Surface micro-structuring of zirconia dental implants.

Abstract

Sandblasting with subsequent acid etching is a potential procedure to generate microstructured surfaces on zirconia implants. The aim of the study was to systematically analyze the effect of these process steps on surface morphology and mechanical strength of the implants. Zirconia implant blanks (ceramic.implant, VITA) were sandblasted (105-μm alumina, 6bar), subsequently HF-etched, and finally heat-treated at 1250°C. Surface topographies were documented by SEM. Surface roughness Ra (n=4), monoclinic volume fraction in the surface layer (n=1), and static fracture load (n=4) were measured. Surface roughness Ra reached a maximum of 1.2μm after 4× sandblasting. Scratches and sharp edges dominated the surface aspect. Fracture load increased with the number of sandblasting cycles with a gain of 30% after 20 cycles. HF etching did not change the Ra values, but sharp edges were rounded and small pits created. A minor decrease in fracture load with increasing etching time was observed. Heat treatment of 1h reduced the fracture load by 1/3. Longer heat treatment had no further effect. The roughness Ra was not modified by heat treatment. Fracture load was strongly correlated with the monoclinic fraction except for the results obtained directly after acid etching, where a constant monoclinic fraction was observed. Sandblasting with 105-μm alumina followed by 1h HF etching at room temperature and 1h heat treatment at 1250°C is a reliable and tolerant process to create a surface roughness of about Ra =1.2μm on zirconia implants.