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الرحيم الرحمن الله بسم

*at the beginning of this lecture there was a discussion between doctor Ashraf and the students about the time of dental lab exam whether it will be at the same week of the theoretical exam or the following week !unfortunately there has been no agreement then the doctor delegate our CR to solve this problem!

*some suggestions:

A) the slides for this lectur in the file of "Morphology of premolar" and we will cover the slides from 11 to 34

B) while u are studying this lecture plz refer to "lower premolar" and" upper premolar" videos in dental CD ,actually will be helpful

C) honestly, sometimes I found difficulties about identifying the structures that the doctor talking about so I added some pictures from the text book and I hope these pictures beside the videos and the handing out make this lecture easy ;p

Ok let us start:

Maxillary first premolar:

Mesial aspect (slides # 11 and 12):-

This is the tooth seen from mesial aspects we can see 2 cusps notice these 2 cusps are unequal size, Bigger cusp is the buccal cusp and smaller is the lingual but the amount of this difference between these two cusps isn’t that big.

The amount of difference between the two cusps in the mandibular first premolar is huge. Ok?

Mandibular first premolar has 2 cusps جدا صغير وواحد جدا كبير واحد

,here we have 2 cusps although they are not equal in the size ,but there is some differences which isn’t that big between the size of the buccal and lingual ok?

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And this actually by itself is a type trait because in the maxillary 2nd premolar , the 2 cusps are of equal in size and prominence, the maxillary 2nd premolar has 2 cusps (bekono nafs el6ool w nafs el7ajem) but the first premolar (bekoon el buccal akbar $wai ).so difference between the size of 2 cusps by itself is a "type trait"

Because it lets u distinguish between the maxillary first premolar from maxillary 2nd premolar.

This is a triangular ridge of the buccal cusp, and the triangular ridge of the lingual cusp, they meet in a straight line we call it mesial edge; we call it the transverse ridge.

Triangular ridge inclined as 40 degree (this triangular ridge and this one is inclined at 40 ok)

From the occlusal plane, and they meet at front angel عن عباره هيبين ما قائمة زاوية

Triangular ridges of the buccal and lingual cusp , (actually the doctor said that the triangular ridges inclined at 40 degree but in the slide u will find 45 ,so take 45 not 40 coz when 2 triangular ridges meet they meet at front angle which is 90 as he said )

The mesial marginal ridge is prominent (this is the mesial margin ridge –it is prominent ok?)

And we have groove that runs through this ridge, this groove runs just lingual to the mid portion. <Go to the middle distance then slightly lingual and u will see a groove as the doctor said >, this groove does not run exactly in the mid portion of the marginal ridge but it is slightly lingual.

This groove is important and we call it mesial marginal ridge groove and the presence of this groove is important in distinguishing this tooth. Because this groove is not present in any other premolars. So if you see any other premolar, if you see the marginal ridge –you see a groove crossing the marginal ridge, this is a maxillary first pre molar because this feature is

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missing in maxillary 2nd premolar and also missing in mandibular premolars. Ok?

The buccal (HOC) is within the cervical third and from this buccal max of contour we see a slight lingually inclination calls a cusp itlit (not sure).

The lingual outline is convex not a straight line like this one, and

Maximum Convexity or the height of contour is in the middle third. Note HOCs in the middle third from lingual side, where it was in the cervical third from buccal side.

The cervical line is convex towards the occlusive part of the tooth.

From the mesial aspect also we see an important feature which is called the mesial interradiculer groove.

Radicular means something to do with the root ( بالسياسه بشتغلوا الليجذري تغيير we will make a redicular thing in the systems or the (بحكو

policy of the country.

So radicular means between two roots, so between the roots of this tooth we have a groove –can you see this groove?

This groove is called the mesial interrdicula groove. In other words, this groove can be called the (canine fossa).

Why it is called canine fossa?

Because if you remember, when we discussed canine – we said the distoincisal angel of canine is very prominent.

Because of this actually – this distoincisal angel makes infet on the premolar while premolar is forming.

