mandibular molar

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    Development Table: (Mandibular First Molar)*

    Initiation of calcification .................................... at birth

    Completion of enamel ........................... 2 to years

    Eruption ....................................................... 6 to 7 years

    Completion of root ................................... 9 to 10 years

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    First permanent molar toFirst permanent molar to.

    It is known asIt is known as toothtooth..

    WHYWHY

    ??

    ItsIts in the lower arch is # 6in the lower arch is # 6..

    &&

    ItsIts is six yearsis six years..

    Functionally, it is considered as theFunctionally, it is considered as the.

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    No. of surfaces:

    It has five surfaces

    No. of roots:

    It has 2 roots

    BUCCAL LINGUAL MESIAL DISTAL

    OCCLUSAL

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    The geometric outline: Trapezoidal with smalluneven side present cervically.

    D M

    BUCCAL ASPECT

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    MD

    Mesial outline: concave till the contact area at

    the junction of the occlusal and middle 1/3. Theheight of contour of the mesial outline islocated at the junction of the occlusal andmiddle 1/3

    Distal outline: straight till the contact area

    beneath the distal cusp ridge. The height ofcontour of the distal outline is located at thejunction of the occlusal and middle 1/3

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    D

    Occlusal outline. !t is divided into threeby two grooves, as

    they pass ontothe buccal surface. Theyare termed buccal (mesiobuccal) groove,and distobuccal groove.

    Cervical outline: straight with dippinginto the root bifurcation

    M

    distobuccal groove.

    BUCCAL ASPECT

    buccalgroove

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    Buccal (mesiobuccal) grooveFrom the occlusal outline, it extends straightcervically to a point about midway betweenthe gingival and occlusal margins, but a littleto the mesial of center in the mesiodistal

    dimension. It most often terminates in a buccalpit.

    .

    Distobuccal grroove.It crosses occlusal outline close to the

    distal margin, and then extends cervically

    and slightly distally to terminate at a pointin the middle third near the distobuccalline angle. It normally ends in a distobuccalpit, but sometimes simplyfades out.

    .

    Distobuccal grroove

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    D M

    Anatomical landmarks:

    *2Developmental grooves (MB, DB

    *Cervical ridge at the cervical 1/3

    *Developmental depression run

    M-D in the middle 1/3

    BUCCAL ASPECT

    .

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    The Roots:

    * Root trunk: 3 mm.

    *The roots twice the length of the crown.

    * The axis of the roots are inclined distally

    * Deep developmental grooveextend on the root trunk.

    MD

    BUCCAL ASPECT

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    DM

    Mesial outline: Straight till the contactarea at the junction of the occlusal and

    middle 1/3

    Distal outline: Convex till the contact

    area beneath the distal cusp ridge

    LINGUAL ASPECT

    The lingual surface is also roughly

    trapezoidal in outline, with the longerparallel side of the trapezoid at theocclusal.

    The height of contour of the distal & mesialoutlines are at the junction of the occlusal and

    middle thirds.

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    DMOcclusal outline: formed by 2 lingual

    cusps,ML, DLof nearly equal width

    Cervical outline: Irregular with dipping

    into the root bifurcation

    Anatomical landmarks:

    Lingual Developmental groove

    LINGUAL ASPECT

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    The root trunk appears longer on the ling. surface due to:

    *the occlusal position of cervical line

    *Lingual conversion

    LINGUALBUCCAL

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    B L

    The geometric outline: Rhomboid and

    inclined lingually.

    Notes:

    1-MLcusp is more pointed thanMBcusp

    ( because it is out of occlusion

    2-The cervical line slants occlusally from the

    buccal to the lingual side.

    MESIAL ASPECT

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    B L

    Anatomical landmarks:

    *Contact area centered B-L below thecrest of marginal ridge

    *Deep developmental depression on the

    mesial surface of the root.

    MESIAL ASPECT

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    DISTAL ASPECT

    LB

    MESIAL ASPECT

    *The crown is shorter distally

    *There is a distal conversion

    *DMRis U- shape, shorter and more cervically than MMR

    *Distal contact area located below the distal cusp

    L

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    M D

    The geometric outline: Hexagonal

    L

    B

    * The crown measurements

    is larger MD than BL .

    * The crown converge lingually

    and distally

    OCCLUSAL ASPECT

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    M D

    B

    L

    Anatomical landmarks:

    Elevations:

    *5 cusps with 5 triangular ridges

    *MMR and DMR

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    *1major central fossae + pit

    *2Minor fossae ( mesial and distal

    triangular fossae

    *Developmental grooves:

    Central groove iszigzagin its MD coarse.

