Tooth Morphology Flashcards
What is the FDI notation for central maxillary incisors?
11, 21
What are the features of central maxillary incisors?
- Square shaped crowns
- Raised marginal ridges
- Lingual fossa present
- Distally skewed cingulum
- More rounded disto-incisal angle
- Undulated cervical line on the medial plane
- 1:1 root:crown ratio
What are the difference between central maxillary incisors and lateral maxillary incisors?
- Laterals have more rounded incised edges
- The crown of the laterals is shorter and narrower mesiodistally
- Laterals have a smaller crown
- Laterals have a more prominent lingual fossa
- Laterals have thinner roots
- Laterals have a larger root:crown ratio
What is the FDI notation for the lateral maxillary incisors?
12, 22
What is the FDI notation for the central mandibular incisors?
31, 41
What are the features of central mandibular incisors?
- Triangular shaped crown
- Distoincisal angle is marginally rounder
- Small cingulum
- Faint marginal ridges
- Very symmetrical
What is the FDI notation for the lateral mandibular incisors?
32, 42
What are the features of lateral mandibular incisors?
- Fan shaped crown
- Distal flare
- More rounded disto-incisal angle
- Longer mesial edge
- More undulated cervical margin on the mesial surface
What are the difference between mandibular central incisors and mandibular lateral incisors?
- Laterals are wider mesiodistally
- Laterals have a fan shaped distal flare
- Centrals are much more symmetrical
What is the FDI notation for the upper canines?
13, 23
Describe the features present on the labial surface of the upper canines
- Broad, diamond shaped crown
- Pointed cusp rather than incisal edge
- Labial surface convex, with a protruding labial ridge
- Distal border is longer and more steeply inclined than the mesial border
- Distal section of the tooth is larger than the mesial
Describe the features present on the palatal surface of the upper canines
- Concave
- Sometimes split into 2 shallow fossae by lingual ridge which runs from the cusp tip to the cingulum
- Cingulum distally displaced
In the upper canines, on which surface is the cervical marginal undulation greater?
On the mesial surface
Which tooth has the longest and strongest root of the human dentition?
Upper canines
Describe the features of an upper canine root
- Longest and strongest of the human dentition
- Irregularly oval
- Mesial and distal surfaces of the root usually faintly grooved
Describe the mesial and distal contact areas of the upper canines
- Mesial contact with lateral incisor is more incisal (closer to the cusp tip)
- Distal contact with 1st premolar = more central (more apical)
What is the FDI notation of the lower canines?
33, 43
Describe the features present on the labial surface of the lower canines
- Labial ridges not as prominent, flatter surface
- Labial surface slanted lingually, with the cusp tip lingually positioned
- Distal border longer and more steeply inclined than the mesial border
Describe the features present on the lingual surface of the lower canines
- Features such as the cingulum, marginal ridges and fossae less conspicuous than in upper canines
- Lingual surface more level and uniform - mimics morphology of the lower incisors
Describe the differences in the cusps of upper and lower canines
- Upper canine - cusp tip is almost vertical
- Lower canine - cusp tip is lingually inclined
Describe the features of the root of a lower canine
- Shorter in length, weaker and slimmer than upper canines
- Flatter and less rounded mesio-distally, hence more slender
Describe the position of the amelocemental junction in upper canines on the lingual and labial surfaces
The level of the amelocemental junction is equal on the lingual and labial surfaces of the crown
Describe the position of the amelocemental junction in lower canines on the lingual and labial surfaces
The amelocemental junction is located more apically on the labial surface as opposed to the lingual surface (lower on the labial surface)
How many premolars are present in the permanent dentition?
8
4 mandibular and 4 maxillary
What is the FDI notation for the maxillary first premolars?
14, 24
How many cusps do the maxillary first premolars have?
2 cusps
How many roots do the maxillary first premolars (usually) have?
2 roots
Wha position are the 2 roots of the maxillary first premolars in?