This proves that canine form after the first premolar انه على يدل هذا?after the premolar alright يتكون canine ال

Again:-

Because of the bulging of the distoincisal angel of the canine this actually produces a groove on the root which is located distal to this canine which is the maxillary first premolar – we call it canine fossa.

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This canine fossa is also called mesio intterredicular groove, it starts from the area of bifurcation of the roofs الجذرين انقسام منطقة And .منgoes up until reaches the cervical line and also it proceeds along the crown to reach (ta8reban ) just the area under the contact point .

So this called the meso interedicular groove or canine fossa the presence of this groove is indicative of this tooth .

السن هذا على يدل وجوده

Because this groove isn’t presence in any other premolar .

If you grab of any premolar – if you see this groove – and particularly you see that the groove passes also within the crown – this means that is a maxillary first premolar.

Because this is not existing in maxillary 2nd premolar or any of mandibular premolars.

Continuing to Slide # 12

The occlusal table is centered over the root trunk, what we mean by occlusal table ?

It means occulsal surface ,the area enclose between cusps tips of any tooth.

The area between cusp tips and the marginal ridges we call it occlusal table. The occlusal table of this tooth is perpendicular ok!

Is perpendicular to long axis of the tooth ,this is the long axis of the tooth and( this is the occlusal area) notice that the occlusal area is centered over the long axis of the tooth ok! Or cantered over the root trunk

We said that root trunk is the area of the root before bifurcation ما قبلقسمين الى الجذر !this area of the root we call it root trunk ok ينقسم

MM and this is (arch trait) because in the mandibuler premolar the occlusal table is not perpendicular to the root trunk , it tends to be inclined في تفيدنا المعلومة هذه

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Mandibuler premolar because the crown tilted lingually ,that’s why the occlusal table isn’t horizontal it slightly inclined so it isn’t central over the trunk of the root ok!

Root commonly received 2 roots ,what is the percentage of having 2 roots in this tooth? 90% ok! So this means it is still possible to see the maxillary first premolar with one root so the number of root is not actually a guide for u to identify this tooth. If u has premolar with one root ok , this doesn’t mean that isn’t the maxillary first pre molar , if u take MMM premolar with 2 roots this doesn’t mean is where this tooth is maxillary first pre molar !

The doctor emphasized that the number of roots in this tooth doesn’t consider as a good indicator to it ! So he advised not to depend on this feature to identify the tooth! (there is 10% possibility to have 1 root in this tooth )

And if the tooth has 2 roots may be it supports but it doesn’t confirm this root exactly belong to the maxillary first premolar or not !

These actually when we have 2 roots they bifurcate and the junction between the middle third and the apical third of the roots.

Distal aspect slide # 13

From the distal aspect we don’t see the mesial marginal ridges groove and we don’t see the canine fossa , but we see a slight shallow grove , between the two roots so similar to mesial aspect except no marginal ridge groove ,no concavity on the cervical third , the concavity is only within the root (elconcavity ma btmtad la trunk area) not like this here see the concavity spreads and reaches an area of the crown just below the contact point distally is only confined to the area between two roots , or on the root trunk and we also can see much more of the occlusal surface, if u see the tooth through view of distal u can see part of the occlusal surface why?, because the distal marginal ridge is lower

than the mesial marginal ridge.

Guys don’t confuse here like me ;p ,note that the lower means toward the cervical line so the occlusal surface that

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could be seen here is more than mesially (mak$ofeh aktar )

In all teeth:

The mesial marginal ridge is higher than the distal marginal ridge this the mesial and this is the distal that’s why if u look to the tooth from distal view u will see 5 of occlusal surface

This is general in all teeth except in mandibular first premolar as we will see( inshalla 8arebn) when we will talk about mandibular first premolar (ray7een nshoof eno howeh besheth 3an el ka3da) distal will be higher than the mesial < and also the distal interradicular groove is very shallow and doesn’t continue on the crown

Occlusal aspect slide #14

The tooth from occlusal aspect this is how the tooth looks like, it is hexagonal in shape , and it is type trait because the look or view of the maxillary second premolar is generally more rounded ,here we see angels. the buccaly profile is inverted( 7arf v alma8loob) ,we have sharp mesobuccal and distobuccal angle , but notice that the lingual angels are very rounded , can u see that !. The mesial and distal outlines are converted lingually.note that the mesial and distal outlines they are not parallel they tend to be converted lingual,this means that the

Lingual cusp is smaller or narrower than the buccual cusp.

