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Questions and Answers
What percentage of the population is affected by congenitally missing third molars?
What percentage of the population is affected by congenitally missing third molars?
What is the primary reason why the loss of first molars is devastating to arch continuity?
What is the primary reason why the loss of first molars is devastating to arch continuity?
What is the typical number of cusps found on the occlusal surface of molars?
What is the typical number of cusps found on the occlusal surface of molars?
How do the crowns of molars taper?
How do the crowns of molars taper?
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What is the significance of molars in maintaining the vertical dimension of the face?
What is the significance of molars in maintaining the vertical dimension of the face?
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How would the loss of a first molar affect the chewing surface?
How would the loss of a first molar affect the chewing surface?
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What is the characteristic of the distal contact area on maxillary molars?
What is the characteristic of the distal contact area on maxillary molars?
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What is the universal numbering system for the first, second, and third molars on each side of the upper and lower arch?
What is the universal numbering system for the first, second, and third molars on each side of the upper and lower arch?
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Which of the following roots is the longest on maxillary first molars?
Which of the following roots is the longest on maxillary first molars?
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Why are molars important in maintaining continuity within dental arches?
Why are molars important in maintaining continuity within dental arches?
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What is the characteristic of the MB root on maxillary first molars?
What is the characteristic of the MB root on maxillary first molars?
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What is unique about the size and shape of molar crowns?
What is unique about the size and shape of molar crowns?
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What is the shape of the crown of maxillary first molars from the occlusal aspect?
What is the shape of the crown of maxillary first molars from the occlusal aspect?
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What is the primary function of molars?
What is the primary function of molars?
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What is the characteristic of the distal roots of maxillary second molars?
What is the characteristic of the distal roots of maxillary second molars?
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Which of the following is a characteristic of the ML cusp on maxillary molars?
Which of the following is a characteristic of the ML cusp on maxillary molars?
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What is the characteristic of the root trunk of maxillary molars?
What is the characteristic of the root trunk of maxillary molars?
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What is the characteristic of the roots of maxillary third molars?
What is the characteristic of the roots of maxillary third molars?
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What is the characteristic of the mesial marginal ridge on maxillary molars?
What is the characteristic of the mesial marginal ridge on maxillary molars?
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What is the characteristic of the oblique ridge on maxillary molars?
What is the characteristic of the oblique ridge on maxillary molars?
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What is the primary description of the maxillary molars?
What is the primary description of the maxillary molars?
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What percentage of the population lacks one or more congenitally missing third molars?
What percentage of the population lacks one or more congenitally missing third molars?
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What role do molars play in the face?
What role do molars play in the face?
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How do the crowns of molars vary in shape?
How do the crowns of molars vary in shape?
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What is the significance of the first molar in the dental arch?
What is the significance of the first molar in the dental arch?
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How many occlusal surfaces are typically found on molars?
How many occlusal surfaces are typically found on molars?
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What is the role of molars in the alignment of other teeth?
What is the role of molars in the alignment of other teeth?
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What happens when a first molar is lost?
What happens when a first molar is lost?
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What is the significance of molars in mastication?
What is the significance of molars in mastication?
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How do the crowns of molars taper?
How do the crowns of molars taper?
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What is the characteristic of the buccal groove on maxillary first and second molars?
What is the characteristic of the buccal groove on maxillary first and second molars?
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Which of the following is a characteristic of the maxillary first molar crown from the proximal aspect?
Which of the following is a characteristic of the maxillary first molar crown from the proximal aspect?
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What is the characteristic of the palatal root of maxillary first molars?
What is the characteristic of the palatal root of maxillary first molars?
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Which of the following is a characteristic of the mandibular molars?
Which of the following is a characteristic of the mandibular molars?
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What is the characteristic of the furcation of maxillary first molars?
What is the characteristic of the furcation of maxillary first molars?
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Which of the following is a characteristic of the maxillary second molar?
Which of the following is a characteristic of the maxillary second molar?
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What is the characteristic of the distal roots of maxillary second molars?
What is the characteristic of the distal roots of maxillary second molars?
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Which of the following is a characteristic of the cusp of Carabelli?
Which of the following is a characteristic of the cusp of Carabelli?
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What is the characteristic of the proximal contacts of maxillary molars?
What is the characteristic of the proximal contacts of maxillary molars?
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Which of the following is a characteristic of the occlusal aspect of maxillary first molars?
Which of the following is a characteristic of the occlusal aspect of maxillary first molars?