One buccal and one lingual
Describe the features present on the occlusal surface of the maxillary first premolars
- Occlusal surface = oval shaped
- Developmental groove present that does not reach distal marginal ridge
- Mesial displacement of the palatal cusp
- Much narrower and lower lingual cusp
Describe the mesial surface of the maxillary first premolar
- Canine fossa - concavity between roots
- If this is not restored well, can lead to overhang
- More occlusally located marginal ridge
Describe the distal surface of the maxillary first premolar
- Convex contact area with 2nd premolar
- More apically located marginal ridge
What is the FDI notation of the maxillary second premolar?
15, 25
How many cusps does a maxillary second premolar have?
2 cusps
How many roots does a maxillary second premolar (usually) have?
1 root
Describe the root surface of a maxillary second premolar
- Convex root surfaces that are deeply grooved
- Distal root surface is more deeply grooved (contact point with first molar)
Describe the occlusal surface of a maxillary second premolar
- More symmetrical occlusal surface
- Sharp mesiodistal fissure that doesn’t reach the marginal ridges
- Slight mesial displacement of the lingual cusp
- 2 cusps are similar in height and width
Describe the distal and mesial surfaces of a maxillary second premolar
- Mesial: more occlusally located marginal ride
- Distal: more cervially/apically located marginal ridge
What are the similarities between upper first and second premolars?
- 2 cusps
- Mesial displacement of lingual cusp
- Both have more occlusally located marginal ridge
- Oval shaped occlusal surface
What are the features present in maxillary first premolars that differ in maxillary second premolars?
- Larger occlusal surface
- 2 roots
- Strong mesial displacement of lingual cusp (as opposed to slight mesial displacement of lingual cusp in 2nd)
- Fissure extends off the mesial marginal ridge
- Mesial root surface has canine fossa
- Much narrower and smaller lingual cusp compared to buccal cusp
Describe the features present on the occlusal surface of a mandibular first premolar
- Distal displacement of the lingual cusp
- Slightly narrower and much shorter lingual cusp
- Small groove running from the mesial pit to the lingual surface
Where are the contact points for the mandibular first premolar?
- Narrow canine contact point that is buccally placed
- Broad second premolar contact point
Describe the mesial and distal surfaces of a mandibular first premolar
Mesial surface: Marginal ridge located more cervically
Distal surface: Marginal ridge located more distally
Lingual cusp is much shorter and there is a strong lingual inclination
What is the FDI notation for mandibular first premolars?
34, 44
What is the FDI notation for mandibular second premolars?
35, 45
How many cusps do mandibular second premolars have?
2 or 3 cusps
How many roots do mandibular second premolars have?
1 root
How many roots do mandibular first premolars have?
1 root
Describe the occlusal surface of mandibular second premolars
- Circular occlusal surface
- Mesially displaced lingual cusp
- Sometimes 2 lingual cusps are present - mesial cusp is the largest
Describe the mesial and distal surfaces of a mandibular second premolar
Mesial = More occlusally located marginal ridge
Distal = More cervically located marginal ridge
Strong lingual inclination and small difference in cusp height
What are the similarities between mandibular 1st and 2nd premolars?
Both have 1 root and a lingual cusp with an inclination
What are the differences between mandibular 1st and 2nd premolars?
1st: Much smaller occlusal surface, distal displacement of the lingual cusp, mesial marginal ridge is cervically located, larger difference in cusp height, smaller oval root
2nd: larger occlusal surface, 2 or 3 cusps, mesial displacement of lingual cusp, mesial marginal ridge is occlusally located, small difference in cusp height, larger rounder root
Of the 4 premolars (1st upper, 2nd upper, 1st lower, 2nd lower) which premolar shows distal displacement of the lingual cusp?
Mandibular first premolar
What is the FDI notation for the upper first permanent molar?
16, 26
How many roots do upper first molars have and what is their arrangement?
3 roots
2 buccal and 1 palatal
The palatal root is in the same plane and the disto-buccal root
Which is the longest and strongest of the 3 roots found in upper first molars?
The palatal root
Describe the occlusal surface of the upper first permanent molar
- Rhomboidal/diamond shape
- 4 cusps (5 incl. Tubercle of Carabelli)
- Longest diagonally from mesio-buccal cusp to the disto-palatal cusp
- Oblique ridge extends across mesio-palatal and disto-buccal cusps
Which is the smallest cusp on the occlusal surface of the upper first molar?
