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Oral Anatomy > molars > Flashcards

molars Flashcards

1
Q
  1. The buccal height of contour for molars is in the middle 1/3. T/F
  2. The lingual ht of contour (aka crests of curvature) is in the middle 1/3. T/F
  3. The ht. of contour of molars is the different than premolars. T/F
A
  1. False. All teeth have their buccal height of contour in the cervical 1/3.
  2. True. The lingual height of contour for molars is in the middle 1/3.
  3. False. Molars have the same general locations for height of contour as premolars - the buccal is found in the cervical third, the lingual ht of contour is in the middle third.
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2
Q

where are the proximal heights of contour found on molars
M:
D:

  1. what is the general trend for location of proximal contacts when comparing M to D locations?
  2. What is an example (hint, not a molar) of an Exception to the trend found regarding M-D proximal contacts?
    3a. what traits causes this exception
A
  1. the mesial ht of contour (aka proximal contact) is in the junction bt the occlusal and middle thirds.

the distal ht of contour is found in the middle of the tooth in the middle 1/3 – and is more cervical compared to the proximal contact on the M side.

  1. A general trend can be seen regarding M/D proximal contacts:: The mesial proximal contact tends to be more occlusal than the distal contact.
    - - this is due to a few other general trends, including that the crown on the mesial side tends to be taller than distal (crown tapers from M to D), and that the mesial cusp bridge tends to be shorter than the distal which leads to the mesial marginal ridge being more occlusal
  2. An exception to the rule is found in the MANDibular 1st premolar- in the MAND 1st premolar, the M contact is more cervical than the D, and this is partially due to the 45 degree angle found in the M marginal ridge connecting the B and L cusps..
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3
Q

When aligned along the vertical root axis, are the lingual or buccal cusps of molars taller (cervico-occlusally)?

A

When aligned along the vertical root axis, the L cusps are taller than the B. Perhaps, counterintuitive, but recall that CEJ is more occlusal on the buccal side than the lingual side, so lingual cervico-occlusal dimension is taller than appears (and lingual tilt of MAND teeth also makes the B seem taller) this relation does not pertain to other teeth where the B cusps (such as in premolars) are taller than the L.

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4
Q

All molars have the M-D dimension longer than the F-L. T/F

A

False. The MAX molars have a F-L dimension slightly longer than the M-D. MAND molars do have a longer M-D than F-L.

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5
Q

what geometric shapes are used to describe

  1. mandibular molars? (and why)
  2. maxillary molars (and why)
A
  1. A rectangle or pentagon is used to describe mandibular molars bc the M-D dimension is larger than the F-L.. and some MAND molars (MAND 1st) have 5 cusps giving a pentagonal outline
  2. Maxillary molars can be described as rhomboid / parallelograor square. The F-L and M-D dimensions are very close, thought he F-L is slightly longer than M-D.
    the rhomboid has 2 parallel sets of lines with different angles. The sharper angles are at the MB and DL, while the more obtuse angles are at the DB and ML ). The acute angles are more acute and obtuse more obtuse on 2nd MAX molars giving it a more twisted look vs MAX 1st molar.
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6
Q

How many roots do MAND molars have? Which one is the longest

A

MAND molars have 2 roots, aligned M and D. The M root is longer than D

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7
Q

How many roots do MAX molars have? Which one is the longest?

A

MAX molars have 3 roots, BM, BD, and Lingual. The lingual is the longest , the mesiobuccal is middle length and wider than the DB, and the distobuccal is the smallest root

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8
Q

On which molar can an oblique ridge be found?

Which cusps are involved with the oblique ridge

A

The oblique ridge can be found on the 1st MAX molar, and runs between the ML to DB cusps

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9
Q

Where is the cusp of Carabelli found? Is it functional (why or why not)

A

The cusp of Carabelli is a possible 5th cusp found on the 1st MAX molar, on the ML cusp. It is a nonfunctional cusp since it does not occlude (not active in occlusion)

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10
Q

True or F. Molars comprise approx. half of the length of each arch.

