jaw relation record ,lec 6

8/3/2019 Jaw Relation Record ,Lec 6

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Jaw Relationship Record

- In the previous lecture we talked about the vertical dimension, and we said there

were several steps during the fabrication of the jaw relationship record. And these

steps require us to go in a sequential so we can make a measurement in the actualpatient mouth. These measurement involves 4 basic things :

i. Vertical dimensionii. Horizontal dimension

iii. Hinge axis relationiv. Teeth selection

>>> So who can tell me what we did during the vertical dimension ofocclusion measurement in the lab??!!

- We placed 2 points on the patient's facewe said we can use more than one

reference -. To make a measurement we need a reference in the upper part of the

patient face & in the lower part of the patient face. In order to make these

measurements we need this kind of reference.

- Today we'll be talking more about horizontal relationship & face bow

record transfer.

" which has beenDental ArticulatorYou will have an instrument called a "-

designed & based on the measurement & references which found in the patient's

head.

- The main reference is :

Frankfurt horizontal plane:which is an imaginary plane runs from the

inferior margin of the orbit to the Ala-Tragus line to the external bony of

acoustic meatus.

- On the patient's head & the articulator we have an axis which naturally

presents & you don't have to measure it which called the two "hinge axis".

the two hinge axis is very close to the frankfurt plane . It's essentially the

axis which goes through the condyles of the mandibular jaw .

- It's the reference which we relate the maxillary arch before we relate

the mandibular to the maxillary.If you were in lab or last week, we repeated many of these steps


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ONSHIPVERTICAL RELATI

- The first thing that we do in the vertical relationship is contour the wax

rim. We said the patient is 50-60 years old & we want visibility

approximately 1-2 mm. we want this visibility to be appropriate for the

patient, it should be Age related, if the patient is too young we see more

visibility at rest, or if the patient is too old we see less. It is also related to

the anatomy of the patient's lip.

- The lip should be unstrained & we're looking also for the naso-labial angle

which approximately - this angle is between the upper lip & the

columella of the nose.

- We decided the contour not only for labial fullness, we look for the space

", when the patient smilesBuccal Corridorin the side which is called "

normally we see a space between upper wax rim & the cheek .

- Then we need to orient the wax rim in relation to our reference in the

patient head before teeth extraction which is the "Camper's Plane" made

up essentially from three lines: interpupillary line & Ala-tragus lines.

We want the wax rim anteriorly to be parallel to the line which runs from

one people to the other !!!

Posteriorly in right & left we want the plane to be parallel from the lower

border of the Ala of the nose to the tragus of the ear (tragus either in the

middle or lower border of it)

- The occlusal plane isn't the same as frankfurt

-

- In order to do these measurement you should use an instrument ( because

U can't see the wax plane through the patient's cheek) this instrument is

called "Fox's Plane", this instrument usually has 2 flat arches: on inside the

patient's mouth, on outside.

Once this plane is inside the patient's mouth it will indicate the angulation of

the wax rim inside the patient's mouth .


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- Once we make the ( inter pupillary line & the camper's plane & the

occlusal plane) once they are parallel to each other and we are satisfied that

the upper rim is in the right position. There are certain checks that we can

do : the phonetic check & the anatomic check. The phonetic check such

as the "S" sound , "F" & "V" sounds.

They will be discussed in details in the lab.

-Once we finish the maxillary rim we need to mark certain lines which are

the midline of the patient's face & the canine lines. In order to know where

to put the teeth & the size of the teeth that we should use.

a. Midline: be careful not the midline of the nose or the lip but the midlineof the FACE , we place a ruler in the midline of the patient's face & we

try to find the centre of the face because the patient's face is

asymmetrical; the nose is asymmetric, the lip & the frenum asymmetric.

So we try to find the centre of the face.

b. Canine lines: which suppose to be on the distal of the canine fromone distal of the canine to the other distal of the canine & this is done

using three or four methods:

1- while the lips are relaxed we use a relatively sharp instrument and we

mark the canine lines at the angle of the mouth ( distal of the canine is

located at the angle of the mouth).

take a line from the inner canthus of the eye to the outer ala of the nose-2

and hopefully should coincides with the angle of the mouth

anguagetake a line straight down from the pupil of the eye. In English l-3

the canine is known as EYE 2.

take a line straight down from the side ala of the nose & you will notice-4

that this line is further in from the other references. This method gives us the

tip of the canine not the distal of it so you need to add 3 mm to our

measurement.

