make no difference to casing protection whether the last row of stator teeth are slanted towards or against the rotational direction slanting the outer row of stator teeth in a direction opposite to direction places the teeth in a u201c holdback u201d position and slanting the teeth in the same direction of rotation is a u201c feeding position u201d further the sidewall angle of the teeth 40 may be between 10 0 to 60 0 and preferably in a range of 15 0 to 45 0 with respect to a radial of the plate and disc the angle 44 in fig3 a of the sidewalls of the last row 66 of stator teeth 40 is selected to deflect refiner material moving through the row and to allow the flow without too much obstruction the rear wall 52 in fig3 b extends to the outer periphery 24 of the stator plate the sidewall of the teeth 40 are extended as a result of the rear wall being substantially normal to the substrate 72 of the stator plate 54 extending the sidewalls provides additional sidewall area to deflect the refiner material the length and angle of the sidewall should be sufficient such that a fast moving particle cannot move along a radial through the gap between the teeth without hitting the sidewall of a tooth accordingly the projection of the width of the sidewall along a tangential direction should be at least as wide as the gap between the teeth of the last stator row the sidewalls on both sides of the outer row stator teeth 40 preferably form the same angles with respect to radii the leading sidewall facing the rotational direction of the rotor.