molar
Configuration,
mastication,
fixedness
1.crown,large cube
buccolingually,trapezia,
developmental grooves for
drainage
proximal surface,quadrangle
occlusal surface,4-5 cusps
point
2.root:sturdy root trunk
maxillary,3 roots
buccolingually
mandible,2 roots
mesioditally
point
1.maxillary first molar 6 6
normally the largest teeth
Molar
Crown
1） buccal surface
a.broad(近远中径 >牙合颈径 )trapezia
slope distolingually
b.mesial outline straight,
cervical line convex
c.two buccal cusps
width and height
近中颊尖的颊轴嵴显著
Crown
d.buccal groove
to middle third,pit
e.crest of contour
cervical third
Crown
2） lingual surface
a.resemble but less than
b.2 cusps(fifth cusp)
c.distolingual groove
d.crest of contuor
middle 1/3
Crown
3） proximal surface
a,quadrangle,buccolingually
wider,buccal margin straight
b.buccal cusp higher（ 2/5）
lingual cusp rounder（ 3/5）
d.long axis
Crown
4） occlusal surface
a,rhombus,buccal margin
sloping D-L
4 angles
acute angle
obtuse angle
b.4 marginal ridges
Crown
buccal surface
c.4 cusps,
inclined surface
buccal cusps higher and sharper
size,M-L>M-B>D-B>D-L
height,M-B>M-L,D-B>D-L
triangular ridges:oblique ridge
（ D-B TO M-L）
Occlusal surface
d.2 fossa（ by oblique ridge）
mesial（ central）,distal
e.3 developmental groove
Crown
Root
3 roots,
2 buccal,1 lingual
Well divided
Root trunk sturdy
and short
L>M-B>D-B
Molar
2.maxillary second molar 7 7
resemble the first one but smaller
Narrower rhomboid
Crown
1） buccal surface
slope more to D-L
size of buccal cusp
Crown
2） lingual surface
size of lingual cusp
Rarely fifth cusp
Crown
3） proximal surface
a,
quadrangle,buccolingually
wider,buccal margin
straight
b.buccal cusp higher（ 2/5）
lingual cusp rounder
（ 3/5）
d.long axis
Crown
3） buccal surface
a,distinct rhomboid
b.much bigger M-L cusp
c.developmental groove
on the oblique ridge
occlusal surface
d.fossa
mesial(central）,distal
e.developmental grooves
Crown
Root
Root trunk longer
Not much divided
Molar
3.maxillary third molar 8 8
(1)Variation of crown and root,smallest
Resemble 7
(2)crown,
axial surface smooth,convex middle 1/3
occlusal,roundness or triangular,less
distinct,much more secondary developmental
grooves
(3)root:usually coniform
4.mandibular first molar 6 6
Molar
Crown
1） buccal aspect
a.wide trapezoid（ M-D>O-C）
b.mesial margin straight
c.2 buccal cusps,1/2 distal cusp
size and height
axial ridge:unconspicuous in distal cusp
crown
d.buccal & distal
buccal groove
buccal groove to middle
1/3,buccal pit
e.crest of contour
cervical 1/3
下颌第一磨牙牙冠
2）舌面
a.形似颊面但略小
b.二个舌尖，舌轴嵴
c.舌沟
d.外形高点
中 1/3
Crown
3） proximal
a,quadrangle,B-L>O-C
buccal margin sloping
lingually
b.buccal cusp（ 3/5）
lingual cusp（ 2/5）
c.distal surface less
Crown
4） occlusal
a.complex rectangle
b.4 marginal ridge
Buccal margin longer than lingual
Mesial margin straight
Distal margin convex
Crown
c.5 cusps:afunctional inclined
surface(lingual surface of lingual
cusp)
size:buccal>lingual>distal
height:lingual>buccal>distal
triangular ridge,
Diatal buccal cusp’ longest
Distal cusp’ shortest
d.2 fossa
distal(central) fossa &
a small mesial fossa
e.5 grooves
Crown
Root
2 roots,mesiodistally,flat and large
Sturdy root trunk,well divided
mesial,bigger,longitudinal groove
in both mesial and distal
tip distally
distal,longitudinal groove only
in mesial side
sometimes divided (22%)
Molar
5.mandibular second molar 7 7
5 cusps or 4 cusps
5 cusps,resenmble the first,more rounded
（ 1） crown（ 4 cusps）
1） buccal aspect,
2 buccal cusps,buccal groove
Crown
2） lingual,
2 lingual cusps,lingual groove
Crown
3） proximal,
Crown
4） occlusal,almost square
4 cusps,4 grooves
Root
Longer root trunk
Not much divided
Molar
6.mandibular third molar 8 8
(1) Many variations,smallest
(2)crown,
axial surface smooth,convex middle 1/3
occlusal,roundness or triangular,less
distinct,much more secondary developmental
grooves
(3)root,coniform usually
1,Difference of maxillary and mandible molar
2.Difference in maxillary three molars
3.Difference in mandible three molars
Questions
1.the first molars:main functional
2.the third molar:impacted tooth
3.about maxillary sinus
To dentist,
