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Oral Anatomy > Morphology of Premolars > Flashcards

Morphology of Premolars Flashcards

1
Q

Universal Numbering of Maxillary Premolars

A

R 4, 5

L 12, 13

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2
Q

Universal Numbering of Mandibular Premolars

A

R 28, 29

L 20, 21

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3
Q

Functions of Premolars

A
  • Mastication
  • Maintaining vertical dimension of face
  • Assist canines to shear or cut food
  • Support cheeks and corners of the mouth
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4
Q

Class Traits of Premolars

A

• Most premolars have two cusps (one buccal and one
lingual) but sometimes there are three cusps (one
buccal and two lingual); therefore, the term
“premolar” is better than “bicuspid”

• Premolars develop from three facial lobes (like
anterior teeth) and from one or two lingual lobes
corresponding to one or two lingual cusps

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5
Q

Class Traits of Premolars Similar to Anterior

Teeth

A

Crowns taper to
cervical

Cementoenamel
junction (CEJ) similar in
shape (but less curve)

Roots: taper narrower
apically and lingually

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6
Q

Class Traits of Premolars That Differ From Anterior

Teeth

A

Two or three occlusal cusps versus incisal edge

Marginal ridges more horizontal (EXCEPT mesial
marginal ridge of mandibular first premolar)

Crowns are shorter

Height of contour: facial in cervical third (not to
close to CEJ, EXCEPT mandibular fist premolar) and
lingual in middle third

Proximal contact areas more cervical and
broader

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7
Q

All Premolars From Buccal View

A

Pentagon outline of
crown (like canine)

Contact areas are
convex; distal contact is
more cervical than
mesial (EXCEPT
mandibular first
premolar)

Mesial cusp ridge
shorter than distal
(EXCEPT maxillary first
premolar)

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8
Q

All Premolars From Lingual View

A

Crown outline narrows toward lingual so some
proximal surfaces are visible (EXCEPT some
three-cusp-type mandibular second premolars with two
lingual cusps [seen best on occlusal view])

Buccal cusp longer than lingual cusp

• Lingual cusp off center to the mesial EXCEPT mandibular first premolar

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9
Q

Which premolar is the exception to the lingual cusp off center to the mesial?

A

mandibular first premolar

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10
Q

All Premolars From Proximal Views

A

Mesial marginal ridges are more occlusal than

distal (EXCEPT mandibular first premolar)

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11
Q

Mesial marginal ridges are more occlusal than

distal, except _________

A

mandibular first premolar)

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12
Q

All Premolars From Occlusal View

A

Wider faciolingually than mesiodistally

Occlusal table bound by marginal and cusp ridges

Proximal contacts are located buccal to the buccolingual midline; lingual embrasure spaces are larger

Triangular ridges join to form transverse ridges (EXCEPT threecusp-type mandibular second premolars).

A groove extends from mesial fossa to distal fossa (EXCEPT some mandibular first premolars)

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13
Q

Arch Traits That Differentiate Maxillary

From Mandibular Premolars

A

Mandibular premolars have more noticeable
lingual crown tilt than maxillary

Mandibular have less prominent buccal ridge

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14
Q

Less prominent buccal ridge (mandibular vs maxillary)

A

Mandibular

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15
Q

All premolars are larger buccolingually than

mesiodistally, true or false?

A

True

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16
Q

______ premolar is closer to square (buccolingual slightly greater than mesiodistal)

while ______ premolar is rectangular

A

mandibular = square

maxillary = rectangle

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17
Q

Relative Size of Maxillary Premolar Crowns From the Buccal View

A

Maxillary first premolar is larger than second

More convergence from proximal contact to cervical on first than second

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18
Q

Location of Contacts for Maxillary Premolars From the Buccal View

A

Mesial contact junction of occlusal and middle third, distal contact middle third (both types)

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19
Q

Location of Buccal Cusp Tip of Maxillary Premolars From the Buccal View

A

Maxillary second: mesial cusp ridge is shorter than distal (cusp tip mesial or centered)

