Effect of working conditions on vision in microcomputer users

Tooth wear is becoming more common in both adults and children. The triad of attrition, abrasion and erosion has been known for many years, but the contribution of erosion (irreversible loss of dental hard tissue due to a chemical process not involving bacteria, or the loss of tooth surface not directly associated with mechanical or traumatic factors or caries) to excessive loss of tooth tissue is now being emphasized. The authors of this paper examine the problem and suggest ways of overcoming it.     

Mathematical shape matching as a tool in tooth wear assessment--development and conduct

The quantitative assessment of restoration and tooth wear usually requires fixed reference points from which measurements are made. In longitudinal patient follow-up the loss or erosion of such points may preclude measurement and an alternative approach is to seek regions of coincidence and conflict in digital models of before and after wear surfaces, with a continuous refinement of the parameters of the coordinate transformations, until the closest correspondence between them is found. A computer program has been written to implement the algorithm and assess the technique's capacity to find the match between surfaces both artificially generated and from tooth replicas recorded from patients at different epochs. The program was able to achieve the desired ends, demonstrating the utility of the technique in tooth wear assessment but identifying the need to refine the program further to enhance both its difference detection capabilities and level of automation. Examination of the theory and practical experience highlighted certain situations when user understanding is invaluable to ensure a satisfactory solution. This strengthened the investigators' resolve against reliance upon commercially based surface fitting programs whose basis may not be fully understood. Notwithstanding this surface matching is a powerful tool in the investigation of dental wear.     

Tooth wear in children: an investigation of etiological factors in children with cerebral palsy and gastroesophageal reflux

This investigation was undertaken to establish the prevalence and distribution of tooth wear in different groups of medically compromised children and to assess the possible influence of gastroesophageal reflux, dietary factors, and parafunctional activity. Four groups of children including twenty-one with cerebral palsy were clinically examined and had in-depth, structured interviews, including information on medical history, medication, gastroesophageal reflux, feeding and drinking habits, parafunctional activity, and tooth-brushing procedures. All the children with cerebral palsy also had twenty-four-hour gastroesophageal pH monitoring. Of the fifty-one children in total, twenty-five had moderate or severe levels of dental erosion. No statistically significant differences were found between the groups as far as dietary influences, feeding habits, and tooth-brushing procedures. There was a significant association, however, between gastroesophageal reflux and erosion. It is concluded that in children with cerebral palsy this reflux may be much more important in the etiology of tooth surface loss than the parafunctional activity, which has classically been regarded as the cause.     

Dental disease in the late Medieval population from Nova Raca, Croatia

Male and female dental disease frequencies were compared to test the hypothesis of differential stress levels between the sexes in the late Medieval population from Nova Raca, Croatia. The following categories of dental disease were compared: alveolar bone pathology defined by the presence of periodontal or periapical abscesses or antemortem tooth loss, caries, hypoplastic defects in the enamel and occlusal surface wear. The results show clear gender differences in the frequencies of alveolar bone pathology, carious lesions and occlusal surface wear. In all cases males exhibited significantly greater frequencies. Further analyses indicated that these differences were related to younger (15-29 years) adults and to the upper jaw. Together with paleodemographic data and the fact that females exhibited higher frequencies of enamel defects, this dichotomy in dental disease frequencies is interpreted as the result of a culturally imposed defensive mechanism which selectively buffered young males from malnutrition, exposing them at the same time to higher levels of cariogenic food and thus to higher frequencies of carious lesions and alveolar bone disease.     

硬质涂层抗喷砂型冲蚀磨损研究现状

为减少材料和能源的损耗, 延长零部件使用寿命, 硬质涂层被应用于喷砂型冲蚀磨损环境。 本文介绍了喷 砂型冲蚀磨损的危害和硬质涂层的应用情况, 综述了硬质涂层力学性能、 基体材料性能、 粒子特性和喷砂参数等 对涂层抗喷砂型冲蚀磨损的影响趋势, 总结了喷砂型冲蚀磨损的动力学模拟和冲击试验的研究情况, 指出了涂层 硬度和韧性以及基体与涂层性能的匹配有助于提高涂层抗喷砂型冲蚀磨损, 展望了通过数字模拟与试验验证相结 合的方式获得各种硬质涂层抗喷砂型冲击磨损机理模型的前景。     

