Maxillary first molar Deciduous : Is the most atypical of all primary or permanent molars … atypical means that it doesn’t look like a molar and premolars .. so the shape of it is intermediate between the two and it’s the smallest molar in all deciduous … but

in all BL triangle .

Cusps : in general this tooth is bicusped ( has two big cusps) only MB and ML cusp are present …. A small DB is frequently present on the distal cusp ridge of the MB cusp … for that we can't say it's like premolars because we have an extra small buccal cusp and also we can't say it's like molars because in any molar we should see two big cusps and this make it atypical tooth , a parastyle present on the mesial ridge of MB cusp and this parastyle look like an elevation ( entefa5 base6 ) . DL cusp is rarely occurs , it is a very small cusp located at the DL corner of the tooth , in some cases it's not a cusp … it’s a nodular tubercle on the lingual portion of the distal MR … it’s an swelling that resembles the DL cusp … so in cases we see this cusp it’s a elevation ( not a real cusp )

Buccal aspect:

the MD diameter is much greater than the crown height ( in fact this is a feature for all the deciduous teeth … the crown height is smaller than the crown width ) .

Mesial part is higher OC than Distal … because its more projected cervically onto the root area . it’s a bigger distance that the cervical line goes apically than mesially.

Marked cervical constriction ( al ta5a9or ) …. That means the cervical is more constricted.…

Root :

u can see 3 roots ( MB , DB ,L ) .. and the root trunk is very small but it tend to be more larger ( greater ) in permanent tooth . in permanent teeth the root trunk could reach 1\3 of the total length of the root . coz in deciduous teeth the root should be …. ( m8owasaeh ) and greatly separated because we need space for the tooth to be develops in this area .. Max. first premolar will develops

between these two roots of this tooth .

tooth trunk ( is the distance between cervical line and the beginning of bifurcation )

Lingual root is midway between the 2 buccal roots and strongly divergent ( mbta3eden 3an b3d )

Mesial aspect

U can see the mesial marginal groove that crosses the marginal ridge , the Buccal HOC is more cervically located

than Lingual HOC .

Buccal cervical ridge is more prominent in first molars than in second molars , in permanent teeth we don’t have this amount of B cervical ridge (profile )

because of the cervical constriction .

Roots : in the mesial aspect u can see 2 roots only, Buccal roots are straight and buccally directed . only MB root is seen , the DB is behind MB root .

Lingual root is banana shaped with strong buccal curvature in the apical 1\3 ( ya3ne curved buccally and

this curved is strong )

Occlusal aspect

The tooth is trapezoidal ( shebah mon7arf ) not rectangular or rhomboidal because we have different size in Mesial and Distal cusps..( if we have distal cusps )

Mesial and distal profile are straight and slightly Lingual converted…. ( aw conversion ) . the Mesial cusp is also called mesiobuccal cusp .. its bigger than mesiolingual cusp.

Buccal triangular ridge is more prominent than Lingual triangular ridge, Buccal groove separated DB cusp from MB cusp( buccal groove is a common groove between these 2 cusps).

We have also central pit and central groove , and instead of having an oblique ridge we have transverse

ridge .

We learn that in Max. first molar we have oblique ridge from ML cusp to DB cusp ..... ML cusp is very big and the DB cusp is very small lingually the Oblique ridge is not oblique …. Its goes transverse … because of the different in size between these 2 cusps, in permanent first molar ML cusp is also bigger and DM is small but the different in size is not that big as w can see in

Deciduous Max. first molar .

For that it's called transverse ridge between the Buccal groove and the distal marginal ridge.

H- shaped pit ( groove ) pattern .. w can see also the central groove and triangular supplemental grooves beside Marginal ridge and the Mesial and distal marginal grooves.

A girl ask the Dr. a question about the transverse ridge … icouldn't here the question well…but the Dr. explain again what he said before.