A

True,. The MAND molars take up apprx 51% of the MAND arch while MAX molars take up apprx 44% of MAX arch

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11
Q

In general, how do molar crowns compare to crowns of other teeth?

A

Molars have the largest crowns, but are the shortest on the cervico-occlusal dimension. Molars have the largest occluding surface of all teeth

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12
Q

what about the MAX 1st molar might defy the general trend for crowns to taper from B to L?

A

The MAX 1st molar has a DL cusp, which is the smallest cusp but can be large enough to skew the general trendfor B-to L tapering (in MAX 1st molar, ML cusp = largest cusp of MAX 1st molar)

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13
Q

What tooth has the widest crown in the mouth?

what tooth has the narrowest crown in the mouth?

A

The MAND 1st molar has the widest crown in the mouth

The MAND central incisor has the narrowest crown in the mouth

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14
Q

ROOTS: 1st Vs. 2nd on molars. Describe, and describe furcation

A

The mesial root is longer and wider. The roots taper from B to L (more narrow on Lingual aspect). When looking at a tooth from mesial aspect, cannot see the distal root bc mesial larger and wider.

1st molars have more divergent roots than 2nd molars which have parallel roots with less divergence

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15
Q

MAND molars can have a diminished CEJ profile (close to the furcation area) and the enamel can touch the bifurcation area ( in other words.. the CEJ can dip into the furcation area) – is this potentially problematic?

A

Yes. Having the enamel so close to the furcation area often leads to periodontal issues (such as exposed furcation area due to gingival recession, decay in the furcation area…)

The MAND 1st molar has a shorter trunk (root area before the bifurcation) than 2nd

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16
Q

T/F. The MAND 2nd molar tapers more from occlusal to CEJ than the 1st MAND molar.

A

False. The 1st molar tapers more from occlusal to CEJ due to the distal cusp. The distal end of the molar crown tilts a bit distally and extends beyond the CEJ profile.

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17
Q

T/F. All MAND 1st molars have 5 cusps

A

False. 15-20% of MAND 1st molars have only 4 cusps.

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18
Q

T/F. MAND molars can have more than 2 roots.

A

True. Molars may have extra roots

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19
Q

The MAND molars have 2 lingual cusps.. the lingual groove between the cusps is prone to caries. T/F

A

False. The lingual groove extending onto the lignual surface from between the lingual cusps of MAND molars is NOT prone to caries

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20
Q

T/F. All molars have their lingual crest of curvature in the cervical third.

A

False. All molars have their lingual crest of curvature in the middle third.

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21
Q

Where is there a particularly prominent ridge on the MAND 2nd molar?

2/ Where is the prominent ridge on the MAND 1st molar?

A

There is a particularly prominent ridge - the buccal cervical ridge, running mesiodistally on the MESIAL aspect of the MAND 2nd molar

  1. The MAND 1st molar is most prominent facially in the middle of the buccal– over the distobuccal cusp (recall, the 3rd facial cusp is the small Distal cusp, and the middle facial cusp is calle the Distobuccal)..
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22
Q

When handheld, are the buccal or lingual cusps of MAND molars taller

A

When hand held (along long vertical axis of root), the lingual cusps are taller than the buccal (and ML taller than DL.. going alng with general trend for crown taper from M to D). Lingual cusps of MAND molar taller and SHARPER than buccal

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23
Q

Describe the behavior of the CEJ line from B to L of MAND molars

A

the CEJ of MAND molars goes occlusally from B to L (CEJ more occlusal on lingual aspect than buccal)

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24
Q

T/F Distal marginal ridge and distal proximal contact is more cervical than the Mesial marginal ridge and mesial proximal contact/.

A

True, the Distal marginal ridge and distal proximal contact are more cervical than the Mesial marginal ridge and mesial proximal contact.

25
Q

Describe the root depressions found in MAND molars

A

the cross-section of MAND molars at the root level shows the D root with one canal, kidney shape- the D root has a slight M root depression and variable depression presence on the D. The Mesial root, though often 1 root is wide, and contains 2 root canals. The M root has a root depression on both the M and D aspects.. – defined depression on the M root is evidence of the 2 canals contained within

26
Q

Describe the ridges of the MAND molars

1st and 2nd

A

The 1st MAND molar has 2 transverse ridge from the triangular ridges joining up. The MB meets w ML, the DB mees w DL, and the distal cusp has a triangular ridge that is on its own

the 2nd MAND molar has 2 transverse ridges, the MB meets w ML, and DB meets w DL.