Disto-palatal cusp
Which is the largest cusp on the occlusal surface of the upper first molar?
Mesio-palatal cusp
Which is the highest cusp on the occlusal surface of the upper first molar?
Mesio-buccal cusp
What fissure pattern is present on upper first molars?
H pattern
Oblique ridge is encompassed by the fissure on each side
Where is a Tubercle of Carabelli usually found?
On the mesio-palatal cusp of an upper first molar
What percentage of upper molars have a Tubercle of Carabelli?
60%
What is the FDI notation for upper second permanent molars?
17, 27
How many roots do second permanent molars have and what is their arrangement?
- 3 roots
- 2 buccal and 1 palatal
Same arrangement as that of upper first permanent molars
Describe the occlusal surface of upper second permanent molars
- Similar features to upper first molars but smaller
- ## Occlusal surface is triangular shaped (due to small/absent disto-palatal cusp)
What is the FDI notation for lower first permanent molars?
36, 46
How many roots do lower first permanent molars have, and what is their arrangement?
- 2 roots
- 1 mesial and 1 distal
- May curve distally
- Mesial root is wider bunco-lingually; distal root concealed behind it
How many cusps do lower first permanent molars have?
5 cusps: 3 buccal, 2 lingual
What is the fissure pattern on lower first permanent molars?
Transverse - extends from buccal surface onto lingual surface
Also a mesio-distal fissure that forms the distal cusp
Describe the buccal and lingual surfaces of the lower 1st permanent molar
Buccal surface is larger than lingual
Lingually inclined
Caries likely to accumulate in pit in buccal surface
What is the FDI notation for the lower 2nd molars?
37 and 47
How many cusps do lower 2nd molars have?
4
Lingual cusps are higher
Describe the occlusal surface of lower 2nd molars
- Symmetrical
- 4 cusps
- shaped fissure
- Square shaped
Which of the 4 cusps is the largest in lower 2nd molars?
The mesio-buccal cusp
Of all the teeth, which is the only one that does not have a more occlusally located mesial marginal ridge?
Lower 4 (has a more occlusally located distal marginal ridge)
On a canine, which contact point is more apically located?
The distal contact point, contacting first premolar
Which premolar may have 2 or 3 cusps?
Mandibular 2nd premolar (Lower 5)
During lateral movement of the jaw, which teeth acts as a guidepost?
Upper canines (canine guidance)
Which tooth has the widest incisal edge?
Upper central incisors (11, 21)
The occlusal plane has a parallelogram shape allowing the mesial contact point to be positioned buccally. Which tooth is this?
Upper 6 (lower first molar)
Which tooth has a pit on its buccal surface which is at increase risk of caries?
Lower 6 (lower first molar)
This tooth has the mesial surface more deeply grooved than the distal surface. Which tooth is this?
Upper 4 (upper first premolar)
Crown is set at an angle to the root producing a convex labial profile from cusp to apex. Which tooth is this?
Lower canines (33, 43)
In which tooth is the lingual cusp distally displaced?
Lower 4 (lower first premolar)
Which tooth has 4 cusps of a similar size and the occlusal surface is square shaped?
Lower 7 (lower 2nd molars)
Which tooth is diamond shaped with the longer diagonal extending from mesio-buccal to the disto-palatal cusp?
Upper 6 (upper 1st molars)
The 2 cusps are similar in height and width due to reduction of the buccal cusp. Which tooth is this?
Upper 5 (upper 2nd premolar)
The lingual surface has a 2 pronounced marginal ridges, where the ridges meet they enclose a depression or fossa. Which tooth is this?
Upper 2s (upper lateral incisors)
The disto-palatal cusp is greatly reduced and may be absent, making the occlusal surface more triangular. Which tooth is this?
Upper 7s (upper 2nd molars)
Looking at the crown from the mesial and distal aspects, it appears wedge shaped and leans lingually. There are faint marginal ridges and a small cingulum. Which tooth is this?
Lower 2s (lower lateral incisors)
Which tooth has a fan-shaped crown with a distal flare?
Lower 2s (lower lateral incisors)
