Copper deficit as a potential pathogenic factor of reduced bone mineral density and severe tooth wear

SUMMARY: The study evaluated if men and women with severe tooth wear were at increased risk of general bone loss. Enamel biopsies obtained from 50 subjects aged 47.5 ± 5 years showed decreased copper content, which was associated with reduced spine bone mineral density, suggesting deficits of this trace element contributing to bone demineralization, enamel attrition, and deteriorated quality of mineralized tissues. INTRODUCTION: The objective of this cross-sectional study was to assess associations between enamel trace minerals and bone mineral density (BMD) in severe tooth wear. We hypothesized that similar factors contributed to both the excessive abrasion of dental enamel and reduced BMD in subjects with tooth wear. METHODS: Fifty patients aged 47.5 ± 5 years with severe tooth wear and 20 age-, sex-, and body mass index (BMI)-matched healthy volunteers with normal dental status were studied regarding dietary intakes of trace elements, serum and salivary copper (Cu), zinc (Zn), and calcium (Ca) concentrations, and serum PTH, osteocalcin, and hydroxyvitamin D levels. Tooth wear was determined using clinical examination based on standard protocol according to Smith and Knight. In all subjects, acid biopsies of the maxillary central incisors were carried out to assess mineral composition of the enamel. Atomic absorption spectroscopy with an air/acetylene flame was used to measure Ca and Zn, and graphite furnace atomic absorption spectroscopy was used to analyze Cu content. BMD was examined using dual energy X-ray absorptiometry. RESULTS: Tooth wear patients had reduced lumbar spine, but not femoral, BMD relative to controls (p < 0.001). No differences were found in enamel Ca concentration and Zn content was slightly higher in tooth wear patients than in controls whereas Cu content was significantly decreased in the patients: 19.59 ± 16.4 vs 36.86 ± 26.1 μg/l (p = 0.01) despite similar levels of Cu in serum and saliva. The differences were independent of serum 25-OH-D, osteocalcin concentrations or PTH either. CONCLUSION: Severe tooth wear is associated with reduced spinal BMD. Enamel in adult individuals with severe tooth wear is low in copper content. Therefore, further work is needed to determine whether copper plays a role in bone pathophysiology in these patients

Relationship Between Masticatory Efficiency and Occlusal Parameters Established in T-Scan II System

The aim of this investigation was to establish possible correlation between parameters of occlusion and masticatory efficiency. MATERIAL: Data were obtained in 15 healthy persons, 23-31 years of age (mean 25 years) with correct own dentition and without any disturbances of the stomatognathic system. METHODS: Masticatory efficiency was measured using Optosil test modified by Slagter et al. after 20 and 80 cycles of chewing. It the time of chewing for 20 and 80 cycles of chewing was also established. Analysis of occlusion was made using T-scan II computerized system. Registration of occlusion was obtained before measuring masticatory efficiency after 20 and 80 cycles of chewing. Statistical analysis was made and p<0.05 was statistically significant. RESULTS: The time of chewing for 20 cycles and for 80 cycles respectively, mean 16 s +/- 3.0, and 55.6s +/- 9.5) reduction of particle size was about 1.5 mm. Time to maximal force ofpressure was shorter when chewing was longer. Maximal force of pressure for a unit of deflection indicator surface was higher after chewing. Share of sides of the teeth arch was about 59 per cent in all measurements. Maximal force of pressure for a unit of deflection indicator surface was correlated with the time of chewing for 20 cycles of chewing (p <0.05). Correlation of time from the first contact of teeth to maximal force of pressure and maximal force of pressure for a unit of deflection indicator surface was statistically significant for 80 cycles . There was no evident correlation between values of X50 and occlusal parameters established in computerizedanalysis. CONCLUSION: Chewing ability is correla ted with occlusion although this relationship is not significant

Justifications-on-demand as a device to promote shifts of attention associated with relational thinking in elementary arithmetic

Student responses to arithmetical questions that can be solved by using arithmetical structure can serve to reveal the extent and nature of relational, as opposed to computational thinking. Here, student responses to probes which require them to justify-on-demand are analysed using a conceptual framework which highlights distinctions between different forms of attention. We analyse a number of actions observed in students in terms of forms of attention and shifts between them: in the short-term (in the moment), medium-term (over several tasks), and long-term (over a year). The main factors conditioning students´ attention and its movement are identified and some didactical consequences are proposed

