Premolars Flashcards
What is the palatal surface of an upper first premolar like compared to the buccal surface?
Slightly lower and much narrower
What is the distal surface of an upper first premolar like?
Very convex
What is the mesial surface of an upper first premolar like?
Convex only in its occlusal half, its cervical half is very concave
What is the canine fossa?
The concavity that continues on to the cervical region of the root
- This is the surface which contacts the distal surface of the upper canine
What is a distinguishing feature of the upper first premolar?
- A well-defined developmental groove in the enamel of the mesial marginal ridge
- This groove is in alignment with the developmental depression on the mesial surface of the root but is not usually connected with it
- The groove continues with the central groove of the occlusal surface
What shape is the occlusal surface of the upper first premolar?
- Roughly oval
Which cusp of the upper first premolar is wider and higher than the other cusp?
The buccal cusp
Which cusp shows a marked mesial displacement?
The lingual cusp
What are the 2 cusps of the upper first premolar joined by?
Marginal ridges, of which the mesial is higher
What are the features of the sharp fissure running mesio-distally on the occlusal surface of an upper first premolar?
- Does not reach the distal marginal ridge but often extends across the mesial marginal ridge on the mesial surface
How many roots does an upper first premolar have?
- Over 50% of upper first premolars have 2 roots, one buccal and one lingual
Where is the bifurcation of the roots on an upper first premolar?
A variable distance from the cervical margin
Which surface of the root of an upper first premolar is more deeply grooved than the other surface and shows concavity in the cervical region?
The mesial surface
Which part of the root of an upper first premolar usually has a marked distal curvature?
The apical part
What is the upper second premolar like compared to the upper first premolar?
- Usually smaller
What are the 2 cusps of an upper second premolar like?
- Usually similar in width and height, due tot the reduction in size of the buccal cusp
Is there a developmental depression evident on the mesial surface of the crown of an upper second premolar?
no, however the mesial surface of the crown is convex
Which cusp of the upper second premolar has slight mesial displacement?
The lingual cusp
How many roots does an upper second premolar usually have?
- Only 15% have 2 roots, although the single root is usually deeply grooved
Does the sharp fissure on the occlusal surface of the upper second premolar reach the marginal ridges?
No
What way is the buccal surface of a lower first premolar inclined?
- Inclined strongly lingually
What is the lingual surface of a lower first premolar like compared to the buccal surface?
- Slightly narrower and much lower than the buccal surface
What is the occlusal surface of a lower first premolar like?
- Almost round
Which cusp of a lower first premolar is displaced distally?
- Lingual
What is the crown of a lower second premolar like compared to a lower first premolar?
Much larger than that of the first
What is the occlusal surface of a lower second premolar like?
- The lingual cusp is much larger than that of the first and displaced mesially
How many lingual cusps does a lower second premolar have?
There may be 2 lingual cusps, if so, the mesial cusp is larger
Which fossa on the occlusal surface of a lower second premolar is generally larger?
The distal fossa
Which marginal ridge of the lower second premolar is more cervical?
Distal marginal ridge
What does unilateral mean?
Affecting only one side
What does bilateral mean?
Affecting both sides
What does ipsilateral mean?
Belonging to or occurring on the same side of the body
What does contralateral mean?
Occurs on the opposite side of the body
