Class III Composite Restoration


Uploaded by UMichDent on 28.05.2009

Transcript:
Welcome to the University of Michigan Dentistry Podcast Series promoting oral health care
worldwide.
We will be doing a class III composite restoration. First of all, we will inspect the lesion with
the mirror to find the exact extent of it in the mouth. If you notice you can see a
grayish area, a grayish tan area, and we're outlining it with the explorer.
Then we will check occlusion on this case. The occlusion is very important to us of course
in any restoration. First of all, check it without any articulating paper and observe
where the teeth strike. Then with articulating paper have the patient close their mouth several
times and then again with a mirror we will check to see where the contact point is in
relationship to the carious lesion. We see here that it is incisal to our lesion.
The next step then will be to look at the X-ray again to see just how large this lesion
is. If you notice the extent here as we come in the dental-enamel junction is broken. We
go down incisally, now actually toward the pulp and notice as it goes to the cervical,
and then back up through the dental-enamel junction.
After completion of the isolation of the tooth with rubber dam, saliva injector and so on,
we will now be ready for our cavity preparation. This is a one-half round bur in the straight,
in the high-speed fan piece. You will notice this: the relationship of this half-round
in size to the carious lesion.
As we point out here this is the extent, again, of the carious lesion with the bur.
The actual cavity preparation that we're interested is here. Notice the lingual opening. Cavosurface
margins have no bevels. As we look at it interproximally we notice the extent of the preparation drops
toward the incisal, curves with the labial, and drops again to the cervical and then come
out to the cavosurface margin on the lingual. If you notice the retention grooves in the
incisal, cervical, and labial. We will now start with a half-round bur. But before we
start I'd like to compare a number two bur with it. Many dentists wish to use a number
two but look at the difference in the size. And as we look back and remember what our
X-rays showed. Now if you notice the first penetration point is just inside the dental-enamel
junction or the marginal ridge. It's a pendulating motion, pendulating motion on and off the
tubes. Pendulating if you notice a piece of tooth flew out there and that will happen
when you go through into the carious lesion.
We're going cervically and incisally with that pendulating motion again. This is what
produces the retentive form that I showed you on the original model.
Now it is well to stop once in a while and look, dry it out and look at what you have
done. We're now drying it out. If you notice now there is decalcification still in the
labial portion on this preparation but we are cutting a normal situation. If you look
closely you can see that there is stain which is possible. Carious lesion still on the actual
wall but we're paying no attention to it. We're going in now and forming what we would
call an ideal cavity preparation. This in itself will give us a convenience form and
access to remove the rest of the carious lesion.
We've decided that there still is that bit of decalcified enamel and also some caries
in the dental-enamel junction so we're back in removing this. We will not use the high
speed bur to remove caries beyond the normal depth of a cavity preparation. Notice with
this arrow we are pointing out again decalcification of the labial and this is of extreme importance
to us because it leaves us with a faulty margin if we do not remove it. Looking against the
actual wall you will see there is a quite a bit of carious lesion remaining. Now with
the conventional speed and a number two round bur now notice the difference in the size
of the bur. We will come in at a conventional, with conventional speed and slowly remove
the rest of the carious lesion. Remembering we have arrived at what we think is a normal
cavity preparation. Light touch, relatively high speed with this conventional speed. Again
on and off the tooth. We do not hold it on the tooth constantly. Notice that motion.
It's of extreme importance in any cavity preparation.
Now a little water and we'll rinse it. Dry it out gently. Do not overdry or dehydrate
the dentin. Now checking with an explorer. Notice we're picking out little bits of debris.
We're checking into the incisal. Now the cervical to see whether or not that lesion is removed.
We've decided that it's stuck a little toward the cervical axial. And again we're still
after that little bit of decalcified enamel. It's of extreme importance to us.
Notice that the outline form is still the same that we started with. The actual wall
is deeper. Now we're in with a hoe that we'll sharpen up that labial wall and the incisal
wall and the cervical using the hoe.
Scrapping motion.
The straight fissure bur, a 55, or a 56, is now utilized. Using this bur we'll only cut
enamel with it. This is very important. Only enamel. This does not cut against the axial
wall, the dentin at all. Just into the enamel itself. This smoothes it off, it gives us
a cavosurface margin that comes at 90 degrees with the tooth. Then you will bring the bur
out toward the lingual and smoothing off that margin as much as possible. Rinse it off and
examine again. If you will note there is still some carious lesion against the axial wall.
This is what we're trying to reproduce now. The number two model that we have given you.
If you will look at it, you will see the retentive form as it goes toward the labial, cervical
and incisal extensions. We have not placed any tension in our cavity preparation in the
axial walls.
