Dental Anatomy Introduction

Dental Anatomy Introduction

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Welcome to the University of Michigan Dentistry
Podcast Series promoting oral health care worldwide. Dental anatomy has a very specific group of
basic terms which are essential to its understanding and communication. The objective of this tape
is to define and illustrate some of these basic terms. We will start by identifying
the structures of an individual tooth. Then we will briefly illustrate the surrounding
or supporting tissues. We will identify the adult teeth and the terms that relate them
to the mouth and to each other. Then we will combine some of these basic terms to more
specifically describe the areas of these teeth. If we look at a cross-section of a tooth we
can start to identify some of the individual structures. The most common one is the enamel
which is the hardest substance in the human body and covers the visible portion of the
tooth. The dentin makes up the bulk of the tooth, the second hardest tissue in the human
body. It covers up the enamel all the way throughout the tooth, it covers the largest
portion or the largest area of the tooth. Then we have the cementum which is a little
bit softer but still a hard structure of the tooth and this covers the root of the tooth
from the crown all the way to the tip of the root. This is the cementum of the tooth. The fourth main structure of the tooth is
the pulp which is composed of the blood vessels as well as the nerves and lymphatics and the
variety of primitive connective tissue and this is housed in what we call the pulp cavity,
a chamber with inside the tooth that is surrounded completely by dentin. Actually the pulp can
be divided down into two areas or our pulp cavity can be divided into two areas. One
is the pulp chamber which consists of that area in the crown portion of the tooth. It’s
usually a little wider, a little broader and the second area is our root canal which is
generally a narrower canal which traverses down the root of the tooth. Actually we can divide our tooth into two
basic areas. One is the crown of the tooth which is that portion of the tooth which is
covered with enamel. And we can divide it into the root of the
tooth which is that portion of the tooth which is covered by the cementum. When we come to the tip of the root we have
a specific term which is our root apex, it’s like the apex of a triangle, it’s the tip
point of the root. Actually we also have another term at the apical area of the tooth and this
is the foramen or the hole in which our pulp exits. This is called the apical foramen. Where our hard structures join in the tooth
we also have terms which combine the two hard structures. In this area here we would have
the cementoenamel junction sometimes abbreviated as C-E-J, the cementoenamel junction. Where our dentin and enamel join we have our
dentinoenamel junction or frequently the D-E-J. Then our third junction area is our cementodentinal
junction, the area in which our cementum and dentin join. If we look at a cutaway section of some teeth,
we can define the periodontium or the supporting structures of the teeth have four basic parts
that make up our periodontium. First is our gingiva or the soft tissue which we usually
see in the mouth. Underlying our gingiva we have our alveolar
bone which is the bone that makes up the socket or the surrounding area of the tooth.
Alveolar bone. Then we have what we call a periodontal membrane
it’s a soft tissue or membrane a ligamentous membrane which connects the tooth and the
alveolar bone. Our periodontal membrane. There’s actually a fourth structure to our periodontium
is a part of the tooth and that is our cementum. The cementum connects the periodontal membrane
to the hard structure on the tooth and then the periodontium membrane is connected to
the hard bone so the cementum is considered part of the periodontium or the supporting
apparatus of the tooth. If we were actually to look to the crown, sometimes this crown
portion is broken down into two areas. What we call the anatomic crown is as we have described
that portion of the tooth which is covered by enamel. This is often broken down into
another crown and that is the clinical crown. The clinical crown is usually that portion
of the tooth which is above the gingiva. If we were to look to a mouth, we would find
that normally and usually the clinical crown does not go all the way down to the C-E-J
or down to the cementum. The clinical crown is about 90% of the enamel but doesn’t go
all the way down but again this may vary. In other instances, such as in children, we
may find that the clinical crown is only half of the enamel. Whereas in a case where we have had gingival
surgery the clinical crown may be exactly the same as the anatomic crown in fact, in
this view, we can see a portion of the cementum or part of the root here. So the clinical
crown varies within the mouth. When we look to a skull there are several
more terms that we can illustrate and identify here. Our upper jaw is referred to as a maxillary
jaw and the teeth in here are maxillary teeth. We will attempt to use this term rather than
upper and lower teeth or upper and lower jaws. Our upper jaw will be a maxillary jaw with
maxillary teeth. Our lower jaw will be referred to as our mandibular jaw, mandibular bone,
mandibular teeth. We have eight individual teeth we want to identify at this time. And
we’ll start right up with the central incisor. This is the one most commonly seen in a person’s
smile and it’s in the center. There’s two of them actually but we’re going to consider
the eight of them which are basically the same here. So we have a central incisor and
the one just lateral to it is also an incisor and it’s called a lateral incisor. These incisor
teeth particularly the central grow more prominent in our rodent animals, in our rats and beavers
and what have you. But our teeth are all basically the same in size. Our third tooth here is a cuspid or canine
tooth again this is the one that gets more prominence in our cats and dogs and lions
and tigers, our carnivorous animals. This is characterized by having just one cusp,
one sharp cusp on it and it’s called our cuspid tooth. We start going around the arch here.
