1. Generals of MolarsGenerals of Molars
and Maxillary Molarsand Maxillary Molars
Howard Chi, D.M.D.Howard Chi, D.M.D.

2. Learning ObjectivesLearning Objectives
• Generals of MolarsGenerals of Molars
• Anatomy of Maxillary MolarsAnatomy of Maxillary Molars

3. Generals of MolarsGenerals of Molars

4. General DescriptionGeneral Description
Of MolarsOf Molars
• There are 12 permanent molarsThere are 12 permanent molars
• First, second and third on each side, bothFirst, second and third on each side, both
on the upper and lower archon the upper and lower arch
• Under universal numbering system they areUnder universal numbering system they are
1,2,3,14,15,16,17,18,19,30,31,321,2,3,14,15,16,17,18,19,30,31,32

5. General DescriptionGeneral Description
Of MolarsOf Molars
• The first molars are centered in the archThe first molars are centered in the arch
anteroposteriorlyanteroposteriorly
• This is one reason their loss is soThis is one reason their loss is so
devastating to arch continuitydevastating to arch continuity
• They are the largest and strongest teeth inThey are the largest and strongest teeth in
the archthe arch

6. General Description Of MolarsGeneral Description Of Molars
• Frequently, one or more of the third molarsFrequently, one or more of the third molars
are congenitally missingare congenitally missing
• This occurs in nearly 20% of the populationThis occurs in nearly 20% of the population
Can be congenitally
missing

7. General DescriptionGeneral Description
Of MolarsOf Molars
• The combined mesiodistal width of the threeThe combined mesiodistal width of the three
mandibular molars on one side make upmandibular molars on one side make up
51% of the mesiodistal dimension of their51% of the mesiodistal dimension of their
quadrantquadrant
• The maxillary molars constitute 44% ofThe maxillary molars constitute 44% of
their quadrants mesiodistal dimensiontheir quadrants mesiodistal dimension
51%
44%

8. FunctionFunction
Of MolarsOf Molars
• Play a major role in the mastication of foodPlay a major role in the mastication of food
(chewing and grinding)(chewing and grinding)
• Lost of first molar can result in more thanLost of first molar can result in more than
80mm of chewing surface gone80mm of chewing surface gone

9. Function OfFunction Of
MolarsMolars
• Important in maintaining vertical dimension ofImportant in maintaining vertical dimension of
the facethe face
• Important in maintaining continuity within dentalImportant in maintaining continuity within dental
arches, thus keeping other teeth in alignmentarches, thus keeping other teeth in alignment
• Function in esthetics by keeping the cheeks fullFunction in esthetics by keeping the cheeks full
and keeping chin proper distance from the noseand keeping chin proper distance from the nose

10. Class TraitsClass Traits
Of MolarsOf Molars
• Crown Size And ShapeCrown Size And Shape
– Have occlusal surfaces with three to five cusps
– Have broader occlusal surfaces than other teeth

11. Class TraitsClass Traits
Of MolarsOf Molars
• Crown Size And ShapeCrown Size And Shape
– Crowns of molars are wider mesiodistally than
long occlusocervically
– Are shorter occlusocervically than other teeth

12. Class TraitsClass Traits
Of MolarsOf Molars
• Taper From Buccal To LingualTaper From Buccal To Lingual
– Molar crowns taper to the lingual (i.e. crown is
narrower on the lingual surface than the buccal
surface)
– Exception may be maxillary first molars with
large distolingual cusps (may taper toward the
buccal)

13. Class TraitsClass Traits
Of MolarsOf Molars
• Taper To The DistalTaper To The Distal
– From an occlusal view all molar crowns taper
distally
M D

14. Class TraitsClass Traits
Of MolarsOf Molars
• Contact AreasContact Areas
– Mesial: At or near the
junction of the occlusal
and middle thirds
– Distal: Middle third

