Anatomy of Peremanent Molars
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Transcript of Anatomy of Peremanent Molars
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DescriptiveDescriptive
Anatomy ofAnatomy of
PermanentPermanent
MolarsMolars
Prof. A. Elsahn
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They are twelve in number, three in They are twelve in number, three ineach quadrant named rst, second,each quadrant named rst, second,
and third molar according to theirand third molar according to their
position from the midline.position from the midline.
1)1)Number:Number:
Prof. A. ElsahnProf. A. Elsahn
GeneralGeneral
CharacteristicsCharacteristics
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2) Location:2) Location:
The mandibular molars The mandibular molars
make up over half !"#$ ofmake up over half !"#$ of
the mesiodistal dimension.the mesiodistal dimension.Prof. A. Elsahn
They are the most They are the mostposteriorly situated teethposteriorly situated teethin the mouth, distal to thein the mouth, distal to thesecond premolar.second premolar.
The three ma%illary molars The three ma%illary molarson each side constituteon each side constitute&$ of the mesiodistal&$ of the mesiodistaldimension of thatdimension of that
quadrant.quadrant.
& & #
& & #
! " # ! " #
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))
!unction:!unction:
They are adapted for crushing and They are adapted for crushing and
grinding of the food.grinding of the food.
They help to maintain the proper They help to maintain the proper
vertical dimension and the continuityvertical dimension and the continuity
within the dental arch.within the dental arch.
Prof. A. Elsahn
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")") #cclusal#cclusal
$urface:$urface:
They have wide They have wide
occlusal surface.occlusal surface.
Prof. A. Elsahn
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%) Cusps:%) Cusps:
'olars are multicusped teeth, their'olars are multicusped teeth, their
occlusal surfaces carry three to veocclusal surfaces carry three to vecusps and a comple% pattern of groovescusps and a comple% pattern of grooves
and ridges characteristic for eachand ridges characteristic for each
molar.molar.
The cusps of upper molars are more The cusps of upper molars are more
pronounced than those of lower molars.pronounced than those of lower molars.
Prof. A. Elsahn
""
"""""" ((
((((
((
))))
))
))
&&
&&&&
!!
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&) Cro'ns:&) Cro'ns:
They have large crowns but shorter They have large crowns but shorter
than the premolars.than the premolars.
Prof. A. Elsahn
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() oots:() oots: 'olars are multirooted.'olars are multirooted.
Prof. A. Elsahn
The roots tend to The roots tend tobecome shorter, closerbecome shorter, closertogether and show atogether and show a
greater backwardgreater backward
'andibular molars have'andibular molars havetwo roots, one mesialtwo roots, one mesialand one distal.and one distal.
'a%illary molars have'a%illary molars havethree roots, two buccalthree roots, two buccaland one palatal.and one palatal.
** **
****
''''
''''+. Aspect+. Aspect.Aspect.Aspect
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*) #cclusal*) #cclusal
#utline:#utline: The ma%illary molars are rhomboidal or The ma%illary molars are rhomboidal or
sometimes parallelogram or heart-shape$ withsometimes parallelogram or heart-shape$ with
the widest measurement buccolinguallythe widest measurement buccolingually..
Prof. A. Elsahn
The mandibular molars are more oblong, The mandibular molars are more oblong,
rectangular or square with the widestrectangular or square with the widestmeasurement mesiodistally.measurement mesiodistally.
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+)+)
$i,e:$i,e:
'a%illary molars are the largest ma%illary'a%illary molars are the largest ma%illary
teeth.teeth. The second molar is smaller than the rst The second molar is smaller than the rst
in the same arch especially mesiodistally.in the same arch especially mesiodistally.
Third molars are generally the smallest. Third molars are generally the smallest.
