Fracture Resistance and color of Advanced Lithium Disilicate (Tessera) Versus Lithium Disilicate (IPS – Emax CAD) Implant Supported Hybrid Abutment Crowns (In vitro study

Aim of the study: To compare the color change (△E) and fracture resistance of implant- supported hybrid abutment crowns fabricated from Advanced Lithium Disilicate (CEREC Tessera) versus Lithium Disilicate (IPS e.max CAD).Materials and methods: A total of 16 (implant with titanium base) samples were fabricated and categorized into two groups according to the hybrid abutment crown material; group 1: Lithium Disilicate (IPS e.max CAD) hybrid abutment crown (L), and group 2: Advanced Lithium Disilicate (CEREC Tessera) hybrid abutment crown (T). All samples were exposed to thermocycling (5000 cycles between 50 and 550). Vita Easy-shade spectrophotometer v was used to determine the Color change(△E) between the specimens and the target shade (A2) of the two materials before and after thermocycling. Fracture resistance was tested using a universal testing machine. Data were statistically analyzed.Results: The IPS e.max Cad hybrid abutment crowns group showed significantly higher (ΔE) color difference than the CEREC Tessera group before thermocycling (7.3 ± 0.74 vs 3.47 ± 0.67) and after thermocycling (7.7 ± 1.11 vs 3.54 ± 0.77) (P-value = 0. 000). Regarding the fracture resistance results, IPS e.max Cad hybrid abutment crowns group showed a significantly higher values than those of Advanced Lithium Disilicate CEREC Tessera hybrid abutment crowns group (787.94 ± 190.96 vs 583.14 ± 104.66) (P=0.02).Conclusions: HAC material had a significant effect on their color and fracture resistance where Lithium Disilicate (IPS e-max CAD) hybrid abutment crowns showed higher color difference (ΔE) and fracture resistance than Advanced lithium disilicate (CEREC Tessera).