Max 2nd & 3rd molars.ppt

MAXILLARY 2ND AND 3RD MOLARS

1. Permanent Maxillary Molars
DR.VANISHREE.M
DEPARTMENT OF ORAL PATHOLOGY

2. Introduction
•17,27 and 18, 28 (FDI sytem of tooth notation)
•No fifth cusp is evident
•DB cusp is not large
•Two types of Max 2
nd
Molars

3. Introduction
•3
rd
Molars-upper wisdom teeth, often appear as
developmental anomaly
•3
rd
M supplements 2
nd
M in function
•3
rd
M design is that of a heart shaped type of
2
nd
M

4. Objectives
•Clinical significance
•Chronology & Tooth Dimensions
•Buccal aspect
•Lingual aspect
•Mesial aspect
•Distal aspect
•Occlusal aspect
•Endodontic Anatomy
•Variations & anomalies
•Summary

5. Clinical significance
•Basis for restorative and prosthodontic treatments in
particular and all phases of dentistry in general
•Knowledge of Pulpal anatomy helps to accomplish the
endodontic treatment.
•Help to understand the functional relation with
adjacent teeth and opposing teeth
•Periodontal instrumentation

6. Chronology of calcification & Eruption
Maxillary 2nd Molar
•First evidence of calcification
2 ½ years
•Enamel completed
7 to 8 years
•Eruption
12 to 13 years
•Root completed
14 to 16 years
Maxillary 3
rd
Molar
•First evidence of calcification
7 to 9 years
•Enamel completed
12 to 16 years
•Eruption
17 to 21 years
•Root completed
18 to 25 years

7. Tooth Dimensions
Cervico-
incisal
Length Of
Crown
Length Of
Root
Mesio-distal
Diameter
Of Crown
Mesio-distal
Diameter
Of Crown
At Cervix
Labio-Or
Bucco-
lingual
Diameter
Of Crown
Labio-Or
Bucco-
lingual
Diameter
At Cervix
Curvature
Of Cervical
Line-mesial
Curvature
Of Cervical
Line-Distal
Dimensions
Suggested
[mm]
17 and
27
7.0
B L
11 12 9.0 7.0 11.0 10.0 1.0 0.0
Dimensions
Suggested
[mm]
18 and
28
6.5 11.0 8.5 6.5 10.0 9.5 1.0 0.0

8. Buccal Aspect
•Crowns are little shorter cervico-occlusally
and narrower mesiodistally than 16
•DB cusp smaller-allows part of distal
marginal ridge and DL cusp seen
17 18

9. Buccal Aspect
•2M-buccal roots same length, parallel and inclined
distally, 3
rd
M roots are usually fused functioning
as one large root
•2M-apex of MB root is on line with buccal groove
of crown (instead of tip of MB cusp as in 1
st
Molar
17 18

10. Lingual Aspect
•DL cusp smaller in 2
nd
M, no fifth cusp
•Apex of lingual root is in line with the DL cusp tip
(unlike 1
st
M)
•Only one large lingual cusp in 3
rd
M, no lingual groove
(in some DL cusp and groove are seen)
17 18

11. Mesial Aspect
•BL dimension of 2
nd
M same as 1
st
M, but
lesser crown length
•Roots do not spread buccolingually
•Taper to the fused roots of 3
rd
M and
bifurcation in the region of apical third
1817

12. Mesial Aspect
•Root portion of 3
rd
M considerably shorter
than crown
•Both crown and root portion of 3
rd
M poorly
developed with irregular outline
1817

13. Distal Aspect
•Because DL cusp is smaller, more of MB cusp
may be seen
•ML cusp of 2
nd
M cannot be seen
•Apex of lingual root in line with the
distolingual cusp
17 18

14. Distal Aspect
•Most of the buccal surface and occlusal
surface seen for 3
rd
Molar
•3
rd
M-The measurement from cervical line to
marginal ridge is short
17 18

15. Occlusal Aspect
•Rhomboid type of 2
nd
M most common but a
heart shaped outline of 3
rd
M
•MB & ML cusps are well developed in 2
nd
M but
DB & DL cusps are smaller
•Lingual cusp large and well developed in 3
rd
M
17 18

16. Occlusal Aspect
•Semicircular outline of 3
rd
M from contact to
contact points, three functioning cusps (two
buccal and one lingual)
•More supplemental grooves, accidental grooves
and pits on both 2
nd
and 3
rd
Molars
17 18

