3D stereophotogrammetry facial analysis of Angle I subjects: gender comparison

[CAD/CAM assisted facial epithesis: Clinical and technical aspects]

The face is an important part of the human body from an anatomical, functional, aesthetic and psychosocial point of view. It can be the site of several mutilations resulting from trauma, treatment of neoplasms and congenital malformations. The plastic facial prosthesis is therefore indicated to restore these facial deformities and to compensate for the various consequences. Recently, digital technologies have shown an increasing impact on the future of maxillofacial rehabilitation. Computer-aided design and manufacturing technique enabled practitioners to acquire numerical data, perform three-dimensional reconstructions, and then materialize and manufacture the facial epithesis through various manufacturing processes, by addition or subtraction. The aim of this article is to describe, through a clinical case, the steps of realization of a nasal epithesis by CAD/CAM, in a patient who underwent a surgical exeresis of the nasal pyramid following a squamous cell carcinoma. Thus, the clinical and technical aspects are highlighted, as follows, the taking of the impression, the materials used, the set-up and the make-up, as well as the software and the useful concepts for the computer-assisted realization of a facial plastic prosthesis of the nasal epithesis type. Our therapy will also focus on the interest of the multidisciplinary approach in Maxillofacial Prosthodontics.

Can a spontaneous smile invalidate facial identification by photo-anthropometry?

Purpose

Using images in the facial image comparison process poses a challenge for forensic experts due to limitations such as the presence of facial expressions. The aims of this study were to analyze how morphometric changes in the face during a spontaneous smile influence the facial image comparison process and to evaluate the reproducibility of measurements obtained by digital stereophotogrammetry in these situations.

Materials and Methods

Three examiners used digital stereophotogrammetry to obtain 3-dimensional images of the faces of 10 female participants (aged between 23 and 45 years). Photographs of the participants' faces were captured with their faces at rest (group 1) and with a spontaneous smile (group 2), resulting in a total of 60 3-dimensional images. The digital stereophotogrammetry device obtained the images with a 3.5-ms capture time, which prevented undesirable movements of the participants. Linear measurements between facial landmarks were made, in units of millimeters, and the data were subjected to multivariate and univariate statistical analyses using Pirouette® version 4.5 (InfoMetrix Inc., Woodinville, WA, USA) and Microsoft Excel® (Microsoft Corp., Redmond, WA, USA), respectively.

Results

The measurements that most strongly influenced the separation of the groups were related to the labial/buccal region. In general, the data showed low standard deviations, which differed by less than 10% from the measured mean values, demonstrating that the digital stereophotogrammetry technique was reproducible.

Conclusion

The impact of spontaneous smiles on the facial image comparison process should be considered, and digital stereophotogrammetry provided good reproducibility.