© 2020 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Aim: The objective of the study was to estimate the conicity of the root canals of maxillary central and lateral incisors by computed nanotomography (Nano-CT). Design: This in vitro study included nine extracted primary maxillary central incisors and 12 maxillary lateral incisors, which were subjected to Nano-CT analysis. The resulting images of each tooth were reconstructed using the OnDemand3D software, and root canal area, volume, and taper analysis were performed using the free FreeCAD 0.18 software for the 3D computer-aided design (CAD) model. Data were statistically analysed using the Stata v14.0 software, adopting a significance level of 5%. Results: The results presented the mean value of the diameter and area of the root canal of primary central and lateral incisors. In addition, the taper values for both dental groups between points D0-D5, D5-D7, and D7-D10 were determined. Considering the diameters obtained over the entire length of the root, with a length of 12 mm, a conical model was constructed. Conclusion: Detailed knowledge of root morphology of maxillary central and lateral incisors of primary dentition by means of Nano-CT is important to achieve faster, more accurate, and efficient endodontic treatments.