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بــســم الله الرحمــن الرحــيـــم

We have some terms related to anterior and posterior teeth, and I showed you all in the lab ( Monday and Wednesday groups).

*Terms related to the posterior teeth:

Cusp: (#1)

It’s not a pyramid; it’s not curved and flat! But we can

identify 4 ridges for each cusp, for example this is a

posterior tooth, it has this ridge and we call it mesial

ridge, and another one we call it distal ridge ,

why we call it mesial and distal ridge ? Because that's

where it's going, so this ridge is going mesialy and called

mesial cusp ridge, and we have this distal cusp ridge, and we have the ridge that goes this way buccully and we have this ridge that's called distal ridge, so again we have: mesial ridge , distal ridge ,lingual ridge and buccal ridge. Notice that this called buccal ridge because it goes buccully toward buccal site of the tooth ,and lingual ridge because it goes lingually, so because we have buccal and lingual ridges sometimes you can get confused because the lingual ridge of this cusp faces the occlusal surface and the buccal ridge of this cusp also faces the occlusal surface, so instead of saying buccal and lingual surfaces we use the term triangular surface, so the ridge of the cusp that faces- or that part of- the occlusal surface can be called triangular cusp ridge. when two triangular cusps meet and make one continuous line, and these cusps are both located on mesial or distal surface- they are not obliquely oriented- we call that a transverse ridge ( #2 ) , for example the cusps that are located at the mesial part of the tooth. the triangular cusp ( #4 ) and the cusp that faces it on the other side form a continuous line and we call it a transverse line , but notice that sometimes we have ridges that do not go transversely, they go obliquely between two cusps located at opposite corners ,we have cusp at one corner of the tooth and the other one at the opposite corner of it ,so if you want to draw them by a line this line will not be transverse, will not be

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buccolingual, but it will be oblique! that is why this line is called obliquely ridge ( #3 ) , you can't see obliquely ridge in mandibular molars we only see it in maxillary molars, so it’s one of the arch traits because it allows you to distinguish between the maxillary molar as a group from the mandibular molar as a different group.

Fossa:

Now we have a term called fossa, which is a depression, like a valley between tow mountains and this valley is like the fossa in the tooth, and at the very bottom of the fossa sometimes we have a pit , which is the deepest point or depression in the fossa ( like any deep hole in the valley )

For example if you remember in the lab we talked about

marginal ridges; one is mesial and the other is distal

you have here a distal marginal ridge ( the oval ),

and the mesial marginal ridge ( the rectangular ) , for

example this mesial triangular ridge, just distal to it in this

region we have fossa, this fossa we call it triangular fossa

( the arrow ) because it’s located near the triangular ridges of these cusps.

so the triangular fossa all the time are located at the tooth margins ( we will talk about it in details later) in the very bottom of the deepest point of these triangular fossa we have a pit, for example we have here mesial pit ( #2 ) and in the distal triangular fossa we have a distal pit ( #1 ) , for the premolars we have two triangular cusps because we have one lingually and another buccully, so if you see the premolars we will not see these two cusps we will see only the buccal and the lingual; because of that we can see only two triangular fossa and that’s all , but for permanent molar or molars generally in addition to these two fossa ( triangular fossa ) there is a fossa in the center we call it central fossa and the deepest point of this fossa is called the central pit ( diamond) .

Developmental groove

We said last time that it's a groove that separates the major parts of the tooth, so what are the major parts of the tooth?

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Generally any tooth has major parts. These major parts

are the cusps and ridges, so any groove that separates

between one cusp and another cusp or between one

cusp and one ridge is called the developmental groove,

like for example this groove ( bold line ) it separates

between the mesiobuccal and distobuccal cusps, why is it called the buccal groove? It's called buccal because it goes buccully, and this one here is called distolingual groove (the dashed line) because it goes distolingually (we will talk about it later when we talk about each tooth apart).

Supplemental groove:

This groove that does not separate any major parts of

the tooth , you can see here these two grooves ( the

bold lines) , these grooves don’t separate any major

parts of the tooth, they're not located between two

cusps or between a cusp and marginal ridge, so that’s why we call it the supplemental groove.

Division into thirds

Now we will talk about division into thirds, we usually divide any tooth into three divisions and we do that in different planes, for example if you take this canine we are facing this labial surface of this canine we can divide the crown of the canine into incisal third, middle third and cervical third and we can also divide the crown into: distal third, middle third, mesial third.

And we can also divide the root into: apical third (because it faces the apex of the root), middle third and cervical third.

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Also we can divide the crown into thirds but if we see it from its proximal surface from the distal surface or mesial surface, (now we see this crown from the side so we have: lingual third, middle third, labial third).

