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Introduction to Dental Anatomy
To start with , The doctor began the lecture in explaining the main topics of
"dental anatomy and occlusion" in general. The lectures topics cover detailed
dental macroscopic anatomy and the basic principles of dental occlusion. Each
lecture covers one class of permanent teeth and there is a separate lecture for
deciduous teeth.
Normally human dentition is diphyodont, diphyodont
means that we have two sets of dentition; we haveprimary dentition and secondary dentition.
Primary dentition is a temporary dentition thats
why it is called deciduous dentition. And the
secondary dentition is the more permanent
dentition.
Remember this term diphyodont means we
have two sets of dentition:
1-primary: is deciduous, temporary this means that these teeth serves for alimited time.
2-secondary: is permanent dentition. Humans have 20 deciduous teeth in
total and 32 permanent teeth
Classes of teeth
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We have three classes for deciduous teeth; we have Incisors, canines, and
molars only three classes. In contrast, we have four classes for permanent
teeth.
Why do we have four classesfor permanent teeth?This means we have an extra class which is " premolars ".So in permanent
teeth we have Incisors, canines, premolars and molars.
Could number of Teeth differ with Age ?!
Now deciduous teeth are smaller in size ,this means we have a
difference on the number of teeth. we have 32 permanent and 20
deciduous .This means that we have 12 teeth that erupt without replacing
previous teeth.
Types of Teeth !
So teeth are divided into two kinds: one kind is successorsthe
other kind is no n successor teeth. Successor teeth ( ): theseare teeth that are going to succeed or replace another set of teeth
.Nonsuccessor teeth: that teeth that erupt without replacing another set of
teeth,
# Permenant incisors are going to replace deciduous incisors
# Permanent canines are going to replace deciduous canines
# Permanent premolars are going to replace deciduous molars
VIPthe permanent molars erupt by themselves without having toreplace another teeth.
So again, Successor teeth are permanents incisors, canines and
premolars. And the non successors teeth are the permanent molars. All thedeciduous teeth are going to be replaced (succeeded) thats why they are
called predecessor (opposite of successors).
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Now let's answer few Questions :
Why do we have two sets of dentition?
Why we are created with two sets of dentition?
Why dont we have only one set?
This is an important info, by age the upper and lower jaws are growing
larger in size. The other important thing that Teeth dont grow in size . Once
the tooth is formed and calcified it doesnt grow in size . Bones are different,
it undergoes growth while teeth dont undergo growth.
Why do we need to change our teeth with age ?
If we were created with one set of dentition .we would have only
deciduous teeth which are small and they are only 20. by growing in age the
jaws will be bigger and the 20 small teeth will have big spaces between
them. Thats why we need to have another set of dentition.
New set means a New Properties :
1-it should be composed of bigger teeth
2- it should be composed of more teeth.
Because the jaws grow in all directions. (anterio posteriorly,mediolaterally
,and also superior inferiorly), so that Permanent teeth should be bigger in
size .
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The dental formula:*
In the dental formula we use the initials of the classes (the first letter)
I for incisor
C for Canines
PM for premolars
M for molars
* VIP
Deciduous teeth are indicated by the letter D before the initial. For example Dm
(for molar(
*Human dental formula:
- Deciduous teeth: for one side
- DI 2/2, DC 1/1, DM 2/2 = 10 "for the two side 10x2 = 20"
Permanent teeth: for one side
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I 2/2, C 1/1, PM 2/2, M 3/3 = 16 " 16x2 = 32 "
Concentrate here*The numbers following the letter refer to the number of teeth of each type in the
upper then the lower dentition for one side only. For example { I 2/2 } means that if
we take teeth from one side we will have two incisor on the lower jaw and another
two on the upper one thats why {2/2{
*Mammal Exceptions
This dental formula for humans but it differ by different mammals for ex: carnivores
have 3 incisor, but all mammals have one canines on each side and its themaximum number for all mammals canines tooth , premolars can be up to four in
one side , molar the maximum number is three so, as humans we have the
maximum number of canines and molars but we haven't got the maximum number
of premolar and incisor so we have 32 .
*The Highest number of teeth!!The maximum number for Mammals to have is 44 teeth. " 3 incisor 1 canines , 4
premolar , 3 molar (11 on each quadrant thus 11x4 = 44.(
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P.S:You have to know what we call "dental formula".because there will be some
question in the exam about it .
*Mirror image theory!!
-Dental formula: it's a way to describe all the teeth in an animal. In general human
& animal have specific dental formula composed of 32 teeth for permanent and 20
teeth deciduous. Teeth in the right side are identical for the teeth in the left side
"mirror image".Thus we don't have to provide the dental formula for both sides
because the teeth in right just like the teeth in the left.