27
Q

The Buccal groove on the 2nd MAND molars is caries prone. T/F

A

True. The buccal groove on the 2nd MAND molar is caries prone – unlike the the lingual groove on the MAND molars which are Not caries prone

28
Q

what is an extra lingual cusp called?

A

an extra lingual cusp is called tuberculum intermedium

29
Q

what is an extra cusp (tubercle) on the distal marginal ridge of the first molar is called….?

A

an extra cusp (tubercle) on the distal marginal ridge of the first molar is called tuberculum sextum

30
Q

What is the largest tooth on the maxillary arch?

A

The 1st maxillary molar is the largest tooth in the MAX arch

31
Q

What is the largest and longest cusp of both MAX molars?

A

The Mesiolingual cusp is the largest cusp of the MAX molars

32
Q

Are the buccal grooves of the MAX molars prone to decay?

A

No. The MAX molars are not prone to decay – they do not have pits.

33
Q

Maxillary roots: How many? What is sizing of roots? Describe furcation

A

Maxillary molars have 3 roots. The lingual root (banana) is the longest and is visible bt the 2 B roots (MB and DB- the MB the 2nd largest). The furcation description for MAX molars is similar to MAND ::: the trunk of the 1st MAX is shorter than 2nd, and the roots of 1st MAX have a wider furcation/ spread than do the 2nd MAX molar.

34
Q

T/F all MAX 2nd molars have 4 cusps

A

False. 33% of the time, the 2nd MAX molar may be missing the DL cusp (which is smaller than the DL cusp of the 1st MAX molar)

35
Q

What does the MAX sinus have to do with the MAX arch? Importance?

A

Sometimes the roots of MAX teeth can poke through the floor of the MAX sinus. This is important to know for sake of root canals, implants, extractions, etc. Infection is possible, and sometimes the floor of the sinus has to be raised in order for dental procedures (like implants)

  • sometimes “tooth pain” may actually be the pain of a sinus infection
36
Q

Are the lingual grooves/ pits caries prone of MAX molars?

A

Yes, the lingual grooves/ pits of MAX molars are caries prone

37
Q

What is the prevalence of the cusp of Carabelli?

A

The Cusp of Carabelli is present about 70% of the time in MAX 1st molars

38
Q

What depression may be visible on the lingual root of MAX 1st molar?

A

A longitudinal lingual root depression may be visible on the Lingual surface of the MAX 1st molar

39
Q

Why is it important to know about location of depressions on roots?

A

Roots depressions can be a site of crud build-up and therefore knowledge of which will allow proper leaning of tooth surfaces

40
Q

What tooth has the largest root-crown ratio?

A

The MAND 1st molar at 1.83.. the MAX 1st molar is close with a root-crown ratio of 1.82

41
Q

where are the heights of contour located on the facial and lingual sides for MAX molars?

A

the facial height of contour is in the Cervical 1/3 (as with ALLLL teeth) . The lingual ht contour is in the middle 1/3, as with all posterior teeth ((note, if large cusp carabelli, the ht of contour on the lingual side for MAx 1st molar could be a bit more occlusal than the middle 1/3)

42
Q

T/F Distal marginal ridge grooves are commonly seen on the MAX 1st molar

A

False. MESIAL marginal ridge grooves are commonly seen on MAX 1st molars.

43
Q

What roots can be seen from the mesial aspect of MAX molars?

A

Only 2 roots can be seen from the mesial aspect– the lingual root (the banana) and the MB root. The DB root cannot be seen mesially since the MB is wider and longer and therefore blocks the view. Keep these size relations in mind as analyzing things like radiographs where structures may be blocked from view by larger structures

44
Q

Describe the root depressions seen on MAX molars

A

MAX molars, root depressions:: the MB root has M and B root depression, the DB less likely to have any depressions

similarly, recall that MAND molars likely to have M and B root depressions on the M root and maybe a M root depression on the Distal root (distal root depression on D root is variable)

45
Q

For MAX molars, is the F-L or M-D dimension larger?

