Validity and reliability of tooth size and dental arch measurements: a stereo photogrammetric study

Background: The development of three-dimensional computer imaging has many applications in dentistry, including the analysis of dental casts.Aims: To assess the validity and reliability of a dental stereophotogrammetric imaging system.Methods: The sample consisted of 35 sets of dental casts. Maxillary and mandibular dental crown widths and selected dental arch dimensions were measured directly using digital calipers. Cast images were also captured by a stereophotogrammetric system and analysed using Australis software. Dahlberg's formula, paired t-tests and intra-class correlations were used to assess the random error, validity and reliability of the measurements, respectively.Results: Most values demonstrated no significant difference between the direct and three-dimensional measurements with mean differences ranging from 0.05 - 0.21 mm. Moreover, values of intra-class correlation coefficients ranged between 0.80 - 0.99 for intra-examiner reliability.Conclusions: Mesiodistal crown widths and dental arch dimensions may be measured accurately with relatively small error by the specially-designed 3D system and confirms its suitability for clinical and research purposes.