Abstract: A blade (2) for a comminution machine of the type having interleaved counter-rotating blades (2) in the case of two shafts (1) or a single set of blades in the case of a single rotating shaft includes a carrier (20) with replaceable teeth (4) and wear plates (3). Each tooth (4) has to tooth tip (121) which projects from it and terminates in a bursting point (121), a forwardly raked receding surface (137) which recedes inwardly from the base of the tooth tip (121) and a receding surface (24) on the wear plates (3A, 3B) which extends inwardly from the base of the tooth (4) to a corner (9) at which it meets a trailing surface (24) on other wear plates (3C, 3D). Shear edges (83) are provided on the teeth (4), on the receding surfaces (24) where they meet the sides (22) of the wear plates (3A, 3D) and on the trailing surfaces where they meets the sides (22) of the wear plates (3C, 3D), and additional bursting points (149) may be provided on the receding surfaces.