We come to what was called our first premolar tooth or our first bicuspid tooth. We actually
have two bicuspids and they are called first and second so the first one would be considered
our first premolar, the first bicuspid tooth and this is characterized by having two cusps
that’s where the term bicuspid comes from. It’s got two individual cusps on it, our first
double cuspid tooth. We have a first premolar or biscuspid and we have a second premolar
or second bicuspid. Then our last three teeth, posterior teeth are molars and these have
multiple cusps on them and these are identified in the order in which they are. We have a
first molar, and a second molar, and we go back to a third molar.
Now these eight basic teeth are duplicated in other portions of the mouth. On the maxillary,
on this side we have the same eight teeth. Except on this side we would be calling them
left, the left central incisor. In fact, we can combine more terms to it. This would be
a maxillary left central incisor and then go right on back. On the mandibular teeth,
we again have the same eight basic teeth but we would be calling them mandibular central
incisor, and more specific mandibular left central incisor so we actually have four terms
which are used to describe our teeth here whether they are a right or a left whether
they are maxillary or mandibular or whether they are central or a lateral or an incisor
and what have you so here we would have maxillary—or mandibular left central incisor.
These groups of teeth since they’re duplicated four times or divides our mouth in to what
we call quadrants or quarters. We’ll have a maxillary right quadrant composed of our
eight teeth in the maxillary right area. Maxillary left quadrant which is a quarter of a section
of these eight teeth here. And then the same on the mandibular. Mandibular right quadrant
and mandibular left quadrant. These are often times used in referring to various procedures
that we do within the mouth. Another general area of breakdown that we have in these is
what we call anterior and posterior teeth. Our anterior teeth are generally our six front
teeth or the six teeth that are most anterior in the mouth. This composes are central incisor,
our lateral incisor and our cuspid. These are our anterior teeth. So we have maxillary
anteriors which would be these six right here. And we have our mandibular anteriors which
are the six on the mandibular and the teeth behind these are simply called posterior teeth.
This is composed of our bicuspids, two bicuspids, and our three molars. So we have our right
maxillary posterior teeth. We have our right mandibular posterior teeth. So we divide them
in to anterior and posterior right in between our cuspid and first premolar. Actually these
teeth have numbers and when they are referred to in our writings as far as our charting
and our literature that we use to identify these, they’re commonly referred to by number.
Instead of having to say maxillary right third molar this particular tooth is known as tooth
number one. And then we will start to number around the
arch until we come to 32 which is the total number of the teeth so let’s get the basic
orientation of how these number. Our maxillary right third molar is tooth number one and
then we just start right down the line the maxillary left, right,… Let’s see, our maxillary
right second molar would be number two. We go right on down the line until we come to
our maxillary right central incisor which would be eight and we continue right around
until we come over to our maxillary left third molar which is number 16. So they’re right
in order right around 16 of them on the maxillary. Then we drop directly below this to tooth
number 17 which is our mandibular left third molar. This is number 17. You’ve got to remember
two teeth in the mouth for this numbering system. One is your maxillary right third
molar and the other is number 17 which is your mandibular left third molar, number 17,
and then we’ll just number right around. For a while it’ll take a little time and you’ll
be counting on your fingers and toes and in your mind and what have you to get these numbers
down but the numbers of these teeth have to become just as common as the letters in your
name because you’ll probably use them more than you will writing your own name. When
you get involved in dentistry these are written many times every day. The numbers of these
teeth. Number 32 then would be directly below one and that is our maxillary right, pardon
me, our mandibular right third molar would be number 32 but the two key ones are just
our number one and number 17 you want to remember those and you could probably fit the rest
of them in a pattern just by counting. Let’s take a look at the individual surfaces
on these teeth. They each have names as well as numbers. Our number one surface is our
mesial surface. This is the surface closest to the midline and in this instance the number
one surface of our two maxillary central incisors are contacting each other. It’s the only surface
in the mouth where we have this occurring. The number one surface or mesial surface is
defined as that surface which is closest to the midline or as we go to the posterior it
would be that surface closest to the anterior or to the front of the mouth and the midline.
