Effect of Nano-Zirconia Dip Coating on the Surface Properties of PEEK for Dental Implants

Abstract

Dental implants that are biofunctionally coated are placed in a strategic location in bone where they assume an integral function in augmenting the process of healing and promoting bone growth in the implantation site. The purpose of this present study was to evaluate the impact of two different nano-zirconia (ZrO₂) coating thicknesses on dip-coated polyetheretherketone (PEEK) implants by using zirconia nanoparticles with a particle size of 40–50 nm and coating layer thicknesses ranging from 18.25–35.14 μm and 58.67–65.34 μm. Both an uncoated control group of PEEK discs and two groups of PEEK discs coated with varying thicknesses were considered. Surface roughness was determined using a profilometer, and field-emission scanning electron microscopy (FE-SEM) was used to study coating morphology, nanoparticle distribution, and coating thickness by image analysis. X-ray diffraction (XRD) was used to identify crystalline phases of the coating. Water contact angle measurements were also performed to analyze wettability; the thickest coating had a contact angle of 34.17°, indicating a significant increase in hydrophilicity. Adhesion tests indicated good interfacial adhesion for the thinner coating (5B, ASTM D3359). The thicker layer received a slightly lower rating (4B) due to some coating removal along the cut edges. A decrease in adhesion strength with increasing thickness was attributed to the accumulation of internal residual stresses and decreased interfacial cohesion. Overall, nano-ZrO₂ dip coatings improved surface morphology and interfacial performance, suggesting their potential as a reliable surface modification strategy for dental implants