•Reliability and reproducibility of dental measurements has been assessed.•Validity of dental measurements obtained from 3D digital model has been assessed.•3D digital models are appropriate for recording dentitions with forensic purposes. The aims of this study were to assess the reliability, reproducibility and validity of mesiodistal and buccolingual measurements comparing these measurements collected using an electronic hand-held digital calliper, on dry dentitions and on dental casts, with measurements obtained from 3D digital models created using a portable intra-oral scanner. The mesiodistal and buccolingual diameter of the crown of 1304 teeth were measured on dry dentitions and on dental casts, and secondly on 3D digital models created using an intra-oral 3D scanner. Reliability, reproducibility and validity were evaluated using the intraclass correlation coefficient (ICC) and the Bland-Altman graphic method. The results of the intraclass correlation coefficient expressed an excellent degree of agreement in the intra- and inter-observer error analysis, as well as in the comparison of the mesiodistal and buccolingual dimensions taken with the calliper and those taken in digital 3D models. The results of the Bland-Altman method showed that the greatest differences were found in the mesiodistal diameter of the molars and in the buccolingual diameter of the upper premolars. Mesiodistal and buccolingual measurements obtained from digital 3D models are suitable for recording dentitions for forensic purposes.