It would the surface closest to the midline here. Our number two surface is our distal
surface and it’s simply defined as that surface which is away from the midline or towards
the posterior of the mouth as we go towards the posterior and it would be the surface
opposite that of the mesial. Our number three surface has three terms really.
This is the surface which we see most commonly and it’s the facial surface that surface
which is on the face side of the teeth. This is the same as the maxillary and mandibular
all these are actually. So we call it facial all the way from number one all the way around
to number 32 the side, surface which is closest to the face that’s number three surface. This
also can be broken down into two different terms, the facial surface in the anterior
six teeth is called the labial surface. It’s the number three surface again for record
purposes. And the facial surface in our posterior teeth
is generally called the buccal surface. These buccal and labial terms are probably more
commonly used in the facial surface although facial is perfectly acceptable and will be
found in the literature too. It divides it down into the posterior surfaces being called
buccal here and the anterior six teeth being called the labial. Our number four surface
is our lingual surface and that’s the term in relation to the tongue surface. Most of
these are in relation to the anatomical terms, most of the anatomical terms of the tongue
are called lingual and the surface next to the tongue is a lingual surface. We might
drop back a little bit when we’re talking about the number three surface, the labial
surface, this is referring to lip that part which is under the lip, ‘labial’ is again
an anatomical term which refers to much of our anatomy in the lip. ‘Buccal’ is a term
which refers to cheek much of our anatomy in the cheek is referred to buccal as far
as our nerves and our arteries and our muscles and a variety of other things are buccal so
this is where the term for this comes. If we go to our number five surface, we’re talking
about the biting surfaces on these teeth. And in the posterior this is called an occlusal
surface that’s with our bicuspids and our molars. Number five is the occlusal and in
the anterior where we are involved more with the cutting edge and the anterior six teeth
we’re talking about incisal surfaces. So again we have two general terms that are referring
to surface number five. Incisal surface in the anterior and the occlusal surface in the
posterior. Both of them referring to our biting surfaces. Section 13 in Kraus’s textbook deals with
alignment and articulation of these teeth. This is something we ought to get a basic
orientation to before we start studying individual teeth because total alignment and articulation
is important in relation to the individual anatomy of these teeth. For instance, if you
were to look to alignment of these teeth you’d find that they don’t sit one right atop of
another like blocks. Like our anterior for instance are at angles and our maxillary anterior
teeth are coming forward considerably and our mandibular anterior teeth are doing the
same thing and these vary somewhat within jaws. We can look to another skull and see the variation
of our maxillary anteriors that are at a very strong angle that they come forward and out
and this varies significantly the anatomy of the teeth. This is one of the reasons that
they’re in this particular anatomical structure and again the mandibular teeth are coming
forward in a different area. You’ll note these teeth will occlude or to bite differently.