Now with the final caries removal, with this angle you can see there is still a carious
lesion remaining on the axial wall. We will take a spoon excavator and with gentle pressure
you will notice here we can peel some of this out. This is sometimes sufficient to remove
all of it. It's often a good time though to take at conventional speed a number two or
a number four round bur depending upon the size of the lesion and gently, with a high
speed and a gentle touch, remove the remaining carious lesion.
The cavity preparation is now ready for its refinement and retention. We first of all
check to see that there is no carious lesion remaining. Check your dental-enamel junctions
very thoroughly with an explorer and also by inspection. Now with a half-round bur or
a quarter-round in some places, we will now start our retentive groove. We will be, the
retentive groove is the slightest, in the incisal, it gets a little larger in the labial
portion and then becomes rather prominent at the cervical. There are times in cavity
preparations of four composite class III that you can get retention only in the cervical
and not the labial or incisal depending upon the thickness of the tooth that remains in
those areas. We must not undermine enamel to gain our retention. Now our final refinement
of this preparation is done again with a hoe. If you notice the look of this enamel it's
beautifully sharp. There's no decalcification left on the margins. We're using the hoe on
the end to scrape the labial and then come down to the incisal. Notice that.
Rinse off your debris. You cannot see into a cavity that is filled with debris.
Notice again now the cavosurface margin is of extreme importance. Very smooth. Coming
at right angles, no bevels and then out to the labial wall how smooth this wall is. We
cannot have a smooth preparation, finished preparation without starting with a smooth
cavity preparation.
This is of course one of the most important steps in our whole procedure. This preparation
as I say relates to your number two, that you have, that you have at your desk.
We will use Cavitec which is a zinc oxide eugenol preparation to place against the deepened
portion of the axial wall. We are hoping then that the zinc oxide eugenol will be an obtundant
for that pulp.
You've all mixed Cavitec as we do here very quickly. Very smoothly, very simple to use.
And small amounts are used. Please note this. We are going to form our pulpal protection
cement bases in line, or take the exact shape of the axial wall as it is. We use here the
back, the convex surface of a small spoon, a 17 or you can use a small ball burnisher
but note now it's just touched against the axial wall. A thin film. This is simply to
reduce the inflammation of the pulp. Notice we're going to cover the entire axial wall
but only on dentin. After about 30 seconds you can use a cavity liner such as Copalite
that you have. Now we have to be extremely careful that no Copalite comes in contact
with the cavosurface margins or any of the enamel really in this preparation but this
is covered over the Cavitec and any dentin that still might be exposed. Keeping it from,
if you notice here, keeping it from the enamel walls. We're mixing zinc phosphate cement
primary and secondary and while the mixing of the cement is going on or if you're doing
it yourself before you start mixing you take a hole and go around all of the margins. Notice
this. Just in case any of that cavity liner had touched them. That will remove any of
the cavity liner. Cavity liner is not compatible with a composite. But we're using it here
as an added protection against the acid of the zinc phosphate cement that we're placing.
Another thing that you should remember while we're doing this is that composites should
not be placed against a zinc oxide preparation.
Zinc phosphate mixed in the regular way. A primary and a secondary mix. Now we're checking
for the primary. Not quite ready. So we add a little powder. Remember when you mix zinc
phosphate cement you are mixing to a consistency. Not just the amount that you put out. Each
day it will vary a little bit. So you mix to a consistency. Should draw up about an
inch. There. Or an inch and a half. A little bit more now will make it just right.
Draws up about an inch, an inch and a half and then breaks off that means that the primary
consistency is just right.
You note now that the operator picks up on the point of a cow horn explorer. Notice how
small that is. And he is going to touch some retentive dots into the preparation, on the
axial wall, but away from the pulp as much as possible. You can see the two, cervically
and incisally. In the meantime, the zinc phosphate cement is being mixed to a very heavy consistency
that you can roll in your fingers and it will not stick to your fingers or the instruments.
This is again rolled in powder, the powder is zinc oxide which is good for the tooth
and the liquid of course is a phosphoric acid. Now with the back of the same spoon that you
used for the Cavitec, you can place a small amount and it will cover this wall contouring
it to the area that was remaining from removing of the carious lesion. Notice the small amount.
Notice the small amount. This is of extreme importance. Put it in and gently tap it and
burnish it to place. And if you mixed it correctly, this is all the time that it takes to place.
Not on any enamel. Not on any enamel. If you notice it, like there was a little piece on
the enamel wall then just go back in with your instrument and pop it out and keep it
out of your retentive groove also. If you look closely you can see the retentive groove
and the labial where we're pointing is very clean and out the incisal. Now it shows there
was a spot so out it comes. So take your explorer and just check. Now in the cervical. Maybe
a tiny spot but much. Notice the contour of it, it is not built out to replace the lost
dentin.
