A movable jaw model for the human face

Cataloged from PDF version of article.Although there is a great deal of work on facial animation, there is not much research on the effect of jaw motion on the movement of the face. The complex nature of the jaw bones makes it difficult to implement all the motions the jaw can do. The human jaw has two widely separated identical joints behaving like a single joint. Widely separated joints of the mandible (lower jaw bone) allow it to translate in any direction and/or rotate about any axis in three-dimensional space although its movements are somewhat restricted by physical constraints and patterns of muscle activity. A simplified jaw model which covers the major movements of the jaw is proposed in this paper. The lower jaw in the model can rotate around the axis connecting the two ends of the jaw and make small translational motions in any direction in 3-D space. The face is modeled as a two layer model which is attached to the jaw. The inner layer of the face moves kinematically as dictated by the jaw. The outer layer moves with the effect of the springs connecting it to the inner layer. The motion of the outer layer is calculated using spring-mass equations. Eating and chewing actions are simulated as applications of the model. (C) 1997 Elsevier Science Ltd. All rights reserved

Conserved but flexible modularity in the zebrafish skull: implications for craniofacial evolvability

Morphological variation is the outward manifestation of development and provides fodder for adaptive evolution. Because of this contingency, evolution is often thought to be biased by developmental processes and functional interactions among structures, which are statistically detectable through forms of covariance among traits. This can take the form of substructures of integrated traits, termed modules, which together comprise patterns of variational modularity. While modularity is essential to an understanding of evolutionary potential, biologists currently have little understanding of its genetic basis and its temporal dynamics over generations. To address these open questions, we compared patterns of craniofacial modularity among laboratory strains, defined mutant lines and a wild population of zebrafish ( ). Our findings suggest that relatively simple genetic changes can have profound effects on covariance, without greatly affecting craniofacial shape. Moreover, we show that instead of completely deconstructing the covariance structure among sets of traits, mutations cause shifts among seemingly latent patterns of modularity suggesting that the skull may be predisposed towards a limited number of phenotypes. This new insight may serve to greatly increase the evolvability of a population by providing a range of 'preset' patterns of modularity that can appear readily and allow for rapid evolution

The characteristics of a high-power diode laser fired enamel coating on a carbon steel

Significant changes to the wettability characteristics of a common engineering carbon steel(EN8) were effected after high power diode laser (HPDL) surface treatment. These modifications havebeen investigated in terms of the changes in the surface roughness of the steel, the presence of any surface melting, the polar component of the steel surface energy and the relative surface O2 content of the steel. The morphological and wetting characteristics of the mild steel and the enamel were determined using optical microscopy, scanning electron microscopy, X-ray photoemission spectroscopy, energy-dispersive X-ray analysis and wetting experiments by the sessile drop technique. This work has shown that HPDL radiation can be used to alter the wetting characteristics of carbon steel so as to facilitate improved enamelling. Furthermore, standard mechanical, physical and chemical testing of the HPDL-fired enamel glaze revealed the glaze to possess similar properties to those of a conventionally fired enamel glaze in terms of bond strength, rupture /impact strength, wear and corrosion resistance. Such similar performance can be attributed to the two glazes possessing the same mechanical properties and similar amorphous structure, despite their very different firing techniques

Development of a Personalised 3D Mandibular Distraction Device for the Management of Craniofacial Microsomia

Introduction: Surgical correction of the facial skeleton in deformity has evolved significantly over the recent past as techniques and technology have improved. Where there exist significant skeletal discrepancies, large skeletal changes are required and there remains a need to further improve upon our current standard to achieve these surgical goals. Distraction osteogenesis (DO) is a technique that induces bone formation without the need for bone grafting and allows for guided shape change in addition to expanding the overlying tissue envelope. Current mandibular distractors are limited as they are bulky; there are wound problems related to the external siting of the actuator; there is a limited geometry of possible distraction; the final result is unpredictable; they function in a discontinuous rather than continuous motion and they require daily winding by the patient. There exists a clear potential benefit to patients should these drawbacks be overcome. Aim: The aim of the project is to design a novel device to modify the shape of the deformed jaw to a prescribed, predetermined shape that is specific to the patient and that does not require external manipulation. Methods: The mechanical properties of helical springs constructed from a nonlinear material were tested to review their suitability for use as actuators to deliver force in a fully buried continuous distractor. A finite element model was then created to generalise the concept for use where different forces may be required. Lastly a prototype was designed and empirically tested ex-vivo to assess whether the aims of the project were fulfilled. Results: The nonlinear material was found to deliver adequate, continuous and relatively constant force over a distance in keeping with DO. The finite element model was demonstrated to accurately represent the empirical properties of the helical spring. The prototype designed was able to modify the shape of a deformed jaw to a predetermined position without requiring external manipulation in a surgical model. Discussion: This project develops and tests a prototype that is fully buried and can achieve multiplanar continuous DO without the need for patient involvement and therefore provides novel technology as a solution to improving practice

Study to design and develop remote manipulator system

Modeling of human performance in remote manipulation tasks is reported by automated procedures using computers to analyze and count motions during a manipulation task. Performance is monitored by an on-line computer capable of measuring the joint angles of both master and slave and in some cases the trajectory and velocity of the hand itself. In this way the operator's strategies with different transmission delays, displays, tasks, and manipulators can be analyzed in detail for comparison. Some progress is described in obtaining a set of standard tasks and difficulty measures for evaluating manipulator performance

PRESURGICAL ORTHODONTIC THERAPY IN A NEWBORN WITH MEDIAN CLEFT LIP ACCOMPANIED BY HOLOPROSENCEPHALY AND AGENESIS OF THE PREMAXILLA