The rst mandibular molars are the largest The rst mandibular molars are the largestmolar but the third molars may be eithermolar but the third molars may be either
larger or smaller than the second molars.larger or smaller than the second molars.Prof. A. Elsahn
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1-)1-)
#cclusion:#cclusion:
Each ma%illary molar occludes with theEach ma%illary molar occludes with the
corresponding mandibular molar and thecorresponding mandibular molar and thene%t more posterior molar e%ceptne%t more posterior molar e%ceptma%illary third molar which occludesma%illary third molar which occludesonly with the lower third molars.only with the lower third molars. Prof. A. Elsahn
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DescriptiveDescriptive
Anatomy ofAnatomy ofPermanentPermanent
Ma.illary MolarsMa.illary Molars
Prof. A. Elsahn
Ma.illaryMa.illary
!irst Molar!irst Molar
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nitial /alcicationnitial /alcication+irth or slightly+irth or slightlybeforebefore
/ompletion of crown/ompletion of crown ((0 1 ) years0 1 ) years
EruptionEruption 2 1 3 years2 1 3 years
/ompletion of roots/ompletion of roots 4 1 "5 years4 1 "5 years
C/#N#L#G0 C/#N#L#G0
Prof. A. Elsahn
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GeneralGeneral
CharacteristicsCharacteristics
".". t is the si%th tooth from the median line.t is the si%th tooth from the median line.
(.(. t is the largest tooth in the ma%illary arch.t is the largest tooth in the ma%illary arch.
Prof. A. Elsahn
""(())
&&
!!
22
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General CharacteristicsGeneral Characteristics
).). t has large crown with four well-formed cusps moret has large crown with four well-formed cusps more
pronounced than those on the opposing lowerpronounced than those on the opposing lower
molar$.molar$.
The two buccal cusps are more pointed The two buccal cusps are more pointed
than the two palatal cusps.than the two palatal cusps.Prof. A. Elsahn
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General CharacteristicsGeneral Characteristics
&.&. A unique feature of the tooth is the presenceA unique feature of the tooth is the presenceof an elevation calledof an elevation called tubercle of Carabellitubercle of Carabelli fth cusp$ on about 25 1 3! # of cases.fth cusp$ on about 25 1 3! # of cases.
Prof. A. Elsahn
G lG l
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GeneralGeneral
CharacteristicsCharacteristics
!.!. ts crown is wider buccolinguallyts crown is wider buccolinguallythan mesiodistally.than mesiodistally.
Prof. A. Elsahn
++
'' **
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2.2. t has three roots two buccal and onet has three roots two buccal and one
palatal as in all ma%illary molars.palatal as in all ma%illary molars.
Prof. A. Elsahn
General CharacteristicsGeneral Characteristics
+. Aspect+. Aspect . Aspect. Aspect
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he Cro'nhe Cro'n
uccaluccal
AspectAspect
The geometric outline of the The geometric outline of thecrowncrown is trape6oidal with theis trape6oidal with the
short of the uneven sidesshort of the uneven sides
cervically.cervically. Prof. A. Elsahn
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Distal outline:Distal outline:
Prof. A. Elsahn
s nearly straight from the cervicals nearly straight from the cervical
line to the mesial contact area, thenline to the mesial contact area, thencurves distally to be continuous withcurves distally to be continuous with
the mesial slope of the mesiobuccalthe mesial slope of the mesiobuccal
cusp.cusp.
MesialMesial
outline:outline:
s conve% from the cervical line tos conve% from the cervical line to
the tip of the distobuccal cusp.the tip of the distobuccal cusp.
ts ma%imum conve%ity is at thets ma%imum conve%ity is at thedistal contact area.distal contact area.
The distal side of the crown can be The distal side of the crown can be
seen from the buccal aspect due toseen from the buccal aspect due to
the obtuse distobuccal line angle.the obtuse distobuccal line angle.
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Contact Areas:Contact Areas:
M3$4ALM3$4AL
At the 7unction of the occlusal and middle third.At the 7unction of the occlusal and middle third.
D4$ALD4$AL
At the center of the middle third.At the center of the middle third.
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#cclusal #utline:#cclusal #utline:
Two buccal cusps, mesiobuccal Two buccal cusps, mesiobuccal
and dislobuccal cusps.and dislobuccal cusps.
