Análise da superfície de cerâmicas vítreas polidas ou glazeadas submetidas a soluções ácidas na presença ou não da película adquirida.
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Data
2018-08-31
Autores
Gonçalves, Silvio César [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste estudo foi analisar as características de superfície da cerâmica vítrea de dissilicato de lítio com diferentes acabamentos de superfície (glaze e polimento manual mecânico) submetidas a soluções ácidas (ácido cítrico e ácido fosfórico) e armazenadas em água ou saliva humana. As superfícies foram analisadas utilizando a energia livre de superfície, rugosidade, dureza e microscopia eletrônica de varredura. Foram utilizadas pastilhas de cerâmica vítrea de dissilicato de lítio, do sistema prensado, dos quais foram obtidas amostras com 6 mm x 4 mm x 2mm (n=120). Os grupos experimentais foram divididos de acordo com o acabamento das cerâmicas (polida ou glaze), desafio (água, ácido cítrico e ácido fosfórico) e meio de armazenamento (água deionizada ou saliva humana). Foram realizados ciclos de 21 dias onde as cerâmicas permaneciam 4 horas na solução de desafio e 20 horas no meio de armazenamento, sendo renovados diariamente. Os dados foram submetidos a ANOVA a 3 critérios seguidos pelo teste de Student-Newman-Keuls. Houve rugosidade maior com o acabamento glaze (p<0,001) e o desafio com ácido fosfórico levou a menor rugosidade (p<0,003). A dureza foi maior para as cerâmicas com glaze e menor quando submetida ao ácido cítrico (p=0,536). A superfície da cerâmica glazeada apresentou maior valor de energia livre (p<0,007), porém nos desafios ácidos armazenados em saliva, o componente doador de elétrons em ambos os desafios, apresentaram menores valores (p=0,148). Concluiu-se que a cerâmica glazeada apresentou maior rugosidade, dureza e energia de superfície do que a cerâmica polida, e os desafios ácidos e meio de armazenamento influenciaram estas variáveis, principalmente nas cerâmicas polidas.
Abstrac : The objective of this study was to analyze the surface characteristics of vitreous ceramics of lithium disilicate with different surface finishes (glaze and mechanical manual polishing) submitted to acid solutions (citric acid and phosphoric acid) and stor ed in human water or saliva. The surfaces were analyzed using surface free energy, roughness, hardness and scanning electron microscopy. Lithium disilicate vitreous ceramic tablets were used, from which the samples were obtained with 6 mm x 4 mm x 2 mm (n= 120). The experimental groups were divided according to the finishing of the ceramics (polished or glaze), challenge (water, citric acid and phosphoric acid) and storage medium ( deionized water or human saliva). Twenty - one day cycles were performed where t he ceramics remained 4 hours in the challenge solution and 20 hours in the storage medium, being renewed daily. Data were submitted to ANOVA at 3 criteria followed by the Student - Newman - Keuls test. T here was greater rou ghness with the glaze finish (p <0.001 ) and the challenge with phosphoric acid led to the least roughness (p <0.00 3 ). Hardness was higher for ceramics with glaze and lower wh en submitted to citric acid (p = 0.536). Th e glaze ceramic surface presen ted higher free energy value (p <0.007), but in the acidic challenges stored in saliva, the electron donor component in both challeng es presented lower values (p = 0.148). It was con cluded that the glazed ceramics presented higher roughness, hardness and surface energy than the polished ceramics, and the a cidic challenges and storage medium influenced these variables, especially in the polished ceramics.
Abstrac : The objective of this study was to analyze the surface characteristics of vitreous ceramics of lithium disilicate with different surface finishes (glaze and mechanical manual polishing) submitted to acid solutions (citric acid and phosphoric acid) and stor ed in human water or saliva. The surfaces were analyzed using surface free energy, roughness, hardness and scanning electron microscopy. Lithium disilicate vitreous ceramic tablets were used, from which the samples were obtained with 6 mm x 4 mm x 2 mm (n= 120). The experimental groups were divided according to the finishing of the ceramics (polished or glaze), challenge (water, citric acid and phosphoric acid) and storage medium ( deionized water or human saliva). Twenty - one day cycles were performed where t he ceramics remained 4 hours in the challenge solution and 20 hours in the storage medium, being renewed daily. Data were submitted to ANOVA at 3 criteria followed by the Student - Newman - Keuls test. T here was greater rou ghness with the glaze finish (p <0.001 ) and the challenge with phosphoric acid led to the least roughness (p <0.00 3 ). Hardness was higher for ceramics with glaze and lower wh en submitted to citric acid (p = 0.536). Th e glaze ceramic surface presen ted higher free energy value (p <0.007), but in the acidic challenges stored in saliva, the electron donor component in both challeng es presented lower values (p = 0.148). It was con cluded that the glazed ceramics presented higher roughness, hardness and surface energy than the polished ceramics, and the a cidic challenges and storage medium influenced these variables, especially in the polished ceramics.
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Palavras-chave
Cerâmica, Propriedades físicas e químicas, Energia, Ceramics