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Template denture & Acrylic RPD

Ammar Aldawoodyeh

Khalid Al-Hamad

17-11-2013

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-Today we'll be talking about 2 topics, template denture and acrylic RPD.

- you don't have to go back to template denture slides as I made sure to include all the information in

the script, however RPD slides were not available so I had so do the script without them.

Template denture:

Let's consider this scenario, if you had a patient who have a denture, any you have no

complaint with it, and you have judged that the patient needs another copy, do you go

for the same conventional technique (primary impression, secondary, JRR, try-in and

insertion)?

No! There is another technique to copy the denture which is template technique (copy

denture technique or replica denture).

Another scenario is that the patient have a complete denture for a long period of time,

and when you ask him why do you want to replace it he would say that the teeth are

worn done and he has no other problems with this CD, this is a tricky situation,

because if you go and check it in reality, you may find that the denture is not very

stable, but the patient is not bothered with this, why is that?

Because the patient has developed neuromuscular control for this particular denture

with time, so he knows how to keep this denture in place, through the action of

muscles (neuromuscular control) which works on the polished surface, and the

muscles have adapted to the shape of the polished surface, elderly patient may never

learn how to control a new denture if the contour (particularly the polished surface) is

different from his old denture!.

Now if you go with the conventional technique for this patient, you'll end up with a

denture which have different polished surface than the old denture, so even if the

fitting surface and the occlusal surface are good or excellent, the patient won't be able

to manipulate this new polished surface, because the technician won't reproduce the

Remember: we have 3 surfaces for the denture:

1-Fitting surface (the inside of the dentures): is the part of the denture on which

the denture set, it's in contact with the tissues (mucosa), which is related to your

impression.

2- Occlusal surface: it's the occlusal surface of the teeth, but not the whole teeth,

just its occlusal part.

3- Polished surface: which is represented by the buccal and the lingual sides of

teeth with the flanges of the denture, with the palatal side for the upper.

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exact same polished surface as the old one, and the patient will have a problem with

that.

The technique which we're going to talk about today would make you able of copying

particular surfaces of the denture.

So the aim now is to transfer the contour from old to new dentures for

maintenance of neuromuscular control, which is the main indication for this

technique.

Scenarios

As we said the main indication for copy denture technique is when you have a denture

of poor fitting and occlusal surfaces but we need to keep the polished surface of the

old denture because the patient adapted to it and it's still intact, the fitting surface may

need changing because of bone resorption, and the occlusal surface may need it

because of wear.

Another scenarios is demonstrated in the table below

You are not required to remember the scenario category it's just used here for

explanation purposes.

So for category (A) the patient just wants another copy and he is not complaining from

any problem, you would use the technique that we'll talk about just in minutes.

For category (B) the problem is on the impression surface (the fitting surface) the

solution will be relining and rebasing which is technique in which we adjust just the

fitting surface (we'll talk about it in another lecture).

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Category (C) we have problem with the occlusal surface only, which may mean that

the vertical dimension or the RCP (retruded condylar position) is wrong, here you

don't need to copy the denture, you can do selective grinding or trim the lower teeth or

you may need to put the lower wax rim again, maybe reregister and re-try-in and re-

insertion again.

(D) is the scenario that we have already talked about, in which the fitting and the

occlusal surfaces are poor and the polished surface is good, so I can use coping

technique to copy the polished surface into my new CD.

(E) is when the polished surface is poor and other surfaces are good, in this case you

can't use copy technique, because this technique mainly copy the polished surface.

(F) is when the patient comes to you with a bag of dentures, and all of them are bad

but one of them is just acceptable, you may be suspicious that the patient is over

exaggerated, because when you check the denture you're not sure what is the problem,

in this situation it's more logical to start with partial success than to start from a

complete failure. now if you try to make changes on his current acceptable denture,

you're work may not be very successful, and the patient will say "you have ruined the

only denture which I consider it acceptable, I want you to return it as it was!!", that's

why it's wise to copy this partially successful denture and work on its copy, while the

original one you leave it and do not modify it at all.

