1,721,822 research outputs found
Re: Nickel chromium and iron levels in the saliva of patients with simulated fixed orthodontic appliances
No full textAnalisi tridimensionale non invasiva della crescita craniofaciale in dentizione decidua e mista precoce
No full textLo scopo del lavoro è di identificare pattern di crescita, modelli di normalità ed eventuali canoni estetici nella forma e dimensioni della faccia dei bambini italiani attraverso l'analisi tridimensionale della morfologia dei tessuti molli della faccia. Il lavoro, così eseguito, è stato valutato su un campione di 175 bambini "normali" (4-9 anni) e 89 coetanei provenienti da un casting pubblicitario, definiti "belli", permettendo di calcolare angoli, distanze e volumi facciali
A New 3D Tool for Planning Plastic Surgery
Full text linkFace plastic surgery (PS) plays a major role in today medicine. Both for reconstructive and cosmetic surgery, achieving harmony of facial features is an important, if not the major goal. Several systems have been proposed for presenting to patient and surgeon possible outcomes of the surgical procedure. In this paper, we present a new 3D system able to automatically suggest, for selected facial features as nose, chin, etc, shapes that aesthetically match the patient's face. The basic idea is suggesting shape changes aimed to approach similar but more harmonious faces. To this goal, our system compares the 3D scan of the patient with a database of scans of harmonious faces, excluding the feature to be corrected. Then, the corresponding features of the k most similar harmonious faces, as well as their average, are suitably pasted onto the patient's face, producing k+1 aesthetically effective surgery simulations. The system has been fully implemented and tested. To demonstrate the system, a 3D database of harmonious faces has been collected and a number of PS treatments have been simulated. The ratings of the outcomes of the simulations, provided by panels of human judges, show that the system and the underlying idea are effectiv
Biomechanical model of the human mandible in unilateral clench: Distribution of TMJ reaction forces between working and balancing sides
No full textIn a previous article we reported on our development of a biomechanical analog of the human mandible and a simple support model was introduced. The model has been further developed to calculate the relative degree of load on the working and balancing sides of the temporomandibular joint during unilateral clench. The relative load on each joint is a function of the biting force, the geometric setting (subject's anatomy, points of application of the biting force on the dental arch and of the resultant of the forces of the masticatory muscles), and the value of the electromyographic asymmetry (relative contribution of working-versus balancingside muscles) and activity indexes (relative contribution of masseter versus anterior temporal muscle of both sides). The proposed biomechanical model showed that the reaction forces that act on the temporomandibular joint during unilateral clench do not always load the balancing-side joint more than the working-side joint. Modifications of the asymmetry index changed the relative load between the two joints, and a higher temporal muscle activity increased the joint load on both the working and the balancing sides
About “Jayaratne YS, Deutsch CK, Zwahlen RA. A 3-dimensional anthropometric analysis of the orolabial region in Chinese young adults” [Br J Oral Maxillofac Surg 2013;51:908–12]
No full textSoft-tissue facial anthropometry in three dimensions : from anatomical landmarks to digital morphology in research, clinics and forensic anthropology
No full textThe quantitative assessment of the dimensions of human facial soft-tissue structures (eyes, nose, mouth and lips, chin, ears), their reciprocal spatial positions and relative proportions, has an interdisciplinary perspective: anatomical and anthropometric descriptions, medical evaluations (clinical genetics, orthodontics,
maxillo-facial and plastic surgery), forensic medicine, they all need reference three-dimensional data collected on healthy, normal individuals selected for sex, age, ethnic group, to be compared to those obtained on the single individual. The data collection technique should be non-invasive, fast, as simple as possible, performed directly on the subjects using low-cost instruments. Data should be collected in digital format, so to allow the creation of
computerized data bases, and the use of the computerized techniques of visualization and simulation of treatment. Independent of classic direct anthropometry, various three-dimensional image analyzers are increasingly being used in clinical investigations and research. The instruments can be divided into two main categories: optical, non contact digitizers, and contact instruments. The first kind of instruments (mainly, laser
scanners and stereophotogrammetric devices) perform a fast digitization of the face, providing a detailed analysis of the soft-tissue surface. Contact instruments (electromagnetic and electromechanic digitizers) use a landmark representation of the soft-tissue facial surface. Landmark coordinates are coupled to a mathematical and
geometric model of the face, and angles, distances and ratios similar to those measured in conventional anthropometry can be obtained. Additionally, multivariate methods of analysis, obtained either from geometric morphometry or from other analytical methods, could be used. Optical instruments provide a larger amount of
information but they cannot assess all the actual anatomical landmarks obtained by contact instruments. Motion artifacts are more common with contact instruments, but they can be easily transported, and they are less expensive. Overall, contact instruments seem sufficiently reliable, simple and fast to be used also in a clinical context, thus providing useful quantitative information to allow a better patient care, without submitting the subjects to potentially harmful procedures
Anatomy of emotion : a 3D study of facial mimicry
No full textAlterations in facial motion severely impair the quality of life and social interaction of patients, and an objective grading of facial function is necessary. A method for the non-invasive detection of 3D facial movements was developed. Sequences of six standardized facial movements (maximum smile; free smile; surprise with closed mouth; surprise with open mouth; right side eye closure; left side eye closure) were recorded in 20 healthy young adults (10 men, 10 women) using an optoelectronic motion analyzer. For each subject, 21 cutaneous landmarks were identified by 2-mm reflective markers, and their 3D movements during each facial animation were computed. Three repetitions of each expression were recorded (within-session error), and four separate sessions were used (between-session error). To assess the within-session error, the technical error of the measurement (random error, TEM) was computed separately for each sex, movement and landmark. To assess the between-session repeatability, the standard deviation among the mean displacements of each landmark (four independent sessions) was computed for each movement. TEM for the single landmarks ranged between 0.3 and 9.42 mm (intra-session error). The sex- and movement-related differences were statistically significant (two-way analysis of variance, p=0.003 for sex comparison, p=0.009 for the six movements, p<0.001 for the sex x movement interaction). Among four different (independent) sessions, the left eye closure had the worst repeatability, the right eye closure had the best one; the differences among various movements were statistically significant (one-way analysis of variance, p=0.041). In conclusion, the current protocol demonstrated a sufficient repeatability for a future clinical application. Great care should be taken to assure a consistent marker positioning in all the subjects
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