Figure 1. Images for experimental protocol. (A) T-shaped titanium implants having an inner chamber prepared with machined surface (bottom) or acid-etched surface (top). (B) Schematic description of implant site. (C) Schematic diagram of the preparation of the osseointegration interface specimen. The gray area indicates bone, and thick line represents where the implant was in place. We harvested the femoral area specimens, including the implant, by cutting at both ends of the implant, and the implant and bone tissue were then carefully separated. Nano-indentation was performed in the lower half of the bone tissue separated from the implant (*). (D) A photo of the osseointegrated bone interface separated from the implant as described in (C). Bar = 1 mm. (E) Schematic diagram of the preparation of the peri-implant bone. Rat femoral area specimens, including the titanium implant, were cut and ground to expose the cross-section of the implant chamber. The gray area indicates bone, and the solid black area represents the implant. Nano-indentation was performed in the lower half of the bone tissue formed inside the inner chamber along the implant surface (*). (F) A photo of the ground surface of the peri-implant bone, prepared as described in panel (E). (G) An optical microscope image of a dent made on copper by a preliminary nano-indentation with a fixed depth of 2 µm, depicting a precise reproduction of the tip of the Berkovich indenter. The well-defined three-sided pyramidal imprint is observed. Bar is 10 µm. (H) An optical microscope image showing the remaining three-sided pyramidal imprint (triangle) of 500-nm-depth nano-indentation applied on the osseointegration interface. Bar is 1 µm.