Implant surface topographies analyzed using fractal dimension

The aim of this study was to assess the fractal dimension (Df) of disks with 3 different surface topographies.

Thirty disk-shaped samples (10 × 2 mm) with 3 different surface topographies (Dental Tech, Misinto, Italy) were analyzed by scanning electron microscopy: group A, machined surface; group B, titanium plasma-spray surface; group C, acid-etched and sandblasted surface (Blasted Wrinkled Surface).

The amplitude roughness parameter (Sa) of the machined surfaces was 0.6 μm, while the developed surface area ratio (Sdr) was 14%; for the titanium plasma-spray surfaces, the values were, respectively, 5.3 μm and 97%, and for the Blasted Wrinkled Surfaces, 1.5 μm and 63%. Images at 1.000, 20.000, and 50.000 magnifications were processed for quantitative analysis of Df using the box-counting method. At 1.000×, Df for group A, B, and C was 1.86, 1.80, and 1.81, respectively; at 20.000×, Df for group A, B, and C was 1.85, 1.71, 1.58, respectively; and at 50.000×, Df was 1.83, 1.61, and 1.51 for A, B, and C groups. Statistically significant differences were found for Df values.

Df provides not only an index of roughness size values but also a measure of roughness spatial organization; therefore, it could be a promising method to differentiate between rough surfaces capable of supporting osseointegration.