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).