Pre-Molars Flashcards
What are the pre-molar #
4,5,12,13,20,21,28,29
Function of premolars include
- Mastication; help molars
- Maintain vertical dimesion of face
- Assit canines in cutting
- Support cheeks and corners of mout
Dimesion from the Bottom of the nose to the tip of the chin.
Vertical DImersion of Occlusion
How many lobes do PM have?
3 facial lobes, 1 lingual
PM
What tooth is the exception to cusp?
Mandibular 2nd PM can have 3 cusps (2 lingual)= 5 lobes instead of 4.
Facial proportion of pre-molars is formed by what?
Their 3 lobes; center buccal ridge, much shorter crown than canine.
All PM crowns taper where?
Cervically.
All PM roots taper where?
Apically
Pre molars have _____ marginal ridge expect what PM what is the diffrences?
Horizontal marginal ridges, but mandibular 1st PM have more verticel (45 degree) MMR
First premolar crowns are slightly ___ than second premolars.
Longer
____ of second premolars are slightly longer than first premolars.
Roots; 2nd PM longer.
Roots on maxillary premolars are considerably shorter than on ____ but similar in length to maxillary incisor roots.
Maxillary canines (much longer roots)
Roots on mandibular premolars are also shorter than on ____ , but longer than on mandibular incisors.
Mandibular canines (longer roots)
On PM, the ____ height of conture is more occlusal than on anteriors that have it much more cervicle at the cingulum.
Lingual more occlusal
Proximal contacts on PM are more what than on anterior?
More cerivcal and broader.
All pre molars except which have a crown that is narrower on the lingual?
3 cups mandibular 2nd PM
Tip of the PM lingual cusp is slightly mesial, Except on which?
Mandibular 1st Pm. Lingual cusp is centered.
On all PM, the MMR is more occlusal (cant see past it) than the distal, EXCEPT?
Mandibular 1st PM cause of that 45 degree marginal ridge.
Proportionally, on PM, what is wider FL or MD?
FL is wider.
Where are the proximal contacts located? How does this affect the emasures?
Contacts located BL midline, this makes lingual embasure much bigger.
How many cusp ridges to PM have? What can be the excepetion?
All but 3 cusped mandibular 2nd pm (2 lingual ridges, 1 buccal) have 1 buccal and 1 lingual cusp ridge that form a transverse ridge.
The transverse ridge on the mandibular first pre molar seperates what?
Mesial and distal fossa!
All pre-molars have a more ___ contact, how does this afffect size of embasure?
More buccal contact= large lingual embasures= better to put wedge in the lingual!
Mandibular crowns tilt in what direction? Maxillarys are ?
Lingual tilt= mand
Straight= max
On Maxillary 2nd PM what are cusp size comparison?
Minimal size diffrence.
On all but maxillary 2nd PM the buccal cups is what compared to the lingual?
Larger and tips to the distal
On maxillary 1st PM the buccal ridge is?
More prominant
Maxillary vs mandibular
WHat arch or PM
The occlusal table is oblong/ rectangular
WIider FL than MD
Maxillary PM
What arch PM?
The occlusal table is equal dimension
same FL than MD
Mandibular PM
What maxillary PM?
- Larger overall.
- More pointed cusps
Maxillary 1st
Where are mesial and distal contacts located on Maxillary Pre-molars?
Both in middle third (distal is more cerviical)
What Max PM?
Buccal cusp is more distal from a buccal view, b/c mesial cusp ridge is shorter.
Max 2nd PM
What Max PM?
Buccal cusp is distal to axis, from a buccal view
Max 1st PM
What Max PM?
Buccal cusp ridge is more prominant, due to following prominant labial ridge on canine.
1st Max PM
What Max PM?
More often bifrucated
Max 1st
Compare Maxillar PM cusp sizes
1st= buccal cusp much bigger
2nd= pretty similar cusp size, more even. Buccal still a little bit bigger.
On which maxillary PM is lingual cusp relativley sharper?
Maxillary second PM
On both max PM, the MMR is what?
MMR = more occlusal!
On maxilary 1st PRe molars, the mesial cusp ridge is what?
Mesial cusp ridge is Longer than the distal cusp ridge.
Maxillary 1st PM have what very distinguishing trait?
Mesial crown concavity!
On Max PM the facial height of conture is where?
Cervical 3rd like all theeth.
On Maxillary PM the lingual height of conture is where?
Middle 3rd like posterior teeth!
Only tooth with more pronounced mesial root depression that distal? + what?
Max 1st PM
mesial root depression + mesial crown concavity
What maxillary PM has a logner central groove?
Maxillary 1st PM
WHat maxillary PM has a shorter central groove but more supplementaal grooves?
Max 2nd PM
On maxillary 1st PM, if these feature is presentm it makes the central groove look even longer. What is it?