Competences of Mathematics Teachers in Diagnosing Teaching Situations and Offering Feedback to Students:Specificity, Consistency and Reification of Pedagogical and Mathematical Discourses

In the study we report in this chapter, we investigate the competences of mathematics pre- and in-service teachers in diagnosing situations pertaining to mathematics teaching and in offering feedback to the students at the heart of said situations. To this aim we deploy a research design that involves engaging teachers with situation-specific tasks in which we invite participants to: solve a mathematical problem; examine a (fictional yet research-informed) solution proposed by a student in class and a (fictional yet research-informed) teacher response to the student; and, describe the approach they themselves would adopt in this classroom situation. Participants were 23 mathematics graduates enrolled in a post-graduate mathematics education programme, many already in-service teachers. They responded to a task that involved debating the identification of a tangent line at an inflection point of a cubic function through resorting to the formal definition of tangency or the function graph. Analysis of their written responses to the task revealed a great variation in the participants’ diagnosing and addressing of teaching issues – in this case involving the role of visualisation in mathematical reasoning. We describe this variation in terms of a typology of four interrelated characteristics that emerged from the data analysis: consistency between stated beliefs/knowledge and intended practice, specificity of the response to the given classroom situation, reification of pedagogical discourses, and reification of mathematical discourses. We propose that deploying the theoretical construct of these characteristics in tandem with our situation-specific task design can contribute towards the identification – as well as reflection upon and development – of mathematics teachers’ diagnostic competences in teacher education and professional development programmes

The evaluation of zinc and copper content in tooth enamel without any pathological changes &ndash; an in vitro study

Elzbieta Klimuszko,1 Karolina Orywal,2 Teresa Sierpinska,1 Jarosław Sidun,3 Maria Golebiewska1 1Department of Prosthetic Dentistry, Medical University of Bialystok, Bialystok, Poland; 2Laboratory of Biochemical Diagnostics Department, Medical University of Bialystok, Bialystok, Poland; 3Department of Materials Science and Biomedical Engineering, Bialystok University of Technology, Bialystok, Poland Objectives: The objectives of the study were to evaluate the content of copper and zinc in individual layers of tooth enamel and to analyze the relationships between the study minerals in individual layers of tooth enamel. Patients and methods: Fifteen human permanent teeth were cut off every 150 &micro;m alongside the labial surface. Acid biopsy of each layer was performed. The zinc content was determined using the air&ndash;acetylene flame method. The copper content was determined using the electrothermal technique with argon. Results: The mean zinc concentrations increased significantly starting from the outer enamel surface, with the maximum concentration in the 150&ndash;300 &micro;m layer. The mean copper concentrations increased substantially from the outer enamel surface to a depth of 150 &micro;m, and then a slight downward trend of this mineral levels was seen, down to a depth of 450 &micro;m. Strong positive correlation was found between the zinc and copper concentrations at depths of 150&ndash;300, 450&ndash;600 and 600&ndash;750 &micro;m. Conclusion: The levels of zinc and copper in the outer enamel layers may have an effect on the increased content of unipolar minerals at deeper enamel layers. The content of the study elements determined may reflect the process of mineralization and maturation of enamel in the pre-eruption period. Keywords: zinc, copper, ename

Proofs, Semiotics and Artefacts of Information Technologies

Abstract. Recently, as part of a larger research project, we carried out a long-term teaching experiment in the 9th and 10th grades of a scientific high school. Assuming a Vygotskian perspective, we focused on the social construction of knowledge and on semiotic mediation as accomplished by the teacher through the use of cultural artefacts. This paper discusses on some results from the teaching experiment with the aim of clarifying the role of information technologies in introducing students to a theoretical perspective. The first part of the paper is devoted to introduce the construct of semiotic potential of an artefact. This construct is part of a model that was developed as result of the teaching experiment. Such a model aimed to describe the functioning of semiotic mediation in teaching – learning processes centred on the use of an artefact. The second part is devoted to discuss two examples concerning the use of two different artefacts. The first example addresses the issue of identifying the semiotic potential of a particular dynamic geometry environment, Cabri. The second example addresses the issue of designing a particular artefact as a tool of semiotic mediation with the specific educational goal of developing the idea of Algebra Theory. In both case I will discuss on the common feature of exploiting the semiotic potential of computer-based environments