Efeito do envelhecimento hidrotérmico na resistência flexural, rugosidade, módulo de Weibull e microestrutura da zircônia monolítica submetida a desgastes e métodos de acabamento de superfície
Carregando...
Data
2018-08-02
Autores
Hatanaka, Gabriel Rodrigues
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Desgastes para ajustes clínicos são necessários para adequada adaptação de próteses em zircônia, mas ainda não há um protocolo estabelecido. Este estudo avaliou o efeito de desgaste e polimento sobre a resistência à flexão (RF) e módulo de Weibull, rugosidade (Ra) e transformação de fase por microscopia eletrônica de varredura (MEV) de duas zircônias monolíticas (Prettau e Prettau Anterior) submetidas à degradação hidrotérmica (LTD). Foram obtidos corpos-de-prova com 20 x 4,0 x 1,2 mm, sem desgaste e com glaze (grupo controle) ou com 20 x 4,0 x 1,5 mm, os quais foram desgastados com fresa diamantada de granulação grossa (90-120 μm) em alta rotação sob irrigação. Após desgaste de 0,3 mm, foram realizados os protocolos de acabamento: sem polimento (D); polimento com borracha diamantada (DP); aplicação de glaze (DG); polimento com borracha diamantada + glaze (DPG). Metade dos corpos-de-prova foi envelhecida hidrotermicamente (EH) em autoclave (134 °C, 2 bars, 20 horas). Os dados de RF e Ra (n=30) foram analisados por teste de Kruskal-Wallis, testes complementares de Dunn e Student-Newman-Keuls, respectivamente (α=0,05). Nos grupos não envelhecidos, o material Prettau apresentou a seguinte ordem de resistência: D = DP > DPG > DG = C, e o Prettau Anterior: D = DP = C > DG = DPG. Após EH, para Prettau: D = DP > DPG > DG = C; e Prettau Anterior DPG = C = D = DP > DG = DPG. O EH aumentou a RF dos grupos D e DP para Prettau e reduziu a RF do grupo DG para Prettau Anterior. O grupo D promoveu os maiores valores de rugosidade, seguido pelos grupos DP, DG, DPG e C, independente do material e do EH. O módulo de Weibull foi mais alto onde foi aplicado glaze. Análise em MEV revelou efeito do EH apenas nos grupos D e DP de Prettau. Concluiu-se que as zircônias monolíticas exibiram diferentes comportamentos mecânicos frente aos tratamentos, e que o EH afetou apenas a Prettau. O desgaste aumentou a rugosidade e os procedimentos de polimento foram capazes de reduzi-la em diferentes níveis, porém o glaze tende a reduzir a RF, mas aumentar a confiabilidade.
The CAD/CAM technology allowed prosthesis with accurate fit, but clinical adjustments are still necessary, and there is no protocol in the literature to guide how to provide it. The aim of this study is to evaluate the effect of grinding and finishing procedures on flexural strength (FS) and Weibull moduli, roughness (Ra) and phase transformation by Scanning Electronic Microscopy (SEM) of two monolithic zirconia (Prettau and Prettau Anterior) submitted to low temperature degradation (LTD). It was obtained bar-shaped specimens in the dimensions of 20 x 4.0 x 1.2 mm, without grinding and with glaze (control group) or 20 x 4.0 x 1.5 mm which were ground with diamond burr (90-120 μm) in high rotation and constant water cooling. After 0.3 mm of grinding, the samples were submitted to different finishing protocols: without polishing (D); polishing with diamond rubber (DP); glaze application (DG); polishing with diamond rubber + glaze (DPG). Half of samples was submitted to LTD in autoclave (134 °C, 2 bars, 20 hours). FS and Ra (n=30) data were analyzed by Kruskal-Wallis test and post-hot Dunn and Student-Newman-Keuls, respectively (α=.05). The median FS for Prettau, without LTD, was in the following order: D = DP > DPG > DG = C; Prettau Anterior: D = DP = C > DG = DPG. After LTD, Prettau: D = DP > DPG > DG = C; and Prettau Anterior: DPG = C = D = DP > DG = DPG. LTD increased FS of D and DP Prettau groups, and it decreased FS of DG Prettau Anterior group. Irrespectively of material and LTD, D treatment produced the highest roughness values, followed by DP, DG, DPG and C groups. Weibull moduli was higher in groups with glaze application. SEM analysis showed effects of LTD in D and DP Prettau groups only. It was concluded that the monolithic zirconia exhibits different mechanical behaviors after adjustment procedures, and LTD affected only Prettau. Grinding increased the roughness and finishing procedures reduced the roughness at different levels. Glaze tend to decrease FS but it improves reliability.
The CAD/CAM technology allowed prosthesis with accurate fit, but clinical adjustments are still necessary, and there is no protocol in the literature to guide how to provide it. The aim of this study is to evaluate the effect of grinding and finishing procedures on flexural strength (FS) and Weibull moduli, roughness (Ra) and phase transformation by Scanning Electronic Microscopy (SEM) of two monolithic zirconia (Prettau and Prettau Anterior) submitted to low temperature degradation (LTD). It was obtained bar-shaped specimens in the dimensions of 20 x 4.0 x 1.2 mm, without grinding and with glaze (control group) or 20 x 4.0 x 1.5 mm which were ground with diamond burr (90-120 μm) in high rotation and constant water cooling. After 0.3 mm of grinding, the samples were submitted to different finishing protocols: without polishing (D); polishing with diamond rubber (DP); glaze application (DG); polishing with diamond rubber + glaze (DPG). Half of samples was submitted to LTD in autoclave (134 °C, 2 bars, 20 hours). FS and Ra (n=30) data were analyzed by Kruskal-Wallis test and post-hot Dunn and Student-Newman-Keuls, respectively (α=.05). The median FS for Prettau, without LTD, was in the following order: D = DP > DPG > DG = C; Prettau Anterior: D = DP = C > DG = DPG. After LTD, Prettau: D = DP > DPG > DG = C; and Prettau Anterior: DPG = C = D = DP > DG = DPG. LTD increased FS of D and DP Prettau groups, and it decreased FS of DG Prettau Anterior group. Irrespectively of material and LTD, D treatment produced the highest roughness values, followed by DP, DG, DPG and C groups. Weibull moduli was higher in groups with glaze application. SEM analysis showed effects of LTD in D and DP Prettau groups only. It was concluded that the monolithic zirconia exhibits different mechanical behaviors after adjustment procedures, and LTD affected only Prettau. Grinding increased the roughness and finishing procedures reduced the roughness at different levels. Glaze tend to decrease FS but it improves reliability.
Descrição
Palavras-chave
Cerâmica, Resistência de materiais, Microscopia eletrônica, Ceramics, Material resistance, Microscopy, Electron