A pair of artificial posterior teeth having co-engageable occlusal surfaces, the upper tooth having an incising ridge on its occlusal surface extending in mesial-distal direction and the lower tooth being concaved in a buccal-lingual direction on its occlusal surface and having sulci which are closed at one end and open at the other, whereby said incising ridge, when moving in lteral excursion in one direction effects shearing engagement with the closed ends of said sulci and when moving in the opposite direction, sluices sheared food from the open ends of said sulci.