scholarly journals Symmetry and Aesthetics in Dentistry

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1741
Author(s):  
Christoph Runte ◽  
Dieter Dirksen

Animal bodies in general and faces in particular show mirror symmetry with respect to the median-sagittal plane, with exceptions rarely occurring. Bilateral symmetry to the median sagittal plane of the body also evolved very early. From an evolutionary point of view, it should therefore have fundamental advantages, e.g., more effective locomotion and chewing abilities. On the other hand, the recognition of bilaterally symmetric patterns is an important module in our visual perception. In particular, the recognition of faces with different spatial orientations and their identification is strongly related to the recognition of bilateral symmetry. Maxillofacial surgery and Dentistry affect effective masticatory function and perceived symmetry of the lower third of the face. Both disciplines have the ability to eliminate or mitigate asymmetries with respect to form and function. In our review, we will demonstrate symmetric structures from single teeth to the whole face. We will further describe different approaches to quantify cranial, facial and dental asymmetries by using either landmarks or 3D surface models. Severe facial asymmetries are usually caused by malformations such as hemifacial hyperplasia, injury or other diseases such as Noma or head and neck cancer. This could be an important sociobiological reason for a correlation between asymmetry and perceived disfigurement. The aim of our review is to show how facial symmetry and attractiveness are related and in what way dental and facial structures and the symmetry of their shape and color influence aesthetic perception. We will further demonstrate how modern technology can be used to improve symmetry in facial prostheses and maxillofacial surgery.

PEDIATRICS ◽  
1971 ◽  
Vol 48 (4) ◽  
pp. 629-635
Author(s):  
Howard A. Pearson ◽  
Louis K. Diamond

This brief review, being limited in scope to the recognition and management of the life-threatening and painful crises in infants and children with sickle-cell disease, has not even touched on the intriguing mystery of the molecular basis for the sickling phenomenon–how one amino-acid substitution (gene controlled) in the beta chain sequence of 146 amino acids can cause such serious disruption in form and function; or how this mutation occurred in the first place and why it has persisted in contrast to the rapid disappearance of many other deleterious mutants. Nor has there been even mention of the many milder symptoms, signs, and complications due to the presence of Hb. S., either in the homozygous (disease-producing) state or heterozygous form when found in combination with other hereditary hemoglobin defects. The accumulated knowledge about this mutant gene, its biochemical effects, and geographic distribution is enormous. From a fundamental scientific standpoint, sickle cell disease is one of the best understood of human afflictions. However, from a practical point of view treatment of the patient himself is often only symptomatic and palliative. Nevertheless, prompt and effective therapy of the myriad manifestations of sickle cell disease can effectively reduce morbidity and mortality. The pediatrician who cares for black children in his practice should be familiar with the cardinal diagnostic and clinical aspects of sickle cell disease and its crises.


Author(s):  
Greg Quinn

There are many theoretical models that attempt to accurately and consistently link kinematic and kinetic information to musculoskeletal pain and deformity of the foot. Biomechanical theory of the foot lacks a consensual model: clinicians are enticed to draw from numerous paradigms, each having different levels of supportive evidence and contrasting methods of evaluation, in order to engage in clinical deduction and treatment planning. Contriving to find a link between form and function lies at the heart of most of these competing theories and the physical nature of the discipline has prompted an engineering approach. Physics is of great importance in biology and helps us to model the forces that the foot has to deal with in order for it to work effectively. However, the tissues of the body have complex processes that are in place to protect them and they are variable between individuals. Research is uncovering why these differences exist and how these processes are governed. The emerging explanations for adaptability of foot structure and musculoskeletal homeostasis offer new insights on how clinical variation in outcomes and treatment effects might arise. These biological processes underlie how variation in the performance and utilisation of common traits, even within apparently similar sub-groups, make anatomical distinction less meaningful and are likely to undermine the justification of a 'foot type'. Furthermore, mechanobiology introduces a probabilistic element to morphology based on genetic and epigenetic factors.


