/home/opencode/cpanel/stomaeduj_hacked/uploads/Art-5-4-2020.pdf www.stomaeduj.com ORTHODONTICS APPLICATION OF MODERN 3D IMAGE ACQUISITION Original Articles SYSTEMS TO THE MORPHOLOGICAL ANALYSIS OF FACES: A NOVEL APPROACH FOR THE ASSESSMENT OF FACIAL GROWTH Daniele Maria Gibelli1a* , Pasquale Poppa2b , Annalisa Cappella1c , Riccardo Rosati1d, Claudia Dolci1e , Cristina Cattaneo2f , Chiarella Sforza1g 1 Department of Biomedical Sciences for Health, Faculty of Medicine and Surgery, University of Milan, Milan, Italy 2 LABANOF, Laboratory of Anthropology and Forensic Odontology, Department of Biomedical Sciences for Health, Faculty of Medicine and Surgery, University of Milan, Milan, Italy a MD, PhD, Associate Professor; e-mail: daniele.gibelli@unimi.it; ORCIDiD: https://orcid.org/0000-0002-9591-1047 b BSc, PhD; pasquale.poppa@unimi.it; ORCIDiD: https://orcid.org/0000-0002-9288-5576 c BSc, MA, PhD; annalisa.cappella@unimi.it; ORCIDiD: https://orcid.org/0000-0002-4527-4203 d DDS, PhD; riccardo.rosati@outlook.com e MD; claudia.dolci@unimi.it; ORCIDiD: https://orcid.org/0000-0002-3060-4097 fBSc, MD, MA, PhD; cristina.cattaneo@unimi.it; ORCIDiD: https://orcid.org/0000-0003-0086-029X g MD, Professor, Head; chiarella.sforza@unimi.it; ORCIDiD: https://orcid.org/0000-0001-6532-6464 ABSTRACT https://doi.org/10.25241/stomaeduj.2020.7(4).art.5 Introduction The assessment of facial growth has always had a relevant importance in anatomy and morphological sciences. This article aims at presenting a method of facial superimposition between 3D models which provides a topographic map of those facial areas modified by growth. Methodology Eight children aged between 6 and 10 years were recruited. In December 2010 they underwent a 3D scan by the Vivid 910 laser scanner (Konica Minolta, Osaka, Japan). The same procedures were performed another five times, in June 2011, September 2011, January 2012 and September 2012; in total 6 analyses were performed on the same subjects in a time span of 21 months. Three-dimensional digital models belonging to the same individual were then superimposed on each other according to 11 facial landmarks. Three comparisons were performed for each individual, referring to the period between December 2010 and June 2011, between June 2011 and January 2012 and between January and September 2012. Results Results show that the protocol of superimposition gives a reliable image of facial growth with high sensibility: in detail, even the slight facial modifications due to different expressions are recorded. The method can also quantify the point-to-point difference between the two models, and therefore give an indication concerning the general increase or decrease of facial volume. Conclusion This approach may provide useful indications for the analysis of facial growth on a large sample and give a new point of view of the complex field of face development. KEYWORDS Anatomy; Morphological Sciences; Facial Assessment; Facial Growth; Laser Scanner. 1. INTRODUCTION anthropological sciences, since the face is the main tool for communication and interaction with the Facial assessment, performed both from a environment; pionieristic studies were performed metrical and morphological point of view, is one by Leonardo da Vinci and Albrecht Dürer, and deal of the most ancient issues in anatomical and with the graphical methods useful to describe the OPEN ACCESS This is an Open Access article under the CC BY-NC 4.0 license. Peer-Reviewed Article Citation: Gibelli DM, Poppa P, Cappella A, Rosati R, Dolci C, Cattaneo C, Sforza C, Application of modern 3d image acquisition systems to the morpho- logical analysis of faces: a novel approach for the assessment of facial growth. Stoma Edu J. 2020;7(4):268-273. Received: October 12, 2020 Revised: October 23, 2020; Accepted: October 25, 2020; Published: October 27, 2020 *Corresponding author: Prof. Daniele Maria Gibelli, Dipartimento di Scienze Biomediche per la Salute, Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, V. Mangiagalli 31, Milan, Italy Tel: +39-02-50315339; Fax: +39-02-50315724; e-mail: daniele.gibelli@unimi.it Copyright: © 2020 the Editorial Council for the Stomatology Edu Journal. 268 Stoma Edu J. 2020;7(4): 268-273 pISSN 2360-2406; eISSN 2502-0285 3D acquisition systems for analysis of faces www.stomaeduj.com of the information obtained. As to the relation Original Articles between craniometric measurements and age, literature provides several articles dealing with the development of different facial traits in children and juveniles; Farkas for example analysed the degree of growth of different cranial and facial parameters, pointing out the percentual modifications [8]. In more recent times, different studies have been published concerning the sectorial development of single facial areas, such as lips [9], ears [10,11], nose [12] and the orbital region [13,14]. The modification of face with age was improved by analyses concerning the movement of facial landmarks with time, with consequent modifications of facial profiles [15,16]; in detail, literature ascertained that between 6 and 11 years of age the vertical diameters of the face increase, especially in the middle and upper thirds of faces: then, at 10 years circa in females and at 13 years circa in males the facial profiles are close to the adult model, with a dislocation of the main landmarks. Up to 11 years the trend is similar in both genders; then females show a spurt at 11-12 years circa, followed by a progressive decrease of bodily development. Figure 1. on the right, 3D laser scanner (Konica Minolta, Vivid 910); on the On the other hand males are affected by a delayed left, example of acquisition of the face of a child recruited in the study. growth, which remains constant from 11-12 to 16- 17 years. As a consequence, at 14-15 years of age facial morphological variation [1]. Charles Darwin females have a facial configuration similar to the first analysed the facial expressions and explored the adult one, whereas males of the same age are still importance of the face in evolutionary programs of in active growth. In females, the upper and lower interaction between individuals of the same species thirds have their higher degree of development up [2]. In the 19th century, with the beginning of modern to 11-12 years circa; on the other side, males begin to forensic anthropology, the metrical analysis of the increase the lower third from 12 to 13 years. face was analysed with identification purposes As one can notice, most of the literature actually by Alphonse Bertillon who developed a system of deals with linear measurements which remain the recording called bertillonage [3]; in the early 20th traditional way to explore facial morphology: in such century, the importance of the face was explored cases, the increase of single parameters is usually for what concerns the relation between personality, assessed as a percentage of the adult measurements. moral behaviour and morphological facial traits, In time, the linear approach to facial growth has by Lombroso [4]. The revolutionary discovery of provided epidemiological information concerning X-rays allowed scientists to perform more precise the modification of different parameters; in the last analyses of facial morphology, which was one of years, research in this field has known a relevant the main issues of the new technology [5]: however, improvement thanks to the advanced 3D image only in the last 30 years the study of the face has acquisition techniques: the main advantage consists gained popularity as shown by the huge increase in the chance of measuring dimensional parameters of studies published on this topic thanks also to which cannot be evaluated in vivo (for example, the introduction of more advanced diagnostic geometrical areas and volumes included within facial technologies such as CT scan and MRI (magnetic landmarks). This was an attempt both at applying resonance imaging). Since the early eighties, both the 3D image acquisition systems and at finding the ot them have been widely applied to the 3D study same standardization as for linear measurements of cranium and facial soft tissues [6]. Also, modern [12,13]. However the measurement of facial surfaces 3D image acquisition systems, both based on a and volumes is only one of the advantages deriving non-contact (laser scanner, stereophotogrammetry) from the application of modern technologies: in fact and contact approach (electromagnetic and these methods allow the operators to acquire a 3D electromechanical digitizers, ultrasound probes) digital model of face, which can be used in a virtual have been introduced for anthropological, space and, for example, superimposed to other anatomical and clinical investigations [7]. The use images. The main task consists in performing a point- of such technologies allowed the operators to to-point comparison between the two surfaces. An perform an easier recording and quantification of example of such application derives from the study facial metrical parameters, in order to increase data of facial motion and mimicry, provided by Popat and to analyse the chances of practical application et al. who used a stereophotogrammetric motion Stoma Edu J. 2020;7(4): 268-273 pISSN 2360-2406; eISSN 2502-0285 269 Gibelli DM, et al. www.stomaeduj.com Original Articles Figure 2. definition of 11 landmarks for facial superimposition. Figure 3. example of chromatic sheet of comparison between two 3D models from the same individual. Figure 4. chromatic figures of growth in child n° 1. Figure 5. chromatic figures of growth in child n° 2. analyzer, recorded subjects during the performance and left ¾ position (Fig.1). The same procedures of verbal and not verbal animations, and assessed were performed another five times, in June 2011, facial motion by superimposing sequential frames September 2011, January 2012 and September on the baseline [17,19]. The superimposition of 3D 2012; in total 6 analyses were performed on the models allows the operators to gain both a qualitative same subjects in a time span of 21 