A

For MAX molars, the F-L dimension is larger than the M-D (the dimensions are closer in size in MAX 1st than MAX 2nd)

46
Q

T/F. The MAX 1st molar Always tapers from B to L like the general trend found in all other teeth. Why?

A

False. Sometimes the MAX 2st molar is larger M-D on the lingual aspect than buccal- contrary to the genral trend- due to the large DL cusp. (though ML cusp = largest on MAX molars)

47
Q

what is the general geometrical shape description for MAX molars?

A

MAX molars are generally described as rhomboid.
The 1st MAX molar has more equal dimensions and can be more square-like.
The 2ns MAX molar is more twisted looking due to a large MB cervical ridge.

on both MAX molars, the sharp angles are found on DL and MB , and the more obtuse on ML and DB .. the angles are more exaggerated (sharp = sharper, obtuse = wider) on 2nd than 1st.

the 3-cusp style MAX 2nd molar is heart-shaped

48
Q

What is the primary cusp triangle?

A

The primary cusp triangle is a triangle formed by the 3 main cusps on the MAX 2nd molar : the MB, DB, and ML. The distolingual cusp is smaller and is sometimes absent (missing 33% of time).

49
Q

What ridges form in the MAX 1st molar?

A

the MAX 1st molar has 2 ridges – and oblique ridge spaning from ML to DB, and a transverse ridge joining the traingular ridges of opposing ML and MB cusps.

50
Q

Name the fossa present in a 4-cusp style MAX molar. What cusp is missing if a 3-cusp MAX molar?

A

There are 4 fossae found in 4-cusp MAX molars –
in order of size:: the Central fossa (largest ), the distal oblique (bt the ML and DL cusps.. cigar shaped), mesial triangular (has a pit, in cnetral groove), and distal traingular (has a pit, along central groove)

if 2nd molar only w 3 cusps, the cigar-shaped Distal oblique cusp is not present

51
Q

Name the GROOVES present on MAX 1st molar1

A

There are 5 grooves present on MAX molars – 1) central groove (from mesial to central fossa), buccal groove (from buccal aspect to central groove), the distal oblique groove (from distal fossa along oblique ridge on distal side..), the lingual groove (the continuation of the distal oblique groove to the lignual surface– * is caries prone**, and the transverse groove of oblique ridge (present on MAX 1st molars w oblique ridge)

  • if a 3 cusp style MAX molar - has 2 grooves - the central groove and the buccal groove
52
Q

Describe the location of the proximal contacts of MAX molars:

A

MAX molars have proximal contacts Buccal tot he BL center. the M prox contact is more buccal than the D prox contact..

EXCEPTION MAX 1st molar has a distal prox contact CENTRALLY located

53
Q

If there is not caries undermining the tooth structure, what ridge should not be drilled through?

A

If caries is not undermining the structure, the oblique ridge of the MAX 1st molar should not be drilled through bc is thick, sound tooth structure.

54
Q

The central groove of the MAX 1st molar – what is its extent?

A

The central groove of the MAX 1st molar only extends from the mesial aspect to the central fossa – it does not cross the oblique ridge and therefore does not run the entire span of the M-D tooth surface

55
Q

What is the only MAX tooth to occlude with only one other tooth?

A

The MAX 3rd molar

56
Q

What is the only MAND tooth to occlude w only one other tooth?

A

the MAND central incisor is the only MAND tooth to occlude with only one other tooth

57
Q

What teeth are the shortest of all teeth?

A

The third molars are the shortest teeth – they have short crowns and short roots.

58
Q

T/F Third molars have the greatest variance of shape?

A

True 3rd molars have the greatest variance of shape

59
Q

Describe the root pattern of 3rd molars

A

MAX 3rd molars usually have 3 roots
MAND 3rd molars usually w 2 roots.

Roots often are fused w long trunk
Roots are thin and often bent distally

Oral Anatomy (6 decks)

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