Premolars

Question 1

Premolars usually have how many cusps? Which tooth is the exception?

Answer 1

Usually 2 cusps

Mandibular 2nd premolar can have 3 cusps - 1 buccal and 2 lingual cusps

Question 2

What is the angle of the mesial marginal ridge on the first premolar with respect to horizontal?

Answer 2

45

Question 3

Where are crests of curvature located on the buccal aspect of premolars?

Answer 3

Cervical third but more occlusally located than on anterior teeth

Question 4

Where are crests of curvature located on the lingual aspect of premolars?

Answer 4

Middle third

Question 5

Where are mesial proximal contacts located on premolar? What is the exception?

Answer 5

Junction of occlusal and middle thirds

Mandibular 1st premolar has more cervical mesial contact and higher distal contact.

Question 6

Where are distal proximal contacts located on premolars?

Answer 6

Middle third

Question 7

Where are proximal contacts located when viewed from occlusal view?

Answer 7

Buccal to the center faciolingually

Question 8

From the facial, what is the shape of the premolars?

Answer 8

Pentagon shaped

Question 9

Where is the buccal cusp tip with respect to the mid-root axis? What is the exception?

Answer 9

Buccal cusp tip is mesial to mid root axis leads to short mesial marginal ridge

Exception is Maxillary 1st premolar, whose buccal cusp tip is distal to midroot axis which leads to longer mesial marginal ridge

Question 10

Which premolar has a longer mesial marginal ridge and why?

Answer 10

Maxillary first premolar has a longer mesial marginal ridge because the buccal cusp tip is located more distal to the midroot axis.

Question 11

From the occlusal view, premolars are wider in which direction?

Answer 11

Premolars are wider faciolingually than mesiodistally

Question 12

From the occlusal view what are shapes made by the mandibular premolar and maxillary premolar?

Answer 12

Mandibular premolar - oblong shape

Maxillary premolar - square in shape

Question 13

What is the shape made by the cervical lines facially and lingually and which way does it point?

Answer 13

Cervical lines are convex

Curves apically facially and lingually

Question 14

What is the shape made by the cervical lines on the proximal aspect and which way does it point?

Answer 14

Cervical lines are convex and they point oclussaly.

Question 15

Which way does the apical third of roots bend?

Answer 15

It bends distally more than mesially