Molars Flashcards
What is the shape of the upper first molar?
- Diamond shaped: with the longer diagonal extending from the mesio-buccal to the disto-palatal cusp and emphasised by the presence of a strong ridge of enamel (oblique ridge)
Which cusp is the largest in the upper first molar?
The mesio-lingual cusp
Which cusp is the smallest in the upper first molar?
disto-lingual
What is there on each side of the ridge of an upper first molar?
A fissure: these 2 fissures are connected by a shallow fissure completing the H-shaped pattern
What is the distal fissure on an upper first molar like?
- Runs parallel to the oblique ridges and continues on to the palatal surface
What is the mesial fissure on an upper first molar like?
- Has a right angles bend
- One arm runs towards the mesial surface, but does not continue on to it, the other run towards, and on to, the buccal surface
On which tooth can a tubercle of Carabelli be present?
The upper first molar
On which cusp can a tubercle of Carabelli be present on an upper first molar?
Mesio-palatal cusp
Roughly what percentage of upper first molars have a tubercle of Carabelli present?
Around 60%
What are the proximal surfaces of the upper first molar like?
- Convex, with the distal more curved than the mesial
How many roots does the upper first molar have?
3 roots
- 2 buccal and 1 palatal - diverging from a common root stalk
Which root is the palatal root of an upper, first molar on the same plane as?
The disto-buccal root
What is the palatal root of the upper first molar like?
- Is the longest and strongest of the 3 roots of the tooth
- Is slightly compressed bucco-lingually
What is the general shape of the upper second premolar?
More triangular shape
How many roots dies an upper second molar have?
3 however the palatal root is often partially fused with either of the buccal roots
What is the crown of the upper third molar like?
- Smallest of the three upper molars. Usually only 3 cusps but various forms
What are the roots of the upper third molar like?
- Usually fused together into one common, bulky root grooved in the positions where separate roots would be divided
How many cusps does a lower first molar have?
Five cusps: 3 buccal and 2 lingual
What is the transverse fissure of the lower first molar?
- Groove starting on buccal surface deepens into transverse fissure across occlusal surface and ends as groove on lingual surface
- In the centre of the crown, it deepens further to form a pit
Where is the mesio-distal fissure of the lower first molar?
- It starts near the mesial marginal ridge, crosses the central pit and divides into 2 branches which pass on each side of the small distal cusps
Which surface of the lower first molar is bigger?
- The buccal surface is larger than the lingual surface
- The buccal surface is lingually inclined
What are the proximal surfaces of the lower first molar like?
- Convex, with the distal much rounder because of the distal cusp
How many roots does the lower first molar have and how are they shaped?
2 roots: 1 mesial and 1 distal
- Both strongly compressed mesio-distally and may show distal curvature. These features are most pronounced on the mesial root
- The distal root is therefore not visible from the mesial aspect. The mesial root is usually curved, grooved and broader than the distal root
What does the lower first molar have which can increase the risk of caries?
The buccal surface usually has a pit which is at increased risk of caries
Which root of the lower second molar is broader?
The mesial root
Which root of the lower second molar is longer?
The distal root
What is the occlusal surface of the lower second molar like?
- More symmetrical and smaller than lower first molar
- Usually only four cusps of similar size
- The occlusal surface is almost square
- The fissure pattern is + shaped
Which cusps of the lower second molar are the highest?
The lingual cusps are the highest
Which cusp of the lower second molar is the biggest?
The mesio-buccal cusp
What are the roots of a lower second molar like compared to a lower first molar?
Roots less divergent than those of lower first molar, and may be fused
What is the crown of a lower third molar like?
Very variable in shape and size
- 50% five cusps
- 40% four cusps
- 10% three or > five cusps
What are the roots of the lower third molar like?
Often fused