months. and quantitative assessment of modifications of The modification of facial morphology on 3D scans faces in comparison with the neutral expression, also was evaluated from a qualitative point of view creating a chromatic image which can provide easily following a protocol of facial comparison. In detail, readable information concerning the facial areas 11 facial landmarks (right and left endocanthion, more affected by modifications. exocanthion, alare, chelion: in the midline selion, However, this procedure has some limits gnathion, subnasale) were identified on all the 3D acknowledged also by the authors, especially for scans from the same individual by VAM (Canfield what concerns the methods of superimposition of Scientific, NJ, USA) software. The system was the 3D profiles which necessarily must be based on required to superimpose two 3D models from the use of a facial reference area which is supposed the same subject in order to reduce the distance to be stable during the different acquisitions. In between the corresponding points (Fig. 2). In order addition, this approach has not yet been applied to to follow facial growth, three comparisons were the analysis of facial growth. performed for each individual, referring to the period This article aims at exposing a novel protocol of 3D between December 2010 and June 2011, between model superimposition for the assessment of facial June 2011 and January 2012 and between January growth dynamics, which, in the future, may provide and September 2012. This procedure allowed the useful information for anatomical and morphological operator to obtain a chromatic sheet of the face, sciences. where the growing zones are colored in blue and the zones which showed a reduction are in red.The 2. MATERIALS AND METHODS unchanged areas are indicated in green (Fig. 3). Eight children, aged between 6 and 10 years, four 3. RESULTS males (n° 1, 2, 5, 7) and four females (n° 3, 4, 6, 8) were recruited: subjects affected by facial pathologies Subject n° 1 (male, analysed between 80 and 101 and deformities were excluded. All the following months of age) showed an increase in the lower analyses were performed after signature of a specific third of the face between December 2010 and June consent by the parents. In December 2010 the 2011: limited areas of increase are observed also eight children underwent a 3D scan by Vivid 910 in the palpebral regions, although they may be laser scanner (Konica Minolta, Osaka, Japan); a 3D due to the different position of the eyelids during digital model was built by five scans obtained in five the second scanning (the child had his eyes closed positions (frontal view, right and left profile, right during the second scan, whereas they were open 270 Stoma Edu J. 2020;7(4): 268-273 pISSN 2360-2406; eISSN 2502-0285 3D acquisition systems for analysis of faces www.stomaeduj.com Original Articles Figure 6. chromatic figures of growth in child n° 5. Figure 7. chromatic figures of growth in child n° 7. Figure 8. chromatic figures of growth in child n° 3. Figure 9. chromatic figures of growth in child n° 4. during the first one). In January 2012 there was an towards increments in facial dimensions, are shown increase of the entire face, but only on the left side in by the three comparisons of subject n° 6 (analysed the perioral region and nose, whereas the right side between 119 and 140 months of age) (Fig. 10). did not show modifications. At the end of the data Subject n° 8 (analysed between 72 and 93 months collection, the same region was affected by a slight of age) showed an increase at the left malar zone; at decrease (Fig. 4). the second and third comparison, an increase was Child n° 2 (male, analysed between 123 and 144 observed at the cheek: however, also in this case, the months of age) first showed an increase in the frontal different expression of the child may have played a area, and at the second comparison an increase in the role (Fig. 11). malar region, bilaterally. However, also in this case, the increase may be due to the smiling expression 4. DISCUSSION of the child. At the end of the experiment, the areas with a true increase were the nose and the perioral The study of facial growth has always been one of region (Fig. 5). Subject n° 5 (male, analysed between the most interesting and frequently treated topics in 131 and 152 months of age) showed an increase at anatomy and morphology, so far conducted through first limited to the left side of the face, whereas in the the assessment of linear measurements, as stated second comparison the entire face was affected by in Farkas’ study [8]. The introduction of modern 3D a decrease in size. In the last time point assessment, technologies gave a relevant impulse to the analysis the nose and the right and left malar zones showed of deeper dynamics of facial development by the an increase in size (Fig. 6). metrical assessment of surfaces and volumes [20,21]. Subject n° 7 (male, analysed between 102 and 123 However, additional information may be available months