Quadrants
Dental formula only describes the teeth of one side and because of that any number
you see in the dental formula you have to multiply it by "2" in order to get the full
number.
-For example : we have {2/2} which means two incisors in the upper over two
incisor in the lower but remember we have 4 incisor because you have to add the
incisor of the other side.
-we have a maximum number for the dental formula in mammals.
The maximum number of incisor is Three , but in human we have Two incisor ..we
are talking about one quadrant.
- What is "Quadrants" ?
If you divide the teeth or the dentition by the vertical line "mid-line" you will get
right & left side. Also you can put line between the upper and the lower teeth and in
this case now you will have Four Quadrants.
-The maximum number of canine is One .. No one can have more than one canine
but some animal have Three incisor which is the maximum Number of incisor ..We
are talking here about the placental mammals. "Placental mammals are mammals
with ovary". While other mammals like "kangaroo" they may have Four incisor.
- For premolars the maximum number is Four and the maximum number for molars
is three, so as human we have got the maximum number in canine and the
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maximum number in molars but we have not got the maximum number in incisor &
premolar.
-If we want to calculate the maximum number in mammals it willbe "44" .How??
We will have : Three incisors 3/3 .. One canine 1/1 .. Four premolars 4/4.. and Three
molars 3/3 that will be 22 . Once again the other side have also 22 that will be
"44. "
-For example: Cats have 3 incisors ,1 canine ,4 premolars ,1 molar.
Do all mammals have 2 sets of dentition?
Yes, but we have one exception."R odents " have one set of dentition thats mean
they don't have deciduous teeth then permanent teeth. All the reminder mammals
have 2 set of dentition..Primary dentition followed by permanent dentition.
}Rodents =}
-Lets divide the teeth into 4 quadrants:
* Right maxillary
*
Left maxillary.
*Left mandibular.
*Right mandibular.What are these numbers from ( 1 to 4) ?
when we divide the teeth into 4 quadrants ,the right maxillary we give it number
1 ,the left maxillary we give it number 2 ,the left mandibular number 3 and the right
mandibular we give it number 4.
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*VIPWhen you examine a patient and you want to go from Q1 to Q4 you will go
clockwise. You have to remember that the right and left is not your R.t & L.f , it'syour patient R.t & L.f
In Genral Dentistry the R.t & L.f is the R.t & L.f of the patient not the DR.
What is occlusion plane !!
-For dental notation system if you want to give the quadrants number you give from
1to 4 for the permanent teeth and from 5 to 8 for the deciduous teeth. As you see
here this is the mid-line and this is the area between the upper and lower teeth and
we call it the occlusion plane
" occlusion plane = "
Occlusion plane is a plane that separate between the upper and lower teeth, also in
addition of giving number to quadrants we give number to teeth and there are
different ways. We use the number starting from the mid-line and going distally we
begin in tooth #1 until tooth # 8. For the deciduous teeth we don't give number we
give letters from A to E.
*VIPRemember that we start giving the number from the mid-line going distally.
THE DENTAL NOMENCLTURE
Naming teeth by their names:
First you have to identify whether the tooth is deciduous or permanent and you
have to mention whether the tooth is in the maxillary or mandible jaw. Then you
have to know the class of the tooth is it an incisor \ canine \ premolar \ molar. For
the deciduous teeth incisor\canine\molar. Then the order within the class ; is the
tooth central o lateral incisor? Is it first or second premolar? And so on .And finally
you give
the side if it right or left, that is how to name the tooth.
For example let's name the central incisor :
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"The permanent maxillary right central incisor"
So you have to give 5 words.
* Once again
1- Identify whether the tooth is deciduous or permanent.2- Mention whether the tooth is in the maxillary or mandible jaw.
3- Knowing the class of the tooth.
4- Ordering within the class.
5- Giving the side if it right or left.
That is how to name the tooth.
Doctor said that "Describing teeth by words is really very boring and sometimes
takes time." What do you think guys?!
If I want for example to name each tooth by words it takes time, specially
sometimes as a dentist , I can refer my patient to another dentist so I have to
indicate the problem in one of the teeth instead of saying : the patient suffers from
pain in the permanent maxillary right central incisor, it's could to agree on a
notation system instead to give the full name of the tooth.
This is called the dental notation system ; which is the way of abbreviating the long
5 words that is used to describe teeth.
* Notation Systems
-Palmer notation system
-Universal numbering system
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-FDI numbering system
*Palmer notation system
The first one is the palmer notation system and is also called the Zsigmondy
notation system. Developed by the American dental association in 1974.
In this system the tooth is represented by a number from 1-8 for permanent, and
by a litter from A-E for deciduous teeth.
*VIP1-We use numbers for permanent teeth or letters for deciduous teeth.
2-All the time we number the teeth from the midline distally.