2019 ◽  
Vol 125 ◽  
pp. 04003
Author(s):  
Oktiva Herry Chandra

Language produced in a specific event of communication will have its form and function. Some messages are delivered in direct ways meaning the form and the functions are symmetric; some others are delivered in indirect ways, asymmetric. Direct or indirect ways will give different perceptions to those who receive the content of the message. Considering the face of receivers is one of the principles that should be made by policy makers as they communicate with people in public space. This article aims to explain the forms of language used to prohibit littering and the way the maker of prohibition thinks about the writing of littering. The research is conducted by using non-participatory observation method. This, then, is followed by applying note taking technique and recording. The result shows mostly the writings of littering prohibition are made an indirect way and less number in indirect way. Having a direct way means society is placed as subordinate in relation to the authorities. Even though less in number, indirect littering prohibition shows some writings see an equal position between the writer and reader. Both take a similar point of view on littering.


2019 ◽  
Author(s):  
Brett David W

The following is an update to a book entitled, “A Historical Review of Enzymatic Debridement: Revisited”, which I wrote in 2003. Since its publication, while the relevant clinical evidence has remained consistent, the amount of biochemical research and knowledge gained has been impressive. In the first chapter a sampling of the typical topical enzymatic debriding agents that have been used in wound care are reviewed and interestingly enough only one remains on the market. The FDA has removed all others from the marketplace and an explanation is provided in chapter one along with descriptions of the use and mode of action (MoA) of these agents. Chapter two is a review of the many different types of collagen found in the body, including their structure, form, and function as so much additional insight into this molecule has been gained since 2003. In chapter three we see an account depicting the many advances in understanding matrix metalloproteinases (MMPs) reviewed in detail. Form, function, tissue orientation and preferred substrates are addressed. Finally, in chapter four we see the history of the MoA of MMPs as compared to bacterial collagenase starting in the early ‘80s to the time of this current publication. In addition we see the level of complexity of bacterial collagenases compared to MMPs, helping us to better understand why bacterial collagenase is much more efficient at removing necrotic tissue from wounds than are our own (endogenous) MMPs. I hope the reader finds this review useful from an academic standpoint, but more importantly from a clinical framework helping to understand the role of these types of therapies in wound care.


The investigations which form the subject of the paper were begun with the object of verifying the statements made by several authors with regard to the origin and development of the so-called "heart" or pericardial vesicle of Echinoderms. A study of the literature soon led to the conclusion that our knowledge of the development of the organ was somewhat defective and that a thorough revision of its development and ultimate fate would be desirable. This work has occupied my attention for the last two years and the results obtained have been fairly satisfactory. Historical Resumé . The Echinodermata offer a number of most interesting problems to the comparative physiologist. They are in many senses the lowest animals, from the point of view of organisation, which possess a true cœlom or secondary body-cavity. It was always assumed by earlier naturalists that these animals must have a circulatory system and strenuous efforts were made to find a heart and blood-vessels. None of these efforts has been very successful because the so-called vessels were found to be mere rents in the loose connective tissue without proper walls of their own, and further, no connection could be traced between vessels in one part and those in another part. The fact that these vessels owe the honour of being denominated blood-vessels at all is because they contain a ground-substance, which unlike the ground-substance of the rest of the connective tissue, stains with aniline dyes such as eosin and methyl green. If there is to be true circulation some part of the system must be rhythmically contractile and so a heart had to be found. A pillar-like organ, lying alongiside the stone-canal in Echinoidea, Ophiuroidea and Asteroidea, was selected for the rôle. Unfortunately, in Holothuroidea, where the so called vessels are best developed, it is absent and this fact may be correlated with the elongated shape of the animal and the contractility of the body wall. Later, as repeated observation had failed to detect any sign of its beating, the non-committal term of "pseudo-heart" was adopted for it. It is now proposed to call it the “pericardial vesicle.”


