Images of electron microscopic scans of titanium disks. (a) Disk with machined surface. Regular machining grooves are apparent on the surface (magnification ×2000). (b) Disk with hydrochloric acid–etched surface shows a poor microtexture without micropits. (c) Disk with hydrochloric/sulfuric acid–etched surface displays a poor microtexture with few micropits and smooth waviness. (d) Disk with surface etched by sulfuric/hydrochloric acids and phosphoric acid. Surface waviness is clearly expressed without microtexture. (e) Disk with surface etched by sulfuric and hydrochloric acid shows micropits of 1 to 10 μm, large valleys of 20 to 30 μm, and peaks of different size.