The effect of hydrofluoric acid concentration and heat on the bonding to lithium disilicate glass ceramic

• Autor(a) principal: Sundfeld, Daniel
• Data de Publicação: 2016
• Outros Autores: Correr-Sobrinho, Lourenço, Pini, Núbia Inocêncya Pavesi, Costa, Ana Rosa, Sundfeld, Renato Herman [UNESP], Pfeifer, Carmem Silvia, Martins, Luis Roberto Marcondes
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1590/0103-6440201601024; http://hdl.handle.net/11449/173931
• topic: FE-SEM analysis; Heat treatment; Hydrofluoric acid; Lithium disilicate glass ceramic; Microshear bond strength

The aim of this study was to evaluate the effects of hydrofluoric acid (HF) concentration and previous heat treatment (PHT) on the surface morphology and micro-shear bond strength (μSBS) of a lithium disilicate glass ceramic (EMX) to resin cement. One hundred four EMX specimens were randomly assigned to two groups (n=52) according to the HF concentration: 5% and 10%. A new random distribution was made according to the PHTs (n=13): control (no PHT); previously heated HF (70 °C); previously heated EMX surface (85 °C); the combination of heated HF + heated EMX surface. The etching time was set at 20 s. All EMX blocks were silanated and received a thin layer of an unfilled resin. Five resin cement cylinders were made on each EMX surface using Tygon tubes as matrices, and then stored for 24 h at 37 °C. One random etched EMX sample from each group was analyzed using field-emission scanning electron microscopy (FE-SEM). The data were subjected to two-way ANOVA and multiple comparisons were performed using the Tukey post hoc test (α=0.05). For the control groups, 5% HF showed statistically lower μSBS values when compared to 10% HF (p<0.05). PHT increased the μSBS values for 5% HF, yielding statistically similar results to non-PHT 10% HF (p<0.05). FE-SEM images showed increased glassy matrix removal when PHT was applied to HF 5%, but not to the same degree as for 10% HF. PHT has the potential to improve the bond strength of 5% HF concentration on lithium disilicate glass ceramic.