modalities (E–D: r = 0.45; D–P: r = 0.34). Bland–Altman analysis indicated a mean bias of +0.26 mm for E–D and −0.09 mm for D–P, suggesting a trend toward systematic overestimation in enamel-dentin regions and inconsistent deviation patterns in deeper dentin–pulp zones. While CBCT provides clinically acceptable accuracy in quantifying intra-tooth structures, it tends to overestimate enamel–dentin thickness in deeper regions. These findings underline the need for refined imaging calibration to enhance quantitative reliability in endodontic and restorative applications.