@Mounir Mallek: that’s the whole surgery course I teach at our school and is hard to answer in a comment. But the key is the handpiece, water port, and then the motion. Most importantly to not torque and heat up the bone. This way it has a chance to regenerate once the source of infection is addressed through a proper apico and retrofilling procedure. My favorite bur for this is the Lindaman Bur and a surgical round #6. I’m a minimalist whenever possible. 🙂