Aim: Evaluation the effect of modification of veneering porcelain bonded to metallic and zirconia cores by silver nanoparticles (SNP) on flexural strength, shear bond strength (SBS) and color change.
Materials and methods: A total of sixty samples were constructed and divided into two groups in accordance with the core material type (n=30). Group I: Zirconia core, while group II: Metal core. Each group was classified into 3 sub-groups (n=10) in accordance with the test performed: flexural strength, SBS and color change, each subgroup was subdivided into two classes (n=5), according to incorporation of SNP. A control class (class I) and Class II: Modified samples. Fracture strength and SBS were tested utilizing a universal testing machine, while color change was measured using spectrophotometer, Data were tabulated and analyzed statistically.
Results: Flexural strength test results showed a significant increase in modified classes on both metallic and zirconia cores (2904±76.4, 1318±58.1MPa) compared to unmodified classes (2542±71.9, 1066.8±47.2 MPa) respectively. Where SBS mean values showed a significant increase in control classes for both metallic and zirconia cores (42.5±0.5, 27.6±0.4 MPa) compared to modified classes (41.4±0.5, 25.7±0.3) respectively. Color change results showed a significantly higher mean values (ΔE=10.75±1.1) in Zirconia core group than those in metallic group (1.65±0.6).
Conclusions: Incorporation of SNP into the veneering porcelain significantly increased flexural strength in both groups while, SBS was significantly decreased. Color change of veneering porcelain on metal core was within the acceptable clinical range, while on zirconia core showed higher mean values & was not clinically accepted.