Andrews’ keys of Normal permanent occlusion
Static occlusal relations (Andrews’ six keys) :
• Molar relationship ( Fig. ). Distal surface of the distal marginal ridge of 6 contacts and occludes with the mesial surface of the mesial marginal ridge of 7; the mesiobuccal cusp of 6 lies in the _groove between the mesial and middle cusps of 6; the mesiolingual cusp of 6 seats in the central
fossa of 6.
• Crown angulation. Gingival aspect of the long axis of each crown lies distal to its occlusal aspect.
• Crown inclination. The gingival aspect of the labial surface of the crown of 21112 li es palatal to the incisal aspect. Otherwise, the gingival aspect of the labial or buccal surface of the crowns of all other teeth lies labial or buccal to the incisal/occlusal aspect.
• No rotations.
• No spaces.
• Flat or mildly increased (<_1.5mm) curve of Spee. Functional occlusal relations .