Each cusp has a tip, a mesial cuspEach cusp has a tip, a mesial cusp
slope and distal cusp slope.slope and distal cusp slope.
The mesiobuccal cusp is broader The mesiobuccal cusp is broaderthan the distobuccal cusp.than the distobuccal cusp.
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#cclusal #utline:#cclusal #utline:
The mesial and distal slopes of the The mesial and distal slopes of themesiobuccal cusp meet at an obtusemesiobuccal cusp meet at an obtuseangle, while the slopes of theangle, while the slopes of the
distobuccal cusp meet at rightdistobuccal cusp meet at rightangle, so the distobuccal cusp isangle, so the distobuccal cusp issharper and at least as long or oftensharper and at least as long or oftenlonger than the mesiobuccal cusp.longer than the mesiobuccal cusp.
Parts of the two lingual cusps can beParts of the two lingual cusps can beseen from the buccal aspect.seen from the buccal aspect.
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he Cervical Linehe Cervical Line
The cervical line is generally irregular The cervical line is generally irregular
and slightly conve% toward the root.and slightly conve% toward the root.
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Morpholo5y #f he uccalMorpholo5y #f he uccal
$urface #f he Cro'n:$urface #f he Cro'n: The buccal surface of the crown is The buccal surface of the crown is
conve%.conve%.
A buccal developmental grooveA buccal developmental groove
separates the two buccal cuspsseparates the two buccal cusps
e%tending to the middle third.e%tending to the middle third.
The groove fades out cervically, ending The groove fades out cervically, ending
by a transverse dip in enamel mesiallyby a transverse dip in enamel mesially
and distally. 8ometimes the buccaland distally. 8ometimes the buccalgroove ends by a pit.groove ends by a pit.
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The roots originate as a The roots originate as acommon undivided part oncommon undivided part onthe base of the crown, thisthe base of the crown, thissingle common root base issingle common root base iscalledcalled root trun6 root trun6 ..
The root trunk of this tooth The root trunk of this toothdivides into three roots9 twodivides into three roots9 twobuccal and one palatal. Thebuccal and one palatal. Thea%es of the roots area%es of the roots areinclined distally.inclined distally.
The length of root trunk is The length of root trunk isabout & millimeters.about & millimeters.
he ootshe ootshe ootshe oots
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The mesiobuccal root is slightly longer The mesiobuccal root is slightly longerthan the distobuccal one.than the distobuccal one.
:n the average, the length of the roots:n the average, the length of the rootsis about twice as long as the crown.is about twice as long as the crown.
he ootshe oots
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The mesiodistal diameter of the lingual The mesiodistal diameter of the lingual
surface is nearly equal to that of thesurface is nearly equal to that of the
buccal surface.buccal surface.
Lin5ual AspectLin5ual AspectLin5ual AspectLin5ual Aspect
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he Mesial #utline:he Mesial #utline: is almost straight and forms ais almost straight and forms aright angle with the mesialright angle with the mesial
slope of the mesiolingual cusp.slope of the mesiolingual cusp.
The two slopes of this cusp The two slopes of this cuspform an obtuse angle.form an obtuse angle.
he Distal #utline:he Distal #utline: is smoothly conve% andis smoothly conve% and
becomes continuous with thebecomes continuous with the
distal slope of the distolingualdistal slope of the distolingual
cusp cusp i.e.i.e. semicircular$semicircular$ Prof. A. Elsahn
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#cclusal #utline:#cclusal #utline:
The two lingual cusps are the only The two lingual cusps are the only
one to be seen from this aspectone to be seen from this aspect
beside the cusp or tubercle ofbeside the cusp or tubercle of
/arabelli when e%ist$./arabelli when e%ist$. Prof. A. Elsahn
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he Mesiolin5ual Cusp:he Mesiolin5ual Cusp:
is the largest and longest cuspis the largest and longest cuspof this tooth.of this tooth.
ts mesiodistal width is aboutts mesiodistal width is about
three fth of the mesiodistalthree fth of the mesiodistal
crown diameter.crown diameter.
he Distolin5ual Cusp:he Distolin5ual Cusp:
is spheroidal and smooth.is spheroidal and smooth. t makes up the remaining twot makes up the remaining two
fth of the crown diameter.fth of the crown diameter.
