The world now pushes for a low-carbon future, and international goals for greenhouse gas emission reductions have been set. Industrial processes, including metallurgical processes, make up more than ...a fifth of the total global emissions, and those have been rising with infrastructure development and the expansion of the middle-class worldwide. This paper focuses on two energy-intensive processes, aluminum production and metallurgical grade silicon production, and how the carbon footprints from these industrial processes have developed in recent decades. The main trend is that the increased demand for these metals has led to expanding primary production for both of them, based on energy with an increasing share of fossil-based electric power. In fact, the average carbon footprint of the energy used in aluminum and silicon production has increased by 38% and 43%, respectively, from 2000 to 2019. The change in energy mix offsets any progress in process efficiencies. This work addresses this and discusses opportunities for improvements.
Graphical Abstract
In this study, we examined the prevalence of specific (dental) phobia among a sample of the Icelandic population. In addition to dental anxiety we explored factors that could be related to dental ...anxiety. In the period 1972-73, a stratified sample of 1641 schoolchildren in Reykjavík was selected for a study on malocclusion, dental maturation and other factors. Twenty-two years later (1995), a postal survey conducted in this group looked at many variables relating to oral health, including orofacial pain, functional oral disorders, self-perception of dental and general appearance and need for orthodontic treatment. Out of 1529 individuals contacted, 1192 completed questionnaires were returned (response rate 78%). Questions based on DSM-IV criteria of specific (dental) phobia (DP) were included. Ninety-six participants reported that they had avoided dental treatment during the previous 6 months. Twenty-one respondents fulfilled DSM-IV criteria for specific (dental) phobia (DP) and 75 admitted to many symptoms of dental anxiety (DA). Specific (dental) phobia (DP) was more prevalent among women than among men. The divorced or widowed were most at risk, as were non-salaried respondents. Most respondents attributed the onset of their phobias to a specific painful or fearful experience. There was a significant difference between the total dentally anxious (TDA = DA+DP) and the not dentally anxious (NDA) with regard to sex (women-higher TDA) and marital status (divorced or widowed-higher TDA). The TDA had statistically fewer teeth than the NDA and received dental treatment less frequently.
Introduction The purposes of this study were to analyze long-term changes in malocclusion traits and to compare the development in orthodontically treated and untreated subjects. Methods The sample ...comprised 308 adolescents in the intermediate, late mixed, or early permanent dentition who were examined clinically at the ages of 8 to 17 years and again 25 years later. The treated subgroup of 58 subjects had received orthodontic treatment with fixed or removable appliances or both. All subjects had a full complement of teeth, except a subgroup of 19 who had premolar extractions as a part of their orthodontic treatment plan. Results The prevalence of maxillary overjet was significantly reduced in the untreated group and the treated subgroups. The prevalence of distal molar occlusion was significantly reduced in the subgroup treated without extractions. Comparison of treated and untreated groups in terms of changes over time showed that development was significantly more favorable in all treatment categories regarding maxillary overjet, and in the nonextraction category regarding distal molar occlusion. Subjects treated without extractions had less favorable development than did untreated subjects regarding molar crossbite. Conclusions The long-term benefit of orthodontic treatment, with or without extractions, was confirmed regarding maxillary overjet, and the lasting effect of nonextraction treatment was confirmed regarding the distal molar relationship. The pattern of changes in treated and untreated subjects indicated that long-term development and individual variation can to some extent conceal the effects of a brief orthodontic intervention.
Objective: The purpose of the study was to estimate the heritability of different cephalometric parameters, according to lateral cephalograms, between parents and their offspring in an Icelandic ...population.
Methods: The material was collected at the Faculty of Odontology, University of Iceland. The subjects were 363 children (6 years of age) and their parents. Material was also collected from the same group of children at the age of 16 years. Twenty-two reference points were identified on each cephalogram, and 33 variables were calculated, both angular and linear. Heritability was calculated at ages 6 and 16.
Results: Daughters had more variables that reached the level of significance than did sons. Daughters showed similar heritability to both parents at both age levels, but more variables were highly significant (
P ≤ .001) in the daughter-father groups. Sons showed stronger heritability to their mothers at both ages. The variables showing the greatest heritability were those representing the position of the lower jaw, the anterior and posterior face heights, and the cranial base dimensions. Heritability was notably low for the dental variables.
Conclusions: Genetic aberrations can be detected for complex polygenetic multifactorial traits. Cephalometric data can support predictions, and analysis of parental data could have predictive value for offspring.
The aim of the present study was to describe the craniofacial changes between 6 and 16 years of age in a sample of Icelandic children. Complete sets of lateral cephalometric radiographs were ...available from 95 males and 87 females. Twenty-two reference points were digitized and processed by standard methods, using the Dentofacial Planner® computer software program. Thirty-three angular and linear variables were calculated, including: basal sagittal and vertical measurements, facial ratio, and dental, cranial base and mandibular measurements. For the angular measurements, gender differences were not statistically different for any of the measurements, in either age group, except for the variable s–n–na, which was larger in the 16-year-old boys (P ≤ 0.001). Linear variables were consistently larger in the boys compared with the girls at both age levels. During the observation period mandibular prognathism increased but the basal sagittal jaw relationship, the jaw angle, the mandibular plane angle and cranial base flexure (n–s–ba) decreased in both genders (P ≤ 0.001). Maxillary prognathism increased only in the boys from 6 to 16 years. Inclination of the lower incisors and all the cranial base dimensions increased in both genders during the observation period. When the Icelandic sample was compared with a similar Norwegian sample, small differences could be noted in the maxillary prognathism, mandibular plane angle and in the inclination of the maxilla. Larger differences were identified in the inclination of the lower incisors. These findings could be used as normative cephalometric standards for 6- and 16-year-old Icelandic children.