(G) is almost the same as (D) but the difference is that in (D) you are sure that the

occlusal surface and the fitting surface are poor but in (G) you are not sure about them,

that's what the question mark mean, so you are just sure that the polished surface is

good, so what you do is to start gradually, for example you find a deficiency in the

fitting surface so you make relining, occlusal surface you did a build-up for it, tell the

patient is satisfied with this denture, what would the denture look like? It would be

like a patch work ( عمرق ّ ), so you make a copy to get rid of this patching.

(H) is when the denture is good but patient was using wrong type of cleansers, so there

is a deterioration in the material of the denture itself, but otherwise the denture was

excellent, so you can copy the denture so the material will be new.

Summery for the indications:

1- Replication of the denture for spare set.

2- Replacement of the denture with the provision of:

A- New impression surface and/or

B- New occlusal surface and/or

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C- Slight modification of the VD.

3- Replacement of dentures whose base material has deteriorated.

4- Production of complete denture that can be progressively modified if the patient

capacity to adapt is in doubt. (Slight increase in the VD or if the cause of the

complaint is not a clear/denture collectors). Once a satisfactory appliance has

been achieved, it can be copied to produce a definitive denture.

The technique

It's an easy technique, but you won't do it during your undergraduate training,

although there are situations in which the copy technique is the best technique.

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Clinic 1: History and assessment: First you start your clinic with history and

assessment, and you correct what needs correction, like if there is under extension you

add to it using tracing compound.

Then you invest the denture till you sink the edges of the denture (the set material may

be trimmed to the edges of the denture if it covers more than the edges), you can use

just alginate.

Now you are only left with the fitting surface which is not sunk, then you can add

another layer of alginate and close the box.

After that if you open the box and remove the denture, remove the tracing compound

from the denture and return it to the patient, and send the template to the lab.

Lab 1: you'll have a box full of alginate that has an empty space that have the same

shape as the denture. Channels (sprue holes, approximately the diameter of pencil) are

cut in alginate from the most distal surface to the exterior.

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Then you pour wax inside this space just to cover the teeth till the gingival margin.

Then you can pour acrylic through one hole to form the base of the denture (the air

inside the template will escape from the other hole), then the wax and acrylic is

trimmed and smoothened, you'll have a denture like the pic next page:

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You as a dentist just assess the denture and modify and invest the denture it and send it

to the technician, it's the technician job to and pour wax and acrylic.

Clinic 2: you take a finial impression as if you're doing relining technique, using

silicone material is preferred because the template is going to be reinserted in the

mouth, so impression is taken with a light body impression material with a closed

mouth technique on the RCP that you have, then you check the occlusion and you may

modify it until it's good, and you register the desired occlusal relation, and then you

send it to the lab again with specification of the shade and the mould of the teeth.

Lab 2: In the lab they remove the wax teeth (one tooth or two at time) and put acrylic

teeth of the same size instead, this work is done on the RCP and the registration that

you have given to him and with the denture articulated, so the technician is guided by

the same copy that you have sent to him because he has the tooth size and it's position

so he is not changing the polished surface, so the patient won't feel any difference in

the neuromuscular control.

Clinic 3: is the same as try-in stage, their border extension is checked, occlusion, jaw

relation and esthetics are checked, post dam is noted and carved on the upper master

cast.

Lab 3: is flasking and packing as usual denture.

Clinic 4: is insertion

So as a summary: the fitting surface we change it usually with impression, the

occlusal surface we change it with a new registration or selective grinding in patient

mouth, the polished surface I can copy it by the copy technique.

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Acrylic RPD

You are aware now that this denture is different than the cobalt-chromium denture,

this denture is transitional (interim) prosthesis.

This is a quick review for Kennedy classifications.

What is the difference between the acrylic RPD and the cobalt-chromium RPD? They

are different in the framework, and the clasps in the acrylic don't have rests,

reciprocation or guiding planes, so many things are present in the final metal RPD

which is not present in the transitional RPD, but in some scenarios you have to use

transitional one.

