RESUMO
PURPOSE: The aim of this study was to compare the effect of different finishing and polishing techniques on water absorption, water solubility, and microhardness of ceramic or glass-polymer based computer-aided design and computer-aided manufacturing (CAD/CAM) materials following thermocycling. MATERIALS AND METHODS: 150 disc-shaped specimens were prepared from three different hybrid materials and divided into five subgroups according to the applied surface polishing techniques. All specimens were subjected up to #4000 grit SiC paper grinding. No additional polishing has been done to the control group (Group I). Other polishing procedures were as follows: Group II: two-stage diamond impregnated polishing discs; Group III: yellow colored rubber based silicone discs; Group IV: diamond polishing paste; and Group V: Aluminum oxide polishing discs. Subsequently, 5000-cycles of thermocycling were applied. The analyses were conducted after 24 hours, 7 days, and 30 days of water immersion. Water absorption and water solubility results were analyzed by two-way ANOVA and Tukey post-hoc tests. Besides, microhardness data were compared by Kruskal-Wallis and Mann-Whitney U tests (P.05). CONCLUSION: Surface finishing and polishing procedures might negatively affect physical properties of hybrid ceramic materials. Nevertheless, immersion periods do not affect the microhardness of the materials. Final polishing by using diamond polishing paste can be recommended for all CAD/CAM materials.
Assuntos
Absorção , Óxido de Alumínio , Cerâmica , Desenho Assistido por Computador , Polimento Dentário , Diamante , Imersão , Borracha , Silício , Silicones , Solubilidade , ÁguaRESUMO
An electrolyte cathode atmospheric glow discharge atomic emission spectroscopy(ELCAD-AES) has been developed to determine the hardness of water. By the standard curves of Mg and Ca, the concentration curves of Mg and Ca measurement were obtained. The limits of detection of Mg and Ca were 0.2 and 0.8 mg/L, respectively. The precision and recovery were experimentally elucidated, which indicated that the homemade ELCAD-AES system has a good performance. Finally, practical water samples such as tap water, boiled tap water, ground water, boiled ground water and lake water were analyzed by the method. The results were in agreement with those by the EDTA titration. This demonstrates that ELCAD-AES has the capacity for on-line determination of water hardness.
RESUMO
OBJETIVO: Estudiar la asociación entre la prevalencia de eczema atópico (EA) y la dureza del agua de uso doméstico. MATERIAL Y MÉTODOS: El estudio ISAAC (International Study of Asthma and Allergies in Childhood) estimó la prevalencia de EA en seis localidades de Castellón, España, en escolares de 6-7 y 13-14 años durante 2002. Se establecieron tres zonas de <200 mg/l, 200-250 mg/l, y >300 mg/l según la dureza del agua doméstica de esas localidades. Se empleo regresión logística en el análisis. RESULTADOS: En escolares de 6-7 años, las prevalencias acumuladas de EA en las tres zonas fueron de 28.6, 30.5 y 36.5 por ciento. Entre la zona 1 y la zona 3, la razón de momios ajustada (RMa) fue 1.58 (IC 95 por ciento 1.04-2.39) (prueba de tendencia ajustada p=0.034). La prevalencias de síntomas de EA en el último año fueron de 4.7, 4.5, y 10.4 por ciento, respectivamente. Entre la zona 1 y la zona 3, la (RMa) fue 2.29 (IC95 por ciento 1.19-4.42) (prueba de tendencia ajustada p=0.163). En escolares de 13-14 años no se apreciaron tendencias significativas. CONCLUSIONES: Se sugiere que la dureza del agua podría tener alguna importancia en el desarrollo de la enfermedad en los escolares de 6-7 años.
Water hardness has been associated with atopic eczema (AE) prevalence in two epidemiologic studies carried out on schoolchildren in England and Japan. OBJECTIVE: To estimate the association between the prevalence of AE and domestic water hardness. METHODS: The prevalence of AE was obtained from The International Study of Asthma and Allergies in Childhood, carried out in six towns in the province of Castellón on schoolchildren 6-7 and 13-14 years of age, using a standard questionnaire in 2002. Three zones were defined according to domestic water hardness of the six study localities: <200 mg/l, 200-250 mg/l, and >300 mg/l. A logistic regression analysis was performed. RESULTS: The lifetime prevalence of AE in schoolchildren 6-7 years of age was higher with the increment of water hardness, 28.6, 30.5 and 36.5 percent respectively for each zone; between zone 1 and zone 3, the adjusted odds ratios (ORa) were 1.58 (95 percent Confidence Intervals [CI] 1.04-2.39) (adjusted tendency test p=0.034). Prevalence of symptoms of AE within the past year were 4.7, 4.5, and 10.4 percent, respectively by zone; between zone 1 and zone 3, the ORa was 2.29 (95 percent CI 1.19-4.42) (adjusted tendency test p=0,163). For 13-14 year-old schoolchildren, tendencies to lifetime prevalence of AE at any time or in the past year were not significant. CONCLUSIONS: This study suggests that in 6-7 year-old schoolchildren, water hardness in the area where they live has some relevance to the development of the disease.