Changes in the esthetic, physical, and biological properties of a titanium alloy abutment treated by anodic oxidation

Abstract

Statement of problem: The grayish appearance of titanium abutments adversely affects peri-implant esthetics in patients with thin mucosa, impacting patient satisfaction with implant-supported restorations in esthetic regions.

Purpose: The purpose of this in vitro study was to change the color of titanium alloys with anodic oxidation and to evaluate alterations in the esthetic, physical, and biological properties of the anodized titanium alloys.

Material and methods: Pink and yellow titanium alloys produced by anodization were the experimental groups, and the untreated titanium alloy and zirconia were used as the control groups. Pig gingiva was placed on the tested specimens to evaluate the esthetic effect by recording the color change in the gingiva. Physical properties including morphology, chemical composition, roughness, and contact angle were evaluated by scanning electron microscopy, atomic force microscopy, and a contact angle analysis system. Biological properties were evaluated by observing the cell behaviors of human gingival fibroblasts, using scanning electron microscopy, fluorescence microscopy, a live/dead viability assay, and a cell counting assay.

Results: A variety of colors can be produced on the surfaces of titanium alloys by anodization at different voltages. Titanium alloys anodized at 60 and 65 V exhibited yellow and pink appearances, respectively. Color differences of gingiva caused by anodized titanium alloys were lower than those of the untreated titanium alloy, but they were higher than those of zirconia. Compared with the untreated titanium alloy, the anodized titanium alloys exhibited grain formation, a lower contact angle, and higher roughness. Cell morphology, proliferation, and viability on surfaces of anodized titanium alloys were similar to those of the untreated titanium alloy but lower than those of zirconia.

Conclusions: Anodization could change the color of titanium alloys to pink or yellow at different voltages. Grain formation, roughness, and hydrophilicity were increased after treatment. The esthetics and biocompatibility of anodized titanium alloys were not as good as that of zirconia, but the pink and yellow titanium alloys treated by anodization achieved better gingival esthetics than the untreated titanium alloy.