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Introduction to removable partial denture (RPD) course

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					    Introduction to removable partial denture
                  (RPD) course

    Treatment options for partially edentulous
                    patients


Slide 2: Definition of RPD:
RPD it is any prosthesis that replaces one or more, but not all
missing teeth. Or we can say some teeth in partially edentulous
arch. It can be removed from the mouth and replaced at well.
Note: fixed partial denture (FPD) can be called "bridge"…and it
can't be removed.

Slide 3: Types of RPD:
We classify RPD according to support mainly into two types:
1- mucosally supported OR tissue supported.
This type of RPD is mainly composed of acrylic. But, it is
important to know that they aren't supported by the
tissue/mucosa one hundred percent. Example: *some of
mucosally supported RPDs achieve their support by the teeth
also and not only from tissues. (Mainly from the edentulous
area).*another example: some clasps that we use for acrylic
partial denture designed in a way that transfer the load to the
abutment teeth (the remaining teeth).so, again they aren't
mucosally supported 100%.
Most of acrylic RPDs is mainly mucosally supported. They don't
achieve much support from teeth. They are called gummo
strippers (because they compress on gum).and these type of
RPDs sink during function. Acrylic RPD can be used as a final
definitive prosthesis. Since, type of material that we use doesn't
indicate if your prosthesis is provisional or definitive. But, most
of the time acrylic RPDs are provisional (temporary).



                                                                  1
**Acrylic RPDs can have a dual support (i.e. from the tooth
and the tissue).

2- Tooth supported OR tooth-mucosally supported.
This type of RPD is mainly composed of metal.


      Just to refresh your memory       Retention, stability &
                                        support all are applied for
                                        both complete denture and
                                        partial denture.


Definition            Complete denture Partial denture
Support- it is a      Always from the         Can be increased by
characteristic of the tissue                  the remaining teeth
supporting tissue to                          (abutment) & not
withstand the                                 only from the tissue.
functional forces
during mastication.
Retention- it is the  Same as the             Clasps also provide
ability of the        definition              additional retention
prosthesis to resist
dislodgment
Stability-it is the   Same as the             Same as the
ability of the        definition              definition
prosthesis to resist
rotational
movements during
function
In conclusion: The concepts of all these 3 terms are the same in
both complete denture and partial denture.




                                                                  2
For slides (4 to 7): please refer to your slides & see the
pictures.

Slide 4:

Acrylic base
Everything is made of acrylic. The base, the artificial teeth &
the junction between the artificial teeth & the base plate all are
acrylic except the clasps are made of metal.



Metal base
Denture base (called also metal framework) is made of metal
except the artificial teeth & the junction between the artificial
teeth & the metal are made of acrylic.

Slide 5:
This is metal base removable partial denture in maxillary arch.

Slide 6:
This is also another example.

Slide 7: Components of RPD

-Each component will be given in a separate lecture. (Refer to
the slides: these components of metal framework -cobalt
chromium- RPD).




                                                                     3
Slide 8: Indications
What do we mean by indications? It means when do we
prescribe RPD for patients, instead of No treatment or instead of
fixed partial denture or implant????
*Long span edentulous area.
For example: missing 3, 4, 5, 6, & 7. In this case, if we want to
fabricate RPD it will be extended from 8 to the lateral incisor.
But, lateral it is not a good abutment. As a result of that the RPD
should be extended to the central incisor. By this you will end
up with a very long bridge & high chance of complications or
may be failure. So, patients can't afford implant therapy. Here
RPD is highly indicated for long span edentulous areas,
especially when we have multiple edentulous areas. And instead
of having 3 bridges, partial denture will replace all these missing
teeth. And you have noticed that artificial teeth can be on the
right side, left side & anteriorly.

* No abutment tooth posterior to the edentulous area.
For example: if somebody has 6, 7 and 8 are extracted. Can we
construct a bridge? No. So, don't do fixed partial denture with
distal extension except if you have very short distal extension
and good abutment. In this case we have free and saddle.
Therefore the option of fixed RPD is dropped, and the only
options that we have are RPD or implant. For some cases the
implant is not an option. So, we have RPD or no treatment.

