A replaceable tooth arrangement for use in grinding discs such as used in wood hoggers and comminuting equipment. A preferred tooth arrangement includes two end to end adjacent tip portions, or a tip portion end to end with a complementary base portion. The contacting faces of the portions are preferably tapered so that tightening together creates a resultant outward movement which tightens them against the walls of a retaining aperture in a disc or disc section. Alternatively or additionally a connection element interacts with a wedge keeper which causes a similar outward component in the keeper and tip portion, tightening them against the walls of a retaining aperture, as the connection element is tightened.