Maxillary Molars Comparison Flashcards
1
Q
Mesiodistal Crown Width
A
First molar crowns are wider mesiodistally than second molars and second molars are wider than third molars
2
Q
Occlusocervical Crown height
A
The occlusocervical crown height of first molars is greater than second molars and second molars are greater than third molars
3
Q
Third molar form variation
A
- Third molars are less well-developed than the other maxillary molars
- Third molars vary from their “normal” form more often than other teeth
- The maxillary third molars frequently exhibits an extra small crown size (microdontia).
4
Q
Crown-root orientation
A
- On second molars, the disital aspect is shorter than the mesial when viewed from the buccal
- This creates a distal tipping on the root trunk with the occlusal surface slanting cervically from mesial to distal
- The distal tipping of posterior teeth is probably most apparent on maxillary second molars when viewed from the buccal.
5
Q
Cusp sizes
A
- The two buccal cusps are closer in size on first molars than second molars since the distobuccal cusp is much smaller relative to the mesiobuccal cusp on second molars
- When comparing cusp heights, it has also been stated that the buccal cusps are of equal height on first molars, the distobuccal cusp is slightly shorter than the mesiobuccal cusp on second molars, and on third molars the distobuccal cusp is much shorter than the mesiobuccal cusp.
6
Q
Buccal developmental grooves
A
- The buccal developmental groove is located farther distally on the crown surface of second molars than first molars, producing a relatively larger mesiobuccal cusp on second molars.
- The buccal groove is shorter on second molars than on first moars.
- According to the Tooth Atlas, there is NO pit at the termination of the buccal groove on second molars wherease first molars may have a pit.
7
Q
Root length
A
- The roots of first and second molars are about the same length, whereas the third molar is the shortest of the three
8
Q
Root form
A
- From a buccal view, the roots of maxillary first molars resemble the handles of a pair of pliers but this form is NOT present on second molars
9
Q
Root separation
A
- The roots have their greatest mesiodistal separation on first molars, less on second molars, and have the least separation (even fusion) on third molars.
- Partial or total fusion is common on second molars as well
10
Q
Root Alignment
A
- The mesial and distal roots are more parallel to each other on second molars than first molars.
11
Q
Root Inclination
A
- The distal inclination of the roots is greatest on third molars, less on second molars, and the least inclination occurs on first molars
12
Q
Root trunk
A
- The buccal furcation is located farther apically on the second molar than on the first molar.
- The cervico-apical dimension (height) of the root trunk is greatest on third molars, less on second molars, shortest on first molars.
13
Q
Cusps of Carabelli
A
- The Cusp of Carabelli is fairly common on first molars but somewhat rare on second molars; “Less common” would be better description.
14
Q
Distolingual cusp
A
- The distolingual cusp of the second molar is much shorter than the mesiolingual cusp
15
Q
Distolingual groove
A
- The distolingual developmental groove does NOT extend as far mesially or as far cervically on the lingual surface of second molars as it does on first molars
16
Q
Palatal (Lingual) Root width
A
- From a lingual view, the palatal root of first molars is wide mesiodistally; it is narrower on second molars, narrowest on third molars.
- The apex of the palatal root is aligned with the distolingual cusp tip on second molars whereas it is aligned with the lingual groove on first molars.
17
Q
Buccolingual crown width
A
- From an occlusal view, maxillary molar crowns are about the same width buccolingually, with first molars being slightly wider than seconds and third molars being narrower.
18
Q
Crown Outline
A
- The occlusal outline of first molars is square to rhomboidal. The Rhomboidal outline is more accentuated on second molars.
- The predominant occlusal outline form of third molars is “heart-shaped”.
19
Q
Third molar crown form
A
- Third molar crowns are more rounded and bulbous than first and second molars.
20
Q
Lingual crown convergence
A
- Second molars are narrower mesiodistally in the lingual half of the crown than first molars, producing a lingual crown taper
- There is even greater lingual convergence in third molar crowns
- First molars frequently have reverse taper (or reverse convergence) being wider on the lingual than on the buccal
21
Q
Distal crown convergence of second molars
A
- There is more distal crown taper on second molars than first molars.
22
Q
Distolingual cusp size
A
- The distolingual cusp is smaller on second molars than on first molars
- The distolingual cusp is usually very small or missing on third molars
- About three-quarters of the third molars have 3 cusps, although we see odd variations from one cusp (looking like a tiny canine) to as many as eight cusps
- When the third molar has 4 cusps the distolingual cusp could be very small or it could be normal-size and look like a smaller version of the second molar
23
Q
Mesiobuccal Angle
A
- When viewing second molars occlusally, the angle between the buccal and mesial surfaces (mesiobuccal angle) is more acute than it is on first molars.
24
Q
Mesiolingual and Distobuccal angles
A
- From an occlusal view, the obtuse angles found in the outline of the crown (distobuccal and mesiolingual) are more obtuse on second molars than on first molars
25
Q
Marginal Ridge Tubercles
A
- There are fewer marginal ridge tubercles on the mesial marginal ridge of second molars than first molars; tubercles are absent from third molars.
26
Q
Third molar occlusal surface area
A
- Third molars have the smallest occlusal surface area (smallest occlusal table)
27
Q
Cusp sizes
A
- On second molars, the two mesial cusps are about the same size as the mesial cusps on the first molars but the distal cusps are smaller and not as well-developed
28
Q
Oblique Ridge
A
- The oblique ridge is smaller on second molars than first molars
- The oblique ridge is rarely crossed by a groove in the first molar but is frequently crossed by a groove in the second molar
- The oblique ridge is barely visible or absent on third molars
29
Q
Pit-groove pattern/number
A
- The pit and groove pattern on the occlusal surface is more variable and there are more supplemental grooves on the occlusal surface of second molars than first molars.
- The pit and groove pattern on third molars frequently creates a wrinkled occlusal surface similar to the maxillary 2nd premoar.