Maxillary first premolar has mesial cusp ridge longer than the distal (UNIQUE) (cusp tip distal)

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20
Q

Shape of the Buccal Cusp of Maxillary Premolars From the Buccal View

A

Cusp is sharper on maxillary first premolar than second

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21
Q

Buccal Ridge and Depression of Maxillary Premolars From the Buccal View

A

Buccal ridge more prominent on maxillary first premolar than maxillary second

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22
Q

Root of Maxillary Premolars From the Buccal View

A

Maxillary first premolar is more likely to have two roots, whereas maxillary second premolar has one

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23
Q

When identifying the difference between maxillary premolars from the BUCCAL view, what 6 traits can help you distinguish between the first and second premolar?

A
  1. relative size of crown
  2. location of contacts
  3. buccal cusp tip location
  4. shape of buccal cusp
  5. buccal ridge and depression
  6. root #
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24
Q

Relative Cusp Size of Maxillary Premolars From the Lingual View

A

Lingual cusp shorter than buccal cusp; more so on maxillary first premolar than second

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25
Q

Cusp Ridges of Maxillary Premolars From the Lingual View

A

Lingual cusp is relatively sharper on maxillary second premolar than on first premolar

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26
Q

Lingual Cusp Position for Maxillary Premolars From the Lingual View

A

Both maxillary first and second premolars have

the lingual cusp tip positioned Mesial to the midroot axis

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27
Q

Marginal Ridges of Maxillary Premolars From the Lingual View

A

Distal marginal ridge is more cervical than

mesial for both maxillary first and second premolars (best seen by comparing mesial and distal views)

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28
Q

Roots of Maxillary Premolars From the Lingual View

A

Maxillary first premolar: lingual root is shorter than buccal root

Root crown ratio is 1.56 on first premolar and 1.82 on second premolar

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29
Q

Crown Shape and Morphology of Maxillary Premolars From the Proximal Views

A

Maxillary premolars have trapezoid outline

Maxillary first premolar is the only premolar to have a crown depression (always on
the mesial)

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30
Q

Relative Cusp Height of Maxillary Premolars From the Proximal Views

A

Lingual cusp shorter than buccal cusp, more so on maxillary first premolar than second premolar

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31
Q

Height (Crest) of Contour of Maxillary Premolars From the Proximal Views

A

Facial height of contour is in cervical third (like all teeth)

Lingual height of contour is in the middle third (like all posterior teeth)

32
Q

Distance Between Cusps on Maxillary Premolars From the Proximal Views

A

Distance between cusps is same for maxillary first and second premolars

Both buccal and lingual cusp tips are located over the root

33
Q

Marginal Ridge Grooves of Maxillary Premolars From the Proximal Views

A

Marginal ridge groove is found most often on the mesial marginal ridge of maxillary first premolar

Not as common on all other maxillary premolar

34
Q

Cervical Lines of Maxillary Premolars When Comparing the Proximal Views

A

More CEJ curvature on mesial than distal on both first and second premolars (as on all premolars and anterior
teeth)

35
Q

Roots and Root Depressions of Maxillary Premolars From the Proximal Views

A

Maxillary first premolar is only premolar with the mesial root depression more pronounced than
distal; only premolar with a mesial crown depression joining with the deep root depression

Distal root depression more pronounced on maxillary second premolar

36
Q

Relative Size of Maxillary Premolars From the Occlusal View

A

Maxillary first premolar likely to be slightly larger than second

37
Q

Grooves and Fossae of Maxillary Premolars From the Occlusal View

A

Central groove of maxillary first premolar is longer than on second premolar

Maxillary second premolar has more supplemental grooves than first

38
Q

Relative Proportions of Maxillary Premolars From the Occlusal View

A

Both maxillary premolars have noticeably greater dimension faciolingually than mesiodistally (by over 2 mm)

39
Q

Outline of Maxillary Premolars From the Occlusal View

A

Buccal ridge more prominent on maxillary first premolar than second

Maxillary first premolar outline is more asymmetrical (hexagonal) than second premolar

40
Q

Contact Areas and Heights of Contour of Maxillary Premolars From the Occlusal View

A

Contacts are near junction of buccal/middle thirds for both

41
Q

Type Traits That Differentiate Mandibular First From Mandibular Second Premolars

A

• Mandibular premolars vary in shape more than
maxillary premolars
• Mandibular second premolar is the only
premolar more likely to have three cusps (one
buccal and two lingual: mesiolingual and distolingual)

42
Q

Which premolar is the only premolar likely to have three cusps?