, we want to see how much"High Smile LineWe also need to mark the "-

of the patient's teeth appear when he smiles because we don't want to see the

gums while the patient smiles. We only want to see two third to three

quarters of the patient's teeth .


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- Now after completing these measurement we want to know the orientation

or the distance between the upper & the lower arches. So we need a

reference: we can use the columella of the nose to the lower of the chin, we

can use the upper lip. But we are looking for a point which doesn't move.

We mark these point and then we do our measurement.

- We want to measure the distance between the lower & upper jaw while the

person closes his teeth. But the patient doesn't have a teeth so how to make

this measurement?? We take advantage of a measurement which it's close to

it which is called " the physiological rest position" or "vertical dimension

at rest". All of us when we're relaxed the lower jaw is hanging from the

upper in tension & pull down by gravity. So there is a space between the

teeth we call it " interocclusal distance" , "interocclusalclearance" , "freeway space". It's usually 2-4 mm or 1-9 mm in rare cases. We give it an

avarage of 3 mm.

NOW: we end up with this relationship :

VDR = VDO + FWS

- Since I know that this equation is correct before & after extraction because

VDR stays the same before & after . so all I do is measure VDR and

subtract FWS from it & it will give me VDO.

- So what I do is to mark a point at the tip on the nose and the tip of the chin

and measure the VDR and I place a ruler and mark a second point and call

it VDO.

- After this I put the lower wax rim in the patient's mouth and I measure

VDW (vertical dimension of the wax rim). Sometimes the patient's mouth

will be larger than VDR, sometimes smaller, because the measurement is

made according to an average. So I have to modify the wax to make VDW

the same as VDO.

the VDR) ??measureNow how to make the patient rest ( how to-

hair. And then we take theup right on the ccomfortablynt sitsMake the patie-1

patient unaware and measure VDR. This is one of the best technique

emost comfortable position when hYou can also ask the patient to tell you his-2

closes but this is less accurate.


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" sound gives us the correct VDR. Make theM, "techniqueUsing the phonetic-3

patient say "mmmmmmm..". it's helpful but not the best.

4- Facial expression, if the muscles of the face are stretched or too tight. Then I

know it's too long. One muscle which is nice to look at & has not too much facialhair is the Mentalis M. this muscle is active when the vertical dimension is too

long. So if U see it contracted then the vertical dimension is too much.

Anatomic land marks, we can use the angle of the mouth & two third of the-5

retromolar pad to determine that the lower wax rim hight is correct.

nt in the muscles. The corrects the elctric movememeasureElectromyography,-6

vertical dimension will give us the best amount of muscular activity at this point.

It's very accurate but not practical.

and swallow. The starting point for the mandiblesMake the patient wet their lip-7

which brings it back to the right position is the "Swallowing"

- We usually use two or three technique to measure the VDR

- Make sure that the patient is in the right posture, lying down or supporting his

head by the chair will give us an incorrect measurement.

- in measuring the points, you can use a calipers, dividers, piece of wax, tongue(blade) depressor, and willis gauge which composed of two parts one goes under

the nose the other goes under the chin which is the mobile part of the instrument.

Now how to know that VDR , VDO are correct ??-

There are many check that we do, the first one is:-

mm so we give the patient 3: we said that the FWS is about 3Phonetic check-

mm. when he talks & the teeth hit each other I know they don't have enough FWS. You should know that there are specific sounds make the teeth very close to each

other but they don't touch. These sounds are "S" , "Ch" , "J" and sometimes "Z".

usually what we do is to tell the patient to say 66 or count from 60 to 70 and if the

wax rims touch, so that 3mm isn't enough so I have to remove more wax from the

lower rim. Sometimes I need to add more wax if it's more than 3 or 4 mm.

plane in the lower arch if it's: we know that the ideal occlusalAnatomic check-

adjusted correctly, the wax rim will be parallel to the residual ridge. Also

posteriorly the wax rim will be at a level between half to two third the hight of


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retromolar pad on the cast. Anteriorly we expect that the side of the wax rim are

level with the angle of the mouth or level with the lower lip. If we ask the patient

to open his mouth, the tongue will be devided into upper half ( dorsum) and lower

half (ventral) by the wax rim. So if the tongue doesn't appear too much or they are

at the same level the wax rim is too high. But if the tongue is showing too much

the wax rim is too short.

