Comparison of properties and cost efficiency of zirconia processed by DIW printing, casting and CAD/CAM-milling.

OBJECTIVES: The aim of this study was to evaluate the mechanical properties and cost efficiency of direct ink writing (DIW) printing of two different zirconia inks compared to casting and subtractive manufacturing. METHODS: Zirconia disks were manufactured by DIW printing and the casting process and divided into six subgroups (n = 20) according to sintering temperatures (1350 °C, 1450 °C and 1550 °C) and two different ink compositions (Ink 1, Ink 2). A CAD/CAM-milled high strength zirconia (3Y-TZP) was added as reference group. The biaxial flexural strength (BFS) was measured using the piston-on-three-balls test. X-ray-diffraction (XRD) was used for microstructural analysis. The cost efficiency was compared for DIW printing and subtractive manufacturing by calculation of the manufacturing costs of one dental crown. RESULTS: Using XRD, monoclinic and tetragonal phases were detected for Ink 1, for all other groups no monoclinic phase was detected. The CAD/CAM-milled ceramic showed a significantly higher BFS than all other groups. The BFS of Ink 2 was significantly higher than the BFS of Ink 1. At a sintering temperature of 1550 °C the mean BFS of the printed Ink 2 was 822 ± 174 MPa. The BFS of the cast materials did not show a significantly higher BFS than the corresponding printed group for any tested parameter-set. The manufacturing costs of DIW printed crowns are lower than the manufacturing costs of CAD/CAM-milled crowns. CONCLUSION: DIW has a high potential to replace subtractive processes for dental applications, as it shows promising mechanical properties for appropriate ink compositions and facilitates a highly cost effective production.

"What's a normal weight?" - Origin and receiving country influences on weight-status assessment among 1.5 and 2nd generation immigrant adolescents in Europe.

Many adolescents struggle with adequately assessing their weight-status, often leading to unnecessary weight-related interventions or preventing necessary ones. The prevalence of weight-status over- and underestimation differs considerably cross-nationally, suggesting that individual weight-status assessment is informed by cross-nationally differing standards of evaluation. For adolescents with a migration background, this brings up the possibility of a simultaneous influence of origin- and receiving country standards. The current study examines the magnitude of both influences using data from the 2014 Health Behaviour in School-Aged Children study. The cross-national design of the study enabled us to aggregate weight-evaluation standards for 41, primarily European, countries. Subsequently, we identified a sample of 8 124 adolescents with a migration background whose origin as well as receiving country participated in the study. Among those adolescents, we assessed the effects of origin and receiving country weight-evaluation standards using cross-classified multilevel regression analyses. Descriptive analyses revealed considerable differences in weight-evaluation standards between the countries. Regression analyses showed that both origin- and receiving country weight-evaluation standards were significantly associated cross-sectionally with weight-status assessment among the immigrant adolescents, with a stronger impact of receiving country standards. Results illustrate the context-sensitivity of adolescent weight-status assessment and reinforce the theoretical notion that immigrant adolescent development is not only informed by factors pertaining to their receiving country but also, albeit to a lesser extent, by those pertaining to their origin country.

Intersectionality and Adolescent Mental Well-being: A Cross-Nationally Comparative Analysis of the Interplay Between Immigration Background, Socioeconomic Status and Gender.

PURPOSE: Intersectionality theory highlights the importance of the interplay of multiple social group memberships in shaping individual mental well-being. This article investigates elements of adolescent mental well-being (life dissatisfaction and psychosomatic complaints) from an intersectional perspective. It tests mental well-being consequences of membership in combinations of multiple social groups and examines to what extent such intersectional effects depend on the national context (immigration and integration policies, national-level income, and gender equality). METHODS: Using Multilevel Analysis of Individual Heterogeneity and Discriminatory Accuracy, we assessed the role of the national context in shaping the interplay between immigration background, socioeconomic status, and gender, using data from 33 countries from the 2017/2018 Health Behaviour in School-aged Children survey. RESULTS: We found no uniform intersectionality effects across all countries. However, when allowing the interplay to vary by national context, results did point toward some intersectional effects. Some aggravated negative effects were found for members of multiple disadvantaged social groups in countries with low levels of income equality and restrictive migration policies, whereas enhanced positive effects were found for members of multiple advantaged groups in these countries. Similarly, mitigated negative effects of membership in multiple disadvantaged groups were shown in countries with higher levels of income equality and more inclusive migration policies, whereas mitigated positive effects were found for multiply advantaged individuals. Although for national-level gender equality results pointed in a similar direction, girls' scores were counterintuitive. High national-level gender equality disproportionately benefitted groups of disadvantaged boys, whereas advantaged girls were doing worse than expected, and reversed effects were found for countries with low gender equality. CONCLUSIONS: To fully understand social inequalities in adolescent mental well-being, the interplay between individual-level and national-level indicators must be explored.

School-Class Co-Ethnic and Immigrant Density and Current Smoking among Immigrant Adolescents.

Although the school-class is known to be an important setting for adolescent risk behavior, little is known about how the ethnic composition of a school-class impacts substance use among pupils with a migration background. Moreover, the few existing studies do not distinguish between co-ethnic density (i.e., the share of immigrants belonging to one's own ethnic group) and immigrant density (the share of all immigrants). This is all the more surprising since a high co-ethnic density can be expected to protect against substance use by increasing levels of social support and decreasing acculturative stress, whereas a high immigrant density can be expected to do the opposite by facilitating inter-ethnic conflict and identity threat. This study analyses how co-ethnic density and immigrant density are correlated with smoking among pupils of Portuguese origin in Luxembourg. A multi-level analysis is used to analyze data from the Luxembourg Health Behavior in School-Aged Children study (N = 4268 pupils from 283 classes). High levels of co-ethnic density reduced current smoking. In contrast, high levels of immigrant density increased it. Thus, in research on the health of migrants, the distinction between co-ethnic density and immigrant density should be taken into account, as both may have opposite effects.