2012 ◽  
Vol 21 (2) ◽  
pp. 170-188 ◽  
Author(s):  
Elena Pallarés-García

Jane Austen’s Emma (1816) is generally considered an ambiguous and unreliable narrative in terms of point of view (Morini, 2009: 53–57; Wallace, 1995: 77–97). These qualities are often attributed to the extensive use of free indirect discourse (Finch and Bowen, 1990: 5–6; Mezei, 1996: 72–75). This article aims to demonstrate that another narrative technique is also responsible for the ambiguity and unreliability of the novel. ‘Narrated perception’ (NP) portrays the sensory perceptions of a fictional character by describing events as they are experienced by that character (Fludernik, 1993: 305–309). NP has been pointed out by some critics to be a distinct narrative technique, but in general perception is included within the broader category of free indirect discourse (FID), and occasionally as an aspect of free indirect thought (FIT). This article suggests that there are some subtle differences between NP and FID/FIT, and thus it can be beneficial to examine NP separately. In fact, NP is frequently similar to pure narration in terms of form and function. As a case study, this article presents a stylistic analysis of a number of passages containing NP in Emma which do not typically feature in studies of FID/FIT. The analysis provides textual evidence of (1) the presence of Emma’s sensory perceptions within what looks like narration, (2) the close connection between perception, thought and emotion, and (3) the difficulty of distinguishing between perception and narration in some cases, which suggests the potential of NP to mislead the reader by presenting as a seemingly objective fact what later on turns out to be Emma’s mistaken assessment.


2014 ◽  
Vol 48 (2) ◽  
pp. 87-90 ◽  
Author(s):  
Sudhir Bhandari

ABSTRACT Intraoral trauma may occur in isolation or in combination with injury of the other parts of the body. Once the life-threatening phase of trauma is over, the primary need for the patient is to restore the form and function of the tissues lost due to trauma. In the oral and maxillofacial region, esthetic consideration does sometimes supersede the need of function. This article briefl y summarizes the scope of prosthodontics in patients with oral and maxillofacial trauma. How to cite this article Bhandari S. Prosthetic Considerations in Oral and Maxillofacial Trauma. J Postgrad Med Edu Res 2014; 48(2):87-90.


2017 ◽  
Author(s):  
Marc HE de Lussanet ◽  
Jan W.M. Osse

One of the great mysteries of the brain, which has puzzled all-time students of brain form and function is the contralateral organization of the forebrain, and the crossings of its major afferent and efferent connections. As a novel explanation, two recent studies have proposed that the rostral part of the head, including the forebrain, is rotated by 180 degrees with respect to the rest of the body (de Lussanet and Osse, 2012, Animal Biology 62, 193–216; Kinsbourne, 2013, Neuropsychology 27, 511–515). Kinsbourne proposes one 180-degree turn while we consider the 180 degrees being the result of two 90-degree turns in opposite directions. We discuss the similarities and differences between the two hypotheses.


1998 ◽  
Vol 201 (12) ◽  
pp. 1871-1883 ◽  
Author(s):  
KJ Quillin

Soft-bodied organisms with hydrostatic skeletons range enormously in body size, both during the growth of individuals and in the comparison of species. Therefore, body size is an important consideration in an examination of the mechanical function of hydrostatic skeletons. The scaling of hydrostatic skeletons cannot be inferred from existing studies of the lever-like skeletons of vertebrates and arthropods because the two skeleton types function by different mechanisms. Hydrostats are constructed of an extensible body wall in tension surrounding a fluid or deformable tissue under compression. It is the pressurized internal fluid (rather than the rigid levers of vertebrates and arthropods) that enables the maintenance of posture, antagonism of muscles and transfer of muscle forces to the environment. The objectives of the present study were (1) to define the geometric, static stress and dynamic stress similarity scaling hypotheses for hydrostatic skeletons on the basis of their generalized form and function, and (2) to apply these similarity hypotheses in a study of the ontogenetic scaling of earthworms, Lumbricus terrestris, to determine which parameters of skeletal function are conserved or changed as a function of body mass during growth (from 0.01 to 8 g). Morphometric measurements on anesthetized earthworms revealed that the earthworms grew isometrically; the external proportions and number of segments were constant as a function of body size. Calculations of static stresses (forces per cross-sectional area in the body wall) during rest and dynamic stresses during peristaltic crawling (calculated from measurements of internal pressure and body wall geometry) revealed that the earthworms also maintained static and dynamic stress similarity, despite a slight increase in body wall thickness in segment 50 (but not in segment 15). In summary, the hydrostatic skeletons of earthworms differ fundamentally from the rigid, lever-like skeletons of their terrestrial counterparts in their ability to grow isometrically while maintaining similarity in both static and dynamic stresses.


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