The lingual profile is strongly convex not like the buccal profile

It is v shaped.

The occlusal table is formed by cusps and marginal ridges, as we said the area enclose by cusps tips and cusps ridges, and also the marginal

ridges we call occusal table lets now draw the occlusal table.

The doctor pointed at( tip of buccal cusp and, the mesial ridge, the margins ridge , casting of the lingual cusp, the distal marginal ridge and

the ridge of the buccal cusp),so this area is called the occlusal table .

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The occlusal table is formed by cusps and marginal ridges .the apex of the lingual cusps is mesial to the midline notice that the tip of the lingual cusp it isn’t exactly in the center of the grind tips because slightly mesially( ma betkoon belwasat tamamn)

Slide # 15

The triangular ridges, the buccal and lingual triangles ridges or the triangles ridges of the buccal and lingual cusp are making straight

Ridges , this is called the transverse ridge.

This transverse ridge is separated by a groove running across the transverse ridge is called the center groove , the center groove starts from apex here called mesial pit and goes this way(don’t know which

way ) then ends at the distal edge .

From mesial pit we have 2 grooves at the each margin of marginal ridge , for example :the groove goes mesialy and buccally called the mesiobuccally margin ridge groove ,another disto buccal , and also the disto lingual , so according to the ridge where the groove goes we call this grooved(mnsame el grooves 7asab eletajeh yalle btmtad feh ). Accordingly all these are developmental groove not sublimental groove

ok!

Mmm the mesial also we have what we called fossa. Between the mesial marginal ridge and the transverse ridge we have depression ,this is called the mesio triangular fossa and the distal triangular fossa

At the tip of this fossa we have the tip , the mesial tip and the distal tip.

Mesial marginal ridge is shorter that the distal marginal ridge and it is interrupted by the marginal ridge groove as we discussed.

The pulp slide #16

The pulp of this tooth , this tooth , this is how we see the tooth in buccolingual section , we see two pulp horns, one is taller than the other , and we see 2 roots. Can u see one root? , yes there is possibility of seeing one root canal in this tooth but generally 90% of people do

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have 2 root canals .when u make treatment for this tooth remember that there is 10% of having one root

If u make a cross section of the pulp system mesiodistally

It will look very slim( thin) it is very important to remember

This morphology, and this is a cross section through the root,

The buccal root canal is bigger than lingual root canal.

Maxillary second premolar slide #17

Hala 2 el Maxillary second premolar is similar to the Maxillary first premolar but with differences , let us see these differences that

Also we call them" type traits"

*the tooth on the left is maxillary second premolar and that on the right is maxillary first premolar

It is similar to Maxillary first premolar but it is slightly smaller, this is tooth number 14 and 15 notice that it smaller in ridge and height also the mesioincisal and the distoincisal angles are less prominent , see here mesioocclusial and the distoocclusal angles , there are less prominent.

so they are not actually outside the profile of the crown.

Note the angels are inclined(not sure!) with the root profile or the second premolar alright. buccal ridge and depressing are seldom seen. We can see buccal ridge and tooth depression.(but for the maxillary second premolar we don’t see very prominent buccal ridges )

From the lingual aspect:

From the lingual aspect ,the buccal profile is seldom seen why ?because in this tooth the size of lingual cusp is similar to the size of

buccal view and this is evident from the occlusal view ,see the size of the lingual cusp equal to the size of buccal cusp that’s why the mesial and distal profile are parallel but in the maxillary first premolar these profiles

are converted lingually.

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Mesial aspect slide # 18

From the mesial aspect we see here two cusps ,but these

2 cusps are of equal size not like the maxillary first pre

Molar ,we have some differences in the size between these two cusps ,we also don’t see concavity on the trunk

We only see concavity on the root so we don’t see what we call canine fossa ,because it is very specific for the mesial aspect of the maxillary

first premolar.