17. Occlusal Aspect
•3
rd
M may show 4 distinct cusps, if present may
have oblique ridge, a central fossa and distal
fossa
•In most cases of 3
rd
M, crown converges more
lingually from buccal areas than the 2
nd
M does
losing its rhomboidal outline
17 18

18. Endodontic Anatomy
Buccolingual Section
•2
nd
M possess 3 roots and 3
canals
•MB root of 2
nd
M not as complex
as 1
st
M
•Rarely presence of 2 canals in
MB root of 2
nd
M
•18 has most variable anatomy of
any of the maxillary teeth
17
Fig
of
18

19. Endodontic Anatomy
…Buccolingual Section
•Pulp horns may be well
developed or absent in 17
•Pulp chambers rectangular for
17 and
•Pulp canals gradually taper
towards the apex
•Apical foramen of palatal root
appear to exit at root tip
17
Fig
of
18

20. Endodontic Anatomy
…Buccolingual Section
•Crown of 3
rd
M is usually triangular
or round, roots have tendency for
fusion
•Max 3
rd
molars are 8-9 years
younger than 1
st
and 2
nd
M, pulp
chamber has less secondary dentin
so, allows easier access
17
Fig
of
18

21. Endodontic Anatomy
…Buccolingual Section
•Because of higher incidence of
malformations of roots,
endodontic procedures may be
very difficult
17
Fig
of
18

22. …Endodontic Anatomy
Mesiodistal Section of 17
•Similar to Max 1
st
M
•Greater tendency of buccal roots
to be fused
•Pulp horns well developed
•MB pulp horn larger than DB pulp
horn
•Some teeth demonstrate absence
of pulp horns
Fig
of
18
17

23. …Endodontic Anatomy
Mesiodistal Section of 17
•Pulp chamber appear much
smaller in MD section than BL
•Pulp chamber is square
•Majority of apical foramen exit at
tip of the roots
Fig
of
18
17

24. …Endodontic Anatomy
Cervical Cross Section of 17
•Angulations of outline are more
extreme than 1
st
M
•MB angle is more acute and DB angle
is more obtuse than 1
st
M, outline
form of pulp chamber reflect these
•MB orifice is located farther buccally
and mesially to pulp chamber
17

25. …Endodontic Anatomy
Cervical Cross Section of 17
•Palatal canal located most lingual
aspect of root
•Orifices of all the canals are much
closer than 1
st
M
•Triangularity of the floor of the pulp
is clearly demonstrated
17

26. …Endodontic Anatomy
Midroot cross section of 17
•Palatal root may be the largest of the
three roots
•MB root may have larger BL
dimension
•DB root and pulpal root have round
or oval pulpal outline
•MB root is rectangular in shape and
is reflected in pulpal outline
17

27. Variations & Anomalies
•3 main variations of 2
nd
molar from classic four
cusped form
–A. 3 cusps with distolingual cusp absent
–B. 3 cusped form compressed mesiodistally
–C. similar to 1
st
M but with reduced DL cusp
•Fusion of roots between buccal roots or between
buccal and palatal roots
•Very rarely a cusp of carabelli may be present

28. Variations & Anomalies
•3
rd
molar subject to more variation than any other
tooth in the human dentition
•3
rd
M crown may be similar to 2
nd
M or be
underdeveloped and peg shaped with small tapering
root
•3
rd
M: accessory cusps and roots absent
•Extreme variation in the degree of distal curvature of
root-3
rd
Molar

29. Summary
•No cusp of carabelli on 2
nd
and 3
rd
molars
•Rhombic occlusal outline of 2
nd
M more obvious
and narrower mesiodistally than max 1
st
molar
•Triangular occlusal outline of 3
rd
M
•Root of 2
nd
M less divergent, parallel and closer
together, slight distal inclination

30. Summary
•Roots of 3
rd
M short, underdeveloped, convergent,
often fused, curve distally, 3 in number
•Only Mesial contact area on 3
rd
Molar and crown
appears ‘too big for its roots’
•Coalescence of roots more common
•2
nd
Molar: Oblique ridge joins mesiopalatal and
distobuccal cusps

31. Book References
•Dental Anatomy, Physiology and
Occlusion -Wheeler’s
•Dental Anatomy -it’s relevance to
dentistry -Woelfel & Scheid
•Dental Anatomy -S.I. Bhalajhi
•Dental Morphology: an illustrated guide-
Geoffrey C van Beek