A

Mandibular second premolar (one

buccal and two lingual: mesiolingual and distolingual)

43
Q

Relative Crown Shape and Size of

Mandibular Premolars From the Buccal View

A
  • Mandibular first premolar is longer than the second
  • Both have rounded shoulders (first wider than second)
  • Buccal cusp apex of mandibular first premolar is sharper than second
  • Cusp ridge notches more common on mesial of first and distal of second
44
Q

Morphology of Mandibular Premolars

From the Buccal View

A

•Buccal developmental grooves on either side of buccal ridge (when present) are likely
deeper on the mesial of first premolar and
on the distal of second premolar
• Mesial cusp ridges shorter than distal

45
Q

Cervical Lines of Mandibular

Premolars From the Buccal View

A

CEJ is more curved on mandibular first

premolar than second

46
Q

Contact Areas of Mandibular

Premolars From the Buccal View

A

• Mandibular first premolar is the only
premolar (only adult tooth) where the mesial contact is more cervical than the distal
• First premolar distal contact is in occlusal third and mesial is at junction of occlusal and middle or middle

47
Q

_____ is the only adult tooth where the mesial contact is more cervical than the distal

A

Mandibular first premolar

48
Q

Roots of Mandibular Premolars From the

Buccal View

A
  • Both types of mandibular premolar roots taper to apex with distal bend of apex more common
  • Root crown ratio on second premolar is larger
49
Q

Crown Shape of Mandibular Premolars

From the Lingual View

A

Most mandibular premolars taper narrower toward lingual (EXCEPT three-cusp type of mandibular second premolar where lingual half may be wider than buccal half)

50
Q

Which mandibular premolar(s) may have a wider lingual half than the buccal half from the lingual view?

a. mandibular first premolar
b. mandibular second premolar
c. mandibular second premolar, 3 cusp type
d. a and b
e. all of the above

A

c. mandibular second premolar, 3 cusp type

51
Q

Lingual Cusps of Mandibular

Premolars From the Lingual View

A

Lingual cusp of mandibular first premolar is quite a bit shorter than the buccal; is non functional and is located just mesially of center

Lingual cusp of mandibular second premolar (with one lingual cusp) is slightly shorter than the buccal, and is mesial to midroot axis

When the mandibular second premolar has two lingual cusps, the mesiolingual cusp is normally wider and longer than the distolingual

52
Q 
Lingual cusp of mandibular
second premolar (with one
lingual cusp) is slightly
\_\_\_\_ than the buccal,
and is \_\_\_\_\_ to midroot
axis
A

lingual slightly shorter than buccal

and mesial to midroot axis

53
Q

When the mandibular second premolar has
two lingual cusps, the mesiolingual cusp is
normally _______ than the
distolingual

A

wider and longer

54
Q 
The \_\_\_\_\_\_ is the only
premolar (only
posterior tooth) to have
its mesial marginal ridge
more cervical than the
distal
A

mandibular first premolar

55
Q

Grooves on Mandibular Premolars From

the Lingual View

A

Only mandibular second premolars with two lingual cusps have a lingual groove separating them

Most mandibular first premolars have a
mesiolingual groove separating mesial marginal ridge from the mesial cusp ridge of the lingual cusp

56
Q

Only mandibular ______ with two lingual cusps have a lingual groove separating them

A

second premolars

57
Q

Most mandibular first premolars have a

________ separating mesial marginal ridge from the mesial cusp ridge of the lingual cusp

A

mesiolingual groove

58
Q

Roots of Mandibular Premolars From the

Lingual View

A

Roots taper lingual to apex

59
Q

Crown Shape of Mandibular Premolars

From the Proximal Views

A

• Crowns tip noticeably to the lingual, more so onbmandibular first premolar
than second
• Outlines are rhomboid
• Lingual cusps are shorter than buccal, more so on first with nonfunctional lingual cusp

