A surgical instrument, in particular for use in dental surgery, includes a machining device and a protector device. The machining device has a shaft with a connection region and a hollow cylindrical head, wherein an active region, in particular for machining and/or for grinding of bone, is formed at a distal edge of the head. The protector device surrounds the head, at least in regions, and is rotatably coupled with a bearing element of the machining device extending, at least in regions, inside of the head.
