Premolars

Position of Premolars Posterior Succedaneous teeth

Maxillary Premolars 1st : (#5, #12) 2nd: (#4, #13)

Eruption of Maxillary Premolars 1st: 10 – 11 years 2nd: 10 – 12 years

Occlusion Maxillary cuspids are distal to mandibular cuspids by a ½ a cusp Maxillary premolars are distal to mandibular premolars by a ½ cusp

Maxillary 1st Premolar Mesial/distal view CEJ straighter than anteriors Buccal and lingual cusps centered over the root Mesial concavity Buccal cusp larger than lingual Single or bifurcated root. Bifurcation more common.

Maxillary 1st Premolar Occlusal view Point angles are sharp on buccal, rounded on lingual More rounding on the distolingual than the mesiolingual. Hexagontal or pentagontal outline Bulkier on the mesial Sharper line angles on the mesial than the distal. Mesial marginal ridge with a mesiomarginal groove Transverse ridge Grooves – 6 (Central, mesial mesiobuccal, mesiolingual, distobuccal, distolingual) Distobuccal groove is the longest.

Maxillary 1st Premolar Buccal view Mesial view Lingual view Occlusal view

Maxillary 1st Premolar (Lingual view) Maxillary Right (#5) Premolars and 1st molar: # 5, #4, #3, left to right

Maxillary 2nd Premolar No mesial concavity or groove Buccal and lingual cusps of equal size Usually one root Short central groove, more secondary grooves Heavier marginal ridges Max. R 1st premolar, #5

Maxillary 2nd Premolar Occlusal view: Cusps bulk on the mesial Rectangular or oval occlusal table Max. R 1st premolar, #5

Maxillary 2nd Premolar Distal view: More of the occlusal table can be seen from the distal than from the mesial view. (True of 1st premolar also.) Usually only one root, sometimes bifurcated. Distal view Mesial view

Maxillary 2nd Premolar Buccal view Distal view Lingual view Occlusal view

Maxillary Premolars (Buccal view) 5 Tip of the buccal cusp is distal to the midline, therefore the mesial cusp ridge is longer than the distal cusp ridge.

Maxillary Premolars (Lingual view) 12 5 13 4

Maxillary Premolars (Mesial/Distal) 2 roots 1 root Notice the depression on the first premolar on the mesial view.

Maxillary Premolars (Occlusal view)

Mandibular Premolars Mandibular 1st: (#21, #28) Mandibular 2nd: (#20, #29)

Mandibular Premolars Mandibular 1st: Two cusps (Buccal and an afunctional lingual cusp) Mandibular 2nd: Two or three cusps (One buccal, with one or two lingual cusps. Lingual cusp(s) afunctional.)

Eruption of Mandibular Premolars Mandibular 1st: 10 – 12 years of age Mandibular 2nd: 11-12 years of age Roots complete: 12 – 14 years of age

Occlusion of Mandibular Premolars Mandibular 1st: Maxillary cuspid and 1st premolar Mandibular 2nd: Maxillary 1st and 2nd premolars Lingual tipping of crowns

Mandibular 1st Premolar Two cusps: large buccal and small lingual Mesiolingual groove Mesial cusp ridge is shorter than distal cusp ridge Tip of the buccal cusp is centrally located over the root Mandibular R 1st premolar

Mandibular 1st Premolar Only premolar where more of the occlusal table can be seen from the mesial view, rather than the distal view Mandibular R 1st premolar

Mandibular 1st Premolar Occlusal view: Transverse ridge (union of two triangular ridges) Pits Diamond-shaped or triangular shaped Mandibular R 1st premolar

Mandibular 1st Premolar (Left) Buccal view Mesial view Lingual view Occlusal view

Mandibular 2nd Premolar Two or three cusps Buccal cusp is the largest In a 3 cusp form: ML is the second largest, DL is the smallest Bulks to the mesial Square or rectangular occlusal table Mandibular R 2nd premolar

Mandibular 2nd Premolar Occlusal view Y shape: B, ML, DL H shape: B, L U shape: B, L Most common Mandibular R 2nd premolar

Mandibular 2nd Premolar (Right) A. Buccal view B. Occlusal view C. Distal view

Mandibular Premolars (Buccal view)

Mandibular Premolars (Lingual view)

Mandibular Right Premolars (Mesial/Distal View)

Mandibular 2nd Premolars (Occlusal view)

References Woelfel and Scheid. Dental Anatomy, 6th Edition. Lippencott, Williams, and Wilkins, 2002, p. 148 - 174. Brand and Isselhard. Anatomy of Orofacial Structures, 6th Edition. Chapter 32 (p. 400 – 425), 7th Edition. Chapter 14 (p. 146 – 165). http://www.youtube.com/watch?v=524GZfAQWyQ http://www.youtube.com/watch?v=Ffz_P-eeR9o