60
Q

Marginal Ridges of Mandibular

Premolars From the Proximal Views

A
  • Mesial marginal ridge of mandibular first premolar slopes at 45º, nearly parallel to buccal triangular ridge
  • Lingual triangular ridge is very short
  • Other posterior marginal ridges are more horizontal
  • Occlusal plane in relation to midroot axis line 45º on first.
61
Q

Marginal Ridge Grooves and Mesiolingual

Grooves on Mandibular Premolars From the Proximal Views

A

• Mesiolingual groove is often present on
mandibular first premolars, not seconds
• Second premolars sometimes have
marginal ridge grooves

62
Q

Mesiolingual groove is often present on

mandibular ____ premolars, not ____

A

first premolars, NOT seconds

63
Q

Height (Crest) of Contour of Mandibular Premolars From the Proximal Views

A

• Buccal height of contour is in cervical third (near CEJ on first premolar)
• Lingual height is in middle third, nearly to cusp tip in mandibular first premolar,
and beyond root outline

64
Q

Cervical Lines of Mandibular

Premolars From the Proximal Views

A

• More CEJ curve on mesial than distal
surface (as on all premolars)
• Lingual CEJ is more occlusal than buccal (as on all premolars)

65
Q

Roots of Mandibular Premolars From the

Proximal Views

A

taper to apex (as all do)

66
Q

Root Depressions of Mandibular

Premolars From the Proximal Views

A

• Mandibular first premolar has mesial
and distal root depressions, deeper on
distal
• Mandibular second premolar likely to have distal root depression, but none on mesial

67
Q

Outline Shape of Mandibular

First Premolars From the Occlusal View

A

– Has more bulk in distal half than mesial half
– Mesiolingual line angle is flat (pushed in)
– Diamond-shaped occlusal outline
– Occlusal table is triangular

68
Q

Shape of occlusal outline of mandibular first premolar (occlusal view)

A

Diamond

69
Q

Shape of occlusal table of mandibular first premolar (occlusal view)

A

Triangle

70
Q

Outline Shape of Mandibular

Second Premolars From the Occlusal View

A

– Two-cusped type has almost rounded outline
– Three-cusped type has more square outline; may actually taper narrower from lingual to buccal
– Occlusal tables are square

71
Q

Shape of occlusal table of mandibular second premolar (occlusal view)

A

Square

72
Q

Ridges, Fossae, and Grooves of Mandibular First Premolars From the Occlusal View

A 
• Prominent transverse ridge
may separate mesial and
distal fossae (with no central
groove)
• Mesial and distal circular
fossae resemble “snake
eyes”
• Distal fossa larger than
mesial
• Mesiolingual groove extends
from mesial circular fossa
73
Q 
Occlusal Fillings (“Snake Eyes”) on \_\_\_\_\_\_ No Fissured Central Groove, Pronounced
Transverse Ridge
A

mandibular first molar

74
Q

Ridges, Fossae, and Grooves of the Two-Cusp Mandibular Second Premolars From the Occlusal View

A

Central groove connects mesial and distal fossae
• Groove pattern may be H or U shaped
• Buccal and lingual triangular ridges form
transverse ridge.

75
Q

Ridges, Fossae, and Grooves of the Three-Cusp Mandibular Second Premolar

A
  • Three triangular ridges; none connect so there is no transverse ridge
  • Only premolar with central fossa
  • Central groove may be called mesial and distal grooves joining at central fossae
  • Lingual groove forms “Y” pattern
76
Q

Marginal Ridge Grooves of Mandibular

Premolars From the Occlusal View

A

Marginal ridge grooves are not common on
mandibular premolars (although the mandibular first premolar often has a mesiolingual groove, which
separates the mesial marginal ridge from mesial cusp ridge of lingual cusp)

Oral Anatomy (6 decks)

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