Shear bond strength of various luting cements to fixed prosthodontic restorative materials

The aim of this study was to evaluate the shear bond strength (SBS) of three different cements to zirconia and lithium disilicate ceramic surface after thermal cycling. Thirty zirconia (Z) and thirty lithium disilicate (L) disk specimens were prepared in 8?mm in diameter and 3.4?mm in thickness from zirconia and lithium disilicate ceramic blocks. Each group was divided into three subgroups (n:10). The specimens from all groups were bonded with three different cements using transparent polyethylene tubes: Zn-Phosphate cement (ZPC); self-adhesive resin cement (SARC); adhesive resin cement (ARS). The specimens were then subjected to thermal aging procedure for 1?week under 37?°C water bath. Shear bond strength (SBS) was determined using a universal testing machine at a crosshead speed of 1?mm/min. The specimens were also examined both with a scanning electron microscope (SEM) and a stereomicroscope. Statistical analysis was performed with one-way ANOVA. Pair-wise statistical comparison was made with Tukey test. The overall significance level was set at α?=?0.05. For the tested groups, the SBS values ranged from 0.29?±?0.03 to 12.10?±?0.25?MPa. L-SARC group yielded the highest SBS value (p?<?0.05) among the groups, while Z-ZPC group had the lowest (p?<?0.05). Significantly higher SBS values were found for all the groups of lithium disilicate disk specimens (L) when compared to those of zirconia disk specimens (Z) (p?<?0.05). Tukey’s pairwise comparisons revealed that SBS values of SARC groups were significantly higher than those of the ARC and ZPC groups (p?<?0.05). Mode of failure analysis results showed that, the modes of failures were mixed with adhesive debonding predominantly with minimal resin residues (<10?%) for SARC groups. However, the other groups showed adhesive failure predominantly. Within the limitation of this in vitro study, it was concluded that selfadhesive resin cement had the highest shear bond strength values when bonded to lithium disilicate and zirconia ceramic surface. However zinc-phosphate cement demonstrated significantly lower shear bond strength values for both ceramic groups.