No concavity in the crown portion of the mesial surface ,and we see single root but still we have the possibility of seeing 2 roots in this tooth .what is the percentage of seeing 2 roots in this tooth?10 %, so in 10 % of the teeth we can see 2 roots for the maxillary second premolar

Distal aspect:

From the distal aspect ,notice that we also don’t see the mesial

Marginal ridge groove.

(Mesial marginal ridge is specific for the maxillary first premolar

Not for the maxillary second premolar)

We see one single root.

mesial aspect very similar to lingual and buccal ,but the( lingual and buccal)cusps equal in height as we discussed .to be honest , am

confused here about what doctor said sorry!

Occlusal aspect # 19:

It is ovoid not hexagonal why ?because they don’t

Have sharp angle they have smooth angle so that

It is ovoid in shape.

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Less convergence of mesial and distal outlines ,in fact the mesial and and distal outlines are parallel why? because the buccal cusp is very nearly equal to the lingual cusp in mesiodistal web .more rounded mesibuccal and distobuccal corners these forms are rounded not very

bulgy and prominent.

Apex of the lingual cusp in the midline it isn’t tilted mesially like in maxillary first premolar.

Shorter acclusal groove ,occlusal groove is very short and the marginal ridges are thick but actually the center groove is long in the maxillary

first premolar and marginal ridges are thin ok!

More Numerous supplemental grooves, we see many supplemental grooves, but we don’t see many supplemental grooves in the maxillary first premolar and we don’t see the mesial marginal ridge groove, these differences are very important ok! And this is among the teeth that are difficult to tell <<da2man el6olab byt3'alabo bel exam>> in differentiating between the first premolar & second premolar

*here the doctor announced that there will be a lecture of oral physiology next week after the exam (ma ba3raf leh 5atar bebalo hala2 ;p )

THE PULP (slide # 20)The pulp is cigar shape with cross section, pulp hornsAre almost in equal height (the doctor admitted that there

Is a mistake in the picture) the two pulps should be equal

In height but here we have a mistake!

Usually we see one single canal but also there is a

Possibility of seeing 2 canals, in my experience <not me the

Doctor > once he made a treatment for the maxillary Second premolar he find 3 canals so there are some

Exceptions! Actually 90% single canal of one tooth .these are the differences that we call a "type trait" between maxillary first premolar and second premolar.

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*doctor didn’t mention anything about the slide 21Mandibular first premolar :

*Buccal aspect *

Now we come to mandibular first premolar ,from the buccal aspect, the mandibular first premolar has long pointed buccal cusp in the occlusal

profile ok ! Can u see very pointed ,it looks like a canine m$ heek?

How to distinguish this tooth from the canine ? We have 2

Cusps from the lingual side, but a canine has only 1

Cusp but here we have 2

The mesial cusp ridge is shorter than the distal cusp ridge which is also similar to the canine.

The cusp tip is little mesial to the tooth midline ,if u make a midline from the tooth ,the cusp will be slightly mesially to this midline.

HOCs are at the same level and they are located just occlusal to the half way of the crown (da2mn ya jama3a 8a3edeh the HOCs) of the mandiblular teeth are higher than the HOCs for the maxillary teeth.

Always the mandibular teeth (el size taba3ha) straight and the HOCs are nearer to the cusps and incisal edges, this is true for canine and premolars but not accurate about the molars alright!

The mesial & distal profiles are marked converging can u see ! The tooth is wide ok ! so these 2 sides converge gingivally or cirvically.

The cervical line is flat mesiodistally compared to that of canine.

Buccal ridge and depression are also evident ,the buccal ridges, and 2 depressions .the root is conical with pointed apex.

*lingual aspect*

From the lingual aspect ,this tooth looks different doesn’t look

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Like the premolar by the way! see the amount of differences

Between the buccal cusp & lingual cusp (fe far8 kbeer bel 7ajem benathom) that’s why many students think that: this tooth

Is a canine! Actually it isn’t! it is a maxillary first premolar . The doctor pointed at the lingual cusp and said: This isn’t a cingulum this is a cusp (keef mnmayeez?)

as a rule the cingulum should be confined to the cervical third ,just located within the cervical third ,impossible to exceed 1/3 of the tooth.

but this small cusp (pointed to the cusp )occupies 2/3 of the crown so this isn’t a cingulum this is a cusp!

the buccal profile & the occlusal surface is visible why? because the lingual cusp is very small so we can see all the teeth occlusal surfaces and buccal profile.