Matrix replacement. The matrix of course is of extreme importance because this really
is the beginning of the finishing of your preparation. Now on your model we have a curved
matrix. We will pretest the matrix in the mouth. We'll show you that in just a moment.
But note how they pull this matrix. You will place it on the tooth and you will put the
pressure on the lingual or labial opening whichever you have and then pull the strip.
Now note when we pretest so that we know how this contours to the tooth itself. Now as
we pull it this way –there!— can you see now that there is a good cervical adaptation.
We do wedge these preparations. The wedge does two things really. It'll sometimes help
maintain the strip for you and we use a soft Stim-U-dent wedge. The second thing that it
does of course is give you a good cervical adaptation. So now we will pretest this wedge.
We want to see just where it will go. Once you mix your materials you do not have time
to do any guessing or trying, everything, you have to know exactly what to do as you
place the material. We don't need the full length of that and we notice that as we placed
it into the preparation or beneath it at the cervical, it was a little too high. This would
result in a concavity of our preparation at the cervical. Which you know of course would
give us a gingival problem and also have a good place for plague and food particles to
catch and thus recurrent decay. Now that cervical, or wedge, is very nice at the cervical.
Back goes the strip. We know now how we're gonna adapt this strip. We place it in place
before we start mixing or getting anything out on the pads. We want that in place but
the wedge is removed.
In the manipulation of the materials and placement, we will use, in placement especially, we will
be using a Teflon, a premier Teflon instrument. It is a flat-bladed instrument on both ends
and it is used to burnish the material into place. Then we have a carrier for the composite
itself. It consists of, sort of a barrel and a plunger and then it has a disposable plastic
tip which has its own little plunger to go into it. This plastic tip will be filled with
material, the plunger tip placed in it such as you're seeing here and then that will be
placed into the syringe.
We're using a toupee system here in which we will use equal amounts of the catalyst
and the universal paste.
This toupee system happens to have tints. Now there are many times when you do need
tints and we will have them out in the dispensing area for you. The one thing to remember about
using tints is that you have to use a tiny amount and it would be well to mix a little
bit and place a tint so that you know what you are doing. If you notice the spatula is
square on the right end and rounded on the left end. This is so you will use one end
in the catalyst and one end in the universal paste. You cannot combine these two with any
amounts or the entire mix, or the entire batch of materials you have will be spoiled. So
in the catalyst we use the curved or the round, 'C' for 'C'.
And of course this spatula is disposable. You use it only the once. Small amounts taken
out and will be dispensed. It's a very expensive material and you do not need a lot of it to
fill most of our preparations. With this paste system we now turn the spatula and we'll take
out the universal paste but we use equal amounts of each. A very simple method, a very simple
method of mixing. We are stirring this as you notice we stirred the catalyst and now
we stir the universal paste. Some of the manufacturers say this is not necessary that it's homogenized
but we feel we get better results if every day at least these are stirred. Now the ladies
in the dispensing clinic will take care of this for you. And they will dispense it on
a pad such as this for you. Now we are ready to mix. It's a matter of putting the two of
them together for 20 seconds. Mixing, padding, keeping it in a small area because you have
a small amount.
It will become one color. They were very close to begin with so you have to watch this and
it is best to time it. Now this is transferred to the small, disposable, plastic tube. Right
from the spatula. The plastic insert is now placed in here and pressed just even with
the orifice. Now it is placed into the syringe.
Into the syringe and a little pressure is placed on the handle to squirt out some of
the material. There. You see the material come out.
Now it is placed into the furthest point of the cavity preparation. Very important. Keeping
it in contact with tooth structure and squirting and withdrawing at the same time that you
are squirting. You have to overfill but do not overfill. Then you saw the Teflon instrument
come in and wipe off the access. And if you notice now the thumb is placed over the lingual
opening and it is pulled to the labial and the wedge is placed in with pressure.
After five minutes, the wedge is removed. That is five minutes from the time you start
mixing. The wedge is removed and the matrix chip is removed. We now wait another five
minutes before we will actively start the finishing. It is well to look at this preparation
and see that we do have it filled completely.
The finishing procedure as I mentioned before actually starts with your filling material,
when you're filling the tooth and also with the adaptation of the matrix but now we will
go into the final finishing. On the left you see a 12 blade, a very sharp curved blade
that you have in your kits on the right with a Wedelstaedt chisel. Now as we pass across
these stones, there's the green stone round and carrot-shaped, the white Arkansas point,
round and carrot-shaped. And the 7901 bur, a Midwest jet bur, for finishing. If you use
a green bur or a green stone rather you have to follow that area with a white Arkansas
point and the 7901. Now at the end we see a mandrill or our sandpapered disks. These
are waterproof disks. And the one on the left of course is fine, the one on the right is
coarse. And we use the K-Y sterile lubricant jelly, water soluble for our polishing with
the disks.
