Prosthodontics LAB 6 ,Jaw relation Record ,cont

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Prosthodontics lab 6 part 1. Done by : Enas Y. Salameh

Jaw Relation Record

After we fabricated the Record Block in the previous lab, today we are going to

learn how to make Jaw Relation Record (JRR) / Jaw Registration / Bite

Registration (informal term), which represents the relation between the maxilla to the

mandible, and the maxilla to the rest of the head, the colour/shade of teeth and so on.

This step will be in the CLINIC which will be the last clinic to register the jawsrelations, then we will attach them to the articulator after that we will start to

do setting of teeth.

The Process of attaching the casts to the Articulator is called Mounting usingPlaster.

** The next process after setting of teeth will be wax trying, if everything is ok we

do processing to the dentures (flasking, dewaxing, curing, deflasking polishing)finally we will do the dental Insertion.

Steps of Jaw Relation record:

1) The Vertical Relationship

** Starts first with the maxillary rim THEN the mandibular rim.

A) Maxillary rim:

1) Labial Fullness:You have to check if the lip has enough support from the opposing teeth (wax

rim till this point).


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In right situations the angle between the lip and the columella of the nose

equals to 90 degrees ,if this angle is less than 90 (acute angle ) this means that

it's too prominent ,but if it's greater than 90 this means there is not enough

support (the patient will look older).

If it is too prominent I use my wax knife ,heat it then I reduce the anteriorangulations, but if it's position is backward I add more wax to it until I have

adequate prominence .

2) Buccal Corridor:

(check the contours posteriorly) when the patient

smiles there is a space between the occlusal rims and

the cheek (at the corner of the mouth) at both sides.

If the wax rim is too prominent the teeth will look

as they continue endlessly and the smile will look like a

wall which is not aesthetic.

In Normal smile we see the anterior teeth and the most prominent surfaces of

the premolars and barely you see the first molars, but if the teeth are too prominent

we will see the whole teeth specially if you choose small teeth, therefore we will

remove the excess wax from the side and if the corridor is small we add wax.

3) Length:

It depends on aesthetic (which we will concentrate on it), phonetics and

functions.

At rest position where the mouth is a little bit open normally you will see about

1-2 mm of the incisal edges of the teeth (occlusal rim) below the upper lip.

In Old patient the upper lip will look longer because of the change of the muscletone with time, and the gravity will bring it down, so less teeth will be seen, and

the lower lip will go down too and more teeth will be visible. "The smile line will

go down".However, in younger patients you will see more of teeth.


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The natural length of the lip, if the patient has a long lip we expect to see less of

teeth. So, you have to use your artistic sense to see if the smile looks nice or not.

4) Orientation:The occlusal rim should be parallel to the patient's natural occlusal plane.

All my measurements depends on where the teeth should be, but the problem is

that the patient has No teeth, so I need references or guides that was and still

present in the patient face before and after teeth extraction which are:

- One anterior reference and two posterior references to make the occlusal plane

which are imaginary references.

1- ** The anterior reference is called Interpupillary line.**The posterior references are called Ala tragus lines.

Anteriorly: use a ruler and put it in front of the patient's face and keep moving

it until you find the interpupillary line ,then I put the wax rim in the patient's

mouth and mark the excess points then remove the wax rim and remove these

excesses by a hot plate ,and if it's not enough add wax until you find the right

orientation (parallel to interpupillary line) .

In some cases the eyes are not levelled due to trauma so we use other

references like lower lobes of the ears, but in worst cases where you can't find

any references ask the patient to stand up and look forward , if the wax rim is

parallel to the floor then it's levelled .

Posterior References: Alatragus line, from the lower border of the ala of the

nose to anywhere in the tragus of the ear (tip/middle/lower border).

But as you can't see the wax rim orientation through the patient's head, you

have to use an instrument to find campre's plane (interpupillary +Alatragus

Camper'sPlane


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lines) which is called Fox's Plane. Put this instruments inside the patient's

imouth and put the ruler in front of the eyes, if it's not well oriented I start to

remove the excess from that side .

5) Check:

To see if everything is okay * aesthetically (see if he/she smiles well) we dont

need a gummy smile.

*Phonetically (check the sounds of some letters like (S), (F and V) .

The wax rim should have the same dimension of teeth.

*Functionally

6) Mark the midline:

Which represents the middle of the face not the lips or nose, because people often

have asymmetrical faces, so we use a floss or a ruler to mark it, and we mark the

midline on the occlussal rim where we will start to put teeth on the right and the

left of this line.Then I have to mark the width of the teeth by marking the distal surfaces of

canines by a line that extends from the intercampus of the eye to the outer edge of

the ala of the nose to the occlussal rim on the right and left and the canines will

be determined there. After that ,measure this distance by a flexible ruler which will

help in determining the size of the teeth .Sometimes we take a straight line from

This is the foxs plane instrument Foxs plane used inside the patient

mouth


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the side of the nose to the occlussal rim which will give me the tip of the canine

,this distance is smaller than what I want, so I use a specific equation to find the

right value.

