Effect of surface preparation with Nd:YAG and Er,Cr:YSGG lasers on the repair bond strength of lithium disilicate glass ceramic to a silorane - based composite resin

Background. This study was undertaken to evaluate the repair bond strength of lithium disilicate glass ceramic to a silorane - based composite resin after surface prep aration with Nd:YAG and Er,Cr:YSGG lasers. Methods. A total of 102 lithium disilicate glass ceramic samples (IPS e.max Press), measuring 5 mm in diameter and 4 mm in thickness, were randomly assigned to 6 groups (n=17): group 1, no surface preparation (control); group 2, acid etching wit h 9.5% hydrofluoric acid (HF); group 3, surface preparation with 4.5 - W Nd:YAG laser; g roup 4, surface preparation with 6 - W Nd:YAG laser; group 5, surface preparation with 1.5 - W Er,Cr:YSGG laser; and group 6, surface preparation with 6 - W Er,Cr:YSGG laser. After preparation of surfaces and application of silane, all the samples were repaired with the use of a silorane - based composite resin, followed by storage in distilled water at a temperature of 37°C for 24 hours and thermocycling. Finally, the samples were subjected to a shearing bond strength test; the fracture modes were determined under a stereomi- croscope. Results. There were significant differences between the HF group and the other groups (P=0.000). Two - by - two comparisons of the other groups revealed no significant differences (P>0.05). Conclusion . Use of HF proved the most effective s urface preparation technique to increase the repair bond strength between lithium disilicate glass ceramic and silorane - based composite resin; compared to the control group