Here we’re… well we’ll show it in this direction. Our maxillary teeth are forward of our mandibular
teeth. Our mandibular teeth are biting up on the lingual surface now of our maxillary
teeth and even in our posterior area here we have a lap of these teeth. They’re not
one on top of the other and the teeth are biting in between each other. If we were to look at a mandibular arch which
is the whole arc of our mandibular teeth here we’ll see that it’s an even semi-circle, but
this is a very specific arc that’s created from these teeth and the teeth alter their
anatomy to fit into this pattern and as we study them we continually point to these various
alternations that exist and even if we were to look at the posterior teeth in here we’d
find that they’re not coming straight up. They’re coming at a rather sharp angle. One
of the diagrams that are… illustrate this quite nicely. As far as varying angulations
of the teeth we have our anterior teeth shown here to be angling, our maxillary anteriors
rather significantly in a forward direction. Our mandibulars, we can see our coming in
a rather specific forward direction. It also shows posterior teeth. These are also tipped
and different teeth are tipped at different angles. This is all designed for a rather
complex functioning mechanism. If we were to look at the maxillary teeth from the posterior
as if we were sitting back on the tongue looking out we would see that these maxillary teeth
are angled rather significantly outward towards the facial surface. They have very definite
angles and this whole complex angulation goes into the anatomy and hence forth into the
function. Again we’re sitting on the posterior tongue looking forward on this mandible and
we’ll see that are mandibular teeth are at a significant angle tapering in. This gives
us rather good support in our mandibular bone as far as the function and also meets and
relates to our maxillary teeth rather significantly. We have identified the surfaces of our teeth
in the skull. Now let’s look to a diagram and see if we can identify them a little clearer
here. We have superimposed a box over this incisor to help us clarify these surfaces.
We can start with our number one surface which is our mesial surface and this is a whole
area of the box that would be on the mesial portion of the tooth here. Our number two
surface would be our distal surface which again would take of the area of the box in
this area. Our number three surface is our labial surface. Sometimes called a facial
surface but I think more commonly in the anterior here a labial surface. Our number four surface
is our lingual surface covering the whole lingual portion of the tooth. And our number
five surface is our incisal surface which is characteristic of our anterior portion
of the mouth, our anterior teeth, the surface is called incisal. Now one of the advantages of our box is that
it helps us to identify the junctions of these surfaces. And where these surfaces join we
have an angle. This is called a line angle. A line angle is an angle formed at the junction
of two surfaces and this is given a specific name according to the surfaces that make up
this angle and in this instance we have a mesio – we note that I said ‘o’ you drop
the ‘al’ on the term ‘mesial’ when you say ‘mesio’ – and then the next surface which
is the labial line angle. Then mesiolabial is one word. So we have a mesiolabial line
angle. Actually this could be called a labiomesial line angle but custom usually identifies the
mesial surface first and our workbook has a little description as to how these are more
commonly or frequently referred to. It’s not wrong to say it, by saying a labiomesial but
it’s more customary to say the mesiolabial. On the distal we have the same basic thing.
We have the distolabial line angle and the same on the two lingual line angles. They’d
be named according to the two surfaces that adjoin them. This also gives us a line angle
on our incisal and in this area here we would have our labioincisal line angle.
This angle here would be identified by the mesioincisal line angle and the same on our
on our lingual and distal angles. Now where three of these surfaces meet, we
have a point angle and the point angle again is named where the three surfaces make it
up. And again this would be basically one word. We would have a mesial, labial, incisal
point angle and again we change the mesial to ‘o’ on both the mesial and labial and use
the ‘al’ on the incisal. So we got a mesiolabioincisal point angle right here and the same exists
for our other point angles. This one would be our mesiolinguoincisal point angle. So
this gives us an identification of our surfaces, our line angles, and our point angles. Let’s
look to a posterior tooth here. We have the same thing basically on the posterior
teeth except we’ve got two different named surfaces. We’ve got our buccal surface and
the surface number five here now is our occlusal surface and again where these surfaces join
we would have our line angles but they would be named according to the surface. So this
line angle here would be our buccal occlusal line angle and the same with the line angles
around the rest of the posterior teeth. We would have our mesial occlusal line angle
and then we can go our point angles again and again this is identified by our three
surfaces. Here we would have our bucco – that would be an ‘o’ now – our buccomesioocclusal
point angle and the same would exist for basically all the rest of our point angles in the posterior
teeth. These are more frequently referred to, these point angles in the posterior teeth
because posterior teeth, uh, are more square or rectangular and these angles are sharper
and much more frequently we refer to our point angles in our posterior teeth. Another way we can help describe these teeth
is by dividing them into thirds which is a fairly common way of describing portions of
our teeth. If we look to a labial surface of an incisor here, we can divide it into
thirds again according to the general areas in which we’re, surfaces in which we’re talking
here. So we’ve got an incisal third, we’ve got a middle third, and we’ve got what’s called
a cervical third. Now this term ‘cervical’ refers to the general area of the teeth around
the cementoenamel junction. And actually the cementoenamel junction which we had described
before is often referred to in three ways. One is by the cementoenamel junction, the
other is by the abbreviation C-E-J and the third which is very common, is called a cervical
line so the cementoenamel junction has another term which is called cervical line which generally
describes the area of the C-E-J and so we’ve got the term ‘cervical’ referring to this
area of the teeth. We have here a cervical third of the crown, we’ve got a cervical third
of the root, a middle third of the root, and an apical third to the root. These terms help
us give us handles in case we want to describe certain things that may happen to the teeth.