The occlusal surface and the buccal triangular ridge and the marginal ridges they all tilt (not sure) lingually and cervically .(ya3nee , the crown of this tooth is tilted lingually that’s why if u look to the tooth lingually u can see all the features are tilted cervically and lingually ok!

The buccal triangular ridge crosses the mid portion of the occlusal surface (because we have 2 cups of unequal size ,the triangular ridge of the buccal cusps is much much longer than the triangular ridge of the

lingual cusp ,that’s why it is crosses the midline of the tooth ok!

Lingual cusp is minor elevation in height and pointed cone in shape ,it may be centric or eccentric (sho ya3nee eccentric?)ya3nee may be it is centered exactly ,for sometimes the tip of this cusp may be centric (ya3nee ray7a la jeha mn eljehat )ok!

Root is narrower from lingual aspect and has a blunt apex ,(always root lingually narrower than buccaly).

* mesial aspect *slide #24

This is the tooth from mesial aspect ,again many students

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Think that this is a canine why? They think that the cusp is

A cingulaum (the doctor repeat what he said in

Differentiating between cengulum and cusp)so this is a tooth with 2 cusps one is huge and the other is small.

The occlusal plane tilted lingually ,it seems that the crown is tilted lingually that’s why the long axis of the crown (goes in this way and the long axis of the tooth on this way pointed to the picture) so the long axis of the root and the long axis of the crown aren’t in a straight line they make an angle ,this is very important in cavity preparation (lazem el cavity tkoon 3ala el long axis of the crown ya3nee bdak t3mal cavity lazem tkoon mayleh m3 mayalan el crown )

Because of the tilty of the crown u have to prepare a cavity according to the long axis of the crown not according to the long axis of the root.

بعملوا للعصب سحب يعملوا بس الطالب من cavityكثير

, ما السن بفكروا يجدوه وال العصب عن يبحثوا وو ينزلوووووووووو بضلوا وخطأ نزلوا بكونوا الحقيقة في عصب الو

:D

All the time we have to go to the long axis of the crown NOT to the long axis of the root (offfffff kteer 3adha !)

Transverse ridge existed between two triangular ridges of two cusps but notice that the triangular ridges of buccal cusp is much longer than that of lingual cusp and that’s why if u draw a line through a center of the root ,this line will not pass through these 2 cusps

If u draw a line in the middle root it will not pass through 2 cusps it will pass through the tip of buccal cusps ok! Because the tilty of the crown

and because the differences in size between 2 cusps.

* mesial aspect *slide #25

Hala2 masially I can see some features which we call the

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mesiolingual groove ,notice that because of the lingual tilty of the crown

and the marginal ridge is also tilty and the marginal ridge meets with the mesial cusp at a groove called MLg

(bekawen )MLG ,this isn’t marginal ridge groove because this groove doesn’t cross the marginal ridge instead cross the end (nehayet )el marginal ridge from the lingual side.

MLG is specific for this tooth ok ! MLG again it isn’t a groove that cross the marginal ridge that’s why it doesn’t call the marginal ridge groove instead it is a groove between the end of marginal ridge and mesial cusp of the lingual cusp so it is called mesiolingually groove and this is specific for the mandibular first premolar ok! so the MLG between the marginal ridge and mesio lingual cusp ridge ok! This is a type trait because for the mandibular second premolar doesn't exist . this is very important in differentiating between maxillary second and mandibular first premolar.

Because of this groove and the tilty of the marginal ridge the distal marginal ridge is higher than the mesial marginal ridge ,we previously said that all the time the mesial marginal ridge is higher than the distal

marginal ridge with one exception ,the mandibular first premolar ok!