Mesial Marginal groove, looks like it falls off side
What maxillary PM is more assymetrical ?
Max 1st
Where are the contacts on Maxillary PM located?
Both are more buccal, but distal is even farther out. = small buccal embasure
The Mandibular 1st pre-molar has a ____ and ____ buccal cusp that the 2nd
Longer And Sharper Buccal cusp (1st)
On **mandibular 2nd pre molars, **the buccal ridge depressions when present are more common where?
Distal cusp ridge notch more common
The location of proximal contact area on the 2nd mandibular pre molars are where?
Both on incisal 3rd, mesial is more occlusal, distal more cervical.
An exception to the rule, mandibular 1st pre molar contacts are where, and why?
The mesial contact is much more cervical, distal contact is more occlusal. This is due to how veritcle the MMR on the 1st PMs are.
The roots of madibular PMs trend how?
The have a distal root bend at the apex, this is because mandible is shorter.
On mandibular 1st pre molars,the buccal ridge depressions when present are more common where?
Mesial cusp ridge notch more common
Most mandibular PMs taper narrower from ____ to ____ EXCEPT on what, and why?
Taper Buccal to lingual, except on 3-cusped mandibular 2nd PMs which have 2 lingual cusps and are therefore; wider on the lingual instead.
The lingual cusp of what PM is much shorter than the distal and almost uselfess?
Mandibular 1st PM
All lingual cusps on PMs tip what way at the midtooth axis?
Mesial
What cusp on the mandibular 2nd PM (3cusp) is wider and longer than what cusp?
ML cus is wider and longer than the DL cusp
mandibular 2nd molar
Which is the only premolar to have its mesial marginal ridge more cervical than the distal?
Mandibular 1st PM
What PM has a Mesio-lingual groove?
Mandibular 1st PM
Compar the lingual tilt of the Mandibular 1st and 2nd PM?
1st PM is much more tilted than the 2nd PM
Outline shape from a proximal view of mandibular PM?
Rhomboid.
Where are the heights of contour on the buccal and lingual of mandibular pre-molars
Lingual height of contour is on the middle 3rd
Buccal height of contour is on the cervical 3rd
Explain root depression on mandibibular PM
Mand 1st PM= depressions on M/D, deeper distal
Mand 2nd PM= none on M, Distal depression
From the occlusal view how does mandibular 1st PM compare to Manibular 2nd PM
Mand 1st= mesial smaller than distal
Mand 2nd= mesial and distal pretty even
Mandibular 1st PMs have a ____ shaped outline, the ____ corner is flat, and the there is more bulk on the ____ half of the crown
Mandibular 1st PMs have a dimond shaped outline, the ML-corner is flat, and the there is morebulk on the Distal half of the crown
Compare the shapes of the 2 types of mandibular 2nd PM
2 cusps= round
3 cusps= squarish
Mandibular 1st PM
There are prominat __ __ that seperate the mesial and distal fossae with no ____ ___
Prominant transverse ridges, no central groove.
Mand 1st PM
ONLY premolar with central fossa/pit
3 cusp Mandibular 2nd Pre molar
3 triangular ridges, no transverse.
Which PMs
Mesial cusp ridge of the buccal cusp is longer than the distal cusp ridge
Max first PM
Has a nonfunctioning lingual cusp.
Mandibular 1st PM
Two premolars that most frequently have a groove crossing the mesial marginal ridge or one groove just lingual to it.
- Maxillary 1st PM
- Mandibular 1st PM
Has a depression in the cervical one third of the mesial side of the crown and root.
Max 1st PM
Maxillary premolar that has the longer sharper buccal cusp.
Max 1st PM
Largest maxillary premolar
Max 1st PM
Mandibular premolar with the longest and sharpest buccal cusp.
Mandibular 1st PM
Maxillary premolar that is most symmetrical (occlusal view).
Maxillary 2nd PM
Two premolars without a central groove
- Mandibular first premolar
- Mandibular second premolar (three-cusp type)
Crowns tipped lingually with respect to the root axis line (proximal view)
All mandibular PM
From buccal view, crown is tipped distally from the root axis.
- Mandibular first premolar
- Mandibular second premolar (two-cusp type)
- Mandibular second premolar (three-cusp type)
Mesial marginal ridge is more cervically located than its distal marginal ridge
ONLY mandibular 1st PM
Has no transverse ridge.
3 cusp mandibular 2nd PM
Longest central groove
Maxillary 1st PM
Has two major cusps almost the same size and length.
Maxillary 2nd PM
Has a central fossa.
3 Cusp Mandibular 2nd PM
Premolars with only two fossae: both are triangular fossae.
Max 1st, 2nd, Mand 2nd
Has a central fossa and two triangular fossae.
3 cups mandibilar 2nd PM
Has a lingual groove
3 cups mandibilar 2nd PM