    M D

    B

    L

    MB , DB and L grooves

    Anatomical landmarks:

    Depressions:

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    -The pulp chamber is broad MD.

    -It is almost rectangular in shape.

    -There is apulp horn beneath eachcusp

    Pulp Chamber:

    Pulp cavity

    Root Canals:

    -3 main root canals.

    -Mroot has2 root canalswhileDroot has1

    root canal.

    Buccal view

    Mesial view

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    - In cross section at this level, bothroots are wider buccolingually, and the mesial roothas a larger outline. The outline is convex buccallyand lingually on both roots. Mesially and distally,

    the outline is flattened or concave, depending onthe presence and prominence of longitudinalgrooves.

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    Note:

    The two mesial root canals appear in x ray

    overlapping each other.

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    Abnormalities you may find:

    1-Three or four roots.

    2-Four root canals.

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    Enumerate the names of the following

    elevations and depression?

    1-Central groove

    2-MMR

    3-Central fossa

    4-Distal triangular fossa

    5-Mesio-buccal groove

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    Label the different surfacesLabel the different surfaces::

    Mesial surface

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    No. of surfaces:

    It has five surfaces

    No. of roots:

    It has 2 roots

    BUCCAL LINGUAL MESIALDISTAL

    OCCLUSAL

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    M DGeometric outline: Trapezoid

    with small uneven side located

    cervically

    The roots are closer and nearly

    parallel with more pointed apex

    than 6

    Anatomical Landmark:

    Buccal developmental groove may end in a buccal pit.

    MB cusp is longer than the DB cusp.

    BUCCAL ASPECT

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    MD

    The lingual cusps are more pointed

    than buccal cusps.

    Anatomical Landmark: Lingual

    developmental groove never pitted.

    The Crown

    The Root

    Short root trunk with a developmental

    depression.

    LINGUAL ASPECT

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    The 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

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    LB

    *DMRis concave but less

    angular than MMR

    *Distal root is narrower than mesial

    root, so both roots are seen

    DISTAL ASPECT

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    The geometric outline: Rectangular.M

    L

    B

    D

    Note:*Disto-Lingual convergence.

    *Mesio-Distally is larger than bucco

    -lingually.

    OCCLUSAL ASPECT

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    M

    L

    B

    DAnatomical landmarks:

    Elevations:

    *4 cusps with 4 triangular ridges ( mesial

    cusps are larger than distal cusps.

    *Mesial and distal marginal ridge.

    OCCLUSAL ASPECT

    B

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    *1major central fossae with central pit

    *2Minor fossae ( mesial and distal

    triangular fossae

    *Developmental grooves: form a typical

    Cross pattern

    M

    B

    D

    L

    *supplemental grooves radiate from

    developmental grooves

    Note :All grooves provide important escape

    ways for food during mastication

    Depression:

    P l it

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    Bucco-Lingually, the pulp

    chamber is square

    -There is pulp horn beneath eachcusp

    Pulp Chamber:

    Pulp cavity

    Root Canals:

    -3 main root canals.

    -Mroot usually has 2 root canals while D root

    has 1 root canal

    Mesio-Distally, the pulp

    chamber is rectangular

    M D B

    P l it

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    Pulp cavity

    Note:

    Cervical cross section:

    Triangular due to small dimension

    distallyMid root section:

    *M root is kidney shape with 2 small

    canals

    *D root is oval with 1 large rounded

    canal

    M D LB

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    No. of surfaces:

    It has five surfaces

    BUCCAL PALATAL

    MESIALDISTAL

    OCCLUSAL

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    MD*The 3rd molar is either 4 or 5 cusp

    type

    *The buccal surface is convex

    *2Short roots (M and D may be

    fused in all or part of their length

    *The roots are more inclined distally

    than 1st and 2nd molars

    BUCCAL ASPECT

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    LB

    The 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

    MESIAL ASPECT

    DISTAL ASPECT

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    M

    L

    DThe geometric outline:

    Rectangular or oval

    There are numerous supplemental

    grooves and pits give a wrinkled

    appearance

    BOCCLUSAL ASPECT

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    Note:1-The 3rd molar shows great

    variation in size and shape.

    2-The pulp cavity also shows great

    variation in size and shape

    3-The pulp chamber of 8 is larger than other

    molars because it is younger than othermolars by 9-11 years

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    What is thisWhat is this??

    L. surface 7

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    What is thisWhat is this??

    D. Surf. 7

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    Occ. Surf. 7

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    MMR 7

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    DL cusp 7

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    CDG 7

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    BDG 7

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    M F 7

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    What is thisWhat is this??

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    What is thisWhat is this??

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    What is this?

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    What is thisWhat is this??