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Study Notes
General Description of Molars
- There are 12 permanent molars: 3 on each side, both on the upper and lower arch
- Under universal numbering system, they are numbered 1,2,3,14,15,16,17,18,19,30,31,32
- The first molars are centered in the arch anteroposteriorly, making their loss devastating to arch continuity
- Molars are the largest and strongest teeth in the arch
- Can be congenitally missing, with 1 or more of the third molars missing in nearly 20% of the population
Function of Molars
- Play a major role in the mastication of food (chewing and grinding)
- Loss of first molar can result in more than 80mm of chewing surface gone
- Important in maintaining vertical dimension of the face
- Important in maintaining continuity within dental arches, thus keeping other teeth in alignment
- Function in esthetics by keeping the cheeks full and keeping chin proper distance from the nose
Class Traits of Molars
- Crown size and shape:
- Have occlusal surfaces with three to five cusps
- Have broader occlusal surfaces than other teeth
- Crowns of molars are wider mesiodistally
- Are shorter occlusocervically than other teeth
- Taper from buccal to lingual: Molar crowns taper to the lingual
- MTaper to the distal: From an occlusal view, all molar crowns taper distally
- Contact areas:
- Mesial: At or near the junction of the occlusal and middle thirds
- Distal: Middle third
Arch Traits of Molars
- Maxillary:
- Crown shape: Square/parallelogram (B-L > M-D)
- Number and relative size of cusps: 4-5 cusps (DB, DL, MB, ML, Cusp of Carabelli)
- Crown centered over roots
- ML cusp: Largest and longest; connects to DB cusp by the Oblique Ridge
- ML > MB > DB > DL
- Mandibular:
- Crown shape: Rectangular/pentagonal (M-D > B-L)
- Number and relative size of cusps: 4-5 cusps (MB, ML, DB, DL, Distal cusp)
- ML and DL cusps are nearly equal in size
- Distal cusp is minor fifth cusp, found on the first and sometimes third molars
- B mandibular tilt: All mandibular teeth, including molars, tilt lingually when viewed from mesial or distal
- Roots of maxillary molars:
- MB, DB, and Palatal roots
- Roots are nearly twice as long as the crown
- Relative length: Palatal > MB > DB
- Roots of mandibular molars:
- Two roots (Mesial and Distal)
- Mesial root is usually slightly longer than distal root
- Mandibular root trunks are shorter than maxillary root trunks, especially on first molars
Anatomy of Maxillary Molars
- Type traits of maxillary 1st and 2nd molars:
- Relative size: Second molar is smaller than the first molar in the same mouth, especially M-D
- 1st Molar is broader than the 2nd Molar
- 2nd Molar crown is often tipped distally on the root trunk
- Buccal groove: Lies between buccal cusps and extends on the buccal surface to the middle third of the crown
- Proximal contacts: Same as for all molars
- Outline shape: The crown appears to tilt distally at the cervix
- Roots: Are attached to a root trunk (longer in second molars) at the cervical line
- Apical to the root trunk there is a split into three roots
- Roots of maxillary 1st and 2nd molars:
- Trifurcation: Three roots splitting of the root trunk
- Much variation in the shapes of roots
- The MB and DB roots are often bent in such a way as to resemble the handles of a pair of pliers
- The MB and DB roots often curve distally
- The apical third of the MB root may curve distally enough to put its apex distal to the buccal groove
- Lingual aspect of maxillary molars:
- Crown: Relative size and taper
- Number and description of lingual cusps: 1st Molar: Two well-defined cusps, ML and DL; 2nd Molar: Two or three cusps, ML and DL (or no DL)
- Roots of first molars from the lingual: Depression on the lingual aspect of the palatal root
- Roots of second molars from the lingual: Note distal bend
- Proximal aspect of maxillary molars:
- 1st Molar: Cusps 1, 2, 3; Mesial marginal ridge is more occlusal than distal
- 2nd Molar: Looks much like the first molar, but no cusp of Carabelli is present
- Crest of curvature:
- On the buccal: Located in the cervical third
- On the lingual (palatal): In the middle third
- Distal taper:
- Narrower to distal
- On both first and second molars, the crown is narrower buccolingually on the distal than the mesial### Molar Teeth
- Molars are narrower on the lingual surface than the buccal surface, except for maxillary first molars with large lingual cusps.
Class Traits of Molars
- From an occlusal view, all molar crowns taper distally.
- Contact areas: mesial (at or near the junction of the occlusal and middle thirds) and distal (middle third).
Arch Traits of Molars
-
Maxillary:
- Crown shape: square/parallelogram (B-L > M-D).
- Number and relative size of cups: 4-5 cups (DB, DL, MB, ML, and sometimes a fifth cusp, Cusp of Carabelli).
- ML cusp is the largest and longest, connecting to the DB cusp by the Oblique Ridge.
-
Mandibular:
- Crown shape: rectangular/pentagonal (M-D > B-L).
- Number and relative size of cups: 4-5 cups (DB, DL, MB, ML, and sometimes a fifth cusp, Distal Cusp).
- ML and DL cusps are nearly equal in size.
-
B Mandibular Tilt:
- All mandibular teeth, including molars, tilt lingually when viewed from mesial or distal.
- Crowns tilt distally relative to the long axis of the root.
Arch Traits of Molars (Roots)
-
Maxillary:
- Number of roots: 3 (MB, DB, and Palatal).
- Root length: nearly twice as long as the crown.
- Relative length: Palatal > MB > DB.
- Root Trunk: a broad cervical root base.
-
Mandibular:
- Number of roots: 2 (Mesial and Distal).
- Mesial root is usually slightly longer than distal root.
- Mandibular root trunks are shorter than maxillary root trunks, especially on first molars.
