Application of Plasma-Sprayed Zirconia Coating in Dental Implants: Study in Implants

The aim was to investigate the osseointegration of a novel coating—plasma-sprayed nanostructured zirconia (NSZ)—for dental implants. Nanostructured zirconia coating on non-thread titanium implant was prepared by plasma spraying, and the implant surface morphology, surface roughness, and wettability were measured. In vivo, nanostructured zirconia-coated implants were inserted in rabbit tibia, and the animals were sacrificed at 2, 4, 8, and 12 weeks after implantation. The bond strength between implant and bone was measured with the removal torque (RTQ) test. Osseointegration was observed by scanning electron microscopy (SEM), microcomputerized tomography (micro CT), and histological analyses. Quantified parameters were calculated, including removal torque, bone volume to tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation/spacing (Tb.Sp), and bone-implant contact (BIC) percentage. The statistical differences were detected with a two-tail Mann-Whitney U test (SPSS 20.0). The surface roughness (1.58 μm) and wettability (54.61°) of a nanostructured zirconia-coated implant was more suitable than the titanium implant (0.598 μm, 74.38°) for osseointegration and hierarchical surface morphology seen on the zirconia coating. The histological analyses showed that a zirconia-coated implant induced earlier and had more condensed bone formation than did the titanium implant at 2 and 4 weeks. Quantified parameters showed the significant differences between these 2 groups at an early healing period, but the differences between the 2 groups decreased with an increased healing period. All these results demonstrated that plasma-sprayed zirconia coated implants induced better bone formation than did titanium implants at an early stage.