Surgical treatment protocols for rare types of clefts do not exist, especially when they are associated with severe anomalies of the brain and face. Surgical treatment of a newborn with holoprosencephaly, premaxillary agenesis and median cleft lip is a big challenge for the surgeon. The complete lack of bone in the nasal bones and premaxilla make surgical therapy almost impossible. The role of pre-surgical orthodontic therapy plays a major role in creating the conditions for surgical repair of cleft-damaged parts of the face.Case presentation. The paper presents presurgical orthodontic therapy in a newborn with a median cleft lip using the RBJ stimulator. Conclusion. The use of stimulators of a specific construction in the therapy of rare clefts is the method of choice

MorphFace: a hybrid morphable face for a robopatient

Physicians use pain expressions shown in a patient’s face to regulate their palpation methods during physical examination. Training to interpret patients’ facial expressions with different genders and ethnicities still remains a challenge, taking novices a long time to learn through experience. This paper presents MorphFace: a controllable 3D physical-virtual hybrid face to represent pain expressions of patients from different ethnicity-gender backgrounds. It is also an intermediate step to expose trainee physicians to the gender and ethnic diversity of patients. We extracted four principal components from the Chicago Face Database to design a four degrees of freedom (DoF) physical face controlled via tendons to span 85% of facial variations among gender and ethnicity. Details such as skin colour, skin texture, and facial expressions are synthesized by a virtual model and projected onto the 3D physical face via a frontmounted LED projector to obtain a hybrid controllable patient face simulator. A user study revealed that certain differences in ethnicity between the observer and the MorphFace lead to different perceived pain intensity for the same pain level rendered by the MorphFace. This highlights the value of having MorphFace as a controllable hybrid simulator to quantify perceptual differences during physician training

Congenital Malformation and Acquired Deformity of the Oral and Facial Structure

An introductory note is followed by a short discourse on the history of the conditions which come under discussion in the treatise. Normal development of the oral and facial structures is reviewed and illustrated diagramatically. A summary of developmental malformations is given, and, in some instances, photographs serve to illustrate the conditions mentioned. Lip and palatal clefts are classified. Photographs of the various types of these malformations are included. A series of selected cases is presented. This series includes cases of congenital and acquired oral deformity. Modes of treatment are described and illustrated. Results, following the application of original procedures in the non-surgical closure of palatal defects, are shown. Methods of overcoming retention difficulties, by means of original appliances, are demonstrated in cases of both congenital and acquired oral deformity. Orthodontic measures, as applied to the correction of premaxillary protrusion in the young patient, are decribed and illustrated. Technical procedures in the construction of original appliances are described. Photographs and diagrams are utilised in the presentation of theses various procedures. Findings are given. These are based upon examination of records of 31,953 infants born during a period of ten years, together with observations noted during the examination and treatment of a series of 250 cases of congenital cleft palate. The main features and characteristics exhibited by those suffering from congential oral deformity are illustrated in a series of 100 cases drawn at random from the main series. The 100 cases are presented in summarised form. A discussion is included. This part of the thesis is presented in two sections. The first section deals with the etiology of congenital malformations. A theory, based upon hereditary predisposition to oral malformation, is advanced and discussed. Existing theories, relating to 'maternal impressions' and 'maternal malnutrition' are investigated, in an attempt to determine whether or not these conditions play any major part in the etiology of congenital deformity. The high incidence of twinning, or history of twinning, observed in families in which occurs oral deformity, is considered. Mention is made of endocrine disturbance, epilepsy and ocular hypertelorism in their relation to congenital malformation. The second section of the discussion is devoted to the treatment of oral deformity. Arguments are put forward in favour of various corrective measures which have proved efficacious during the researches which have been pursued. Consideration is given to prosthetic measures in relation to the functions of speech, deglutition and aesthetic appearance. Non-surgical methods of closure of palatal defects, by the application of original orthodontic measures, are discussed. Surgical procedures are considered, both as independent modes of treatment, and in conjunction with prosthetic and orthodontic measures. The conclusion arrived at, as a result of the researches which have been undertaken, are enumerated. A bibliography appears at the end of each main section of the treatise

Aquatic-terrestrial transitions of feeding systems in vertebrates : a mechanical perspective

Transitions to terrestrial environments confront ancestrally aquatic animals with several mechanical and physiological problems owing to the different physical properties of water and air. As aquatic feeders generally make use of flows of water relative to the head to capture, transport and swallow food, it follows that morphological and behavioral changes were inevitably needed for the aquatic animals to successfully perform these functions on land. Here, we summarize the mechanical requirements of successful aquatic-to-terrestrial transitions in food capture, transport and swallowing by vertebrates and review how different taxa managed to fulfill these requirements. Amphibious ray-finned fishes show a variety of strategies to stably lift the anterior trunk, as well as to grab ground-based food with their jaws. However, they still need to return to the water for the intra-oral transport and swallowing process. Using the same mechanical perspective, the potential capabilities of some of the earliest tetrapods to perform terrestrial feeding are evaluated. Within tetrapods, the appearance of a mobile neck and a muscular and movable tongue can safely be regarded as key factors in the colonization of land away from amphibious habitats. Comparative studies on taxa including salamanders, which change from aquatic feeders as larvae to terrestrial feeders as adults, illustrate remodeling patterns in the hyobranchial system that can be linked to its drastic change in function during feeding. Yet, the precise evolutionary history in form and function of the hyolingual system leading to the origin(s) of a muscular and adhesive tongue remains unknown