Maxillary second molar

Morphologically considered a model for the permanent first maxillary molar .. its looks like the tooth that erupt behind it ( ma bshbaho 100% aked ) but we have a little differences are only because of the set trait ( difference in size , color , in cervical constriction ) …. Ya3ne al far8 ben al Max. second molar w al sen ele erupt behind it ( max. first molar) fro8 3amah . 4 example ….. if the Max. permenant should have cusp of Carrabelle …. This tooth should have cusp of Carrabelle ( lazm ekon zaio )These similarity( concordance ) between the two teeth ( Max. deciduous second molar and the Max. permanent first molar) is called Isomorphy . It's important in prediction … we can predict the shape of Max. first molar based on the shape of this tooth . Max. second molar erupts early .. 2and half year ( 2.5 Yrs ) …and law la7dna shwaet e5telafat feh w msh 6abe3e … bkoon al Max. permanent first molar msh 6abe3e bar9'o

For the " Malaysian people" … the translator for the last 2 lines … ( if we notice that there is a different in the Max. Dec. second molar we will know that also the Max. Per. First molar will have different in shape … the tooth look like the tooth erupt behind it(Max. per. First molar) not like the tooth that will replace it(Max. per. Second premolar ).. .. remember that .

How we can distinguish ?? We use the set traits:

Cervical construction Cervical 1\3 bulging Little root trunk Roots thinner and

divergent The dr. just mention them without explain each one .

The same for the Mandibular second molar … morphologically considered a model for the permanent first Man. Molar ( bnafs al 6are8a ) – Isomorphic How 2 distinguish between them ?? using the set traits

Mandibular Deciduous first molar

Molariform ( looks like the molar ) unlike the Max. first molar ( it doesn’t look like a molar or a premolar its intermediate between the two )It have 4 cusps .

Buccal aspect :

We can see 2 cusps ( Mb and DB ) Mesial half is bigger than Distal half and also

the mesial half is higher than the distal half . M half projects more occlusally and occupied

2\3 of the crown area . M profile is straight … and the D profile is

curved and overhanging Cervical line inclined downward from distal to

mesial and its looks like S shape (sigmoid)…

Roots : two divergent roots …(M and D) and notice that the mesial one is longer than the distal .

Lingual aspect :

We can see 2 cusps …( ML and DL ) ML cusp is conical and larger than the DL Outlines of Buccal cusps are visible because the

Buccal cusp is more bigger than the lingual cusp.

CL is more straight and horizontal than that of the Buccal aspect ( not S shape )

Mesial aspect

We can see the prominent Buccal cervical ridge (BCR) and the cervical constriction

From MB cusp tip a straight line to BCR Transverse ridge connecting MB and ML cusps

are also seen Mesial marginal groove separates Mesial MR

from ML cusp ridge ( like the Man. First premolar.. but here its less prominent)

CL is convex occlusally and lower on the Buccal end

Roots : Extremely broad Mesial root.. and u can see a concavity here

And notice frequently bifid ( mashromah ) … sometimes the bifid(BL bifid) of root is much bigger than the bifid of the crown .

Distal aspect :

all 4 cusps are seen from this aspect , and Mesial root profile are visible

Buccal profile is less bulging than from mesial aspect

Distal MR is lower and less prominent than Mesial MR

CL is more straight and horizontal than that of the Mesial aspect

Occlusal aspect :

Without the BCR its rectangular , but if u includes it the tooth is not rectangular anymore

BL width is greater from Mesial than Distal ( distal 8a9er )

MB cusp is the largest , followed by ML,DB,DL MB > ML > DB > DL

Mesial transverse groove , interrupted by central groove .. extends from Mesial pit to central pit ( ben M pit and the central fe M transverse groove )

Mesial pit :: two supplemental grooves , of which ML crosses Mesial MR … ( the Dr. mentions that it's not an important note )