15. Arch Traits Of MolarsArch Traits Of Molars
Crown Shape From OcclusalCrown Shape From Occlusal
Maxillary
– square /parallelogram
– B-L>M-D
Mandibular
– rectangular/pentagonal
– M-D>B-L

16. Arch Traits Of MolarsArch Traits Of Molars
Number and RelativeNumber and Relative
Size of CuspsSize of Cusps
Maxillary: 4-5 CuspsMaxillary: 4-5 Cusps
– Crown centered over roots
– ML cusp: Largest and longest; connects to DB
cusp by the Oblique Ridge
– ML>MB> DB>DL
DL ML
DB MB

17. Arch Traits Of MolarsArch Traits Of Molars
MaxillaryMaxillary
Cusp of Carabelli:Cusp of Carabelli:
• If present, is the fifth andIf present, is the fifth and
smallest cuspsmallest cusp
• Usually on lingual of MLUsually on lingual of ML
cusp of maxillarycusp of maxillary
first molarsfirst molars

18. Arch Traits Of MolarsArch Traits Of Molars
Number and Relative Size of CupsNumber and Relative Size of Cups
• Mandibular: 4-5 CuspsMandibular: 4-5 Cusps
– ML and DL cusps are nearly equal in size (in
contrast to maxillary molars)
– Distal Cusp is minor fifth cusp, found on the
first and sometimes third molars

19. Arch Traits Of MolarsArch Traits Of Molars
• Mandibular TiltMandibular Tilt
– All mandibular teeth, including
molars, tilt lingually when
viewed from mesial or distal
(this is not apparent on maxillary molars)
– Crowns tilt distally relative to the long axis of
the root
B L

20. Arch TraitsArch Traits
Of MolarsOf Molars
• Maxillary RootsMaxillary Roots
– MB, DB, and Palatal
roots
– Roots are nearly twice
as long as the crown
– Relative length: Palatal>MB>DB
MBDB
Palatal

21. Arch Traits Of MolarsArch Traits Of Molars
• Maxillary RootsMaxillary Roots
– Roots converge into a
broad cervical root base
called the Root Trunk

22. Arch TraitsArch Traits
Of MolarsOf Molars
• Mandibular RootsMandibular Roots
– 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
Root Trunk

23. Anatomy ofAnatomy of
Maxillary MolarsMaxillary Molars

24. Type Traits ofType Traits of
Maxillary 1stMaxillary 1st
and 2nd Molarsand 2nd Molars
• Relative SizeRelative 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

25. Type Traits ofType Traits of
Maxillary 1stMaxillary 1st
and 2nd Molarsand 2nd Molars
• Buccal GrooveBuccal Groove
– Lies between buccal cusps and extends on the
buccal surface to the middle third of the crown
– Pit is sometimes present at the end of the
groove that can be the site of caries

26. Type Traits ofType Traits of
Maxillary 1stMaxillary 1st
and 2nd Molarsand 2nd Molars
• Proximal ContactsProximal Contacts
Same as for all molars:
– Mesial: Junction of
occlusal and middle thirds
– Distal: Middle third
Mesial

27. Type Traits ofType Traits of
Maxillary 1stMaxillary 1st
and 2nd Molarsand 2nd Molars
• Outline ShapeOutline Shape
– The crown appears to tilt
distally at the cervix
– This, coupled with a short distobuccal cusp
makes the crown appear shorter on the distal
than the mesial

28. Type Traits ofType Traits of
Maxillary 1stMaxillary 1st
and 2nd Molarsand 2nd Molars
• RootsRoots
– 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
– Furcation usually located at the junction of the cervical
and middle thirds of the roots

29. Type Traits ofType Traits of
Maxillary 1stMaxillary 1st
and 2nd Molarsand 2nd Molars
• RootsRoots
– Three roots splitting of the root trunk is called a
trifurcation

