(1) crown 1) facial aspect a. pentagon s imilar to the can ine tip of the fac i l cusp located distally; distal ridge short and convex b a slight indentation at mesial ridge; the mes ial contact concave（1）crown 1）facial aspect a. pentagon similar to the canine;tip of the facial cusp located distally;distal ridge short and convex b.a slight indentation at mesial ridge;the mesial contact concave