Central pit Buccal and Lingual grooves Often u can see distal pit

Dr. said : "" al tafa9el al mohmah ele mmkan as2l 3nha in the exam is the Buccal CR , sizes of the cusps … grooves w al pits 3shan koon ma3koo 9are7 ma bs2l 3nha because its variable 4 the Malaysian students … u need in this tooth 2 focus on the size of the cusps and BCR .. don’t go in deep with the grooves and pits . "" Deciduous teeth – size and eruption is not included """ hay al 9owar kant maholah .. 6olabe lma knt adarsom in Australia.. and I told them this is my hospital where I teach my student .. and all says …ooOOooh :P .. bs law fato7a 6b3n kano 3'ero ra2hoom … :P "

Next topic: Occlusion

-Notice that the dynamic part of occlusion has been covered in the lecture of mastication in Oral Physiology, but here we are talking about some definitions and some relationships

Slide#2

Definition of occlusion

1 *It is the act of closure or being closed.

2 *The static morphological tooth contact relationship.

3 *It includes all factors concerned with the development and stability of the masticatory system and the use of teeth in oral motor behavior. (This sentence has been covered in details in Oral Physiology.)

4 *It includes the integrated system of functional units involving teeth, joints, and muscles of the head and neck.

-point 3* and 4* don’t worry about them because the doctor will not ask us about them in the exam because he already covered them in Oral Physiology

Slide#3

# Concepts of Occlusion :

1* Balanced occlusion :

-Bilateral contacts in all functional excursions,,, now I am going to tell you an important thing which is: if you have a patient, in occlusion when he/she closes his/her teeth on each other ask him/ her to move the mandible laterally to one side either right or left ,,then what will happen

-on the Working Side: the relationship between teeth

will become cusp to cusp relationship(That means the cusp tip of the lower tooth will contact with the cusp tip of the upper tooth).

-on the Other Side : when you move the mandible laterally to one direction then the condyle process of the Other Side will translate against the articular eminence (it will slip down) so the mandible in this side will be far away and that is why teeth on the Other Side will not be contact.

In Arabic:

يعني لما اتحرك الفك السفلي جانبيا بحيث تخلي اسنانك في الجهة اللي حركتها بعالقة

فاألسنان على الجهة الثانية ما رح تكون مطبقة على بعضها..cusp to cusp

**And this is normal because in dentate people each tooth works as a single unit so there will not be a problem in having a space in the other side , but people who wear denture it is all act as one unit so in this case if we have a space in the other side the denture will fall down, that is why in these people we need specialized form of occlusion or specialized relationship called “BALANCED OCCLUSION” so this term is for people who wear dentures…remember this .

QS. So what do we mean by “balanced of occlusion???“

ANS : when you move your teeth laterally to one side the teeth on the other side will remain in contact, otherwise if we have a space in people who wear denture then the denture will fall down ,so balanced occlusion is important to prevent tipping of the denture bases. Remember this piece in the 3rd year because it is very important,,

*That is why if you want to provide for example a bridge or if you want to provide a crown don’t worry about balanced occlusion because each tooth acts as a single unit, but if you want to make a full denture for a patient you have to

provide a balanced occlusion .

2* Intercuspal Position :

*is a position where all the cusps are located against fossae and marginal ridges of the occlusing teeth; that means when you put your teeth on each other 100% (full occlusion) then for example the buccal cusp of mandibular molars will be in the fossae and also it will be against marginal ridges of maxillary molars, this is called “INTERCUSPAL POSITION”

3* Centric Occlusion :

*it is actually the static position when your teeth are held likely in contact (when the mandibular teeth are held likely in contact against the maxillary teeth)

*These three concepts are important and developed in a relation to orthodontics, complete dentures and full mouth rehabilitation(some people don’t have any teeth so they do full mouth rehabilitation for all the upper and lower teeth) so here we have to be aware to occlusion.

