Validity and reliability of three-dimensional modeling of orthodontic dental casts using smartphone-based photogrammetric technology

• Published in: Journal of the world federation of orthodontists 2023-02, Vol.12 (1), p.9-14
• Main Authors: Al-Rudainy, Dhelal, Adel Al-Lami, Hadeel, Yang, Liu
• Format: Article
• Language: English
• Subjects: Cone-beam computed tomography; Documentation; Models, Dental; Photogrammetry; Photogrammetry - methods; Reproducibility of Results; Smartphone; Software; Technology
• ISSN: 2212-4438; 2212-4438
• DOI: 10.1016/j.ejwf.2022.11.002

•Three-dimensional (3D) modeling of orthodontic dental casts can be accomplished by smartphone-based stereophotogrammetry.•The accuracy of virtual orthodontic dental casts produced by smartphone-based stereophotogrammetry was about 0.34 mm, and the error of repeated 3D models using this method was 0.03 mm.•Stereophotogrammetry using smartphone devices is a simple and low-cost technology for the 3D modeling of orthodontic dental casts.•This method is a helpful low-cost tool for the digital archiving of dental casts, eliminating physical storage shortcomings, such as broken models and space requirements. The development of intraoral scanning technology has effectively enhanced the digital documentation of orthodontic dental casts. Albeit, the expense of this technology is the main limitation. The purpose of the present study was to assess the validity and reliability of virtual three-dimensional (3D) models of orthodontic dental casts, which were constructed using smartphone-based 3D photogrammetry. A smartphone was used to capture a set of two-dimensional images for 30 orthodontic dental casts. The captured images were processed to construct 3D virtual images using Agisoft and 3DF Zephyr software programs. To evaluate the accuracy of the virtual 3D models obtained by the two software programs, the virtual 3D models were compared with cone-beam computed tomography scans of the 30 dental casts. Colored maps were used to express the absolute distances between the points of each compared two surfaces; then, the means of the 100%, 95th, and 90th of the absolute distances were calculated. A Wilcoxon signed-rank test was applied to detect any significant differences. The differences between the constructed 3D images and the cone-beam computed tomography scans were not statistically significant and were accepted clinically. The deviations were mostly in the interproximal areas and in the occlusal details (sharp cusps and deep pits and fissures). This study found that smartphone-based stereophotogrammetry is an accurate and reliable method for 3D modeling of orthodontic dental casts, with errors less than the accepted clinically detectable error of 0.5 mm. Smartphone photogrammetry succeeded in presenting occlusal details, but it was difficult to accurately reproduce interproximal areas. [Display omitted]