>>> What happens if we change the vertical dimension or we didn't give the

patient the right vertical dimension and give him too high vertical

dimension??

- It will cause changes in the patient's face. It might cause pain in the TMJ,

instability in the dentures, Atrophy (bone resorption) to the residual ridge, pain

underneath the dentures. So it's not acceptable.

>>> What will happen if we do the opposite ( give the patient a small vertical

dimension) ??

- This cause similar problems, even the TMJ cannot support the muscles correctly

so the muscles cannot contract enough for the patient to chew in a comfortable

position. FaciallyAesthetically- the patient isn't in a good state because he'll

look older, so what's the point in making denture without restoring functional &

aesthetic & phonetic.

- A student asked: if the patient was having a class 2 or class 3 before teeth

extraction like having retruded mandible or protruded mandible, do I have to

make the denture the same as the teeth??

- Answer: I try my best to get them to class 1, but sometimes because the

bone is far away I can't do this, so I try to get it back to where it was.

DIMENSIONHORIZONTAL

- The relationship between the upper & lower jaw when the teeth are present

".Maximum Intercuspation" or "Centric Occlusionis called "

Researchers found out that "centric occlusion " & "centric relation" are very

close to each other.


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- All of U now if you close your teeth together now.. You will be in the

centric occlusion or maximum intercuspation. If you push your mandible

further backward, in most people the mandible can go 1 to 2 mm, this

position with mandible further behind is called "Centric Relation",

mandible is in most posterior position.

- This centric relation is important for you as a dentist because the patient

comes to you without teeth so when you ask him to close down, the teeth

can't come together, you don't know where to put his mandible.

- In centric relation tha Mandible will be in the most retruded or posterior

position. This means that the Condyle will be in the most superior-

anterior position in the glenoid fossa. This position is repeatable because

it's a bone to bone position not tooth to tooth. That means I'm depending on

the joint not on the teeth. And it's correct if the vertical dimension is correct.

So first I have to adjust the vertical dimension then I try to find the

horizontal relationship.

- Now how to make the relation in the patient's mouth??

- First I ask the patient to close in centric relation and I put a material

between the upper and lower rims, I use a bite registeration material or

centric relation registration material. These materials are similar with

impression material but they set faster. Because with impression material I

want to register the patient mouth and do border molding. But in centric

relation patient without teeth they slight they don't have one position and

this gives us inaccurate record, so I want it to set fast.

- So we can use special type of wax called " Alu wax" which include fine

aluminum metal powder in it. This allow us to heat it very quickly and cool

down very quickly because wax isn't a good thermal conductor but when

you use metal in it it'll transmit heat in and out very quickly. The wax has a

green metallic color because of the aluminum powder in it. In order for the

top of the wax rims to meet we have to put notches in the upper wax rim.

Then we put the soft wax on the lower one and ask the patient to close. The

soft wax will go inside the notches and when it cools down I'll have

something like Lego, the two pieces will fit together.


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- We can use impression material like silicon material but they are more

rigid and should set very fast usually 1 or 1.5 mins. Here I squeeze the

silicon between the upper and the lower then it will go inside the notches, I

can also make notches in the lower rim.

- We can use special type of ZOE paste which sets fast (1- 1.5 mins).

to close in the right position ( centricpatientHow do I get the-

relation)??

- If I push the mandible backward the protective mechanism for the patient

is to bring it forward. We should make the patent relax and trust us, this is

called "Neuromuscular release". The thing I do is bimanual palpation, I

put a thumb on each side of the baseplate, then I ask the patient to open and

close gently when I feel that he trusts me that the jaw is loose, I ask him to

open and close on the soft material and he'll close in the relaxed hinging

position. >.

