-The mandibular premolars number four , TWO in each quadrant .

-The mandibular first premolars are developed from four lobes,

as were the maxillary premolars , two buccal and two

lingual.

- The mandibular second premolars has two forms

. three cusp type : ( 5 lobs .. 3 buccal and 2 lingual )

. . two cusp type : (4lobs .. 2 buccal and 2 lingual )

The mandibular first premolars

- The mandibular first premolar has 2 cusps , large buccal cusp, ,

with a small, nonfunctioning lingual cusp

It has one root . –

Chronology

Enamel (crown ) completed 5–6 yr

Eruption 10 –11 yr

Root completed 12–13

yr

:l aspect The bucca

ith the smallest side in shape w Trapezoid: Geometrical outline

cervically

: sOutline

slightly re aMesial and distal outline the starting from cervical line -

dle and occlusal ( at junction of mid till the contact area concave

thirds , distal c.a more cervically )

concavethe distal slope is , slightly concavemesial slope is -

esial slopethan the m longerThe distal slope is

- the cervical line is convex root wise .

The root outline resembles canine , the apex may bend distally . .

Surface anatomy

The buccal surface is generally convex .-

cervical third representing the cervical ridge ( maximum convexity ). -

- Buccal ridge is present as well developed middle lobe, having two

developmental grooves on each side.

: The lingual aspect

The outline is similar to the buccal but :-

. -The crown and root show more convergence lingually

-The lingual cusp is short and poorly developed with pointed tip (the

lingual cusp is 2/3 the length of the buccal cusp)

•The mesial and distal triangular fossae

al developmentalmesiolinguA characteristic of lingual aspect is the -

r fossa occlusallywhich extend into mesial triangula groove

( separates the mesial marginal ridge and mesial slope of lingual

cusp ) .

:The mesial aspect

and the rhomboidIt is : Geometrical outline -

constricted occlusally

Outline :

-The buccal outline is convex with the maximum

convexity at the cervical 3rd (the cervical

ridge).

-The lingual outline is convex with the

. rdmaximum convexity at the middle 3

-The buccal cusp is higher than the lingual cusp

(the lingual cusp is 2/3 the length of the buccal

cusp) .-

-The buccal cusp tip is in line with the root apex where the lingual cusp tip is

with the lingual border of the root.

-The mesial marginal ridge is obliqe to the midline and continuous with the 2

cusp , there is misiolingual developmental groove , which extends on the

mesiolingual line angle .

The root : It tapers to a pointed apex (is in line with the buccal cusp tip ) and

has deep developmental depression

The distal aspect

Similar to the mesial aspect but :

-The distal marginal ridge is higher and straighter than the mesial

-No developmental groove

-The distal contact area is broader

The occlusal aspect

- Geometrical outline is diamond or round shape with highly

converged lingually .

-The buccal cusp is well developed with large triangular ridge and the lingual

cusp is less developed with small triangular ridge.

-The buccal and the lingual triangular ridges are connected by transverse ridge

( C.F ).

- the central developmental groove is concentric ( cross the transverse ridge).

-the mesial & distal marginal ridge slope form the buccal to lingual surface .

-the central developmental groove extended mesially crossing the MDG to

form misiolingual developmental groove .

-On the mesial and distal sides of the marginal ridges there are ( distal and

mesial triangular fossae ).

The Mandibular second premolar

This tooth has two types

similar to the first premolar but larger in size , with higher , Two cusp type -1

lingual cusp .

has one buccal and tow lingual cusp .which , Three cusp type -2

-both 2 types have single root .

both two types are similar in all aspect but differ occlusally-

Chronology

Enamel completed 6-7 years

Eruption 11-12 years

Root completed 13-15 years

The buccal aspect

in shape with the smallest side Trapezoid : Geometrical outline

cervically.

The tooth is similar to the lower 1st premolar

but differs in :

-The mesial and the distal contact areas are also at the same level (occlusal

third )

The root is broad with blunt apex-

:The lingual aspect

-well developed lingual cusps with more functional occlusal surface ( so

less of occlusal surface can be seen )

- the root is conical with blunt apex

In the three cusp type :

-lingual developmental groove between the 2 lingual cusps

- mesiolingual cusp larger than distolingual cusp .

- no lingual convergence

In the two cusp type :

-no lingual developmental groove , but is a distolingual

developmental depression on the lingual cusp ( distolingual line

angle .

The mesial aspect

It differs from the mesial aspect of the first premolar in :

The crown and the root are wider buccolingually .-

-The buccal cusp is not centered over the midline .

