THE RELIABILITY AND VALIDITY OF 3D STEREOPHOTOGRAMMETRIC MEASUREMENTS VS 2D AND DIRECT ANTHROPOMETRIC MEASUREMENTS: AN IN-DEPTH COMPARATIVE ANALYSIS

Introduction- Quick capture times and usability has rendered 3D surface imaging technology to be used more frequently in craniofacial clinics and research facilities, making 3D digital stereophotogrammetry the preferred facial surface imaging technique. By doing away with the need for observer-dependent techniques to overlap anatomic landmarks, stereo-photogrammetry creates 3D images that can be enhanced, rotated, and rendered for better analysis with specialized software. The objective of the study is to compare, verify, and corroborate the fi Objective/Aim - ndings of both unilateral and bilateral measurements made by direct anthropometry and 2D photographs in 3 different facial types (Average, Short and Long) with that of 3D stereophotogrammetric measurements in order to present a costeffective alternative of 3D stereophotogrammetry. A cross-sectional observational study Materials And Methods - design was adopted to assess eight midline and seven bilateral distances on the faces of 36 participants of 3 different facial types. The same measurements were taken on two-dimensional (2D) images and three-dimensional (3D) models created from 2D images. For all measurements, interobserver consistency was obtained with 3 observers measuring the same dimension and the mean of those measurements were taken. The Wilcoxon Signed Rank Test was used for statistical analysis, and the difference between the absolute values of the three methods of measurement was calculated. Results - Direct anthropometry and two-dimensional (2D) measurement for unilateral reference points revealed the greatest variation for average facial types in the distances N-Prn (±0.053) and Sn-Ls (±0.061), while the greatest variation for long and short facial types was in the Ls-St distance (±0.115 and ±0.053, respectively). When comparing unilateral measurements made by direct anthropometry and three-dimensional (3D) stereophotogrammetric values, the identical Sn-Ls (±0.067) had the greatest fluctuation in average facial type and Ls-St changed in long and short facial types (±0.052 and ±0.109, respectively). The Cphr and Cphl had the most variation among the bilateral characteristics assessed among the three facial types using direct anthropometry and either 2D or 3D approaches. Thus, it can Conclusion - be concluded that 3D stereophotogrammetry can be used in place of the current gold standard of measurement i.e., direct measurement, in orthodontic diagnosis and treatment planning.