Effect of nanoparticle infiltration into the opaque agent of pink composite resin on its bond strength with base metals

Objectives The aim of this study was to evaluate the effect of titanium dioxide (TiO2) nanotube incorporation into the opaque agent of a pink composite resin (PCR) on its bond strength to two different base metal alloys.Materials and Methods A total of 84 CoCr and Ti specimens (4 mm in diameter, 2 mm in height) fabricated via SLS/DMLS were assigned to eight experimental and four control groups (n = 7). All metal surfaces were sandblasted and primed. TiO2 nanotubes synthesized in a chemistry laboratory were incorporated into the opaque agent of PCR at 0.5% and 1.0% (w/w). Control groups were coated with heat-polymerized acrylic resin and PCR. Shear bond strength (SBS) between metal–resin interfaces was measured using a universal testing machine. Microscopic and spectroscopic analyses were performed to assess nanotube incorporation and characterize interfacial failure.Results The highest SBS values were observed in the CoCr-TiO2n4 (18.5 MPa) and Ti-TiO2n4 (16.2 MPa) groups, whereas the lowest SBS values belonged to the acrylic resin control groups (CoCr-A: 5.0 MPa; Ti-A: 4.6 MPa). A statistically significant difference was detected between the Ti-TiO2n2 and Ti-TiO2n4 groups (p = 0.033).Conclusion Incorporation of functionalized TiO2 nanotubes into the opaque agent tended to improve the bond strength of PCR to metal substrates. These findings indicate potential benefits of nanotube integration; however, further studies with larger sample sizes and optimized concentrations are recommended.