Influence of Chemical Degradation and Toothbrushing on Surface of Composites

Objective: The aim of this study was to evaluate the effect of chemical degradation media associated with brushing on surface roughness (Ra) and Knoop microhardness (KHN) analyses of different composites. Materials and methods: Eighty specimens were prepared for each composite: GrandioSO (Voco), Amaris (Voco), Filtek Supreme (3M ESPE), Filtek LS (3M ESPE). The specimens were divided into four groups according to the immersion in chemical degradation media for 7 days: artificial saliva (control), heptane, 0.02 M citric acid, 70% ethanol. The surface of specimens was submitted to 10950 brushing cycles (200 gm load) in an automatic toothbrushing machine with abrasive slurry. Surface roughness and microhardness measurements were obtained at baseline, after immersion in chemical degradation media and after brushing. Data were submitted to three-way repeated measures ANOVA and Tukey’s test (p < 0.05). Results: The KHN means for composites were: Grandio (153.5± 35.9)a, Filtek Supreme (87.0 ± 24.9)b, Amaris (64.5 ± 24.5)c, LS (69.0 ± 15.3)c; for storage media: artificial saliva (97.3 ± 46.7)a, ethanol (93.3 ± 49.9)a, citric acid (95.8 ± 42.1)a, heptane (87.6 ± 36.7)b; and after treatments: after chemical degradation (104.8 ± 49.7)a, baseline (93.8 ± 42.5)b, after brushing (81.9 ± 36.5)c. The Ra results for composites were: LS (0.15 ± 0.25)a, GrandioSO (0.19 ± 0.24)ab, Filtek Supreme (0.20 ± 0.22)ab, Amaris (0.23 ± 0.37)b; for storage media: artificial saliva (0.18 ± 0.31)a, heptane (0.18 ± 0.25)a, ethanol (0.20 ± 0.26)a, citric acid (0.21 ± 0.28)a, and after treatments: brushing (0.11 ± 0.14)a, after chemical degradation (0.23 ± 0.32)b, baseline (0.24 ± 0.32)b. Conclusion: Brushing after chemical degradation reduced surface roughness values. In general, chemical degradation did not affect composites roughness, but microhardness was significantly reduced. Heptane produced the biggest reduction in composites microhardness. Clinical relevance: The food-simulating solutions and brushing simulating alter the composites properties, and these alterations are material-dependent.Department of Restorative Dentistry Institute of Science and Technology Universidade Estadual PaulistaDepartment of Restorative Dentistry Institute of Science and Technology Universidade Estadual Paulist

Winds of change: engaging with conflicting perspectives in renewable energy

This study examines public attitudes towards climate change and policies to limit greenhouse gases such as through the expansion of renewable energy sources. The study includes a critical examination of the apparent contradiction between belief in climate change and generalized support for renewable energy, as revealed in this survey, and of opposition to the placement of large-scale renewable energy generators such as wind farms. The literature identifies significant psychogenic influences leading to opposition to specific wind farm sitting as well as strong policy support for coal mining in Australia, but these appear to be ignored or dismissed by environmentalists, leading to ineffective communication on the issues and, ultimately, to entrenched opposition to an energy transition. We use social marketing benchmarks to identify engagement strategies that may increase understanding of the need to reduce fossil fuel consumption, alleviate anxiety about wind farm impacts and improve acceptance of renewable energy generation strategies overall

Staining Beverages and Cigarette Smoke on Composite Resin and Human Tooth Fluorescence by Direct Spectrometry

Introduction: This study evaluated the fluorescence intensity (FI) of different brands of composite resins (CRs) and compare those values with the FI of human tooth, under the action of cigarette smoke (CI), coffee (CA), and soft drink (CO), measured by direct spectrometry. Materials and methods: A total of 30 specimens of each brand (Filtek Z350, Esthet-X, Amelogen, Durafill) were made. Others 30 tooth specimens (3 mm/diameter) were obtained from human molars using a trephine bur. The specimens were randomly divided into three groups (n = 10), according to substances: CI, CA, CO. The FI was directly measured using an optic fiber associated with a spectrometer and was measured at baseline and after staining. Data were submitted to Kruskal-Wallis, Dunnett, and Dunn tests. Results: Staining influenced FI mean values among CRs and between those with human tooth. Z showed the closest FI mean values of tooth after staining. Conclusion: Staining beverages and cigarette smoke negatively influenced on FI of CR and human tooth. Clinical significance: The study shows darkening treatments influenced on the fluorescent property of the dental tissues and restorative materials according to the direct spectrometry analysis.Department of Restorative Dentistry Institute of Science and Technology São Paulo State University - UNESP, São José dos CamposDepartment of Biophotonics Institute of Biomedical Engineering University Anhembi Morumbi, São José dos CamposDepartment of Restorative Dentistry Institute of Science and Technology São Paulo State University - UNESP, São José dos Campo