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The fth cusp or tubercle of The fth cusp or tubercle of/arabelli is a small elevation,/arabelli is a small elevation,
commonly found in about 25commonly found in about 25per cent of cases on theper cent of cases on thelingual surface of thelingual surface of themesiolingual cusp.mesiolingual cusp.
t is outlined occlusally by ant is outlined occlusally by anirregular developmentalirregular developmentalgroove.groove.
f it is well developed, its cuspf it is well developed, its cuspridge is nearly ( mm cervicalridge is nearly ( mm cervicalto the cusp ridge of theto the cusp ridge of the
mesiolingual cusp.mesiolingual cusp. Prof. A. Elsahn
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Cervical Line:Cervical Line:
/ervical line is irregular./ervical line is irregular.
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Morpholo5y #f he Lin5ualMorpholo5y #f he Lin5ual
$urface:$urface: The lingual surface of the crown is The lingual surface of the crown isconve%.conve%.
A lingual developmental groove dividesA lingual developmental groove divides
unequally the two lingual cusps.unequally the two lingual cusps. t ends nearly at the center of thet ends nearly at the center of the
lingual surface.lingual surface.
;rom the end of the lingual groove a;rom the end of the lingual groove a
shallow depression e%tends to theshallow depression e%tends to thecenter of the lingual surface of thecenter of the lingual surface of thelingual root crossing the cervical linelingual root crossing the cervical lineand fades out at the middle third of theand fades out at the middle third of the
root.root. Prof. A. Elsahn
hh thh thh thh thh t
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he ootshe ootshe ootshe ootshe ootshe ootshe ootshe ootshe ootshe oots
The three roots are seen The three roots are seenlingually.lingually.
The large lingual palatal$ root The large lingual palatal$ rootis conical ending in a bluntlyis conical ending in a bluntly
rounded ape%. This ape% is on arounded ape%. This ape% is on a
line with the lingual groove.line with the lingual groove.
Parts of the buccal roots areParts of the buccal roots are
seen from this aspect behindseen from this aspect behind
the lingual onethe lingual one Prof. A. Elsahn
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Mesial AspectMesial Aspect
The geometric outline is The geometric outline is
roughly trape6oidal with theroughly trape6oidal with the
uneven short side occlusally.uneven short side occlusally.
;rom this aspect the great;rom this aspect the great
buccolingual dimension of thisbuccolingual dimension of thistooth is evident as in all uppertooth is evident as in all upper
molars.molars.
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uccal #utline:uccal #utline: 8tarting from the neck and ending at the8tarting from the neck and ending at the
tip of mesiobuccal cusp tip9 it is conve%,tip of mesiobuccal cusp tip9 it is conve%,then concave and nally slightly conve%.then concave and nally slightly conve%.
The crest of the cervical conve%ity is The crest of the cervical conve%ity islocated at the cervical third representinglocated at the cervical third representingthe ma%imum conve%ity of the cervicalthe ma%imum conve%ity of the cervicalridge.ridge.
The following concavity is shallow, The following concavity is shallow,representing the terminus of the buccalrepresenting the terminus of the buccaldevelopmental groove.developmental groove.
Then, the slight conve%ity circumscribed Then, the slight conve%ity circumscribedthe mesiobuccal cusp.the mesiobuccal cusp.
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Lin5ual #utline:Lin5ual #utline: ingual outline is smoothly conve% fromingual outline is smoothly conve% from
the cervical line to the mesiolingualthe cervical line to the mesiolingual
cusp tip if the tubercle of /arabelli iscusp tip if the tubercle of /arabelli is
undeveloped.undeveloped.
The crest of this conve%ity is at the The crest of this conve%ity is at the
middle third of the crown.middle third of the crown.
f the tubercle is well developed, thef the tubercle is well developed, the
lingual outline dips inward to illustratelingual outline dips inward to illustrateit.it.