Or you can use the corners of the mouth; when the patients lips are at restplace a lecron carver in the corner of his mouth which will mark the distal

surface of the canine.

The canines is called eye tooth because its located below the pupil of the

eye .

Then I need low and high smile lines, when the patient relaxes draw a curve

line with a lecron carver that represents the position of the lips at rest (low

smile line), then let the patient smile and I draw another line curve (high smile

line) which is important in selecting the length of teeth.

~END OF PART ONE~


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Prosthodontics lab 6 part 2. Done by: Osama Yusuf

Now that we have finished the vertical relation of the maxillary occlussal rim, we

are going to make the same for the mandible.

B)THEMANDIBULARRIM

There is a reference called VerticalDimension ofOcclusion (VDO). It is

a measure I take, which start from the tip of the nose to the chin. This

measure will help me to select how tall the mandibular rim should be.

Unfortunately this reference is gone when there are no teeth present,

meaning this reference is not found on edentulous patients.

Luckily, I have another reference I could use which is not affected by

the presence or absence of teeth. It is called Vertical Dimension at Rest;

(VDR).

This reference is always constant before or after teeth extraction. Most

of us when resting (watching TV, listing to a lecture ...etc) our teeth are

not touching each other; the mandible is hinging a specific distance

below the maxilla with a space between the teeth (Freeway space).

The hinging of the mandible at rest depends on A) Gravity B) the

muscles.

Please take into consideration that VDR measures the space between

the jaws, but Freeway space is between the arches (teeth).


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Asking the patient to sit upright, the lower jaw will relax in a specific

distance between the upper and lower arches. Measuring this distance

will result in a reference that is stable; VDR.

You dont need VDR, you need VDO. You measure VDR because thepatient has no teeth, and then you calculate VDO = VDR3.

The number 3 came from many studies which have concluded that the

freeway space in a huge numbers of patients to be 3-4 mm. Take in mind

in some rear cases this might reach to 9mm.

Now we got the VDO, we have to do a check to make sure that it is correct. We will

do a visualcheck and aPhonetic check

In the patient mouth I should see that the lower wax rim should beleveled with the vermilion border (the red border which is between

the mucosa and the skin )

Wax rim should be leveled with the corner of the mouth by thesides.


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The height of the wax rim should be 2/3 of the height of theretromolar pad

The occlussal rim plane must divide the tongue into an upper half and alower half when the tongue at rest; in other words the occlussal rim plane

must be in the equatorial of the tongue.

We said that there is a natural space between teeth when at rest; we said

it is called freeway space. This space is good, teeth touching each other

always are not good for many things (TMJ, muscles ... etc) even when

talking you dont hear yourself clicking your teeth, and you talksmoothly without your teeth touching.

I have to make a check to make sure that when applying the wax rims to

the patient mouth that when he is talking he is not touching his teeth

together. How to do this?

There are some specific sounds, when pronounced the teeth willbe as

close as possible (try to say Faaa , and try to say Saaah , in

Faa they are not close as in Saaah ). Saah , Chaah are some examples

when the teeth are very close to each otherbut they dont touch.

Asking the patient to count from 60-70 fast, we observe if the wax rims

are touching or not. This is one example for this; there are too many

other tests you can do on your patient. Anything with Shaa and Chaah is

good.

If there is 2 mm between his teeth when he says these words, fantastic.Even if there is 1 mm this is still good, there must not be a contact

between teeth when speaking.


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This space is included within the freeway space, it is called the Closets

speaking Spaceand it is less than the free space (1 mm while freeway is

3 mm).

Now that we have finished the vertical occlussal relationship, logicallywe have to do the 2

ndstep which is the Horizontal relationship

What relates the upper jaw and the lower jaw together? It is the TMJ.

From this I know that my reference for the horizontal relation is the

TMJ, but still the lower jaw can move lots of movement, we need

something accurate which is Centric Relation reference.

We use it to bring the rims together in the horizontal plane, if you didnt

do the horizontal relationship and just inserted the rims in the patients

mouth he could close them many directions each time he close. This is

certainly not good and more importantly not natural.

Centric Relation means the zero point or the middle point. I want themandible to be at the mostposterior position (which is the natural

position of the mandible).

If the lower jaw is in the most posterior position, the condoyle will be

actually on the mostAnterior Superior position in the genloyid fossa.