Anatomy of Maxillary Molars
-
Type Traits of Maxillary 1st and 2nd Molars:
- Relative size: second molar is smaller than the first molar in the same mouth, especially M-D.
- 1st Molar is broader than the 2nd Molar.
- 2nd Molar crown is often tipped distally on the root trunk.
- Buccal groove: lies between buccal cusps and extends on the buccal surface to the middle third of the crown.
- Proximal contacts: same as for all molars (mesial: junction of occlusal and middle thirds, distal: middle third).
- Outline shape: the crown appears to tilt distally at the cervix, making it appear shorter on the distal than the mesial.
Roots of Maxillary Molars
-
First Molars:
- Attached to a root trunk at the cervical line.
- Apical to the root trunk, there is a split into three roots (trifurcation).
- MB and DB roots are often bent, resembling the handles of a pair of pliers.
- The apical third of the MB root may curve distally enough to put its apex distal to the buccal groove.
-
Second Molars:
- Attached to a root trunk at the cervical line.
- Apical to the root trunk, there is a split into three roots (trifurcation).
- MB and DB roots are nearly parallel.
Lingual Aspect of Maxillary Molars
-
Crown:
- Relative size and taper: due to the prominent DL cusp, the crown may be as wide or wider on the lingual for the first molar.
- The crown of the second molar usually appears smaller than the first molar.
-
Number and Description of Lingual Cusps:
- First Molar: two well-defined cusps, ML and DL.
- Second Molar: two types, 4-cusp or 3-cusp, with or without a DL cusp.
Roots of Maxillary Molars (from the Lingual)
-
First Molars:
- Palatal root is the third longest of any maxillary tooth.
- Tapers apically to a blunt or rounded apex.
- There is usually a depression on the lingual aspect of the palatal root.
-
Second Molars:
- The lingual (palatal) root is as long as the lingual root of the first molar.
- The buccal roots bend towards the distal and are more parallel.
Proximal Aspect of Maxillary Molars
-
First Molars:
- Cusps: 1-2-3.
- From the mesial, the crown appears broad faciolingually.
- Two or three cusps can be seen from the mesial (MB, ML, and Cusp of Carabelli).
- Distal cusps are shorter and generally not seen from the mesial.
-
Second Molars:
- From the mesial and distal aspect, looks much like the first molar, but no cusp of Carabelli is present.
- DL cusp is absent on more than one-third of these teeth.
Crest of Curvature and Distal Taper
-
Crest of Curvature:
- On the buccal, located in the cervical third.
- On the lingual (palatal), in the middle third.
-
Distal Taper:
- On both first and second molars, the crown is narrower buccolingually on the distal than the mesial.
Mesial Marginal Ridges and Tubercules
-
Mesial Marginal Ridges:
- On both first and second molars, the mesial marginal ridge is concave and more occlusally located than the distal marginal ridge.
-
Tubercules:
- If present, are usually found on the mesial marginal ridge of first molars (rarely found on 2nd molars or distal marginal ridge of first molars).
Cervical Line and Proximal Contacts
-
Cervical Line:
- The mesial cervical line has a slight occlusal curvature.
- There is slightly less curvature on the distal than the mesial.
-
Proximal Contacts:
- The mesial contact area is at the junction of the middle and occlusal thirds.
- The distal contact area is in the middle third.
Roots of Maxillary Molars (from the Proximal)
-
First Molars:
- MB root is broad buccolingually and is shorter than the lingual root.
- The MB root obscures the view of the DB root.
- The apex of the MB root is in line with the MB cusp tip.
-
Second Molars:
- On second molars, roots are much less spread apart.
- The lingual root is also straighter, usually not extending past the confines of the crown.
Occlusal Aspect of Maxillary Molars
-
First Molars:
- The contour of first molars is not square, but gives that impression when compared to other teeth.
- It is roughly a parallelogram.
-
Second Molars:
- The second molar is wider buccolingually than mesiodistally and tapers to the lingual.
- Much variation in second molar due to size and location of DL cusp.
Number and Size of Cusps
-
Generally:
- There are four cusps.
- First molar possesses a fifth cusp 70% of the time.
- Second molar may be missing the DL cusp.
Oblique Ridge and Fossae
-
Oblique Ridge:
- Unique to maxillary molars.
- Connects the DB cusp with the ML cusp.
- Present in second molars, but smaller than the oblique ridge of first molars.
-
Fossae:
- There are generally four fossae on four-cusp molars.
- On three-cusp molars, the distal fossae and both the distal oblique and lingual grooves are absent.
Maxillary Third Molars
-
General Description:
- Difficult to describe due to great variation.
- Roots and crown are shorter than the first or second molar.
- Crown often possesses more supplemental grooves.
- May possess three, four, or five cusps.
-
Mesial Roots:
- Possess three roots, but more often they are fused for most of their length.
- Roots are shorter than those of the first and second molar.
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Description
Test your knowledge of molar anatomy, including the shape and features of maxillary and mandibular molars, and their contact areas. Learn the class and arch traits of molars from an occlusal view. Essential for dental students and professionals.