There is, oh there is a strip as you can see at the bottom of this sterile lubricant tube.
It has a coarse grip on the right, an open space in the middle, and a finer grit on the
left.
In this case, we're going to start by using a round, green stone on the lingual portion
because we did have a bit of excess which most of us will have as we fill these.
This again is a light touch, relatively high speed but very light we want to reduce the
friction and the heat generated as much as possible.
You notice the on and off motion. This is true of nearly everything that we do in dentistry
with a rotating instrument. On and off. Not holding it in contact with the material or
the tooth at all times. Taking off the excess with the green stone. You're starting now
to see I think the cavity outline. This is the 12-blade that we mentioned before. A little
dryness shows you just where that is. Now this instrument is used to score the material
away from the margin. Do not try to score this right at the margin or you will have
a void in your margin and then after scoring it is lifted out as you could see. Now the
carrot-shaped stone is run along the marginal ridge to develop the outer incline of the
marginal ridge and also at the cervical to take off any of the excess we might have.
It is very important for you in the finishing procedure to not touch onto the enamel, if
possible. We're all going to touch it a little as we do it but keep that to a very, very
minimum because these stones will roughen it.
Now we check. We notice there's a little heaviness here and there. The white Arkansas point is
now brought into play and we will go over any area that has been touched which in this
case has been the entire lingual portion on the preparation. Anything that has been touched
by the green stone must now be touched by the white stone or it will leave a roughness.
Roughness of course will not be comfortable to the patient and it will also have a tendency
to collect plague and have recurrent caries more readily.
Carrot-shaped stone brought into play. This can also it depends on the contour of the
tooth how you use these stones. This again is mainly for the contouring of that outer
incline of the marginal ridge. Now look closely at the cervical. You'll see we still have
a little excess but at this point with, it's rather a spade-shaped central so that we were
able to get our carrot-shaped stone in on the entire surface which gives us a very beautiful
contour of the tooth itself. Now he's going at the cervical slightly.
Check again. Always inspect. Always keep checking. Don't overdo. One of our problems when we're
first doing these things is that we have a tendency to over finish.
Now this 7901 bur, it's a 12-bladed carbide bur. Run at conventional speed and very light
touch. Very light touch. You'll notice we're at the cervical now. Being so careful not
to touch the cervical enamel.
The K-Y jelly is now placed over the restoration and we can come back. We noticed that there
were a few little grooves placed on that lingual surface so we will come back with a white
Arkansas point, the very fine one, with the lubricant and just gently touch again. Patient's
tongues are very susceptible to any change and they'll often say to you, "Doc that feels
rough." So after we get the rubber dam off this is a final check really what we can do.
Now with the disks we will break the back of the disk on our fingernail just gently
press it against the back of the disk against your fingernail and press and it loosens that
up for us so that we do not cut ridges into our restoration.
I think you can see the cavity outline, now the cavity preparation outline and how smooth
it really is. It turned out very nicely but we will check again. There is really no indication
when we are going from tooth to restoration or from restoration to tooth.
We have to remember that this did have a slight tendency to come out toward the labial so
now we will check the labial portion on this tooth. If you look at it from the labial you
will see that there is a slight bit of excess at the cervical and even down to the incisal
a little.
So with our 12-blade we will now trim. We will trim that labial area, cutting with the
blade touching the tooth and the restorative material. Now checking again. Now placing
our lubricant because we will put a little disk in there just to smooth up what we have
done and this fine waterproof disk gives us a very nice finish.
I think you can see the cervical now. You can see the labial extension of it. Look very
closely.
Checking once more because checking you can't do it too often. You have to have a feel and
know what you're look for.
Now the strip that you saw earlier. The coarse side is on my, on the left but there is a
placement no grip on it in the middle so that we do not touch contact. Now notice that was
placed through and then pulled and rubbed against the cervical. You place your thumb
or finger against the tooth and the strip on the lingual.
And then pull it out and that finishes the cervical down very beautifully for you. Keeping
contact with the finger or thumb against the lingual. Rinse it off and check.
And now we are ready to remove the rubber dam because we still have to check occlusion
and have the patient feel the restoration with their tongue.
With the rubber dam removed, before we put carbon paper on anything put your finger on
the tooth you've been working on and have the patient close. You can sometimes feel
a jar or a knot. This is a good indication. Then the final check with the articulating
paper and as you notice the lowers you can two or three places it's marked now look back
on, into the mirror, and you will see we have the contact to incisal to the restoration
where it was in the beginning.
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