Keep in mind that the condoyle isbone to bone relationship not tooth to

tooth, because of its bone to bone relation it saves repeatable positions

this is why I use the condoyle as my reference, because it is repeatable

or habitual position. This means when I put the teeth on, the patient will

close and open in the same position. Keep in mind that this will only be

correct if the vertical relation is correct.


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This is the facebow instrument

From all the information above I can say that, the centric position is

when:

The mandible is at the most posterior position There is bone to bone relationship in the TMJ The condoyle is at the most superior anterior position in the genlyoid fossa It is a repeatable/Habitual positionas long as the vertical relation is correct.

Now that we have talked about the vertical and horizontal, the third step is

facebow record.

This step came from the need to know where exactly I put the upper and

lower rims on the articulator. In this step we use another instrument

called Facebow.

Its function is tomeasure the relation between the upper jaw and the rest

of the skull or between the upper jaw and the hinge axis that go through

the TMJ. Keep in mind it is unlink the Foxs plane instrument which

locate (not measure) the occlussal plane. While the facebow relates the

occlussal plane to the base of the skull.


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100 years ago anatomists gathered in Frankfort-Germany and agreed that

the zero reference is called Frankfort Horizontal Plane; it is present on

the patients head as follows: from the inferior margin of the orbit we

mark a point to the external auditory meatus we mark a point. If I drew aline between them while the patient is standing this will give me two

lines. (4 points, 2 for the orbit and 2 auditory meatus = 2 lines). So my

reference for this step is the Frankfort plane.

Keep in mind 3 points are enough to draw this plane (2 auditory meatus

/TMJ and one infraorbtial will make a line).

FH = Frankfort plane


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Although we will not use the Facebow instrument, it is wise to show you

how to use this instrument. It will become handy to learn this now and

be ready to use it in the upcoming years nshallah.


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This step includes choosing the proper teeth, teeth color and other

properties; we will talk about this more in later lectures.

With this we have finished the theory part for this lab. The only thing

left now is the practical part, but before that we will show you the

different parts of the articulator.

You have three types of Articulators,Non-adjustable, Semi-adjustableandFully adjustable. And you also haveaverage value andnon-

average value.

If you look at your Articulator box there is a phrase says AS 5000 which means

your articulator doesnt accept facebow record. But if it were AS 5010 it can

accept facebow record but costs more.


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A very important note you should note, is that the condylar in nature is attached tothe mandible. But in the articulator it is attached to the maxilla ( not like nature ).

A new classification rises with this note, we haveArticulator Condylar orARCON. Which they have their condylar attached to the maxilla.

We haveNon-Articulator Condylar or Non-ARCON, Which have it onmandible.


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The articulators are not always centered by default by the manufacture.

So I need you every time you use yours to make a check on the

following things:

- Open the incisal pen screw, allowing the incisal pen to movefreely. Look at the incisal pen you will see we have three lines

above and then a heavy line and then a three line below. The heavy

line should be leveled with the top of the articulator, after you

adjust it tighten the screw to hold it in the correct place.

- Some of you when opening the condylar screw you will hear aclick. This click is because it is tripped in a wrong position, what

you have to do is using the condylar screws; adjust them by

pushing them in the correct way and then hold them in that place

by tighten the screw.

Angles :In (1) which is the angle of the incisal table laterally

which is 10. And the angle of the incisal table (2)

which is 15. You also have the angle of the condylar

assembly which is 30.


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Keep in mind that each one of you has a different length of wax rims. We wanted

you to be all equal so we didnt do the facebow technique, instead we made a

maxillary jug and a mandibular jug (not sure of the word but it is something jug),Attached them to the rim while working. So you all had the same method of

constricting it. So you are not going to do any of what we disscuesd , but you must

remember it.

Before doing anything we have to bring the cast and make a three retention

notches one labillay and two behind. If you are not sure

where to trim the cast using the bur draw three triangles

and then cut it like the pictures on the right.

After that we will use the jigs (or whatever their name is

look at the last right picture) for the upper and lower.

Remember we dont do this at the clinic it is just a

method to make us all have equal results.

Then we will pour the plaster and we will remove the

excess using the plaster knife until we have a nice clean

looking plaster attached to the cast. We can polish the

surface of the plaster with sandpaper.

We soak the cast for 3-5 min, do you know why?

Because the plaster will not sick to the cast when it is

dry (the thin layer between the cast and the plaster will

become dry because the water moved from the plaster to

the cast). While if we soaked the cast in water we can

start the mounting without any problems.

Done by : Osaka Yusf (yes Ali it is Osaka )

Date post:	07-Apr-2018
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Prosthodontics LAB 6 ,Jaw relation Record ,cont

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