Same here to the posterior teeth; we have distal third, middle third and mesial third. We have occlusal instead of incisal third, middle third cervical third. And here the same for the root, and from the proximal site, we have lingual, middle, buccal (instead of labial third).

So these terms are very important for description anatomy.

These slides include all the terms we have mentioned before and you need to know and memorize all these slides.

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The Dr. mentioned some of them …

Proximal surfaces: Are the distal and mesial surfaces, so if you want to talk about distal or mesial surfaces but not in a specific way you can use proximal surfaces.

Apex: related to the tip of the root.

Axial : is along the axis of the tooth , for example if you curve in the tooth and you make a surface and this surface is parallel to the axis of the tooth, we say it’s an axial surface so axial means here along the axis of the tooth.

Facial: means labial and buccal.

Embrasure: I talked about it in the lab last Monday and today but I’ll talk a little about it, so embrasure is a V shaped space between the proximal surfaces of two adjoining teeth in contact, unfortunately this is the only definition you will find here, but generally teeth don’t have flat surfaces as we drew when we were children and if they were flat the contact area of the tooth is all the tooth , but our teeth are curved so when they meet they meet just at the contact area not at the whole tooth, so because they meet at the contact area we have a space above and below this contact area from the four sites,

occlusal embrasure and the surface that is located here is

called buccal embrasure and this one is called lingual and the

one that’s located below the contact area we call it

cervical embrasure (the arrow ), which is filled with soft tissue

(Interdental gingiva).

Fissure: fissure and groove are the same (developmental fissure or developmental groove is the same).

Lobe, Mamelon, fossa, proximal root concavity, pit, ridge and edge (incisal ridge and incisal edge) is very important to know. The Dr explained them in the lab, transverse ridges, oblique ridges, cusp ridges, triangular ridge, and marginal ridges.

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(I'm sorry I can't put them here cuz I don't have soft copy, so plz go back to the hard copy to get them.

Root bifurcation: when we have one root that divides into

Two or three roots, the point it divides from is called

the trunk (the area before the one root divides , #1)

when we have three roots (one divides into three)

we call it trifurcation ( #2), root trunk is the cervical part of the root,

First part before it divides.

Sulcus: don’t worry about it, we know the lingual and buccal sulcus,we know that the sulcus is the space between the tooth and the lips or cheek , and sulcus is a term of a tooth itself but don’t worry about it because you will get confused between the sulcus and fossa .

Contact area: the two teeth meet actually side by side, they meet at an area called the contact area, this area is not the same for all teeth.

For example: this incisor, it meets with the adjacent

one at (#1) which is a high contact area, and meets

with the other adjacent tooth at (#2) which is low contact area.

So the contact area here isn’t similar at both sides.

A student asked: is the contact area related to the size of the tooth?

DR.: yes it is related to the size of the tooth; big teeth like molars and premolars have wider contact areas than the small teeth.

So what I want you to know is where the tooth actually contacts another tooth.

The tooth in the picture above has a curvature, the maximum bulging of this curvature is the area of contact, and this is what we will teach you in carving, we will teach you the maximum

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When we say high contact area, we mean toward the occlusal and Low means toward the gingiva.

height of contour which is a term that describes the maximum bulging point in the side of the tooth.

Heights of the contour are not the same; usually mesial height of contour is higher than distal height of contour in general.. I’ll give you this in details later.

here I’ll show you the Embrasure and what we

mean by embrasure.. it is the area between two teeth

and here this is the buccal embrasure ( #1) and this is

the lingual embrasure ( #2).

Similarly, we have here what’s called the occlusal embrasure

(#1) and the other one which is called the cervical embrasure

(#2) , but it is not straight.

Now we’ll start a new topic which is Maxillary Central Incisor.

Permanent incisor:

Eruption sequence:

We know that the first tooth to appear in the mouth is the mandibular central incisor followed by the maxillary central incisor then the mandibular lateral incisor and then the maxillary lateral incisor so this is the sequence of emergence or eruption.

What are the functions of pair of incisors?

1) For cutting; when you actually bite an apple, you will cut this apple, so that’s why they are cutters.

2) They also function in Esthetics which is the science of beauty.

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- People without incisors or with pigmented or stained incisors don’t have good appearance.. That’s why they are important in esthetics.

3) For Speech production; without incisors, you don’t be able to produce perfect sounds.

When you say “F” for example, we put the lower lip against the incisal edge of the upper incisor.. If you don’t have upper incisors, “F” will not be produced.

Class traits:

Class traits mean what are the means of characteristics that distinguish incisors from canines from premolars from molars, incisors as one group.

*What are those characteristics specific for incisors?

