Effects of hydrofluoric acid concentration and etching time on the shear bond strength between lithium disilicate ceramic and resin cement / 대한치과보철학회지

ABSTRACT

PURPOSE: The objective of this study was to evaluate the effects of hydrofluoric acid concentration & etching time on the shear bond strength between IPS Empress 2 ceramic and resin cement. MATERIAL AND METHODS: Thirty three rectangular shape ceramic specimens(20x12x5mm size, IPS Empress 2 core materials) were used for this study. The ceramic specimens divided into ten experimental groups with three specimens in each group and were etched with hydrofluoric acid(4%, 9%) according to different etching times(30s, 60s, 90s, 120s, 180s). Etched surfaces of ceramic specimens were bonded with resin cement(Rely X Unicem) using acrylic glass tube. All cemented specimens were tested under shear loading until fracture on universal testing machine at a crosshead speed of 0.5mm/min and the maximum load at fracture(kg) was recorded. Collected shear bond strength data were analyzed with one way ANOVA and Duncan tests. All etched ceramic surfaces were examined morphologically using SEM(scanning electron microscopy). RESULTS: Shear bond strength of etching group(35.89~68.01 MPa) had four to seven times greater than no-etching group(9.53+/-2.29 MPa). The ceramic specimen etched with 4% hydrofluoric acid for 60s showed the maximum shear bond strength(68.01+/-11.78 MPa). Ceramic surface etched with 4% hydrofluoric acid for 60s showed most retentive surface texture. CONCLUSION: It is considered that 60s etching with 4% hydrofluoric acid is optimal etching methods for IPS Empress 2 ceramic bonding.