*So in general occlusion is important in Orthodontics and its important in Prosthodontics

*NONE of the three concepts are completely applicable to natural dentition: example ; balanced occlusion is only applicable for full dentures and should present in complete prosthodontics , so you don’t have to be aware of balanced occlusion when you are treating a dentate

patient

Slide #4

# Overview of Primary Occlusion :

*notice that each tooth (each primary tooth) should occlude with 2 teeth of the opposing jaw and this also applied to permanent teeth, thatz mean when deciduous

teeth are in contact ,) (سنين مقابله يكون سن but theكلexceptions are:

1*the mandibular central incisor which occludes only with the maxillary central incisor.

2*the maxillary second molar which only occludes with the mandibular second molar.

*otherwise (rather than those two exceptions each tooth when it occludes then it occludes with two teeth )

*Occlusion is supported and made more efficient after eruption of first permanent molars: the occlusion of the deciduous teeth remain premature until the eruption of permanent first molars and that is why the eruption of the permanent first molar is important, some children may have problems in occlusion but these problems could be corrected after the eruption of the first permanent tooth (1st molar) which is usually the biggest tooth and it guides

you to the condition of occlusion .

**THE PERMANENT FIRST MOLAR THE MOST EFFECTIVE TOOTH IN DETERMINATION OF OOCLUSION ,,IT CONTRIPUTES IN OCCLUSION MORE THAN THE 2ND AND 3RD MOLARS ..Remember this..

*Interdentally spacing is important for future sufficiency of space in permanent teeth: you may have a child with many spaces between teeth and this leads the parents to concern about that in the future, you should know that this is natural because deciduous teeth have to be SPACED because permanent teeth are much bigger in size and in fact children with no spaced teeth will have crowding permanent teeth in the future, that’s why spacing is important but it should be minimum in size.

*Probability of crowding in permanent teeth is related to the amount of intermodal spacing in primary dentition :

-so far we took incisors relationship ,canine relationship and angles molar relationship, now let us talk about primary molars relationships;

Here in the picture(fig 1 & 2) : tooth(*) in the figure is the maxillary 2nd molar and this is(**) the mandibular second molar, notice that the mandibular second molar is wider MD than the maxillary, that’s why the maxillary 2nd molar only occludes against one tooth ..(Remember it is one of the exceptions)

Slide #5

# Primary Molar Relationship :

*Terminal Plane Relationship:

-we said terminal because we are talking about the last plane we are going to put on the distal side of teeth as in fig.3 (maxillary and mandibular 2nd molar notice that it is

the right side here )(A,B,C) (in slide #5)

CASES OF THE PLANE :

A* FLUSH: when terminal plane is straight then it is called flush relationship, that means maxillary and mandibular 2nd molar is in flush relationship ,,here in A:

- 56% of flush teeth will have class I Angel’s molar relationship.

- 44% of flush teeth will have class II Angel’s molar relationship.

- But it is impossible to develop class III (0%), that is why terminal plane relationship is important in predicting Angel’s molar relationship

B*DISTAL STEP : pointing to distal direction, if you have this relationship then the maxillary 2nd molar should be located anteriorly to the mandibular 2nd molar:

- this will develop class II Angel’s molar relationship usually in most cases.

C*MESIAL STEP: pointing to the midline then:

-we have a greater possibility for class I Angel’s molar relationship.

- and lesser probability for class II Angel’s molar relationship.

*this slide (#5) is very important the doctor is going to ask us about it in the exam, at least one or two questions. And the numbers in this slide are not specific 100% because sometimes we have issues in development of bone that change this relationship but the previous cases occur usually .

Slide#6

#Factors Influencing the effect of terminal plane relationship on Angel’s molar relationship includes :

1*Differential growth of the jaws : the difference in development between maxilla and mandible ;for example if the mandible growth become more than maxillary growth then it might not become class II in flush relationship .

2*Forward growth of the mandible.

3*Sufficient Leeway space to accommodate a mesial shift of permanent molars:

- LEEWAY SPACE: (there is a question about this in practical and theory exams and this will be covered in orthodontics) It is the difference in mesiodistal width between deciduous molars(1st and 2nd) and permanent premolars(1st and 2nd )and all the time the mesiodistal width of deciduous molars should be greater than the mesiodistal width of premolars.

