Figure 9

Histological analysis for necrosis assessment: the necrotic depth was assessed by measuring the normal distance from the trench profile to the dashed black line, which marks the interface between the zone with empty lacunae (i.e., necrotic zone) and the zone with filled lacunae (i.e., necrosis-free zone): (a) Control sample free of necrosis, as all lacunae are filled with osteocytes, (b) Picosecond laser machining at 5 mm/s (PF) exhibits a necrotic depth of 79 ± 7 µm, while also depicting the smallest trench, (c) picosecond laser machining at 1 mm/s (PS) shows a necrotic depth 190 ± 39 µm and shows a trench depth that almost reached the bottom of the sample, (d) continuous wave laser machining at 20 mm/s caused a necrotic depth of 194 ± 19 µm, which is similar to the one in c, but in this case the trench is much shallower, (e) nanosecond laser machining at 5 mm/s showed a necrotic depth of 268 ± 67 µm, while also exhibiting a deep trench and carbonisation traits in the trench profile