6 lower 7 & 8
TRANSCRIPT
Dr: Mahmoud Dr: Mahmoud 3mmar3mmar Abd El-hamied Abd El-hamied
MobileMobile: 0106 39 700 30: 0106 39 700 30
EmailEmail : :[email protected]
Addres: Addres: knowledge village centerknowledge village center..Hihan st, mansoura opposite GalaaHihan st, mansoura opposite Galaa gategate
No. of surfaces:
It has five surfaces
No. of roots:
It has 2 roots
BUCCAL LINGUAL MESIAL DISTAL
OCCLUSAL
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
Two buccal cusps & tips of two lingual cusps are visible from this side because the non-functional lingual cusps are slightly
longer.
MDThe 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
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
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
: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)
BLBL
LB
*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
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
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
*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:
-► 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 LB
☻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 LB
No. of surfaces:
It has five surfaces
BUCCAL lingual
MESIAL DISTALOCCLUSAL
MD
*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.
**lingual cusps are longer than buccal cusps.
.. * *ML cusp isis larger than DL cusp
Lingual ASPECTLingual ASPECT
LBThe buccal cusp tips are closer to the lingual cusp tips giving a small occlusal table
L BThere 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
M
L
DThe geometric outline:
Rectangular or oval
There are numerous supplemental grooves and pits give a wrinkled appearance
BOCCLUSAL ASPECT
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.
Mission Impossible III
??? ๑