ANALISI TRIDIMENSIONALE DELLA MORFOLOGIA FACCIALE CON L'UTILIZZO DELLA STEREOFOTOGRAMMETRIA.

Three dimensional analysis of facial morphology using stereophotogrammetry The human face has been largely evaluated from the quantitative point of view in medical literature, using manual anthropometry, photography and radiography. The limits of these techniques are: long-time procedure in analogic data acquisition for manual anthropometry, bi-dimensionality for photography, invasivity for radiography. Stereophotogrammetry promises to be a new, digital, three-dimensional, non invasive technique for evaluating the human face, in several medical fields, such as maxillofacial surgery, aesthetic surgery, orthodontics, prosthodontics, general dentistry. The instrument is based on the binocular vision: two pairs of cameras, with known reciprocal distance and angulation, capture two different images of the same object, allowing its three-dimensional virtual reconstruction, using a dedicated software. The current thesis proposes and evaluates three different applications of this technology: the first study proposes a new possibility in medical imaging, merging the superior dental arch with the 3D image of the face in a unique image. The procedure resulted accurate and reliable, with a relative error magnitude <1.2%, in comparison with direct anthropometry. Applications are possible in the diagnosis and treatment of the dento-facial pathologies, in the monitoring of the orthodontic and orthopaedic therapies. The second study investigates the morphological changes of the facial soft tissues, after dental additive modifications. A dental treatment was simulated by applying veneers with different thicknesses (1 and 2 mm) to the vestibular surfaces of the superior anterior teeth and the resulting new position of the facial tissues was compared with the baseline one. The highest amount of morphological response (from 0.4mm to 0.6mm) was concentrated in a central area around the upper and the lower lip, even using 1mm thickness. The study can help physicians to formulate more complete diagnosis and treatment planning, especially in the aesthetic field of dento-labial region. The third study is an anthropometric and aesthetic-related research of human face proportions, including references to the golden ratio. Out of a population of 600 subjects, who underwent a stereophotogrammetric facial acquisition, two groups of 20 subjects were extracted and divided in “very attractive” and “not attractive” by a panel of 4 judges. 10 facial ratios were compared between the two groups, using an ANOVA test, in order to find differences based on gender and attractiveness. The values of the facial ratios were also compared to the golden ratio (1.618) using a paired t-test. No significant differences were found in any group. Only a few facial ratios have significant relationships with the golden ratio. Beyond the technical results, the study is an example of how much helpful stereophotogrammetry could be in anthropometric research. In conclusion, stereophotogrammetry proved to be a reliable technique in several face-related medical fields. Its characteristics of high-quality imaging, three-dimensionality, non-invasive and easy-to-use procedure will ensure its wider diffusion and affordability in the future.