Iodine intake and the pattern of thyroid disorders: a comparative epidemiological study of thyroid abnormalities in the elderly in Iceland and in Jutland, Denmark

Gastroesophageal reflux (GOR) is often a self-limiting condition but nevertheless is a common cause of morbidity in childhood. Studies of adult patients with hiatus hernias and GOR have suggested that there is an increased incidence of dental erosion in these individuals. The aim of this study was to investigate the relationship between dental erosion and GOR in children. Fifty-three children aged 2 to 16 yr (mean 4.9 yr) with moderate to severe GOR, defined by pH monitoring, were examined for dental erosion. A questionnaire investigating dietary habits, other relevant medical conditions, and erosion risk factors was also completed. Results showed that the prevalence of dental erosion was low, when compared with the UK National Survey, with only 9 (17%) children showing any signs of erosion, and of these only one had erosion involving dentine. These results suggest that dental erosion may not be as great a problem in children with GOR as it is in adults. It may be that refluxing is limited to the oesophagus, and further work is needed to investigate those children that positively reflux into the mouth.     

Culture, dental professionals and oral health values in multicultural societies: measuring cultural factors in geriatric oral health research and education

Culture has significant impacts upon professional practice and patient health behaviours, especially in multicultural societies. This paper introduces the concept of culture and examines how it may be of importance to dental health professionals. Using the Dental Impact Profile and other dental social science measures, dental researchers and students can be engaged in studying cultural values and characteristics as a way of dealing with cultural differences.     

Tooth diseases in the medieval population of Gracanica near Valjevo

The analyses of the pattern of dental disease in the Late Medieval Serbian population from cemetery excavations in the archaeological site Grachanica were based on the study of tooth wear, ante-mortem tooth loss, caries, hypoplasia, alveolar resorption, abscesses and calculus. The total sample of all available skeletons with almost complete permanent dentition numbers 45 individuals. Dental sample comprises 178 maxillary teeth and 337 mandibular teeth. The presence of dental caries was scored taking into consideration the size of the lesion (four degrees) and its position on the tooth. The degree of tooth wear was graded into one of four categories: atrition of enamel only; atrition involving dentin; atrition up to the level of fissure at the occlusal surface of the molar teeth, and exposure of the pulp chamber. The cystic defects within the alveolar bone were recorded according to their aetiology, size and position. Radiographic study had not been done in order to detect periapical destruction, so the presence of such destruction was recognizable in advanced stages associated with the appearance of fistula penetrating the compact alveolar bone usually at the buccal side. The condition of the alveolar crest resorption, as the evidence of periodontal disease, was graded into three categories, and the distance from the cemento-enamel junction to the alveolar crest was measured. The analysis of dental pathology profile consisted of the two reporting methods: individual count method (prevalence of disease based on the number of individuals affected) and tooth count method (distribution of lesions frequency on tooth type and class). The Grachanica dentition exhibits a dental pathology profile typical of agricultural medieval populations in this region. Tooth wear was the most frequent, affecting 95% of individuals. Dental caries and ante-mortem teeth loss exhibit also high frequency (51% and 69%). Dental pains of low prevalence include abscesses (13%) and enamel hypoplasia (20%). In the material examined, the carious process was responsible for pulp exposure to infection in all cases of abscess formation. The results obtained suggest that food processing technology and nature of diet allowed use of abrasive in the food and that oral hygiene was at the low level. On the other hand, there were not a lot of people who were subjected to stress-induced growth disruptures. The findings reported here contribute to understand how dietary change and life conditions are related to the changing patterns of dental diseases in medieval populations.     

创造性人才培养的研究

教育决策过程的思维方式主要是以相应时代科学文化能提供的方法论为基础的。据此，文中阐述了当今时代相适应的创造性人才培养的基本概念、定义、及其内涵。同时分析了我国当务之急培养创造性人才的必要性，研究提出了培养资本家、企业家、策划家、风险投资家4大类型的创造性人才培养的近远期目标，为保证创造性人才培养目标的实现，研究拟出了政府、大专院校、企事业单位应采取的配套措施和策略，供领导及部门参考。     

The inadvertent emergence of a phenomenological perspective in the philosophy of cognitive psychology and psychoanalytic developmental psychology.

