premolar Bicusp id: confi gurati on and funct ion
Bicuspid:configuration and function premolar
premo lar 1. maxillary first premolar 44 The bi ggest one of the premolar, the tip of the fac i al cusp is located di stal ly to the midline
premolar 1.maxillary first premolar 4 4 The biggest one of the premolar,the tip of the facial cusp is located distally to the midline
(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
Cr own c axia ridge parallel to long axis; two devel opmental grooves d crest of contour: the cervica third of the crown, cervi cal ridge
Crown c.axial ridge parallel to long axis;two developmental grooves d.crest of contour:the cervical third of the crown,cervical ridge
Cr own 2)Lingual aspect a.ess than bucca l aspect, convex b. I inguaI cusp mes ial ly c crest of contour middle third
Crown 2）lingual aspect a.less than buccal aspect,convex b.lingual cusp mesially c.crest of contour: middle third
Cr own 3) proximal sur face a. quadr angle b buccal cusp longer and more pointed than lingua l one C mes i al marginal groove and mes i a deve l opment l depression d straight axis
Crown 3）proximal surface a. quadrangle b.buccal cusp longer and more pointed than lingual one c.mesial marginal groove and mesial developmental depression d.straight axis
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 flat
Crown 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
Cr own d. fossa e developmenta groove
Crown d.fossa e.developmental groove
Root flat. bi fur cated common (80%) tip of the root di ly b i furcated: bucca root arger and longer single: groove found
Root flat，bifurcated common （80%） tip of the root distally bifurcated:buccal root larger and longer single: groove found
Premo ar 2. maxillary second premolar 55 Resemb le the maxillary first premo I ar s less angular more rounded. smaller
Premolar 2.maxillary second premolar 5 5 Resemble the maxillary first premolars less angular ,more rounded,smaller