There is a slide that represents that are the "costs" that the patient pay if he wear an

acrylic RPD, there will be plaque accumulation, which may cause caries and

inflammation in the gingival, and the patient may be directly traumatized by the

denture or the clasp (which may cause abrasion to the teeth), the denture if not will

fabricated may cause excessive transfer for the load on the teeth or the ridge, and if

there is occlusal errors it may cause tooth mobility and muscle dysfunction or

inflammation to the underlying mucosa, in metal RPD these problems will be at least

less severe than acrylic RPD.

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So why do we need to use such a bad denture? We do it when the patient has to wear

something for a short period of time, like during treatment, or if you are waiting for

something to happen until you can provide your final treatment.

Imagine that we have extracted central and lateral incisor, and we put an implant, and

we are waiting for the gingiva to heal around the implant so we can make final

restoration on the implant, mean what the patient would wear? A final metal RPD?

No!, you can just use acrylic RPD.

Another scenarios is that we are waiting for the gingiva to heal after extraction, or the

patient have perio treatment, or caries treatment, because you know that the prostho is

the last thing to do, so you have to get the perio and the caries (restorative work) done

before providing a final prosthesis, so we can use acrylic RPD so the patient is

stabilized until we can provide the final prosthesis regardless if it's cobalt-chromium,

fixed bridge, implant or whatever.

The teeth may also have tendency to move (especially in younger patients), sometimes

during the period of waiting you don't want the teeth to move around, because we

don't want the things to be more complicated later on, so acrylic RPD can act like a

space maintainer.

To establish occlusal relationship, sometimes you can use the acrylic RPD as a splint

to adjust the occlusal relationship, but in this situation the best case for the RPD when

it's tooth supported, if it's mucosa supported there will be changes in the occlusion and

it will not support the occlusal treatment that you are after.

Sometimes you can use the transitional denture through interim situation, in which the

patient has remaining teeth and they are periodontally involved so you can't use them

as abutments for a final treatment as a cobalt-chromium, actually this teeth may need

extraction but the patient insists to keep them or to slow down the change to

edentulous situation, so you can't go for full clearance and complete denture although

these teeth are going to be extracted in the end, so you make an acrylic RPD to

transform the patient slowly from partially edentulous to complete edentulous

situation, so every time the patient extract a tooth you add a tooth to the RPD till the

patient is completely edentulous you through the RPD and fabricate a CD.

In these scenarios we can't go for cobalt-chromium because it needs rests and guiding

planes which are irreversible changes.

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How many clinical visits for RPD?

It depends on the case, if you have a bounded suddle, a primary impression maybe enough, also if

there are enough teeth in the upper and lower, you can relate the casts without registration so you

don't do it, and if it's posterior I won't need a try-in, so I can go directly to the insertion, so 2 visits

(primary impression then insertion), this is the shortest situation.

Sometimes primary impression maybe enough but you need a registration, but you may not be able

to take it directly because the saddle is slightly long, so you ask for a wax rim, so you'll need a visit

for occlusal registration, and because you did occlusal registration you'll need a try-in visit, then

insertion, so how many visits? 4.

Another scenario is kennedy class 1 (free-end saddle), you make a primary impression and it's not

enough, so you ask for a custom tray to adjust the extensions to the sulcus, and because it's a free-end

most probably you'll need registration, because you can't relate the casts together, so you'll ask for

wax rim, so you have a third visit for JRR, and if you do JRR you better do try-in to assess your

work, then insertion, so 5 visits just lick CD.

So you should by now know when you bring a patient how many visits, if it's kennedy classification

then you are talking about 5 visits, you may sometimes go without try-in and this depends on the

scenario, so minimally 2 visits and maximum of 5 visits.

The Dr mentioned that the survey line represents the height of contour.

The most probably problem to occur is when you try to make fit for acrylic dentures it doesn't fit, as

a clinical hint mostly you have to adjust the acrylic exactly from the area where the clasp is attached

to the acrylic, because it causes jamming in this areas, and also the buccal and the lingual flanges

may contain undercuts, and also the area proximally (between the teeth) in order to avoid this

problem you can make a mild relief for the interproximal area, you can also make relief for anything

beyond the survey line(not too much because it may become very loss) but in the same time

maximum contact in the other areas.

Good luck in the exams ^_^

Done by: Ammar aldawoodyeh