The effect of surface treatment of zirconia with hydrofluoric acid in high concentrations on surface resistance bond: an in vitro study

Abstract

Abstract Objectives This study aimed to evaluate whether conditioning with hydrofluoric acid in higher elevations with a longer application time can promote an increase in surface roughness and shear bond strength to zirconia. Methods Fifty zirconia cylinders (Vipiblock- Zinconn- Vipi-Brazil) were made using CAD / CAM system and cemented with Panavia F 2.0 resin cement (Kuraray-Japan) in composite resin cylinders filtek Z-350 XT (3M / ESPE-EUA), after different surface treatments of zirconia (n = 10): Group 1 - No surface treatment; Group 2 - Conditioning with 40% hydrofluoric acid, for 2 minutes; Group 3 - Conditioning with 40% hydrofluoric acid, for 4 minutes, Group 4 - Conditioning with 50% hydrofluoric acid, for 2 minutes and Group 5 - Conditioning with 50% hydrofluoric acid, for 4 minutes. Right after cementation, all specimens were subjected tothermocycling (5000 cycles; 5º to 55ºC), storaged in distilled water at 37ºC for 730 days and subjected to the shear bond strength test in a universal testing machine until fracture. The F test (ANOVA) for one factor and the multiple comparison tests of Tamanhe were used (p < 0,05). Results The highest mean corresponded to group 3 (4.47 Mpa), followed by group 5 (4.05 Mpa), Group 4 (3.28 Mpa) and group 2 (3.14 Mpa). Significance Conditioning with 40% hydrofluoric acid for 4 minutes obtained the highest values of bond strength to zirconia, however there was no statistically significant difference in relation to the concentration of 50%, for 2 and 4 minutes.