Configuration,
mastication,
fixedness
1.crown,large cube
buccolingually,trapezia,
developmental grooves for
drainage
proximal surface,quadrangle
occlusal surface,4-5 cusps
point
2.root:sturdy root trunk
maxillary,3 roots
buccolingually
mandible,2 roots
mesioditally
point
1.maxillary first molar 6 6
normally the largest teeth
Molar
Crown
1） buccal surface
a.broad(近远中径 >牙合颈径 )trapezia
slope distolingually
b.mesial outline straight,
cervical line convex
c.two buccal cusps
width and height
近中颊尖的颊轴嵴显著
Crown
d.buccal groove
to middle third,pit
e.crest of contour
cervical third
Crown
2） lingual surface
a.resemble but less than
b.2 cusps(fifth cusp)
c.distolingual groove
d.crest of contuor
middle 1/3
Crown
3） proximal surface
a,quadrangle,buccolingually
wider,buccal margin straight
b.buccal cusp higher（ 2/5）
lingual cusp rounder（ 3/5）
d.long axis
Crown
4） occlusal surface
a,rhombus,buccal margin
sloping D-L
4 angles
acute angle
obtuse angle
b.4 marginal ridges
Crown
buccal surface
c.4 cusps,
inclined surface
buccal cusps higher and sharper
size,M-L>M-B>D-B>D-L
height,M-B>M-L,D-B>D-L
triangular ridges:oblique ridge
（ D-B TO M-L）
Occlusal surface
d.2 fossa（ by oblique ridge）
mesial（ central）,distal
e.3 developmental groove
Crown
Root
3 roots,
2 buccal,1 lingual
Well divided
Root trunk sturdy
and short
L>M-B>D-B
Molar
2.maxillary second molar 7 7
resemble the first one but smaller
Narrower rhomboid
Crown
1） buccal surface
slope more to D-L
size of buccal cusp
Crown
2） lingual surface
size of lingual cusp
Rarely fifth cusp
Crown
3） proximal surface
a,
quadrangle,buccolingually
wider,buccal margin
straight
b.buccal cusp higher（ 2/5）
lingual cusp rounder
（ 3/5）
d.long axis
Crown
3） buccal surface
a,distinct rhomboid
b.much bigger M-L cusp
c.developmental groove
on the oblique ridge
occlusal surface
d.fossa
mesial(central）,distal
e.developmental grooves
Crown
Root
Root trunk longer
Not much divided
Molar
3.maxillary third molar 8 8
(1)Variation of crown and root,smallest
Resemble 7
(2)crown,
axial surface smooth,convex middle 1/3
occlusal,roundness or triangular,less
distinct,much more secondary developmental
grooves
(3)root:usually coniform
4.mandibular first molar 6 6
Molar
Crown
1） buccal aspect
a.wide trapezoid（ M-D>O-C）
b.mesial margin straight
c.2 buccal cusps,1/2 distal cusp
size and height
axial ridge:unconspicuous in distal cusp
crown
d.buccal & distal
buccal groove
buccal groove to middle
1/3,buccal pit
e.crest of contour
cervical 1/3
下颌第一磨牙牙冠
2）舌面
a.形似颊面但略小
b.二个舌尖，舌轴嵴
c.舌沟
d.外形高点
中 1/3
Crown
3） proximal
a,quadrangle,B-L>O-C
buccal margin sloping
lingually
b.buccal cusp（ 3/5）
lingual cusp（ 2/5）
c.distal surface less
Crown
4） occlusal
a.complex rectangle
b.4 marginal ridge
Buccal margin longer than lingual
Mesial margin straight
Distal margin convex
Crown
c.5 cusps:afunctional inclined
surface(lingual surface of lingual
cusp)
size:buccal>lingual>distal
height:lingual>buccal>distal
triangular ridge,
Diatal buccal cusp’ longest
Distal cusp’ shortest
d.2 fossa
distal(central) fossa &
a small mesial fossa
e.5 grooves
Crown
Root
2 roots,mesiodistally,flat and large
Sturdy root trunk,well divided
mesial,bigger,longitudinal groove
in both mesial and distal
tip distally
distal,longitudinal groove only
in mesial side
sometimes divided (22%)
Molar
5.mandibular second molar 7 7
5 cusps or 4 cusps
5 cusps,resenmble the first,more rounded
（ 1） crown（ 4 cusps）
1） buccal aspect,
2 buccal cusps,buccal groove
Crown
2） lingual,
2 lingual cusps,lingual groove
Crown
3） proximal,
Crown
4） occlusal,almost square
4 cusps,4 grooves
Root
Longer root trunk
Not much divided
Molar
6.mandibular third molar 8 8
(1) Many variations,smallest
(2)crown,
axial surface smooth,convex middle 1/3
occlusal,roundness or triangular,less
distinct,much more secondary developmental
grooves
(3)root,coniform usually
1,Difference of maxillary and mandible molar
2.Difference in maxillary three molars
3.Difference in mandible three molars
Questions
1.the first molars:main functional
2.the third molar:impacted tooth
3.about maxillary sinus
To dentist,
