lower78

1. Dr: MahMouD
Dr: MahMouD 3MMar
3MMar abD El-haMiED
abD El-haMiED
Mobile
Mobile: 0106 39 700 30
: 0106 39 700 30
Email
Email
:
:
m.3mmar9428
m.3mmar9428@yahoo.com
@yahoo.com
Addres:
Addres: knowledge village center
knowledge village center
.
.
Hihan st, mansoura opposite Galaa
Hihan st, mansoura opposite Galaa gate
gate

3. No. of surfaces
:
It has five surfaces
No. of roots
:
It has 2 roots
BUCCAL LINGUAL MESIAL DISTAL
OCCLUSAL

4. M D
Geometric outline: Trapezoid with
small uneven side located cervically
 The roots are closer and nearly parallel with
more pointed apex than 6
Anatomical Landmark
:
Elevations
:
1
.
cervical ridge
.
2
.
nearly equal MB , DB cusps but the MB cusp is usually longer
.
Depressions: BDG may end by buccal pit
.
BUCCAL ASPECT

5. Two buccal cusps & tips of two lingual cusps
are visible from this side
because the non-functional lingual cusps are slightly longer
.

6. M
D
The lingual cusps are more pointed , longer
than buccal cusps.
Ml cusp is wider , longer than DL cusp.
Cervical line is irregular , may dropping
cervically over root bifurcation.
Anatomica landmarks : Short Lingual developmental groove never pitted.
The Crown
The Root :Short root trunk with a developmental depression.
LINGUAL ASPECT

7. geometric outline: Rhomboidal
with lingual inclination
*
The mesial root is only visible
*
Longitudinal depression on the mesial surface of mesial
root
*MMR is concave L B
MESIAL ASPECT

8. Outlines
:
1
-
buccal outlin: convex with maximum of convexity at
cervical 1/3
2
-
lingual aoutline: convex with maximum
of convexity at middle third
3
-
cervical outline: slightly curved occlusally
,
it runs occlusally from buccal to lingual
.
4
-
occlusal outline
:
-
ML cusp slightly longer than MB cusp
.
-
occlusal surface is more constricted BL
-
tip of ML cusp is in line with lingual outline of mesial root
- MMR is sharply concave , often V-shape

9. :
Surface anatomy
mesial contact area
.
-
at junction of occlusal , middle third (c-o
(
.
-
at junction of buccal , middle third (B-L
(
)
buccal to long axes of tooth
(
B
L
B
L

10. L
B
*
DMR is concave but less angular than MMR
*
Distal root is narrower than mesial root, so both roots are seen
DISTAL ASPECT
*
DB cusp is the shortest of 4 cusps
.
*
Distal contact area is centered on distal aspect
BL & OC (thus its more cervically
,
more lingually stuated than
the mesial contact area
(
*
There is distal convergence

11. geometric outline: Rectangular.
M
L
B
D
Note:
*Disto-Lingual convergence.
* Mesio-Distally is larger than bucco -lingually.
*The distal outline is more convex (semi-circular).
* The mesial outline is nearly straight.
OCCLUSAL ASPECT

12. M
L
B
D
Anatomical landmarks:
Elevations: a) 4 cusps with
4 triangular ridges
( mesial cusps are larger than distal cusps).
b) Mesial and distal marginal ridge
.
OCCLUSAL ASPECT

13. *
1
major central fossae with central pit
*
2
Minor fossae ( mesial and distal
triangular fossae
(
*
Developmental grooves: form a typical Cross pattern , its straight.
. - central greeove: extend from central fossa to M , D fossa
.
-
BDG: separate 2 buccal cusps
.
-
LDG: seprate 2 lingual cuspa
.
N.B: BDG , LDG meet the central groove at right angle at central pit of central fossa
.
M
B
D
L
*
supplemental grooves radiate from developmental grooves
Note : All grooves provide important escape ways for food during mastication
Depression
:

14. -
►
Bucco-Lingually, the pulp
chamber is square
-
There is pulp horn beneath each
cusp
Pulp Chamber:
☻
Pulp cavity
Root Canals
:
-3 main root canals.
-M root usually has 2 root canals while D root
has 1 root canal
►
Mesio-Distally, the pulp
chamber is rectangular
M D L
B

15. ☻
Pulp cavity
Note:
Cervical cross section:
Triangular due to small dimension
distally
Mid root section:
*M root is kidney shape with 2 small
canals
*D root is oval with 1 large rounded
canal
M D L
B

18. No. of surfaces
:
It has five surfaces
BUCCAL lingual
MESIAL
DISTAL
OCCLUSAL

19. M
D
*
The 3rd
molar is either 4 or 5 cusp type
*
The buccal surface is very convex
*
2
Short roots :(M & D) may be fused in all or part of their length
,
more inclined distally than 1st
and 2nd
molars
BUCCAL ASPECT
*
Buccal cusps are short , rounded
.
*
MB cusp is the widest , highest of Two or 3 buccal cusps
.
*
Axis of the tooth incline distally
.

20. *
*
lingual cusps are longer than buccal cusps
.
.
.
*
*
ML cusp is
is larger than DL cusp
Lingual ASPECT
Lingual ASPECT

21. L
B
The buccal cusp tips are closer to the lingual
cusp tips giving a small occlusal table
L B
There is a distal conversion
Distal root is narrower than mesial root,
so both roots are seen
There is no DCA
MESIAL ASPECT
DISTAL ASPECT
Mesial root is pointed , hidden the distal root

22. M
L
D
The geometric outline:
Rectangular or oval
There are numerous supplemental
grooves and pits give a wrinkled
appearance
B
OCCLUSAL ASPECT

23. Variation of mandibular third molar
:-
.
-
Its variable tooth but less than upper third molar
.
-
crown may show 3 , 4 , 5 or multi-cusps
.
-
most anomalies is having large crown than normal
.
-
tooth may have one or more extra roots .
(multi-rotted forms
(
-
The pulp cavity also showed great variation in the size and shape
.

24. Mission
Impossible III
??? 
๑ 