Introduction/Objective Rapid developments in information technologies lead to the wider use of digital
representations of dental study models in orthodontics. Most popular way of digitizing the models
is to use a 3D scanner and then perform measurements on 3D models, which requires additional and
expensive hardware and software resources. In this paper we present an alternative approach based on
the use of photogrammetry in the newly developed OrthoPhoto4D software that calculates and corrects
perspective distortion errors.
Methods We measured individual tooth width for 24 teeth, 12 two-teeth segments as well as inter-molar
and inter-canine distances on 50 models. Measurements are performed in OrthoPhoto4D software that
uses four photographs of each model for measurements, uses QR codes for automation, calculates the
camera position and corrects perspective distortion-caused errors in measurements. Obtained measurements
are compared to ones obtained from models generated by structured light 3D scanner.
Results Statistical analysis strongly indicates that there is no significant difference between the two
methods. The recorded differences also have no clinical impact as they have mean values of 0.2 mm for
individual tooth widths, approximately 0.2 mm for two teeth segments, and under 0.3 mm for both intercanine
and inter-molar distances. All recorded differences fall within the expected measurement error.
Conclusion We concluded that the described photogrammetry measurements performed in OrthoPhoto4D
can be used in diagnosis and therapy planning.