"tooth number one will be close to the midline and tooth number A also will
be close to mid-line in case of Deciduous teeth".
Example : Number 8(the third molar) will be far away from the midline"
Then we have to provide 2 lines , on line is a horizontal line presenting a
horizontal plan, and the second is a vertical line presenting the midline " these
lines are in the palmer notation system ".For example if we want to describe the
maxillary right central incisor we say first:
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It is tooth number one , then we put the two lines the first one is the midline and
the second is the occlusal plane. We must put them in a way to describe the
region of the tooth.
this is the maxillary right central incisor located in the maxillary right
quadrate .The number is at the left of the line and above the the occlusal plane
thats why it should be presented this way.
Let's suppose that we have 2 teeth in the palmer system; and I want to describe
the maxillary right central incisor and the maxillary right first premolar , I will put
1and 4
1:the maxillary right central incisor
4:the maxillary right first premolar
*Remember that :Sometimes in the palmer notation system we can use the lines for more than
one tooth.
P.S : Nothing more you should know about palmer notation system.
*The FDI Notation system:
*Rules
-we don't use lines or letters.
-we use numbers only
Each tooth is presented by two digits, the first digit which is on the left the
quadrant where the tooth belongs, and the second describes the order of thetooth in that department.
For example:
If I want to describe the mandibular right permanent canine, first I have to put a
number which is 4 that indicate this tooth belongs to mandibular right quadrant
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( which is number 4) , the second number (3) presents the order of the tooth in
the midline.
This is the FDI Big Four !
1-In the deciduous tooth we must make sure that the numbers are
from 5-8(not 1-4).
2-The tooth is permanent If it begins with 1,2,3,4.
3-The tooth is deciduous if it begins with 5,6,7,8.
4-The second number describes the order of that tooth starting from the midline.
It is wrong to say that the tooth number is 11(eleven) it is 11(one one) because
in the Universal system it is possible to have a tooth called ( eleven ) .
Q: Is it possible to have a tooth number (56)?
No 5 mean deciduous and there is no 6 teeth per quadrant.
Q: Do we have zero in the FDI notation system?
No..Impossible.
*The Universal Numbering System:-This system was developed because palmer system
was hard to type on keyboard.It is developed by the
dental American association In 1968.
*In this system
-In this system we use numbers for permanent teeth
and letters for deciduous teeth.
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-In this system the order of this number is this way , we star in the maxillary
third molar and then we go to maxillary right central incisor then maxillary left
central incisor and we continue to tooth number 16 which is the maxillary left
third molar then to 17 which is the mandibular left third molar and then we go
until we 24 which is the mandibular left central incisor then mandibular right
central incisor then to 32 which is the mandibular right third molar.
-In this system we go this way (clockwise(.
- In this system we don't read it as two digits we read it as one number. For
example: We don't say 25(two five) we say twenty five.
For example when a patient come to me suffering from tooth number twenty five .it
is obvious to know it is the universal system and in America they use the American
system.In Jordan we use palmer notation system but I am sure your Malaysian
colleagues when they back to their country they will use FDI .Because I cannot be
sure that all of you are Jordanian or all of you will work in Jordan so you need to
understand other systems. For example when I go to Australia I use FDI system .
* Again for deciduous teeth we use letters start with A , end with T .
*Zero Theory !!In Universal system the zero is possible like 10, 20, 30 ,BUT it is impossible to see
zero in FDI system and Palmer notation system.
That's all about today lecture,Next week lecture will be a Full Practice about Dental
Notation System.
Dont close your Sheets there is one important page left !!
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To sum up, this is the Skeleton of this Lecture
1-Human dentition : 2 sets of dentitions,
-Primary/deciduous
-Secondary/permanent
2-Why do we have to have two sets of teeth.
3-Dental formula such as:
I for incisors, C for canines... Etc
4-Quadrants:Tooth-bearing region of the jaw can be divided into 4 quadrants.
Quadrants in permanent dentition have the numbers 1 - 4 and in deciduous have
the numbers 5 8.
5-What do we mean by "notation system". It's tooth numbering orshorthand system of tooth notation.
6-How to call teethThree main systems:
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-Palmar notation system.-Universal notation system.-FDI notation system.
Quote of the Day : the only person who dont have any mistakes , is the person who
do nothing in Life.
This Work Done by
Dental Anatomy Script team
Sawsan Z. Jwaied
Hadeel Sumrien Hebah Ramadnah
AseelGhawanmeh Russia ElShboul Salam Ahmed Abeer M. Dirawi
Sondos Abu-zaid Eman Idkaidek
Eman Nazal Hibah Jarrah
Rmz Rabadi Noha Mohamad
Rawda Najjar GaYda'a Kana'an
Ahmed AlShamary
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