Reverse Engineering and photogrammetry for diagnostics in Orthodontics

Objective: To develop a non contact 3D measure system, based on digital close range stereophotogrammetry, designed and realized for the surface diagnostics.

Main characteristics are: measurement accuracy, scanning speed, scanning simplicity, robustness, portability and low weight, low cost, non-invasive procedure (absence of ionizing radiations).

Methods: This system uses digital high resolution photo sensors, the projection of coded targets on faces and a software elaboration of images for extraction of three-dimensional points. Current application is the study of face features, proportion variations during time, pathology and treatment, for groups between 8 and 14 years (normal subjects in growing age, patients with lower jaw lack of growth problem, malformed patients).

Results: The reconstruction of human faces surface done by acquisition of photos, allows to construct different 3D models of the corresponding subject face. Some of them have been compared also with measurements done using Laser face scanners.

Main results are the applicability of a simple and safe non contact 3D measurement technology in orthodontic and dento-facial therapy, using also a powerful three dimensional surface diagnosis. As regards the accuracy, photogrammetry is well suited for high precision: almost any level of accuracy can be achieved by using a sufficient number of cameras, considering that the CCD sensors technology is continuously increasing resolutions with lower costs.

Conclusion: Validation and recording of therapies that impact on growth and development, such as those orthodontic (with assessment of their real effectiveness, their actual needs, and the best time for their implementation), and programming maxillofacial surgery and / or orthodontic through a more accurate and objective analysis of soft tissue, are just some of the results that could be achieved through the use of this methodology.