30. Maxillary FirstMaxillary First
Molar RootsMolar Roots
• Much variation in the shapes of rootsMuch variation in the shapes of roots
• The MB and DB roots are often bent in suchThe MB and DB roots are often bent in such
a way as to resemble the handles of a paira way as to resemble the handles of a pair
of pliersof pliers
• This is a contrast to second molars whichThis is a contrast to second molars which
have MB and DB roots closer and morehave MB and DB roots closer and more
nearly parallelnearly parallel
1st 2nd

31. Maxillary FirstMaxillary First
Molar RootsMolar Roots
• The MB and DB roots often curve distallyThe MB and DB roots often curve distally
• The apical third of the MB rootThe apical third of the MB root maymay curvecurve
distally enough to put its apex distal to thedistally enough to put its apex distal to the
buccal groovebuccal groove

32. Maxillary SecondMaxillary Second
Molar RootsMolar Roots
• MB and DB roots less curved than on firstMB and DB roots less curved than on first
molarmolar
• More nearly parallel with each otherMore nearly parallel with each other
• Both bent toward the distal in the apicalBoth bent toward the distal in the apical
thirdthird
2nd

33. Lingual AspectLingual Aspect
Of Maxillary MolarsOf Maxillary Molars
• Crown - Relative Size and TaperCrown - Relative Size and Taper
– Due to the prominent DL cusp, crown may be
as wide or wider on the lingual for the first
molar
– This is not as likely on the second molar

34. Lingual AspectLingual Aspect
Of MaxillaryOf Maxillary
MolarsMolars
• The crown of the second molar usuallyThe crown of the second molar usually
appears smaller than the first molarappears smaller than the first molar
• This is due mainly to the smaller orThis is due mainly to the smaller or
nonexistent DL cuspnonexistent DL cusp
1st 2nd

35. Number And Description OfNumber And Description Of
Lingual Cusps - First MolarLingual Cusps - First Molar
• Two well defined cusps, ML and DLTwo well defined cusps, ML and DL
• ML is usually the highest and largest of allML is usually the highest and largest of all
cusps on any maxillary molarcusps on any maxillary molar
• Often a fifth cusp, the cuspOften a fifth cusp, the cusp
of Carabelli, which variesof Carabelli, which varies
greatly in size and developmentgreatly in size and development
1st

36. Number AndNumber And
Description Of LingualDescription Of Lingual
Cusps - Second MolarCusps - Second Molar
• There are two types of maxillary secondThere are two types of maxillary second
molars based on number of cusps, 4 or 3molars based on number of cusps, 4 or 3
• On the four-cusp second molar there is aOn the four-cusp second molar there is a
ML and DL cuspML and DL cusp
• On the three-cusp second molar the DLOn the three-cusp second molar the DL
cusp is missingcusp is missing

37. Roots Of First MolarsRoots Of First Molars
From The LingualFrom The Lingual
• On first molars the palatal root is the thirdOn first molars the palatal root is the third
longest of any maxillary tooth (after caninelongest of any maxillary tooth (after canine
and second premolar)and second premolar)
• Tapers apically to a blunt or rounded apexTapers apically to a blunt or rounded apex
• There is usually a depression on the lingualThere is usually a depression on the lingual
aspect of the palatal rootaspect of the palatal root
Depression

38. Roots Of Second MolarsRoots Of Second Molars
From The LingualFrom The Lingual
• The lingual (palatal) root is as long as theThe lingual (palatal) root is as long as the
lingual root of the first molarlingual root of the first molar
• The buccal roots bend towards the distalThe buccal roots bend towards the distal
and are more paralleland are more parallel
Note Distal Bend

39. Proximal AspectProximal Aspect
Of First MolarsOf First Molars
• CuspsCusps
– 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
1 2
3