- When the patient opens and closes about 5 mm the condyle will only

rotate, if the patient opens a lot the condyle will come down on the articular

eminence and now I don't have centric relation. So I ask him to open only

about 0.5 cm and make him feel relaxed and I'm not going to hurt him.

When you will feel the jaw is loose or relaxed you put the material and ask

the patient to close.

- The other technique which is more complicated is using a special type of

marker called " Gothic arch tracing ". you will learn about it later on.

FACE BOW RECORD

ionship thatTransfers the maxillary arch to the articulator in the same relat-

it has with the skull.

- I need something that gives us the relation between the upper jaw and the

rest of the skull. These things are: Terminal hinge axis which runs through

the TMJ, Frankfurt horizontal plane.


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- The face bow is a device which records the relationship between the

maxillary arch and either the terminal hinge axis, the base of the skull or the

frankfurt horizontal plane.

-To understand how s face bow works you need to understand how an

articulator works. In the articulator the upper part opens and the lower stays

stable, this is the reverse of the normal. We want to put the casts in the

articulator the same way that the teeth were in the patient's mouth.

ARTICULATORS

- Articulators come in different types, we have classification; some we can

change the angulation on some we can't:

1- Non-adjustable articulator2- Seme-adjustable articulator3- Fully-adjustable articulator

-The articulator that you use is called " average value non-

. This means that the articulator looks like"adjustable articulator

the patient's head but you can't change the angle of the condyle. You

can't change the angle of the overjet and overbite. It's an average

setting.

- Some other types of articulators allow us to change these settings,

they are more expensive and more complicated. We have fully

adjustable articulator which helps us to recreate the shape of the

condyle perfectly even the distance between the condyles we can

adjust it.

-In your articulator we can't use the face bow to transfer the records,

you have to use an average measurement.


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Back to the Face Bow:

- The face bow is used to transfer the relationship between the

maxilla and the base of the skull. It comes in two basic types:

1- Arbitary face bow2- Kinematic face bow

- The aim of the face bow is to find the three points which represent the

Frankfurt horizontal plane.

are: terminal hinge axis, the TMJ on both side. Orposterior pointsThe-

two close points which are : external auditory meatus or the ear.

is usually the inferior margin of the orbit.anterior referenceThe-

- Articulators which can locate the exact position of terminal hinge axis are

". This ( kinematic) isKinematic or actual hinge axis Face Bowcalled "

used for fully-adjustable articulators.

Arbitary Facethe exact position are called "can't locateArticulators which-

bow".

- They are things which we try to locate by estimation based on accurate

scientific information. So I try to locate TMJ and if I'm within 1cm radius

adjustable-semiwhere it is, it's good enough. This is usually forof

articulators.

- Arbitary face bow, there are two types: on of them uses the TMJ the

other uses the ear.

1- Facia bow : the one which uses the skin or the TMJ.

2- Ear bow : the one which uses the ear.

- So we place the face bow, we have a relator on the eye, a relator on the

TMJ and a fork inside the patient's mouth. The fork will relate the teeth to

the joints, the joints will relate it to the bow and the bow will relate it to

the Frankfurt horizontal plane.


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TEETH SELECTION

We will be talking about it when we start

setting of teeth

We will talk about it in terms of shade , shape and size.

Finished..Alhamdulellah

- Important note about the exam : the exam will be online multiple

choice and written. The whole exam will be in the computer labs

(10H's)

- Written means: match, list, fill in the blank, define and short essay.

Short essay in English language means: any answer which fills a

paragraph (6 10 ) lines. So study well for written exam.

- The material comes from : 15% theoretical from the book, 10 %

lab.

- In the book you should study the whole 13 & 14 chapters, the

doctor will tell us the pages that we should study from chapters 15 &

16 .Done by: AYAH M. Tareef

The thing always happens that you really believe in; and the belief in a

thing makes it happen.

Frank Loyd Wright

jaw relation record ,lec 6

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