A tooth system for a tool for earth moving machinery that includes a holder located on the tool and a front tooth portion that is detachably arranged on and in relation to the holder, which tooth portion is in the form of a replaceable wear/replacement part with a rear leg and the holder embodies a cavity designed to receive the leg of the tooth portion. This achieves a unified joint for assimilation of occurring loads via a predetermined connection geometry embodying special, opposite, mutually interacting contact surfaces and clearance surfaces arranged along the tooth portion and holder. The joint includes a multi-armed, preferably cruciform, cross section comprising at least four projection arms and at least four grooves each that interact with each projecting arm. Each projection arms includes a vertically arranged, upper arm, lower heel and two, essentially horizontally and laterally arranged, wing portions, with a tensioning device.