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#cclusal #utline:#cclusal #utline:
The tips of the two mesial cusps are within The tips of the two mesial cusps are within
pro7ected outlines of the root base.pro7ected outlines of the root base.
The mesiobuccal cusp is on a line with the The mesiobuccal cusp is on a line with the
long a%is of the lingual root.long a%is of the lingual root.
Prof. A. Elsahn
#cclusal #utline:#cclusal #utline:
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#cclusal #utline:#cclusal #utline:
The center of the occlusal The center of the occlusal
surface between the cusps is insurface between the cusps is inline with the root a%es as in allline with the root a%es as in all
ma%illary posterior teeth.ma%illary posterior teeth.
The mesial marginal ridge is The mesial marginal ridge isirregular and curving cervicallyirregular and curving cervically
about one-fth the crown length.about one-fth the crown length.
t is continuous with the cuspt is continuous with the cusp
ridges of the two mesial cusps.ridges of the two mesial cusps.
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he Cervical Line:he Cervical Line:
The cervical line is irregular and slightly The cervical line is irregular and slightly
conve% occlusally.conve% occlusally.Prof. A. Elsahn
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Morpholo5y #f heMorpholo5y #f he
Mesial $urface:Mesial $urface: The mesial surface is almost The mesial surface is almost
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Morpholo5y #f he MesialMorpholo5y #f he Mesial
$urface:$urface: A shallow concavity isA shallow concavity is
usually found 7ust belowusually found 7ust below
the mesial contact area.the mesial contact area.
This concavity may e%tend This concavity may e%tend
to the mesial surface ofto the mesial surface ofthe root trunk at itsthe root trunk at its
cervical third.cervical third.
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he ootshe ootshe ootshe ootshe ootshe oots
he oot run6 he oot run6
is a little shorter mesially thanis a little shorter mesially thanbuccally about ) mm$ with abuccally about ) mm$ with a
smooth depression at thesmooth depression at thebifurcation e%tending occlusally andbifurcation e%tending occlusally and
lingually.lingually.
he Mesiobuccal oothe Mesiobuccal oot
is broad and
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he Palatal oothe Palatal oot is longer and narrower than theis longer and narrower than the
mesiobuccal root.mesiobuccal root. The palatal root is the most divergent root The palatal root is the most divergent root
in order to follow the bone around thein order to follow the bone around the
ma%illary sinus.ma%illary sinus.
t ist is banana7shape8banana7shape8 , e%tending lingually., e%tending lingually.
he Distobuccal oothe Distobuccal oot can not becan not be
seen from this aspect.seen from this aspect.
t is hidden behind the mesiobuccal one.t is hidden behind the mesiobuccal one.
Prof. A. Elsahn
Distal AspectDistal Aspect
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Distal AspectDistal Aspect
t is similar to the mesial aspectt is similar to the mesial aspectwith certain variations.with certain variations.
The crown tends to converge The crown tends to converge
distally, due to the slant of thedistally, due to the slant of the
buccal side.buccal side.
8o, the buccolingual measurement8o, the buccolingual measurementof the crown distally is smaller thanof the crown distally is smaller than
that mesially, thus part of thethat mesially, thus part of the
buccal surface can be seen distally.buccal surface can be seen distally.
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The distal surface of the crown is The distal surface of the crown is
generally conve% e%cept for agenerally conve% e%cept for a
small concave area at thesmall concave area at thecervical third near thecervical third near the
distobuccal root.distobuccal root.
This area e%tends to the distal This area e%tends to the distal
surface of the distobuccal root upsurface of the distobuccal root up
to the furcation area.to the furcation area.
The distal marginal ridge is more The distal marginal ridge is more
curved cervically, e%posing partcurved cervically, e%posing part
of the occlusal surface distally.of the occlusal surface distally.
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he Cervical Linehe Cervical Line
s almost straight.s almost straight.
:ccasionally it may curve apically.:ccasionally it may curve apically.