40. Proximal AspectProximal Aspect
Of First MolarsOf First Molars
• Mesial marginal ridge is moreMesial marginal ridge is more
occlusal than distal, thus very little of theocclusal than distal, thus very little of the
occlusal table can be seen from mesialocclusal table can be seen from mesial
• There is considerable narrowing of theThere is considerable narrowing of the
occlusal surface from crest of curvature,occlusal surface from crest of curvature,
resulting in a narrow occlusal tableresulting in a narrow occlusal table

41. Proximal AspectProximal Aspect
Of First MolarsOf First Molars
• From the distal, four cusps are visible (mayFrom the distal, four cusps are visible (may
also see Cusp of Carabelli)also see Cusp of Carabelli)
Distal

42. Proximal AspectProximal Aspect
OfOf
Second MolarsSecond Molars
• From the mesial and distal aspect, looksFrom the mesial and distal aspect, looks
much like the first molar, but no cusp ofmuch like the first molar, but no cusp of
Carabelli is presentCarabelli is present
• DL cusp is absent on more than one third ofDL cusp is absent on more than one third of
these teeththese teeth
Mesial Distal

43. Crest OfCrest Of
CurvatureCurvature
• On the buccal is located in the cervicalOn the buccal is located in the cervical
thirdthird
• On the lingual (palatal) in the middle thirdOn the lingual (palatal) in the middle third
L B

44. Taper NarrowerTaper Narrower
To DistalTo Distal
* On both first and second molars, the crown* On both first and second molars, the crown
is narrower buccolingually on the distalis narrower buccolingually on the distal
than the mesialthan the mesial
2nd
Distal
1st
Distal

45. MarginalMarginal
RidgesRidges
• On both first and second molars the mesialOn both first and second molars the mesial
marginal ridge is concave and moremarginal ridge is concave and more
occlusally located than the distal marginalocclusally located than the distal marginal
ridgeridge
• It is also longer buccolingually than theIt is also longer buccolingually than the
distal marginal ridgedistal marginal ridge
2nd
Mesial
1st
Mesial

46. TuberculesTubercules
• If present are usuallyIf present are usually
found on the mesialfound on the mesial
marginal ridge of firstmarginal ridge of first
molars (rarely found onmolars (rarely found on
2nd molars or distal2nd molars or distal
marginal ridge of firstmarginal ridge of first
molars)molars)
1st
Mesial

47. MarginalMarginal
RidgeRidge
GroovesGrooves
• Marginal ridge grooves are more commonMarginal ridge grooves are more common
on the mesial than the distalon the mesial than the distal
• More common on first molars than secondMore common on first molars than second
molarsmolars
2nd
Mesial
1st
Mesial

48. CervicalCervical
LineLine
• The mesial cervical line has a slightThe mesial cervical line has a slight
occlusal curvatureocclusal curvature
• There is slightly less curvature on the distalThere is slightly less curvature on the distal
than the mesialthan the mesial
1st
Distal
1st
Mesial

49. • The mesial contact area is a the junction ofThe mesial contact area is a the junction of
the middle and occlusal thirdsthe middle and occlusal thirds
• The distal contact area is in the middleThe distal contact area is in the middle
thirdthird
1st
Distal
1st
Mesial
ProximalProximal
ContactsContacts

50. Roots Of MaxillaryRoots Of Maxillary
Molars FromMolars From
The ProximalThe Proximal
• From the mesial view the MB root is broadFrom the mesial view the MB root is broad
buccolingually and is shorter than thebuccolingually and is shorter than the
lingual rootlingual root
• The MB root obscures the view of the DBThe MB root obscures the view of the DB
rootroot
• Apex of the MB root is in line with the MBApex of the MB root is in line with the MB
cusp tipcusp tip
MB

51. Roots Of MaxillaryRoots Of Maxillary
Molars FromMolars From
The ProximalThe Proximal
• The lingual root is the longest and oftenThe lingual root is the longest and often
banana shapedbanana shaped
• On first molars extends well beyond theOn first molars extends well beyond the
crown linguallycrown lingually
• Usually curved buccolinguallyUsually curved buccolingually
L

