Propriedades mecânicas e ópticas das cerâmicas feldspáticas e dissilicato de lítio: Revisão de literatura / Mechanical and optical properties of feldspathic ceramics and lithium disilicate: literature review

Objetivo: o objetivo dessa revisão de literatura é apresentar os dados existentes sobre capacidade estética e resistência à fratura das cerâmicas feldspáticas e dissilicato de lítio confeccionadas para o uso em CAD/CAM. Material e Métodos: para realizar o estudo foram levantados artigos originais sobre as cerâmicas feldspáticas e dissilicato de lítio em periódicos na base de dados PubMed e ScienceDirect, desde 2015 até 2020 utilizando como termos de busca "lithium disilicate AND esthetic AND CAD/CAM", "lithium disilicate AND fadigue AND CAD/CAM", "lithium disilicate AND fracture AND CAD/CAM", "feldspathic AND esthetic AND CAD/CAM", "feldspathic AND fadigue AND CAD/CAM", "feldspathic AND fracture AND CAD/CAM". Ainda, foram selecionados artigos de relevância publicados em datas anteriores selecionados pelos autores. Constam trabalhos longitudinais, de revisão de literatura, casos clínicos e pesquisas in vitro. Resultados: no total, 209 artigos foram encontrados e somente 16 foram incluídos para comparação. Os dados apresentaram boa capacidade estética para ambos materiais, sendo o dissilicato com maior resistência à fratura. Conclusão: concluiu-se que cerâmicas feldspáticas e dissilicato de lítio para CAD/CAM apresentam capacidade ópticas satisfatórias para restaurações estéticas quando utilizado os blocos multicores, devendo-se optar pelo dissilicato de lítio em situações de maior esforço mastigatório ou menor espessura da peça protética

Objective: this literature review presents the existing data on the esthetic capacity and fracture resistance of feldspathic and lithium disilicate ceramics made for CAD/CAM. Material and Methods: original articles on feldspathic ceramics and lithium disilicate were collected in journals in the PubMed and ScienceDirect databases from 2015 to 2020 using the search terms "lithium disilicate AND esthetic AND CAD/CAM," "lithium disilicate AND fatigue AND CAD/CAM," "lithium disilicate AND fracture AND CAD/CAM," "feldspathic AND esthetic AND CAD/CAM," "feldspathic AND fatigue AND CAD/CAM," "feldspathic AND fracture AND CAD/CAM." relevant articles published previously to 2015 were also selected by the authors. Longitudinal studies, literature reviews, clinical cases and in vitro studies were included. Results: in total, 209 articles were selected and 16 included for comparison. Data presented good esthetic capability for both materials, disilicate presented higher fracture strength. Conclusion: the study concluded that feldspathic ceramics and lithium disilicate for CAD/CAM have satisfactory optical capacity for esthetics restorations when multicolor blocks are used. Lithium disilicate should be chosen in situations of greater masticatory effort or thinness of the prosthetic piece

Do new matrix formulations improve resin composite resistance to degradation processes?

The aim of this study was to determine the degradation resistance of three new formulations-silorane-, Ormocer- and dimer-acid-based materials-and compare them to the traditional dimethacrylate-based materials. One silorane- (Filtek P90, P90), one Ormocer- (Ceram-X, CX), one dimer-acid- (N'Durance, ND) and two dimethacrylate-based (Filtek P60, P60; Tetric Ceram, TC) materials were investigated. Water sorption (Wsp) and solubility (Wsl) were determined after the materials were immersed in water for 28 days. Knoop hardness (KH) was determined before and after 24 h immersion in pure ethanol. The flexural-strength (FS) was determined by the bending test after one-week storage in a dry environment or after one-week immersion in pure ethanol. Data were submitted to analysis of variance (ANOVA) and Tukey's test (95%). The three new formulations showed lower Wsp than the dimethacrylate-based formulation. CX (0.50 ± 0.17%) and ND (0.72 ± 0.19%) exhibited the lowest Wsp, whereas P90 (0.02 ± 0.03%) and P60 (0.04 ± 0.03%) showed the lowest Wsl. All resins showed reduced Knoop hardness number (KHN) after ethanol immersion. P60 presented the lowest decrease in KH value (19 ± 5%). TC (48 ± 3%) and P90 (39 ± 9%) showed the highest KHN decrease after ethanol storage. The FS of CX, ND and TC were affected by ethanol storage. The new formulations did not improve the degradation resistance, as compared with the traditional methacrylate-based materials.