Hint: some dentists do extension to the bridge for 6 and 7 areas.
After a few months or may be one year, if you hold the 7 area
you can move the bridge 1 cm buccally and 1 cm lingually. And
you can take out the abutment tooth by your hand without need
to the forceps. (I know it's not clear enough but, this is what the
dr. said!!!!!!!!!).

* reduced periodontal support for remaining teeth.
i.e.: if you have mobile teeth due to periodontal disease. So, how
can you decide which one to extract? According to "Grade of
                                                                  4
mobility". Grade 1 & grade 2 aren't indicated for extraction.
Grade 3(severe mobility) is indicated for extraction.
Furthermore if the tooth can't be retained in good health and the
patient can't do proper brushing around this tooth, then
extraction is indicated. But, if the patient can clean the tooth
properly extraction isn't indicated.
  -Do you think a mobile tooth is a good abutment to construct a
bridge? When you want to fabricate a 3 unit bridge(example:6, 7
 are missing) already the periodontal membrane is reduced for
the teeth. The 5 and 8 gain the forces of the missing teeth in
addition to the forces that applied to them. So, what does this
mean? RPD might be indicated in this case. Especially, acrylic
RPD. If it is metal it might be tooth/tissue supported. And if it is
only tooth supported you can distribute the load on more than 2
teeth by applying rests on all remaining teeth. By this in RPD
you can transmit the forces to more teeth.

* need for cross arch stabilization.
In RPD you can do cross arch stabilization, while bridge is only
on one side.

* Excessive bone loss within the residual ridge.
In case of excessive bone loss Implant is not an option. But,
only when we do bone grafting implant is accepted. Sometimes
the patient can't afford for this treatment or even for medical
reasons he can't have it. So; what's the option? RPD. Why??
Because we have acrylic flange that replaces the missing bone.

* Physical or emotional problems exhibited by patients.
For example: if somebody has missing teeth from canine to
canine, so what's the treatment option? Do we choose implants
as a treatment for this patient? Of coarse no. this patient can't
physically (i.e. ability to eat & to speak) and psychologically
withstand for a period of time without teeth (it is not
acceptable). Therefore RPD is the treatment option & within 3
weeks to 1 month the patient can have teeth and function.


                                                                    5
* Esthetics.
 Some people think that implants or even veneers provide best
esthetics. Actually, in some cases they provide the worst
esthetics. So, don't think that implants give the best esthetics. It
might give the least esthetic outcome, while using RPD can give
the best esthetic outcome. That depends on case selection.
Dr. said: I remember a 30 years old woman that had 8 implants
and a fixed prosthesis on them. She spends thousands of money
for those implants. After came again to the clinic and
complained that she doesn't like the prosthesis. Unfortunately,
we can't solve the problem now and do a complete denture to
her as a better esthetic option. So, it depends on case selection.
* Immediate replacement of teeth that need extraction.
We can't construct a partial denture before extraction of teeth.
So, you extract the teeth and immediately insert them.
Especially that the big psychological trauma for patients is
accompanied with missing or extracted teeth.

* Patient's desire.
Sometimes, we let our patient decide which treatment option he
prefers. Especially if we have an old patient (in his 60s or 70s)
the most favorable treatment is to have quick & cheap teeth
(RPD). Or sometimes if you tell your patient about the
complexity of other modalities of treatment, then he will say to
you please do the simplest one.

* Unfavorable maxillomandibular relationships.
For example: if someone has severe class 2 or class 3, implant
dentistry or even fixed prosthodontics is not the straight forward
procedure for those patients. But, removable prosthesis is much
easier than fixed & implant prosthesis.(besoholeh mnet3ada el
discrepancy).i.e. if the patient has class 3, what do we need to
do?! Just to retrocline the lower anteriors a little pit and to
procline the upper anteriors a little pit. By this we transfer from
class 3 to edge to edge. Can I do this in implants? No. why??
Because, if we want to do it by putting implant we should direct

                                                                    6
them labially. And unfortunately there is no enough bone and
may be we cause sever recession of the gum.