of age) showed an increase at the nose, by the superimposition of 3D models from the same bilateral malar zones and perioral region. However, individual, which may provide a topographic point- since the second comparison, the entire face was to-point visualization of growth processes. affected by a strong decrease, first limited to the The study aimed at verifying the relation of a novel left side of the face, and then extended to the right protocol for the superimposition of 3D models, as side (Fig. 7). On the other hand, the girls analysed a study model for the assessment of facial growth: showed different modifications: subject n°3 (ana- the preliminary results showed interesting starting lysed between 86 and 107 months of age) in all the points for further research. comparisons showed an increase of the oral region, First, the analysis of facial surfaces pointed out that with limited modifications (slightly prone to the the increase of surfaces does not show a progressive decrease) in the rest of the face (Fig. 8). trend in time; this indicates that the modification However, also in case of the females, strong diff- of facial surfaces is affected by other variables erences between age ranges within the same in specific periods, such as environmental and individual were noticed; subject n°4 (analysed individual factors. between 108 and 129 months of age) both during Another interesting information deriving from the the first and second comparison was affected by a analysis of facial surfaces in vivo is the general lack decrease of facial areas, followed by an increase of of symmetry in growth for both males and females. the entire facial zone in the last time point (Fig. 9). This is an interesting datum, since it confirms the The same differences, although with a stronger trend general information concerning the asymmetry of Stoma Edu J. 2020;7(4): 268-273 pISSN 2360-2406; eISSN 2502-0285 271 Gibelli DM, et al. www.stomaeduj.com Original Articles Figure 10. chromatic figures of growth in child n° 6. Figure 11. chromatic figures of growth in child n° 8. facial measurements [19,22]. The asymmetry of the general, the present technical note has shown the face is well known, and is observed both in adults large potential of the applied method in the study of and children: the actual study points out that facial facial morphology. growth also seems to follow the same asymmetry. Finally, the method of superimposition was able to CONFLICT OF INTEREST detect the slight modifications due to the different None. facial expressions: this provides an additional indication concerning the sensitivity of the approach. AUTHOR CONTRIBUTIONS 5. CONCLUSION DG: concept, protocol, data gathering, data analysis, data interpretation, revision of the manuscript, PP: protocol, data From this point of view, the actual study points out gathering, data analysis, AC: data gathering, data analysis, that the superimposition of 3D models may provide data interpretation, RR: data gathering, data analysis, data additional information, especially with respect to the interpretation, CD: data gathering, data analysis, data sectorial development of facial areas. The application interpretation, CC: concept, data interpretation, revision of the of this technique to few children provided some manuscript, CS: concept, data interpretation, revision of the insight into a deeper analysis of the phenomenon of manuscript. facial growth: clearly further studies are needed, on larger samples, in order to test the new protocol and ACKNOWLEDGMENTS provide a more decisive contribution to the analysis of facial age-related modifications. Nonetheless, in None. 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His areas of expertise include 3D surface acquisition (laser scanner and stereophotogrammetry) and 3D image elaboration for documentation and analysis of faces and osteological and dental material, 3D segmentation from CT-scan and NMR, the validation of novel techniques for 3D acquisition and assessment of their reliability in the analysis of facial anatomy. The specific topics include the study of facial morphology in acquired and genetic pathologies, of facial mimicry in healthy subjects and patients affected by facial nerve palsy, the analysis of anatomical variants of the cranium, the assessment of skeletal morphology. He authored more than 120 articles published in peer-reviewed impacted journals. Questions 1. Which technique of acquisition is not X-ray based? qa. Laser scanner; qb. CT-scan; qc. Conventional radiography; qd. CBCT scan. 2. Who analysed facial growth in children setting percentual modifications? qa. Leonardo da Vinci; qb. Charles Darwin; qc. Leslie Farkas; qd. Alphonse Bertillon. 3. Through which methods can facial morphology be analysed? qa. Laser scanner; qb. CT-scan; qc. NMR; qd. All the above. 4. Which facial measurements most increase between 6 and 11 years? qa. Horizontal ones; qb. Vertical ones; qc. Both of them; qd. None. Stoma Edu J. 2020;7(4): 268-273 pISSN 2360-2406; eISSN 2502-0285 273