Cr own 4)occlusal aspect a. hexagon: shorter and nar rower mes iodistal ly b cusp r idges and marg ina ridges: c. buccul cusp distal ly: ong and pointed I inga cusp mes ial ly: short and flatCrown 4）occlusal aspect a. hexagon:shorter and narrower mesiodistally b.cusp ridges and marginal ridges: c.buccul cusp distally:long and pointed lingual cusp mesially:short and flat