The lingual cusp(s) are well developed ( longer )-

-The mesiolingual cusp appear but the distolingual cusp can not

be seen

-The mesial marginal ridge is horizontal and perpendicular to the

long axis of the tooth ( at the right angle to midline )

-The maximum convexity on the lingual outline is located at the

occlusal third

-There is no mesiolingual developmental groove

The distal aspect

It is similar to the mesial surface except :

-The distal marginal ridge located at a lower level than the mesial

marginal ridge. So more of the occlusal surface can be seen-

-The tips of both lingual cusps are seen ( distolingual cusp is shorter

smaller ) . &

The occlusal surface

Three cusp type

-The geometrical outline is square ( no lingual convergence ).

-It has one buccal cusp and two lingual cusps with broad (

buccal is the largest then the misiolingual cusp , finally the

distolingual cusp ( according the size ) ) .

-Every cusp has a triangular ridge which separated by developmental groove

the central developmental groove having Y shape.

-many supplemental grooves are present .

-The central developmental pit present in the center of the Y shape from the

central pit mesial developmental groove extends to the mesial triangular

fossa. And distal developmental groove extends to the distal triangular fossa.

Two cusp type The geometrical outline is round in it's lingual half ..

There is lingual convergence..

There is only one lingual cusp(well developed, functioning cusp ) ..

The buccal and the lingual cusps connected by transverse ridge..

The central developmental groove is straight or has U or H shape..

The occlusal surface has supplemental grooves ..

The mesial and the distal fossae are present with 2 marginal ridge ..

The pulp cavity of the lower premolars

lingual section-Bucco

In lower 1st premolar : ☻

The pulp chamber is wide with one pulp horn.-

-Single root canal , extending into the root it has a round cross

section with one apical foramen .

In lower 2nd premolar : ☻

pulp 3similar but with cusp type are 3& 2The pulp cavity of the -

horns in the 3 cusp type.

-the buccal pulp horn is slightly higher than the lingual pulp horn

single root canal is present , which wide and has one apical

foramen.-

there may be two root canal opening by one apical foramen .-

distal section-Mesio

Similar to that of the lower canine

-one pulp horn under buccal cusp an singe root canal ang single apical

foremen

PERMENANT MOLARS

They are 12 in number 6 in each jaw (upper first , second and third -

lower first , second and third )

they have larger but shorter crowns than the premolars -

-maxillary molars has 3 roots ( 2 buccal , 1 palatal ) , Mandibular molars

has 2 roots ( one buccal , 1 palatal)

-The crowns of upper molars centered over their roots , but lower molars

are inclined lingually .

-the molars decrease in size as we go distally , because the distolingual cusp

gradual reduction in the size , and it may absent in the 3rd molar .

may be either larger or rdis the largest one , the 3 stin the lower molars : 1 -

. ndsmaller than the 2

- the occlusal outline of upper molars is wider buccolingually , while in the

lower molars it's wider mesiodistally .

PERMENANT MAXILLARY MOLARS

Maxillary first molar

-maxillary molars is the largest tooth in the maxillary arch

nonfunctioning cusp thit has 4 cusps ( 4 developmental lobes ) and 5 -

(tubercle ) , this tubercle is attached to the mesiolingual cusp and it is called

cusp or tubercle of carabelli

- it has 3 roots , (2 buccal , 1 palatal ) they give this tooth the maximum

anchorage against forces .

Chronology

Enamel completed 3–4 yr

Eruption 6 yr

Root completed 9–10 yr

The buccal aspect

with the smallest , trapezoid is Geometrical outline-

side cervically .

Outline

-Mesial outline is straight till the contact area (at the

junction of occ. and middle 1/3 s) , then become

convex till the cusp .

-The distal outline is convex till the contact area (at

the middle third)

-Mesial slope of the MB cusp and distal slope of the

DB cusp are convex

-The The cervical line is straight or slightly convex root

wise with some irregularities .

The occlusal outline

-occlusal show two buccal cusp , the mesiobuccal and distobuccal cusps

--The MB cusp is broader than the DB cusp which is longer and sharper

. -The ML cusp can be seen between the two buccal cusps

-the two buccal cusps are separated by buccal developmental groove .

- Surface anatomy

- the buccal surface is convex , the maximum convexity ( Cervical ridge )

- -Buccal developmental groove extends to the middle of the buccal surface

separates the two buccal cusps.

- The roots

Three roots, two buccal and one palatal.

- The MB root curves distally at the middle third.

- There is root trunk at cervical third. It has a developmental groove.

The DB root curves mesially at the apical third.

The palatal root is the longest one, and appears between the two buccal roots

Lingual aspect .

-The geometrical outline and outline is similar to the

buccal aspect

Outlines

-Two lingual cusps + cusp of carrabelli ,

One lingual root ( two parts of buccal root are seen)

- Mesial outline : straight till the contact area then

become convex till mesiolingual cusp tip.

- the ML cusp is larger than the DL cusp .

-The lingual developmental groove separates the two

lingual cusps and may end in a pit.

The lingual groove is in line with the palatal root apex .-

Tubercle of Carabelli present on the ML cusp.-

The palatal root has developmental depression.-

-cervical line is irregular .