LEEWAY SPACE(fig 4) = MD WIDTH OF DECIDUOUS

MOLARS – MD OF PREMOLARS

Fig.4

*So Leeway Space is the amount of space gained by the difference in the mesiodistal diameter between deciduous

molars and premolars*.

**NOTE: the MD width in upper and lower premolars are usually almost equal, but for deciduous molars they are not equal in MD width because upper molars are thin MD but its great MD in lower molars, so we conclude that:

Leeway space in mandible < leeway space in maxillae.

*Ya3ne bel3arabi ino elfareg been 3ard el deciduous molars o el premolars belfak el sofle akbar mn el fareg bel fak el 3olwei la2eno il deciduous molars bel fak el sofle da2eman a3rad mn ele bel fak el 3olwei *

-And because the space in lower jaw is bigger than that of the upper jaw this will make the flush terminal relationship, so this tooth which will appear here(permanent 1st premolar) will erupt mesially and flush will convert into class I ,imagine if leeway spaces were equal in upper and lower jaws then the flush will always convert into class II and that doesn’t happen (in 4th and fifth years you will take these stuff in details).

Slide #7,8,9,10 &11

#Permanent Occlusion : ( here the dr. started to just read the slides because he already covered them in previous lectures )

*Anteroposterior relationship: -incisors: class I, II(division 1 and 2), III

- Canine: class I, II, III

- Molars : Angel’s class I,II, III

* Faciolingual relationship

- Premolas

- molars

The doctor moved directly to slide #12..

# Arch occlusal relationship :

According to the figure in the slide (figure from 1 to 8):

-the dr. was pointing to teeth number 5 in the fig. and start talking about the faciolingual relationship: these are premolars, and we should have supporting cusps like the buccal cusp of lower tooth(*) and(**) ,also we should have non-supporting cusps,(I tried to put a clear figure from the net so u can get the idea)and in this figure it is the natural relationship

Qs. What will happen if the relationship is inverted????

Answer:-that means the buccal cusp of upper tooth become between the two cusps of the lower teeth, then something called “CROSS BITE” will occur ,and this leads us to the curves of occlusion that we have already talked about in previous lectures(Curve of Spee, Curve of Wilson and Sphere of Monson).

SLIDE #14

# Inclination & angulation of the roots of the teeth :

*in the previous figure that was a normal relationship but this relationship will not be efficient if the teeth are positioned vertically and this will not be healthy , but Allah create our teeth with in oblique pattern and not vertically and that is the healthy condition ,so upper teeth are inclined outward and lower teeth are inclined inward and in this case the line that passes through the upper teeth will also passes through the lower teeth (like figure in slide14).

*SO The Mandibular arch is wider than Maxillary arch, although upper teeth are buccally located in a relationship to lower teeth to keep the stability of occlusion (sub7an ALLAH).

*Each tooth must be placed at the angel that best withstands the occlusal portion(not sure from the word)

Slide #15

# ANTAGONISTS (in permanent teeth) : *With the exception of the mandibular incisors and

maxillary third molars, each tooth contacts two antagonist teeth in the opposing arch.

The overall thing you need to know is that: IN CLASS I people: if you extract the mandibular first molar then you have to extract the maxillary 3rd molar because the maxillary 3rd molar will remain without antagonist tooth in the other jaw so we extract it to prevent supra-eruption.

IN CLASS II people : when you extract the maxillary 3rd molar you should extract the mandibular 3rd molar because it will remain with no contact with the upper jaw.. and in other teeth that antagonize with two teeth extraction on one will not need extraction of the opposite one because it will remain in contact with the other tooth.

-loss of one tooth keeps the adjacent tooth in contact with opposing antagonist.