Lingual profile is straight as u see and then convex up to the cusp tip .the buccual convexity is between the cervical third and the middle third of the crown .the tip of the lingual cusp is in line with the outline of the root .ya3nee if u want to draw the outline of the root btkamlo m3 el outline why ? Because the cusp is very small,but the tilt of buccal cusp is inlined with the long axis of the tooth. .the lingual HOCs is within occlusal 1/3 ,the buccal HOCs between the cervical third and middle third .theses in contact area is in lined with the apex of buccal cusp.

Under the cusp mesial area it is an area(mesial contact area) with this tooth comes in contact with which one ?(meen bekoon 8ablo )?

Canine yat8a6a3 with this tooth in the contact area ,this contact area aren’t between cusps just below the buccal cusp ok !

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But in posterior teeth we said that the contact area will be between two cusps (buccal ,lingual fbetkon bel wasa6 ) alright!

Root is broad bucolingually but narrow mesiodistally here is a broad buccolingually.

* distal aspect *

The DMR is more prominent and not tilted lingually , more horizontally. NO distal lingual groove like the mesiolingual groove that seen

mesially .the contact area is more extensive.

Why the contact area is more extensive ?this distal surface is in contact with the second premolar (the second premolar wider than canine )

(tooth bdo y3mal elte8a2 m3 el second premolar distally ,mesially bdo y3mal elte8a2 m3 canine ) according to the size of the tooth (btkoon

masa7et el) contact area!

Mandibular first premolar slide # 26

* occlusal aspect *

From occlusal aspect we can see a very very small lingual cusp

It Is diamond in shape.

Inverted v shaped buccal profile ,mesial and distal profile they converge lingually that’s why lingually is convex but buccaly is less convex.

Distal profile is more convex , can u see? than the mesial profile ,lingual profile is half of length of buccal profile ya3nee lingual profile is very

small just 1/2 the distance of buccal profile.

2/3 of buccal surface can be visible because the crown of this teeth is tilted lingually ,when u look at this teeth u will see 5 surfaces that’s why

almost 1/2(yalle mnshofo 3ebara 3an)buccal surface.

The occlusal table is triangular ok ! the tip of buccal cusp is in the midline of the crown (beno9 el crown ).mesiolingual cusp ridge with marginal ridge is straight ok ! it is interrupted by the mesial (mesolingual groove

yalle 7akena 3ano )ok !we don’t have a groove in the distal aspect.

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The mesial marginal ridge is shorter and less prominent than the distal marginal ridge and also we have this mesolingual groove that marks the mesial area of the groove.

This is the features sometimes distinguish mesial from distal groove

when u see this groove behind the marginal ridge then it is mesial side ,distal side doesn’t have groove!

pulp (slide # 28)

we see here in the mesial plate at the distal joint by the

central groove and regarding to pulp system of this

tooth it is mesiolingual sectioning it is similar to

canine ok ! buccolingually section is slightly broad but we see very huge pulp point and very small pulp point.

In cross section it is ovoid ,the possibility of having 2 canals in this tooth is also 30% similar to the possibility of lower incisor and lower canine.

Mandibular second premolar (slide #29)

*buccal aspect *&*lingual aspect*

From the buccal aspect it is very similar to The mandibular first premolar

But from the lingual aspect the cusp of the lingual side are bigger than

the cusp of lingual side of mandibular first premolar ,so mesiodistally diameter from the lingual aspect is much much greater than the lingual

mesiodistal dimension of the lingual part of mandibular first premolar.

Ya3nee this tooth lingually wider than mesiodistally in mandibular first premolar ok!

Also:

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Occlusal surface cannot be seen .2 lingual cusps are more prominent ok because they are prominent the lingual or the crown isn’t very much tilted lingually

The occlusal plane is perpendicular to the toothaxis (occlusal plane ma bkoon mbayen mtel ma a5adna bel mandibular first molar bekoon perpendicular on the axis of the tooth).

Often we see 2 cusps ,we see mesiolingual and distolingual cusps .can u see one cusp ?yes ,what is the percentage of seeing 2 cusps for this tooth?60% ,what is the possibility of seeing 1 lingual cusp ? 40%

So that’s why it is more often to find 2 cusps for this tooth ,if u find lingual cusp for this tooth usually mesiolingual is larger than distolingual

In exam u are responsible to know if this side is mesial or distal!