The phenomenological perspective described by M. Merleau-Ponty seems to be emerging in the context of contemporary developmental research, theories of communication, metaphor theory, and cognitive neuroscience. This emergence is not always accompanied by reference to Merleau-Ponty, however, or appropriate interpretation. On some cases, the emergence of the perspective seems rather inadvertent. The purpose of this essay is to ferret out some of the points which contemporary thinking has in common with Merleau-Ponty's phenomenology. Though it may appear that the examples chosen for this essay might be scrutinized separately, the thread that ties them together is Merleau-Ponty's work. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

镍铬铸铁的冲蚀磨损行为

利用MCF-30型冲蚀磨损试验机对镍铬铸铁进行冲蚀磨损试验,采用扫描电镜(SEM)、透射电镜(TEM)、XRD技术对其组织和冲蚀磨损后的形貌进行表征,分析了冲蚀角、冲蚀介质酸碱度对其冲蚀磨损性能的影响,总结了其冲蚀磨损规律。结果表明,镍铬铸铁在960℃风淬+250℃回火处理后,Cr与Fe、C形成(Fe,Cr)3C型合金碳化物,呈断续网状分布,起到了抗磨骨架的作用,Ni固溶于铁素体中强化基体;不同冲蚀角下,其冲蚀磨损曲线呈现"M"形,最大冲蚀率出现在60°冲蚀角;强酸对其冲蚀磨损影响较大,当pH≥3的时候,弱酸对其冲蚀磨损量几乎无影响。对其冲蚀磨损机理进行了分析。     

Changes in pulmonary calcitonin gene-related peptide and protein gene product 9.5 innervation in rats infected with Mycoplasma pulmonis

Epithelial-mesenchymal interaction is a prerequisite for tooth morphogenesis. To study this interaction, inner enamel epithelium and dental papilla mesenchyme of molar tooth germs from a 16.5-day mouse embryo were dissociated enzymatically and cultured alone or after recombination. Characteristic matrix protein synthesized and secreted by recombined tooth germ was determined quantitatively by enzyme-linked immunosorbent assay. The protein was detected in the culture of recombined tooth germ but not of dissociated enamel epithelium alone. The amount of enamel protein increased until 8 days in culture. Morphological differentiation of the recombined epithelial rudiment into ameloblasts and enamel protein production were confirmed.     

Dynamic variations in the expression of type I collagen and its molecular chaperone Hsp47 in cells of the mouse dental follicle during tooth eruption

Tooth eruption is a precisely timed and sequenced event that brings the tooth from within bone into a functional position in the mouth. Every part of the developing tooth has been theoretically implicated as a primary factor in this process, but it now appears that eruption is multifactorial, with the dental follicle and type I collagen playing an important part. Immunological probes were used here to investigate in vivo and in vitro the temporal and spatial expression of type I collagen and its molecular chaperone Hsp47 in the dental follicle during eruption. Mandibles were dissected from 2-, 5-, 9- and 11-day-old neonatal mice and fixed in 95% ethanol overnight. Sections of 7 microns were obtained and reacted with antibodies directed against type I collagen. Dental follicles were isolated from 2-, 5-, 9- and 11-day-old neonates and cells were grown in culture for 8 days. Slides were then reacted with antibodies directed against type I collagen and Hsp47. The production of type I collagen and Hsp47 in the follicle varied with the stage of dental development and eruption. There was a progressive decrease of type I collagen in the coronal part of the follicle, leading to an arrest of its production in these areas. These findings support the notion that cells of the coronal portion of the dental follicle stop producing type I collagen as a prerequisite to the initiation of tooth eruption and that this phenotype persists in vitro.     

Contexts of child rearing: Problems and prospects.

Contends that, as yet, child psychology remains a science of development-out-of-context. More is known about children than about the environments in which they live or the ecological conditions that foster psychological growth. On the basis of the limited knowledge available, 4 propositions are offered specifying environmental properties presumed critical to human development. In addition to certain patterns of activity and interpersonal relations occurring within the settings containing the growing child, such conditions include the existence of supportive links between settings—especially between home, school, and work place. The progressive erosion of such links in contemporary American society is seen as contributing to the disorganization of families, schools, and other childrearing settings with consequent disruption of the socialization processes essential to the development of cognitive competence and socially constructive behavior. Research designs for testing the validity of this analysis are suggested. They include experimental strategies for increasing the participation of children and adults in each other's worlds. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Race as Biology Is Fiction, Racism as a Social Problem Is Real: Anthropological and Historical Perspectives on the Social Construction of Race.