-mesial or distal drifting into the space disturbs occlusal contact with antagonist teeth : here we are talking about another problem than the supra-eruption which is : when we extract a tooth the two teeth on the sides will move like this : the mesial one will go distally and the tooth located distally will go mesially , the two

teeth close to each other to close the space between them and this leads to malocclusion and you can’t put a bridge in the future.

Slide #16

# CENTRIC STOPS: the Dr just read this because it has been covered ..

-lingual cusp tips of maxillary posterior make contact with opposing fossae and marginal ridges of mandibular posterior teeth.

-buccal cusp tips of mandibular posterior teeth make contact with opposing fossae and marginal ridges of maxillary posterior teeth.

-lingual cusps of maxillary posterior teeth and buccal cusps of mandibular posterior teeth are called “supporting cusps” and the other cusps are none supporting cusps.

-areas of occlusal contact that a supporting cusp make with opposing teeth in centric occlusion Are “centric stops” the example here is the very bottom point of a fossa and sometimes the marginal ridges .

-the tip of that cusp is also a centric stop.

-knowledge of centric stops are important In restorative dentistry.

Slide #17(the dr also here was reading only …)

#movement away from centric occlusion :

*lateral:

- working side and non-working side : we already talked about previously.

- In complete dentures:

- balancing side and non-balancing side : we said that we should provide balancing occlusion in denture but this is not important in natural teeth and that is why in prosthodontics we don’t call it working side and non-

working side instead we call it balancing side and non-balancing side.

-movement in TMJ :when you move your mandible to the right side for example

The TMJ of the right side will not move significantly but the TMJ of the left side will move and go downward against the articular eminence and that is why this leads to separation of teeth on the other side

*tooth guidance:

- group function & canine guidance : when you move your teeth to one side to make the cusps in contact in some people only the canine cusps are in contact these called “canine guidance “ but in other people all the teeth

become in contact and we call these “ group function “

*Protrusive:

- Incisal guidance : the lower incisal have to pass against the lingual fossae of upper incisor “but guys I think the dr

should say the opposite “ check it plz!!

*retrusive: - the most retrusive position is the centric occlusion in

complete dentures. (we already covered this in oral physiology ): people who wear dentures don’t have 0periodontal ligaments in lower teeth or receptors so they don’t have any mechanism in guiding the mandible in occlusion so that is why in these people we have to put

the centric occlusion as the most retrutive position.…

Fin.

Malaysian Students: don’t worry about Arabic words or sentences in this lecture because they are

just translated, beside that most of the dr’s examples were in Arabic you are not gonna miss

anything Insha'Allah .…

in the second part ( occlusion ) we didn’t have the soft copy the figures are not from the slides

DIFAF: first of all I wanna send a hug for my dearest sister at medical school samah rjoub( you are the best thing happened 2 me so far ;) ),O 6ab3an ma bansa my sis nevo ;) (mahma haneb2a b3ad we beena blaad haege ma3aad o yegama3na) and my hiz goes to you raghas(wish you luck ,,just be strong )

Just one last thing wanna share it with you my sisters and brothers in my lovely class:

Life is a ticket to the greatest show on earth.Martin H. Fischer

The healthiest response to life is joy.Deepak Chopra

We must learn to live together as brothers or perish together as fools.Martin Luther King, Jr.

Neveen…

Big Hiiiii 2 all my friends … 97 dof3a shway zen5a bs bantha 3a al ras wallah .. kakosh, samorah , ra3'as,sana2, hadel, raya, difaf,do7do7,bayan,aya,shoro8,sana2,danya,mais,sara,rawan,bayan,nadosh,manar,saroorte,9afa2,O5te .. nur ;),lames,katia,kothar,raneem,7anen,wala2,raga2…. And 2 all girls

Tsnem.. am always here .. u no me..

Good FRIENDS are hard to find, harder to leave, and impossible to forget When it HURTS to look back, and you're SCARED to look ahead, you can look beside you and your BEST FRIEND will be there

Difaf .. blzab6 malo talefoonk??

Itrust You