38 Questions
What is the geometric shape of the occlusal aspect of a mandibular molar?
Hexagonal with unequal sides
What is the order of size of the mandibular cusps?
Mesiobuccal, mesiolingual, distolingual, distobuccal, distal
What is the characteristic of the cusp ridges of the buccal cusps and distal cusp?
They are flattened
What is the number of major and minor cusps on a mandibular molar?
4 major, 1 minor
What is the shape of the central fossa?
Circular
What is the mesiodistal measurement of the crown compared to the buccolingual measurement?
Greater than
What is the shape of the lingual surface of the crown compared to the buccal surface?
Narrower
What is the characteristic of the lingual cusps?
They are sharp with well-defined cusp ridges
What is the base of the mesial triangular fossa?
Mesial marginal ridge
How many pits are present in the occlusal aspect?
3
Where does the central developmental groove originate from?
Central pit
What is the characteristic of the distal marginal ridge?
It is shorter and at a lower level than the mesial marginal ridge
How many developmental grooves are present in the occlusal aspect?
4
What is the shape of the mesial aspect of the mandibular right first molar?
Rhomboidal
Where does the distal course of the central developmental groove end?
Distal triangular fossa
Where is the height of the buccal contour located?
Cervical third of the crown
What is the shape of the lingual outline of the mesial aspect of the mandibular right first molar?
Convex
Where is the height of the lingual contour located?
Middle third of the crown
What is the relationship between the buccolingual measurement of the crown and root of the mandibular right first molar?
Greater mesially than distally
Which cusps can be seen from the mesial aspect of the mandibular right first molar?
Both the mesiobuccal and mesiolingual cusps
Where is the mesial contact area located?
At the junction of the occlusal and middle third of the crown
What is the characteristic of the mesial surface of the mesial root?
Convex at the buccal and lingual borders
What is the geometric shape of the distal aspect of the Mandibular right first molar?
Rhomboidal
What is the characteristic of the buccal surface compared to the lingual surface in the distal aspect?
The buccal surface shows more convergence than the lingual surface
What is the location of the distal contact area in the distal aspect?
More buccally
What is the characteristic of the distal marginal ridge compared to the mesial marginal ridge?
It is shorter and at a lower level
What is the characteristic of the distal root compared to the mesial root?
It is narrower buccolingually
What is the shape of the surface of the crown of the mandibular right first molar?
Spherical
What can be seen from the distal aspect of the Mandibular right first molar?
Most of the buccal surface and some part of the lingual surface
What is the characteristic of the two lingual cusps of the mandibular right first molar?
They are sharper and longer than the buccal cusps.
What is the shape of the cervical line in the distal aspect?
Straight
What is the level of the mesiolingual cusp tip compared to the distolingual cusp tip?
Higher
What is the characteristic of the distal cusp ridge and the distolingual cusp ridge?
They meet at an obtuse angle
Why does the length of the roots seem more extreme lingually than buccally?
Because the cusp ridges and cervical line are at a higher level.
What is the characteristic of the cervical line on the lingual surface?
It is curved apically and at a higher level than the buccal surface.
What is the feature of the root trunk on the lingual surface?
A developmental depression is present on the root trunk.
Where does the root bifurcation begin on the lingual surface?
About 4 mm below the cervical line
What is the characteristic of the distal cusp on the lingual surface?
It is at a lower level than the mesiolingual cusp.
Study Notes
Mandibular Right First Molar
Buccal Aspect
- The buccal surface of the crown is smooth and spheroidal
- The mesial and distal outlines are similar to the buccal aspect
- MBDG (Mesiobuccal developmental groove) is present
- CL (Cervical line) is present
- MR (Mesial root) and DR (Distal root) are present
- DBDG (Distobuccal developmental groove) is present
- DC (Distal cusp), DLC (Distolingual cusp), and DBC (Distobuccal cusp) are present
Lingual Aspect
- The surface of the crown is smooth and trapezoidal
- The two lingual cusps are almost equal in width and are sharper and longer than the buccal cusps
- The lingual developmental groove runs for a shorter distance on the lingual surface and is in line with the bifurcation of the root
- The mesiolingual cusp tip is at a higher level than the distolingual cusp
- The crown tapers lingually, making the lingual surface narrower than the buccal surface
- The cervical line on the lingual surface is irregular and curved apically
Mesial Aspect
- The geometric shape is rhomboidal
- The buccal outline is more convex in the cervical third (the cervical ridge) then slightly convex to the mesiobuccal cusp tip
- The height of the buccal contour is in the cervical third of the crown
- The lingual outline is convex from the cervix to the mesiolingual cusp tip
- The height of the lingual contour is at the center of the middle third
- Only the mesiobuccal and mesiolingual cusps can be seen from this aspect
- The mesiolingual cusp tip is sharp and at a higher level than the flattened mesiobuccal cusp tip
Distal Aspect
- The geometric shape is rhomboidal
- The buccal and lingual outlines are the same as the mesial aspect
- The distal surface is shorter and narrower than the mesial surface
- Most of the buccal surface and some part of the lingual surface can be seen from this aspect
- The distal marginal ridge is shorter and at a lower level than the mesial marginal ridge
- The distal contact area is placed more buccally
- The cervical line is straight
Occlusal Aspect
- The geometric shape is hexagonal with unequal sides
- The mesiodistal measurement of the crown is greater than the buccolingual measurement
- The crown is bulkier mesially than distally because the crown tapers in a distal direction
- All mandibular molars have four major cusps (MB, DB, ML, DL) and one minor cusp (distal cusp)
- The size of the mandibular cusps in decreasing order is: mesiobuccal cusp, mesiolingual and distolingual cusps, distobuccal cusp, and distal cusp
- There is one major fossa (central fossa) and two minor fossae (mesial triangular fossa and distal triangular fossa)
- The central fossa is bounded by the distal slope of the mesiobuccal cusp, the mesial and distal slopes of the distobuccal cusp, and the mesial slope of the distal cusp
- The marginal ridges are: mesial marginal ridge, distal marginal ridge, and central developmental groove
- There are three pits: central pit, mesial pit, and distal pit
Identify the different parts of the mandibular right first molar, including roots, cusps, and developmental grooves. Test your knowledge of dental anatomy!
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