The invention relates to a surgical instrument, particularly for use in dental surgery, comprising a machining device (1) and a protector device (8), said machining device (1) having a shaft (2) with a connection region (3) and a hollow-cylindrical shaped head (4), an active region (6) being formed at a distal edge (5) of said head (4), particularly for cutting or grinding bones, and the protector device (8) enclosing at least some parts of the head (4) and being rotatably coupled to a bearing element (7) of the machining device (1), which bearing element at least partially extends within said head (4).