BUT HOW);

By looking at the two lingual cusps ,the biggeris the one located at the mesial side and the smaller on at the distal side so as simple as that

*mesial, distal ,occlusal aspects * (slide # 30 ,31 ,32 )

This is actually the tooth seeing from the side of mesial aspect,

Here we see 2 cusps ,these are high m$ heek!

Notice that it is much higher than the lingual cusps of first premolar because of the occlusal surface isn’t tilty perpendicular alright!

So triangular ridges of buccal & mesodistal cusp they can't form a continues (sorry can't hear!)And this important why? In most time we have 2 cusps lingually, and one cusp buccaly ,we can't see the transverse ridge .(la7ata a$oof transverse ridge lazem ykoon el cusps mo8abel ba3ad, 3ende 1 buccal cusp and 2 lingual cusps mot8abelat )that’s why u don’t see continues outlines for transverse ridges between the triangular ridges of occlusal cusps.

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* distal aspect * & *occlusal aspect *

From the distal aspect both lingual cusps are seen ok ! why?

Because the distolingual cusps is shorter than the lingodistal cusps

If u look from lingual aspects u can see both cusps.

This is the tooth how to look from the occlusal surface one cusp buccaly and 2 cusps lingually, mesolingual is bigger than distolingual.

The doctor said that in lab exam he gives us groove patterns alone and u don’t have a tooth and we should know that ,this groove belong to the following tooth ……..and also u need to know if it is right or left !(seems piece of cake )

For example y shape groove means that we have buccal cusps and 2 lingual cusps .how we can determine where is mesial and where is

distal?

The bigger one is the mesial (mesolingual akbar mn el distolingual )ok!so square profile ,mesial and lingual profiles are parallel ok !less than half of the buccal surface is visible ,because the crown isn’t much tilted lingually that’s why the amount of buccal side seeing from the occlusal

surface is less compare to the mandibular first premolar.

The buccal ridge is less prominent ok !the buccal ridge is less prominent than the buccal ridges of the mandibular first premolar and this is a

"type trait. "

Mesial and distal marginal ridges are equal in length not like the case in mandibular first premolar they weren’t equal in length and also not

equal in prominent and heights !

The root pattern is y shape ,we have central pit ,mesial pit and distal pit

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The mesial separate buccal and mesiolingual triangular ridges ,this is here the buccal triangular ridge , and also we have mesolingual

triangular ridge ,theseare seperated by central groove alright.

Mesial and distal triangular fosses are also visible ,each contain the pits and we have the marginal ridge groove.

Remember when we have 2 cusps for this groove , 40% of the cases , in this case we will not able to see the y shape profile ,very similar to any premolar (ma ra7 ykoon $akloo mtel y )because it doesn’t have 2 cusps lingually just straight groove (laken bs ykoon 2 cusps bekoon fe groove benathom !)

Pulp (slide # 33)

Pulp system of the tooth

Because actually we have 3 cusps we have 3 pulp horns ,the

Biggest or the highest pulp horn is the buccal pulp horn followed by the mesiolingual followed by the distolingual because the level of

prominence of pulp horns follows the prominence of cusp ok!

Often we can see 2 canals in this tooth and the percentage is 30% , and these are the differences "type trait" between the mandibular first and

mandibular second premolar.

Slide # 34

these are different measurements u don’t have to remember!!!!!

finally ,we have to discuss what we call the curve of occlusion

hala2 we have something called curve of spee ,curve of Wilson ,sphere of monsoon ,I will leave these( w mna5dhom m3 el molars la 7ata testaw3ebohom)!w la hoon bekoon el emte7an el curvs of occlusion m$

da5leen ,break 5 minutes ba3deen mn$ofkoom bel oral physiology!!!

العالمين رب لله الحمد

Forgive me for any mistake dentists

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Best wishes to get high marks in the exam inshalla

Your sister : Alaa Khalaf

Big thanks to my best friends Sana'a Qasem ,Ruba ghanem*

And Nanoos bdair

Believe in the impossible, hold tight to the incredible, and live

each day to its fullest potential .u can make a difference in your world

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