52. Roots Of MaxillaryRoots Of Maxillary
Molars FromMolars From
The ProximalThe Proximal
• From the distal, the DB root is shorter andFrom the distal, the DB root is shorter and
narrower than the MB rootnarrower than the MB root
• Can see the outline of both roots from theCan see the outline of both roots from the
distaldistal
Distal

53. Roots Of MaxillaryRoots Of Maxillary
Molars FromMolars From
The ProximalThe Proximal
• On second molars roots are much lessOn second molars roots are much less
spread apartspread apart
• Lingual roots is also straighter, usually notLingual roots is also straighter, usually not
extending past confines of the crownextending past confines of the crown
2nd
Mesial
1st
Mesial

54. Occlusal AspectOcclusal Aspect
OfOf
First MolarsFirst Molars
• The contour of first molarsThe contour of first molars
is not square, but gives thatis not square, but gives that
impression when compared to other teethimpression when compared to other teeth
• It is roughly a parallelogramIt is roughly a parallelogram

55. Occlusal AspectOcclusal Aspect
OfOf
Second MolarsSecond Molars
• The second molar is wider buccolinguallyThe second molar is wider buccolingually
than mesiodistally and tapers to the lingualthan mesiodistally and tapers to the lingual
• Much variation in second molar due to sizeMuch variation in second molar due to size
and location of DL cuspand location of DL cusp

56. Occlusal AspectOcclusal Aspect
OfOf
Second MolarsSecond Molars
• The four-cusp version of the second molarThe four-cusp version of the second molar
is less square in appearanceis less square in appearance

57. Number AndNumber And
Size Of CuspsSize Of Cusps
• Generally there are four cuspsGenerally there are four cusps
• First molar possess a fifth cusp 70% of theFirst molar possess a fifth cusp 70% of the
timetime
• Second molar may be missing the DL cuspSecond molar may be missing the DL cusp
14
3 2
5
14
3 2

58. Oblique Ridge UniqueOblique Ridge Unique
To Maxillary MolarsTo Maxillary Molars
• The oblique ridge connects the DB cuspThe oblique ridge connects the DB cusp
with the ML cuspwith the ML cusp
• It is present in second molars, but smallerIt is present in second molars, but smaller
than the oblique ridge of first molarsthan the oblique ridge of first molars

59. Fossae OnFossae On
Four-CuspFour-Cusp
MolarsMolars
• There are generally fourThere are generally four
fossae on four-cusp molarsfossae on four-cusp molars
1) Central Fossa
2) Mesial Triangular Fossa
3) Distal Triangular Fossa
4) Distal Fossa
1
23
4

60. Grooves On Four-Cusp MolarsGrooves On Four-Cusp Molars
Buccal Groove
Central GrooveCentral Groove
Transverse Groove
Of The Oblique
Ridge
Lingual Groove
Fifth Cusp Groove
Distal Oblique
Groove

61. Fossae And GroovesFossae And Grooves
OnOn
Three-Cusp MolarsThree-Cusp Molars
• The distal fossae and both the distal obliqueThe distal fossae and both the distal oblique
and lingual grooves are absentand lingual grooves are absent

62. Maxillary ThirdMaxillary Third
MolarsMolars

63. Maxillary ThirdMaxillary Third
MolarsMolars
• General description difficultGeneral description difficult
due to great variationdue to great variation
• Roots and crown shorter than first orRoots and crown shorter than first or
second molarsecond molar
• Crown often possess more supplementalCrown often possess more supplemental
groovesgrooves
• May possess three, four or five cuspsMay possess three, four or five cusps

64. Roots OfRoots Of
MaxillaryMaxillary
Third MolarsThird Molars
• Possess three roots, but more often they arePossess three roots, but more often they are
fused for most of their lengthfused for most of their length
• Roots are shorter than those of first andRoots are shorter than those of first and
second molarsecond molar
Mesial Buccal