Maxillary Second Molar

Question 1

Buccal cusp size

Answer 1

• The distobuccal cusp is smaller in size and height than the esiobuccal cusp

Question 2

Buccal cusp form

Answer 2

• The sharpness of the two buccal cusps is equal

Question 3

Buccal Groove

Answer 3

• 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.

Question 4

Root length

Answer 4

• The buccal roots are about the same length; the palatal root is the longest.

Question 5

Root trunk

Answer 5

• The root turnk is relatively long

Question 6

Root form & proximity

Answer 6

• 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.

Question 7

Root Curvature

Answer 7

• The roots are slightly curved and have a prominent distal inclination.

Question 8

Distobuccal root extension

Answer 8

• The distobuccal root extends slightly distal to the surface of the crown

Question 9

Occlusocervical crown height

Answer 9

• The distal half of the crown is shorter than the mesial half

Question 10

5th cusp

Answer 10

• 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.

Question 11

Lingual cusp sizes

Answer 11

• The mesiolingual cusp is much larger and taller than the distolingual cusp

Question 12

Lingual groove

Answer 12

• The lingual groove terminates distal to the center of the lingual surface.
• The lingual groove terminates occlusal to the center of the lingual surface.

Question 13

Root visibility

Answer 13

• The roots curve distally and the close approximation of the buccal roots hide large portions of these roots from view

Question 14

Palatal (lingual) root curvature

Answer 14

• The palatal root curves distally.

Question 15

Distal crown width

Answer 15

• The crown is narrower buccolingually in the distal half

Question 16

Crown outline

Answer 16

• 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.

Question 17

Mesiobuccal angle

Answer 17

• The angle between the buccal and the mesial surface is quite acute.

Question 18

Lingual crown convergence

Answer 18

• The crown has a lingual taper.

Question 19

Mesial proximal contact

Answer 19

• The buccolingual position of the mesial proximal contact has been located buccal to the middle of the crown

Question 20

Distal proximal contact

Answer 20

• 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.

Question 21

Distolingual cusp size & Presence

Answer 21

• 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.

Question 22

Buccal cusp sizes

Answer 22

• The mesiobuccal cusp is noticeably larger than the distobucal cusp

Question 23

Supplemental grooves

Answer 23

• The pit and
  groove pattern
  is quite variable
  with multiple
  supplemental
  grooves on the
  occlusal surface.
• The central groove
  frequently crosses
  the oblique ridge.

Question 24

Marginal ridge groove

Answer 24

• 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.

Question 25

Marginal ridge tubercles

Answer 25

* On second molars, 38% of the teeth had mesial marginal ridge tubercles (not shown).

Question 26

Buccal root dimensions

Answer 26

* The mesiobuccal root is wider buccolingually than the distobuccal root (not visible from this view).

Question 27

Palatal (lingual) root form

Answer 27

* The palatal root is relatively straight.

Question 28

Root extension

Answer 28

* Except on rare occasions, the roots are contained within the peripheral contours of the crown.

Question 29

Distal crown convergence

Answer 29

* The buccolingual width of the distal aspect of the crown is considerably less than that of the mesial half of the crown.

Question 30

Distal crown convergence

Answer 30

* The buccal and lingual surfaces are visible because of this distal taper.

Question 31

Mesial cusp visibility

Answer 31

* Due to shorter distobuccal and distolingual cusps the mesial cusps are readily visible.

Question 32

Occlusal surface visibility

Answer 32

* 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.

Question 33

Marginal ridge groove

Answer 33

* The distal marginal ridge has a groove 38% of the time, tubercles 9% of the time (neither is shown).

Question 34

Cervical line form

Answer 34

* 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.

Question 35

Distobuccal root dimensions

Answer 35

* The distobuccal root is narrower buccolingually and may be shorter than the mesiobuccal root. * They could also be the same length.

Question 36

Palatal (lingual) root apex location

Answer 36

* The palatal root apex is frequently aligned with the distolingual cusp tip.