Introduction The objectives of this study were to record the extent of orthodontic treatment and the prevalence of occlusal anomalies in an adult sample in Iceland. Methods The study was based on a ...random sample of 829 subjects, 342 men and 487 women, aged 31 to 44 years, who completed questionnaires about their orthodontic treatment experiences and were available for clinical examination. Results Complete dentitions in both jaws were present in 52.8% of the women and 45.3% of the men at the examinations. Significantly higher percentages of the women had received orthodontic treatment of some kind (24.3% compared with 16.9% for the men) and treatment with fixed appliances (16.0% compared with 9.5% for the men). Malocclusion traits were recorded with a standardized method, describing sagittal and vertical incisor relationships, sagittal and transverse molar relationships, and mandibular and maxillary space conditions. The results showed that 45.5% of the subjects had no malocclusions, 33.9% had 1 malocclusion trait, and 20.5% had 2 to 4 traits. The most frequent malocclusion traits were distal molar occlusion (27.7%), mandibular anterior crowding (13.4%), molar crossbite (11.9%), excessive overbite (11.8%), maxillary anterior crowding (7.1%), mesial molar occlusion (6.9%), and excessive overjet (5.3%). The prevalences of mandibular overjet, mesial occlusion, and scissors-bite were significantly higher in the men than in the women. Conclusions The prevalences of malocclusion traits were similar in treated and untreated subjects, except for a significantly lower prevalence of overjet and a higher prevalence of molar crossbite in the treated group. Comparison with other studies showed low prevalences of overjet, overbite, open bite, and maxillary and mandibular spacing and crowding; other variables fell within the ranges of prevalence in previous surveys.
Introduction The purposes of this study were to analyze long-term changes in anterior spacing and crowding and to compare the development in orthodontically treated and untreated subjects. Methods ...The sample comprised 308 adolescents in the late mixed or early permanent dentition who were examined clinically at the ages of 7 to 17 years and again 25 years later. The treated subgroup of 58 subjects had received orthodontic treatment with fixed or removable appliances or both. All subjects had a full complement of teeth, except for 19 who had premolar extractions as part of their orthodontic treatment plan. Results The prevalence of maxillary anterior spacing was substantially and significantly reduced in both the untreated and treated groups from the first examination to the second. The prevalence of mandibular crowding increased significantly in the untreated and the nonextraction treated groups. The prevalence of mandibular crowding in patients treated without extractions increased by 25.6%, significantly more than in the untreated controls. The prevalence of maxillary crowding decreased by 15.8% in patients treated with maxillary premolar extractions, significantly more than in the untreated controls. Conclusions Long-lasting developmental factors seem to result in universally reduced maxillary anterior spacing, orthodontic treatment notwithstanding. Compared with untreated subjects, the long-term development of mandibular anterior crowding was unfavorable in subjects treated without extractions. Compared with untreated subjects, the long-term development of maxillary anterior crowding was favorable when treatment included extraction of the maxillary premolars.
Editor's Comment and Q&A Jonsson, Teitur; Magnusson, Thordur Eydal
American journal of orthodontics and dentofacial orthopedics,
October 2010, Letnik:
138, Številka:
4
Journal Article
Recenzirano
Introduction The purposes of this study were to analyze long-term changes in anterior spacing and crowding and to compare the development in orthodontically treated and untreated subjects. Methods ...The sample comprised 308 adolescents in the late mixed or early permanent dentition who were examined clinically at the ages of 7 to 17 years and again 25 years later. The treated subgroup of 58 subjects had received orthodontic treatment with fixed or removable appliances or both. All subjects had a full complement of teeth, except for 19 who had premolar extractions as part of their orthodontic treatment plan. Results The prevalence of maxillary anterior spacing was substantially and significantly reduced in both the untreated and treated groups from the first examination to the second. The prevalence of mandibular crowding increased significantly in the untreated and the nonextraction treated groups. The prevalence of mandibular crowding in patients treated without extractions increased by 25.6%, significantly more than in the untreated controls. The prevalence of maxillary crowding decreased by 15.8% in patients treated with maxillary premolar extractions, significantly more than in the untreated controls. Conclusions Long-lasting developmental factors seem to result in universally reduced maxillary anterior spacing, orthodontic treatment notwithstanding. Compared with untreated subjects, the long-term development of mandibular anterior crowding was unfavorable in subjects treated without extractions. Compared with untreated subjects, the long-term development of maxillary anterior crowding was favorable when treatment included extraction of the maxillary premolars.
The purpose of the study was to describe the craniofacial characteristics of Icelandic adults on lateral skull cephalograms. The material consisted of 155 (47.8%) males and 169 (52.5%) females. The ...mean ages were 35.5 and 34.2 years, respectively. Twenty-two skeletal reference points and 11 soft tissue points were digitized and processed by standard methods with the Dentofacial Planner® computer software program. The 45 variables calculated were both angular and linear. Two-sample t-tests were used to study the differences between sexes. Mandibular prognathism was significantly greater in males (P ≤ 0.05), but the inclination of both the upper and lower jaws was greater in females (P ≤ 0.01). Linear measurements were usually larger for males. The lips were less protrusive in males (P ≤ 0.01), but the thickness was greater compared with females (P ≤ 0.001). The nose was significantly more protrusive in males (P ≤ 0.001). When the Icelandic sample was compared with closely related ethnic groups, such as the Swedes and the Danes, it was interesting to note that the Icelanders seem to be more like the Swedes than the Danes.
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