-First of all, the incisal part or the incisal two third is flattened mesiodistally and compressed labiolingually, which means that the incisor is very narrow labiolingually and wide mesiodistally.

-Secondly, we have long, horizontal mesiodistal biting

edge or what we call the incisal edge. Also we can have

two or more mamelons.. Look at the picture below, this tooth here

has three mamelons or lobes. The mamelons are the incisal edge

of the lobes, so the edge here of the lobe called mamelon.

We all have brothers and we watched their tooth eruption, once they erupt we can see the mamelons but after few months of using these incisors, (these will be worn out to be flat and now nobody of us have mamelons.

Also, incisors are characterized by marginal ridges that

are parallel to the long axis.. see here, we have the mesial

marginal ridge (#1) and the distal marginal ridge (#2), these

are visible on anterior teeth only lingually . So these marginal

ridges and their long axis is parallel with the long axis of the

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tooth, but marginal ridges of posterior teeth are perpendicular

to the long axis of the tooth.

Permanent maxillary incisors:

What are the arches traits? meaning how can we distinguish maxillary incisors from mandibular incisors?

This is an example of maxillary incisor (#1) and this is a mandibular incisor (#2)

Let’s start with the crown:

First of all, the crown is wider mesiodistally in the upper incisor than the lower incisor which has narrower mesiodistally crown.

-Secondly, we have a proportion; we want now the height over the width:

take the height of the crown of the upper incisor over its width: let’s assume its height is 10mm and its width is 8mm >>> 10/8=1.2… then take the height of the crown of the lower incisor and assume it is also 10mm but its width is 5mm >>> 10/5=2… we can see that the proportion of the lower incisor is higher than that of the upper incisor so that’s why maxillary incisors have smaller height over width proportion.

Also we have another proportion in another dimension which is mesiodistal over labiolingual :

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Now, take this crown of the upper incisor and measure the mesiodistal that is going to be over the labiolingual dimension then assume the mesiodistal here is 8mm and the labiolingual here is 7mm so it will be 8/7…. Then the crown of the lower incisor, it is 5 over 7, so it will be smaller, so that’s why if we have the maxillary incisor, we have greater mesiodistal over labiolingual proportion.

And now regarding the root, also the roots of maxillary incisors have greater mesiodistal over labiolingual proportion and generally for upper incisors, the roots are conical ( If you make a cross section through a maxillary central incisor, you will have a .. (قمعيةcircle but the mandibular one is labiolingually more than the mesiodistal.. that’s why we can identify these teeth based on the shape of the root.

Type traits:

The meaning of type trait is how we can distinguish maxillary central incisor from maxillary lateral incisor.

*Size: The size of maxillary central is bigger than maxillary lateral incisor

*Height / width proportion: I’ll show you this later when we talk about the lateral incisor but in general we use the size and height over width proportion because maxillary lateral incisor is narrower than maxillary central incisor and we also use mesiodistal over labiolingual proportion in crown and root and we will discuss this when we talk about lateral incisor.

The maxillary central incisor

Let's start now with permanent maxillary central incisor which is the tooth that we are going to carve next week, this tooth has 5 surfaces , to be able to describe it properly, we have to describe it surface by surface , so we will start with the labial surface .

The labial aspect :

so now we are looking to the tooth from the labial aspect

it is the widest incisor mesiodistally ( this tooth is the widest )

and this is a type trait because the maxillary lateral incisor

is narrower so that we can use it as a type trait and arch trait.

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This tooth has:

** 3 mamelons; the middle one (#2) is the smallest in width, the mesial one (#1) has raised shoulder, the distal one (#3) has low shoulder, as you can see here, the middle mamelon is the smallest one, the mesial one is higher than the distal one (y3ne the tooth has two shoulders, one is high which is the mesial and the other is low which is the distal).

** 2 labial grooves, because we have 3 mamelons; we have grooves, but these grooves are not actually grooves; they are just small depressions.

This piece of information that I'm going to say is very important …

which is the mesioincisal line angle is 90º , this angle between

the mesial surface and the incisal surface (the bold angle

at the right), so if you want to know if this

is the mesial surface or the distal surface, simply look for

the 90º angle, the angle which is 90º , is located on the

Mesial side and the angle which is rounded and has a low shoulder is on the distal side.

** Mesial contour line is straight but the distal contour is somewhat rounded (curvature), the distal height of contour (the empty circle) is lower than the mesial height of contour (the bold circle), they are not at the same level.

Q- Which one is higher? … A- The mesial one is higher.

The mesial height of contour located within the incisal third, but the distal height of contour located at the junction between the incisal third and the middle third.