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he ootshe oots
The root trunk shows the The root trunk shows thelargest length distallylargest length distally
reaching ! mm or more.reaching ! mm or more.
The distobuccal root is The distobuccal root is
narrower than the othernarrower than the other
two roots.two roots.
Prof. A. Elsahn
# l l A t# l l A t
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#cclusal Aspect#cclusal Aspect
The geometric outline of The geometric outline ofthe crown occlusally isthe crown occlusally is
somewhat rhomboidalsomewhat rhomboidalwith acute mesiobuccalwith acute mesiobuccaland distolingual anglesand distolingual angles
and obtuse mesiolingualand obtuse mesiolingual
and distobuccal angles.and distobuccal angles.
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The buccolingual measurement of the crown mesially is The buccolingual measurement of the crown mesially isgreater than distally.greater than distally.
The mesiodistal measurement lingually is greater than The mesiodistal measurement lingually is greater thanbuccally.buccally.
Thus, Thus,
The crown is wider mesially than distally and wider lingually The crown is wider mesially than distally and wider linguallythan buccally, due to buccal convergence of the distal surface.than buccally, due to buccal convergence of the distal surface.
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The ma%illary rst molar has four The ma%illary rst molar has four
well developed cusps namedwell developed cusps named
according to their location.according to their location.
A small fth cusp or tubercle ofA small fth cusp or tubercle of
/arabelli appearing on the/arabelli appearing on the
lingual surface of thelingual surface of the
mesiolingual cusp near themesiolingual cusp near the
mesiolingual line angle.mesiolingual line angle.
This tubercle may be ill dened This tubercle may be ill dened
or absent.or absent.
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The mesiolingual cusp is the largest The mesiolingual cusp is the largestfollowed in decreasing order of si6e by thefollowed in decreasing order of si6e by the
mesiobuccal, distolingual in 3(# andmesiobuccal, distolingual in 3(# and
distobuccal cusp in "=# of the cases.distobuccal cusp in "=# of the cases.
The fth cusp tubercle$, if present, is the The fth cusp tubercle$, if present, is the
smallest.smallest. Prof. A. Elsahn
i8i8
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i85es:i85es:
Each of the four cusps has a denite triangularEach of the four cusps has a denite triangularridge.ridge.
>nion of the triangular ridges of the>nion of the triangular ridges of themesiolingual and the distobuccal cusps formsmesiolingual and the distobuccal cusps forms
anan obli9ue ri85eobli9ue ri85e crossing the occlusal surfacecrossing the occlusal surfaceobliquely characteristic of ma%illary molars$.obliquely characteristic of ma%illary molars$.
This ridge is reduced in height in the center of This ridge is reduced in height in the center of
the occlusal surface.the occlusal surface. Prof. A. Elsahn
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i85es:i85es:
The mesial and distal The mesial and distal mar5inal ri85esmar5inal ri85es are continuous with the ad7acent cuspare continuous with the ad7acent cusp
ridges.ridges.Prof. A. Elsahn
!
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!ossae!ossae
here are two ma7or fossae?here are two ma7or fossae?
he central fossaehe central fossaehe 8istal fossaehe 8istal fossae
And two minor fossae?And two minor fossae?he mesial trian5ular fossaehe mesial trian5ular fossae
he 8istal trian5ular fossaehe 8istal trian5ular fossae
Prof. A. Elsahn
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he Central !ossahe Central !ossa t is roughly large triangulart is roughly large triangular
concave area.concave area.
t is near the center of the occlusalt is near the center of the occlusal
surface, and mesial to the obliquesurface, and mesial to the oblique
ridge.ridge.
t is bounded by the oblique ridget is bounded by the oblique ridge
and the distal and mesial slopes ofand the distal and mesial slopes of
the mesiobuccal and distobuccalthe mesiobuccal and distobuccal
cusps respectively.cusps respectively. The central fossa contains in its The central fossa contains in its
depth a central developmental pit.depth a central developmental pit.
