1
Q
Buccal cusp size
A
- The distobuccal cusp is smaller in size and height than the esiobuccal cusp
2
Q
Buccal cusp form
A
- The sharpness of the two buccal cusps is equal
3
Q
Buccal Groove
A
- The buccal groove is located distal to the center of the crown, producing a relatively large mesiobuccal cusp
- The buccal groove does NOT extend to the middle third of the crown.
4
Q
Root length
A
- The buccal roots are about the same length; the palatal root is the longest.
5
Q
Root trunk
A
- The root turnk is relatively long
6
Q
Root form & proximity
A
- The second molar roots are relatively close together.
- The roots are relatively straight
- The buccal roots are nearly parallel.
- All these features (long root trunk, straight, parallel roots) decrease the bony anchorage relative to that of the first molar.
7
Q
Root Curvature
A
- The roots are slightly curved and have a prominent distal inclination.
8
Q
Distobuccal root extension
A
- The distobuccal root extends slightly distal to the surface of the crown
9
Q
Occlusocervical crown height
A
- The distal half of the crown is shorter than the mesial half
10
Q
5th cusp
A
- The Cusp of Carabelli is seldom found on second molars, but it is a possibility.
- “Seldom” is misleading; it’s less common than on the first molar but it’s still frequently present.
11
Q
Lingual cusp sizes
A
- The mesiolingual cusp is much larger and taller than the distolingual cusp
12
Q
Lingual groove
A
- The lingual groove terminates distal to the center of the lingual surface.
- The lingual groove terminates occlusal to the center of the lingual surface.
13
Q
Root visibility
A
- The roots curve distally and the close approximation of the buccal roots hide large portions of these roots from view
14
Q
Palatal (lingual) root curvature
A
- The palatal root curves distally.
15
Q
Distal crown width
A
- The crown is narrower buccolingually in the distal half
16
Q
Crown outline
A
- The outline of the crown has most commonly been described as being rhomboidal.
- The outline of the crown has sometimes been described as resembling a parallelogram, triangular or heart shaped.
- Triangular and heart shaped arise from those teeth where the distolingual cusp is absent.
17
Q
Mesiobuccal angle
A
- The angle between the buccal and the mesial surface is quite acute.
18
Q
Lingual crown convergence
A
- The crown has a lingual taper.
19
Q
Mesial proximal contact
A
- The buccolingual position of the mesial proximal contact has been located buccal to the middle of the crown
20
Q
Distal proximal contact
A
- The buccolingual position of the distal proximal contact has been located at the middle of the crown, an exception to the rule that the contacts are oriented buccally.
- The contact is usually a broad, flat area rather than a point.
21
Q
Distolingual cusp size & Presence
A
- There is considerable variation in the size of the distolingual cusp, but usually it tends to be relatively small.
- According to the Tooth Atlas it is absent 33 to 38% of the time, but that percentage seems too high.
- The three cusp second molar is heart-shaped.
22
Q
Buccal cusp sizes
A
- The mesiobuccal cusp is noticeably larger than the distobucal cusp
23
Q
Supplemental grooves
A
- The pit and
groove pattern
is quite variable
with multiple
supplemental
grooves on the
occlusal surface. - The central groove
frequently crosses
the oblique ridge.
24
Q
Marginal ridge groove
A
- There is disagreement
whether the tooth has
a mesial marginal ridge
groove. - One expert says the
marginal ridge does
not have a groove,
another says it has
a groove 67% of the
time.
25
Marginal ridge tubercles
* On second molars,
38% of the teeth had
mesial marginal ridge
tubercles (not shown).
26
Buccal root dimensions
* The mesiobuccal root
is wider buccolingually
than the distobuccal
root (not visible from
this view).
27
Palatal (lingual) root form
* The palatal root is
relatively straight.
28
Root extension
* Except on rare
occasions, the roots
are contained within
the peripheral contours
of the crown.
29
Distal crown convergence
* The buccolingual
width of the distal
aspect of the crown
is considerably less
than that of the mesial
half of the crown.
30
Distal crown convergence
* The buccal and
lingual surfaces
are visible because
of this distal taper.
31
Mesial cusp visibility
* Due to shorter
distobuccal and
distolingual cusps
the mesial cusps
are readily visible.
32
Occlusal surface visibility
* The less prominent
distobuccal and
distolingual cusps
permit a greater
portion of the occlusal
surface to be visible
from a distal view.
* Another reason that
the occlusal surface is
visible from the distal
is that the crowns of
all the posterior teeth
are slightly tipped to
the distal.
33
Marginal ridge groove
* The distal marginal
ridge has a groove
38% of the time,
tubercles 9% of
the time (neither
is shown).
34
Cervical line form
* There is less occlusal
curvature of the
cervical line on the
distal, averaging
between 0.0 (flat)
and 0.2 millimeters.
* Even when present,
the curvature is so
small as to be barely
noticeable, and this
represents the end
point of the trend
that the cervical line
flattens as we move
from mesial to distal.
35
Distobuccal root dimensions
* The distobuccal
root is narrower
buccolingually and
may be shorter than
the mesiobuccal root.
* They could also
be the same length.
36
Palatal (lingual) root apex location
* The palatal root apex
is frequently aligned
with the distolingual
cusp tip.