**Cementoenamel junction (CEJ) or the cervical line (bold line) is

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Here when we are talking about the height, the higher one is the nearest to the incisal surface, and the lower is the nearest to the

gingiva.

convex cervically (toward the cervix of the tooth ).

**Root is conical and is inclined distally.

The lingual aspect :

It is scoop- like (like spoon) and it has a concavity, you all can put your

tongue against palatal surface of maxillary central incisor, you can feel it .

Q- Why do we have a cavity? A- Because we have a cingulum which

is raised.

This is the cingulum which is located at the cervical third of the crown

and we have 2 marginal ridges at the side, between these 3 structures

we have a fossa called the lingual fossa.

* Lingual fossa is bordered by:

The mesial and distal ridges and by the cingulum. This fossa is deep in the maxillary central incisor and it's deeper than the mandibular one. So if you want to distinguish between maxillary CI and mandibular CI, look at the lingual fossa, if it is deep then we are talking about the maxillary CI, if it is shallow then it is mandibular CI.

We have prominent cingulum and mesial, distal ridges because of lingual fossa.

*Root is narrower seen from lingual aspect than labial.

The mesial aspect:

Now let us look at the tooth from the mesial aspect, it is chisel- shaped.

The CEJ (bold curved line) which is curved to the cervical line

( It's convex incisally .)The labial height of contour is located

in the cervical third and the lingual height of contour is also

located in the cervical third.

The incisal edge is coincides with the long axis.

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This information is very important, let's imagine a line going through the

long axis of the tooth (the dashed line), this line will pass through the tip of

the incisal edge, this case is in the maxillary CI, in the mandibular CI it's slightly lingual.

And the root is conical.

The distal aspect:

It's similar to the mesial aspect but we have one difference which is the CEJ is less curved than seen from distally.

The incisal aspect:

It's triangular in outline, the labial outline (bold line)

is slightly convex but notice here the lingual outline

( the dashed line )is highly convex, the mesial and lingual

outlines at sharp line angles, the mesial outline is longer

than the distal one. We can also see a labial lobe grooves.

Pulp

About the pulp of this tooth, it looks like the tooth from

outside so the pulp mirrors the external configuration of the tooth.

BUT we have one important thing; we have what we call Pulp horns

(Bound by circles ,)as you see here this is the pulp of the tooth,

it looks like the tooth but here in the pulp we have one horn

that goes this way and one horn goes this way, so we have two pulp horns

and only one single root canal.

This is very important and the Dr always asks about it in the exam ..

Q- What is the possibility to have second root canal in this tooth? A- 0%

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This is the maxillary CI from different aspects

The maxillary lateral incisor

The labial aspect :

It looks like the maxillary CI but this tooth is narrower

mesiodistally and shorter incisocervically, this is a type trait because

we can distinguish between maxillary CI and maxillary LI .

the root is of the same length, but this root generally is more

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It's possible to find second root canal in mandibular CI and the percentage is 30%,

but in maxillary CI it's impossible

rounded so that's why the mesioincisal angle ( the bold line) is more rounded than that of the maxillary CI, and the distoincisal angle (the dashed line) is very rounded ( like a piece of circle ). The mesial and distal outlines are also slightly curved.

The heights of contours (the filled circles) are located generally

lower than the height of contours of maxillary CI .

The height of contour represents the contact area, the area where tooth come in contact with the adjacent tooth.

Root is conical and inclined slightly.

The lingual aspect:

We see two marginal ridges, cingulum and we

see the fossa which is deeper than maxillary CI ,

and because it's deep; cingulum and two ridges are prominent

Sometimes we may have a pit (the deepest point in the fossa) we

call it lingual pit, and sometimes we have a groove that process in the cingulum that actually originates from that pit we call it lingual developmental groove, this is very important because this tooth is highly attacked by caries because food will be gathered in that pit. But in maxillary CI and mandibular CI we have less percentage of caries because there's no fossa and pits in them.

The mesial aspect:

It's similar but the cingulum is more convex, the CEJ is less curved.

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The maxillary HOC is generally higher (near the incisal edge)

The distal aspect:

Similar to the mesial aspect.

The incisal aspect:

This tooth is ovoid, smaller mesiodistal than CI, the labial outline is more

rounded than the labial outline of then maxillary CI. The mesiodistal and

distolingual angles are more rounded.

Pulp

Similar to the CI. The possibility of having two root canals

is 0%.

Many people think that the cusps of the elephant is the canines, but

actually these are the Lateral incisors.

تم بحمد الله

Forgive us for any mistake … we did our best :)

Done by:

Wala'a Khdour , Eman Tawalbeh , Haneen Al-Kawamleh

Some people make your life perfect just by being in it

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