We may have a fracture which may be a horizontal fracture and it could be through the middle
third of the tooth or the incisal third. It helps us to identify them. If on removing
the tooth we were to break the root, we possibly could break it in the apical third. And we
refer to these portions of the teeth generally by the thirds. While I’ve got this diagram
also I might combine a couple other terms. When we’re talking about fractures, we could
have a vertical fracture in the tooth which would allow us to combine some terms here
and this would be called a vertical fracture in which we have a fracture in the incisal
cervical direction. Sometimes it would be called a incisal cervical fracture. If we
had a fracture in this direction, we may call it a mesial distal fracture. Sometimes in
measuring these teeth we’ll measure the distance from the incisal to the cervical. This will
be our incisal cervical distance and we have the same thing on the mesial distal. We’ve
got measurements that measure our mesial distal distance. So these surfaces can be combined
in many ways to aid us in describing these teeth. Let’s look at the labial view and divide our
tooth into thirds in a different direction here. We’ve got a third here which would be
a mesial third of the crown, a middle third to the crown, and a distal third to the crown.
We may have a fracture which involves the mesial third of the crown and we may have
some caries or something that is in the mesial third so again these are just descriptive
handles that we can use in describing these portions of the teeth. Let’s look to a mesial
view. We can also divide it down here. We have a labial third, a middle third and a
lingual third to our crown and actually the roots are basically the same thirds. These
are basically by the surfaces that are involved. If we look to our posterior teeth we find
that they’re divided in basically the same thirds except we have a little different terminology
on a couples surfaces so we’ll use those surfaces in dividing them into thirds. The first one
is our occlusal third, our… instead of having an incisal as we have in the anterior and
the posterior, we’re talking about our occlusal surface so we have an occlusal third, a middle
third, a cervical third of our crown, a cervical third of our root, and then the middle third
again which we probably best identify as middle third of our root, and then an apical third.
If we were to look to the buccal surface and divide these teeth from mesial to distal into
thirds then we would have a mesial third, we would have a middle third again, and we
would have a distal third. If we look to the mesial surface of our posterior tooth, we’ll
find that we have a buccal third, the surface being the buccal surface, we’ve got a buccal
third to our crown, a middle third, as well as our lingual third. We hope that these illustrations
and definitions have given you a better grasp of some of our basic dental terminology. These
terms are essential to the communication of dental anatomy and important before we start
studying the individual teeth. You have been listening to a presentation
from the University of Michigan’s School of Dentistry which is dedicated to supporting
open learning and open educational resources. This recording is licensed under the creative
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48 thoughts on “Dental Anatomy Introduction”

  1. all videos R great, and very helpful, but here is a request, can i get a video about splints, splints in dentistry, its types, fgunctions indications… plz if u hav any such material available, then plz plz uplaod, i shall B very thankful

  2. i'm in the first yr of dentistry and watching this video has made it so much easier..i was wondering if it possible to show the carving of a tooth on one of these video plz.thanx

  3. thank you sir………….i am a student of first year bds….i am actually facing lots of problem…….since our teachers r nt atall supportive…your lecture was a grt help thnk u once again………if u could plz teach us carving also..its a request

  4. Thanks a lot. It made my understanding clear.. please upload a video explaining the different ridges too… πŸ™‚

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