Prof. A. Elsahn
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he Distal !ossahe Distal !ossa
The distal fossa is roughly elongated The distal fossa is roughly elongated
and distal to the oblique ridge.and distal to the oblique ridge.Prof. A. Elsahn
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The small mesial and the minute distal The small mesial and the minute distaltriangular fossae are immediately distaltriangular fossae are immediately distal
and mesial to the mesial and distaland mesial to the mesial and distal
marginal ridges respectively .marginal ridges respectively . Prof. A. Elsahn
DevelopmentDevelopment
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DevelopmentDevelopment
al Groovesal Grooves
8tarting from the central pit of the central8tarting from the central pit of the central
fossa the following grooves radiate?fossa the following grooves radiate?
The The buccal 8evelopmental 5roovebuccal 8evelopmental 5roove e%tendse%tends
from the central pit buccally and continuesfrom the central pit buccally and continues
between the buccal cusps onto the buccalbetween the buccal cusps onto the buccal
surface of the crown as the buccal groove.surface of the crown as the buccal groove.
8tarting from the central pit of the central8tarting from the central pit of the central
fossa the following grooves radiate?fossa the following grooves radiate?
The The buccal 8evelopmental 5roovebuccal 8evelopmental 5roove e%tendse%tends
from the central pit buccally and continuesfrom the central pit buccally and continues
between the buccal cusps onto the buccalbetween the buccal cusps onto the buccal
surface of the crown as the buccal groove.surface of the crown as the buccal groove.Prof. A. Elsahn
he Central Groovehe Central Groove
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he Central Groovehe Central Groove
The central groove e%tends mesially The central groove e%tends mesially
from the central pit to terminate atfrom the central pit to terminate at
the ape% of the mesial triangularthe ape% of the mesial triangular
fossa.fossa. Prof. A. Elsahn
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#ccasionally#ccasionally, a short, a shortdevelopmental groovedevelopmental groove
radiates from the central pitradiates from the central pitand runs transversely andand runs transversely anddistally across the obliquedistally across the obliqueridge to the distal fossaridge to the distal fossa
7oining the central and distal 7oining the central and distalfossae.fossae.
This groove is called the This groove is called thetransverse 5roovetransverse 5roove, of the, of theoblique ridge.oblique ridge.
Prof. A. Elsahn
he Distal #bli9uehe Distal #bli9ue
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t is irregular developmental groovet is irregular developmental groove
traverses the distal fossa from the distaltraverses the distal fossa from the distaltriangular fossa lingually between thetriangular fossa lingually between thelingual cusps and continues onto thelingual cusps and continues onto thelingual surface as the lingual groove.lingual surface as the lingual groove.
he Distal #bli9uehe Distal #bli9ue
Groove:Groove:
Prof. A. Elsahn
h !if h C Gh !ifth C G
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lf the fth cusp groove or tubercle$ islf the fth cusp groove or tubercle$ isdistinct, this groove separates thedistinct, this groove separates the
tubercle from the mesiolingual cusp andtubercle from the mesiolingual cusp and
7oins the lingual groove. 7oins the lingual groove.
he !ifth Cusp Groove:he !ifth Cusp Groove:
Prof. A. Elsahn
GG
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GroovesGrooves
GroovesGrooves
At the ape% of the mesialAt the ape% of the mesialtriangular fossa,triangular fossa,
supplemental groovessupplemental grooves
radiate as branches fromradiate as branches fromthe terminus of the centralthe terminus of the central
groove into the triangulargroove into the triangular
fossa.fossa.
#ccasionally#ccasionally one or moreone or more
supplemental grooves crosssupplemental grooves cross Prof. A. Elsahn
he Distal #bli9uehe Distal #bli9ue
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he Distal #bli9uehe Distal #bli9ue
GrooveGroove
t shows several supplemental grooves.t shows several supplemental grooves.
This developmental groove terminates This developmental groove terminates
distally in the distal triangular fossa by twodistally in the distal triangular fossa by two
terminal branches that form the two sides ofterminal branches that form the two sides of