The present invention in some embodiments thereof relates to bone material removal devices (2100) for example devices which change effective diameter. In some embodiments a bone removal device comprises an expandable portion. In some embodiments the expandable portion comprises one or more bone removing elements such as cutting teeth (2106). In some embodiments a cutting tooth is movable between an open position in which it is configured to widen a bore in a bone and a closed position. In some embodiments a cutting tooth of the bone removal device is formed with a curved such as convex cutting face (2114).
