Abstract: A tree stump grinding machine includes a rotor having at least one or more peripheral slots therein and defining a rotor plane. One or more teeth are removably disposed in corresponding slots and form a primary cutting face. A secondary cutting face is formed by a protrusion on the tooth and/or a keeper plate associated with the tooth. The secondary cutting face may be formed by a protrusion on the keeper plate oriented perpendicular to the plane of the rotor, and/or the secondary cutting face may be disposed circumferentially and/or radially offset with respect to the primary cutting face on either of both of the tooth and the keeper plate.