6 lower 7 & 8

Dr: Mahmoud Dr: Mahmoud 3mmar3mmar Abd El-hamied Abd El-hamied

MobileMobile: 0106 39 700 30: 0106 39 700 30

EmailEmail : :m.3mmar9428@yahoo.com

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

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