Racialized science seeks to explain human population differences in health, intelligence, education, and wealth as the consequence of immutable, biologically based differences between "racial" groups. Recent advances in the sequencing of the human genome and in an understanding of biological correlates of behavior have fueled racialized science, despite evidence that racial groups are not genetically discrete, reliably measured, or scientifically meaningful. Yet even these counterarguments often fail to take into account the origin and history of the idea of race. This article reviews the origins of the concept of race, placing the contemporary discussion of racial differences in an anthropological and historical context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dental innervation and CGRP in adult p75-deficient mice

Adult dental tissues have unusual neurotrophin biology. Pulpal fibroblasts express nerve growth factor (NGF) and the low-affinity p75 neurotrophin receptor, their sensory nerve fibers express p75 and trk A, and pulpal sympathetic fibers lack p75. Following tooth injury, there is increased pulpal NGF, sprouting of sensory nerve endings, and increased immunoreactivity for the sensory neuropeptide calcitonin gene-related peptide (CGRP). In the present study, we have analyzed tooth structure and innervation of pulp and periodontal ligament in young (6-8 weeks, 3 months) and older (5-12 months) adult mice carrying a null mutation in the p75 gene and compared the results with those of age-matched wild-type controls. Our hypotheses were that tooth structure would be abnormal and that pulpal innervation would be greatly reduced because it consists primarily of nociceptive fibers that have been found to be severely depleted in skin of p75(-/-) mice. Tissues were fixed, X-rayed for gross dental morphology, decalcified, and analyzed for immunoreactivity for CGRP and for a general nerve marker, protein gene product 9.5. Radiographs showed worn-down molar crowns in p75-deficient mice. Light microscopy confirmed the accelerated molar wear and showed intense CGRP immunoreactivity in pulp nerve endings of mutant mice, compared with a gradual decrease in CGRP intensity in controls during normal aging. The CGRP intensity in 5-12-month-old pairs of mice was threefold greater in the mutants (P < 0.03), and in younger mice the mutant always had more CGRP than its matched control. The innervation of molar ligament in all p75-deficient mice was similar to that of controls except there was nerve sprouting near bone loss in mutants. The incisors of mutant mice did not have unusual wear and their pulpal CGRP immunoreactivity remained normal, but their periodontal ligament had fewer thin branched nerve endings at all ages. Thus, most innervation of teeth and their supporting tissues developed normally, and the only neural changes in p75(-/-) mutant mice were the reduction of incisor ligament sensory receptors and increased molar CGRP. Sensory nerves in teeth gradually lose neuropeptide intensity during aging, but that did not happen in the mutant mice, suggesting that the accelerated molar wear stimulated persistent high levels of CGRP.     

Dental caries, restoration and tooth conditions in U.S. adults, 1988-1991. Selected findings from the Third National Health and Nutrition Examination Survey

This article provides estimates of dental caries experience and selected restorative and tooth conditions among U.S. adults, obtained from Phase 1 (1988-1991) of the Third National Health and Nutrition Examination Survey. Between 1988 and 1991, 94 percent of adults in the United States showed evidence of past or present coronal caries. Based on the data collected, the authors estimate that about 40.5 percent, or 61.6 million, dentate adults had at least one tooth or tooth space that could potentially benefit from professional treatment. Minimally, it is estimated that 135.6 million tooth or tooth spaces among U.S. adults may benefit from professional treatment. These estimates supplement information available from the DMF index to provide a broader profile of the impact of dental caries on permanent tooth of U.S. adults.     

Crown lengthening: a clinical review

The use of crown lengthening surgery as an adjunct to restorative therapy was first suggested by Rosen and Gitnick. This technique is designed to increase the clinical crown heights of teeth requiring restoration following extensive wear through attrition, abrasion and erosion. This loss of tooth tissue and resulting clinical crown height may be localized to a few teeth or affect the entire dentition. This clinical problem is reflected by the increasing number of reports of treatment of the worn dentition.