Assessment of lipopolysaccharide microleakage at conical implant-abutment connections.

OBJECTIVE: The aim of this in vitro study was to assess lipopolysaccharide microleakage at conical implant-abutment connections of two-piece dental implants in terms of the expression levels of genes involved in lipopolysaccharide-mediated proinflammatory cytokine production. MATERIALS AND METHODS: Two implant systems with conical implant-abutment connections were inoculated with lipopolysaccharide and submerged in human whole blood. Positive-control blood samples (without implants) were stimulated with 4 µg/ml, 2 µg/ml, 200 ng/ml, and 20 ng/ml lipopolysaccharide. Sampling was performed after 1, 8, and 24 h of incubation. Changes of gene expression levels of Toll-like receptor 9, tumor necrosis factor-α, nuclear factor kappa light chain enhancer of activated B cells, interleukin-1ß, and interferon-γ were assessed by real-time quantitative PCR. In addition, protein expression levels of interleukin-6, tumor necrosis factor-α, interleukin-1ß, and interferon-γ were determined by immunoassay. RESULTS: Changes in cytokine expression at the genomic and proteomic levels indicated lipopolysaccharide leakage at the interfaces of both tested implant systems, although some implants showed no sign of microleakage. Any tested concentration of lipopolysaccharide stimulated similar gene expression. CONCLUSIONS: Conical implant-abutment connections of two-piece dental implants do not prevent microleakage on a molecular level. Changes in lipopolysaccharide-induced proinflammatory cytokine gene expression facilitate the detection of lipopolysaccharide microleakage at implant-abutment interfaces. CLINICAL RELEVANCE: Small amounts of lipopolysaccharide released from intra-implant cavities can stimulate a detectable immunological response in human whole blood and may induce alveolar bone resorption via the osteoclast-activating pathway.

General well-being as an important co-factor of self-assessment of dental appearance.

PURPOSE: This study aimed to correlate the general well-being of patients and their judgment about their dental appearance. MATERIALS AND METHODS: Based on internationally accepted guidelines regarding dental esthetics, a questionnaire was developed to measure subjective assessments of dental appearance. Fourteen items defined an esthetic sum score (0 = satisfied; 56 = dissatisfied). Further, general well-being was evaluated with a long-established and highly reliable test. Eighty participants were included (47 women, 33 men). Participants were.drawn from 4 different groups (n = 20): natural dentition (group N), fixed partial dentures (group F), removable partial dentures (group R), and patients who had an esthetic problem with their teeth (group P). RESULTS: Seventy-five participants showed a normal well-being. Five participants showed a depressive state and formed a new group (group D). The medians of the sum scores (25th, 75th percentile) were: group N: 12 (10, 14); group F: 14 (8, 29); group R: 14 (9, 27); group P: 23 (18, 35); group D: 30 (26, 35). Significant differences were found between groups N and P, as well as between group D and groups N, F, and R. CONCLUSION: Because of the significant difference between groups N and P, basis validation of the sum score was achieved. Further, self-assessments of dental appearance appeared to be more negative for participants with a depressive state compared with the other groups. In clinical studies, selection bias can be prevented by using a test that measures well-being to verify if a study sample includes a normal number of depressive subjects and therefore represents the general population.

Assessment of dental appearance following changes in incisor proportions.

This study aimed to evaluate the assessment of attractiveness of standardized changes in incisor proportions. Two original photographs, showing the maxillary anterior teeth in the frame of a smile, were computer-manipulated. From the so-produced symmetrical 'golden standard' images, two sets were constructed. Each set contained one golden standard image and seven images with different standardized changes concerning (i) width-to-length ratios of the central incisors (60-96%) and (ii) tooth-to-tooth proportions between the widths of lateral and central incisors (43-87%). The judges, consisting of three groups of individuals (24 dentists, 24 medical students, and 179 patients), ranked each photo set for attractiveness on a visual analogue scale. The width-to-length ratios were assessed as most attractive within a range of 75-85% (medical students, patients) or 75-80% (dentists), respectively. The tooth-to-tooth proportions showed the best results concerning attractive appearance within a range of 50-74% (medical students, patients) or 56-68% (dentists), respectively. No significant differences between the participant groups were found except for some extreme variations. It was concluded that a most attractive 'golden range' could be identified for both the width-to-length ratios and the tooth-to-tooth proportions of the maxillary incisors.

Assessment of dental appearance following changes in incisor angulation.

PURPOSE: This study evaluated the assessment of attractiveness of standardized changes in incisor angulation of different tooth arrangements. MATERIALS AND METHODS: Four sets of images showing the maxillary anterior teeth without lips against a black background were used for evaluation. Each set contained the original photograph, one computer-manipulated symmetric image, and four images with different standardized changes in incisor angulation (10 degrees). The judges, consisting of three groups (30 dental students, 30 medical students, 30 art students), ranked each photo set for attractiveness from 1 (most attractive) to 6 (most unattractive). RESULTS: The mean ranking (in parentheses) showed that symmetric teeth with ideal axes (2.5) and changes in the angulation of one (2.8) or both (2.5) lateral incisors were significantly more attractive than the angulation of one (4.2) or both (4.6) central incisors. There were no differences between the groups of participants. All findings were reproducible. CONCLUSION: Tooth arrangements showing central incisors with ideal axes were more attractive. Slight changes in the angulation of one or both lateral incisors did not influence attractiveness negatively.