This is what I found on dentistry and due to little text I can only give you this as help

The younger Laetolil hominids provide evidence of a unique anterior cutting complex with a chisel-like action occurring between the lingual-distal C face and a transverse ridge on the P3 perpendicular to it, extending between the subequal cusps. An earlier adaptation to more efficient grinding may have resulted in reduced canine projection and the development of the lingual P3 cusp, raising the ridge between it and the buccal cusp. This development acted to retain the anterior cutting function by shifting it to the top of the premolar.