Slide 9 + slide 10: Advantages of RPD

-it restores function and esthetics. And this is what we want
most of the time.

-it improves speech and occlusal stability. This point fulfills the
criteria of a dental prosthesis which is function (includes
mastication and speech), esthetics and stability.

-replaces one or more missing teeth in one side or both sides of
the upper or lower jaw. So, one
prosthesis replaces many missing teeth.

-more affordable than fixed. Because it is very cheap. For
instance; acrylic partial denture costs 50 J.D and one implant
650 J.D.
 Some students, who have relative dentists that say to them that
RPD is a part of history, don't believe them. It is still wherever
you go in the world…in the United States… in Australia … in
Canada…& in Europe; there are cases that must be treated only
by RPD. For example: postmenopausal woman is highly
exposed to osteoporosis and they can't have implants. So,
osteoporosis contraindicates the use of implants. And according
to this the option is RPD. Furthermore, no way to plan the
implant case without starting with RPD. Because, we don’t
know the final outcome. To conclude, you must have to start
with complete denture for edentulous patients and with RPD for
partially edentulous arches.

- replaces missing soft tissue and bone as well.

-less accurate techniques than fixed prosthesis and easy
occlusal adjustments.


                                                                      7
In RPD occlusal adjustments is only for 5 minutes, but in
bridges for 0.5mm we need have an hour (in order to remove the
ceramic).

-easy to clean because it's removable.
-may provide as an interim prosthesis. (Something provisional).

-quite easy to adjust and add more teeth if later loss occurs.
(We will talk about it in provisional restorations).

By the way any prosthesis has advantages and disadvantages. If
you have done RPD and the patient doesn't like, he can get rid of
it.. But in case of implant there is prescription and installation.
So, you can't remove it easily. So, you must remove part of the
bone.
If you construct a bridge can you do this (remove it)? Another
bridge means that cut the bridge, refine preparation again and
take a new impression (because already teeth are prepared and
the bridge is cemented).in abroad, bridges cost 5000 dollars and
even in Jordan 4 unit bridge costs 800 J.D.
Don't think by implant dentistry you can get rid off traditional
prosthodontics. It is still indicated in many cases. Especially, in
our countries.


Slide 11 -15: Disadvantages of RPD

-Can cause caries for adjacent teeth depending on the design of
the RPD, age of the patient, and the oral hygiene efficiency.
Some patients have bad oral hygiene and this indicates caries.
Such criterion is not limited only for RPD. It is also suitable for
fixed partial denture in which they will have more serious
carious cases.

-Can damage the supporting tissues if poorly designed and
cause tooth loosening and mucosal ulceration. Especially if it is
tissue supported can cause trauma.

                                                                      8
-Unsuitable for many patients who don't like removable
prosthesis. I.e. a lot of patients they are reluctant especially
young patients. They don't like to remove their prosthesis and
then retain it. (It is not acceptable socially).

-The RPD rotates during function especially the mucosally or
dually-supported one which reduces efficiency and increases
trauma. So, RPD during function rotates not as fixed partial
denture.

-Its construction involves some preparation and adjustment of
the remaining dentition. We need to do adjustment on teeth
especially in metal framework in which we have rests and so
on…

-The acrylic teeth wear and require later replacement. When
acrylic opposes teeth the wear is more than in acrylic teeth in
complete denture. That's regarding to the hardness number of
enamel which is more than acrylic. (For enamel it is 350, and for
acrylic it is 30).but, it is not a big problem. We can replace the
distorted teeth by other new acrylic teeth.

-The clasps may be unaesthetic if placed anteriorly. This is
really a big disadvantage. For example: if the patient with
missing canine (3) or (4), you need a clasp for retention on the
canine. And this is not esthetic.

-May stimulate candidal infection of the mucosa underneath
especially if not cleaned frequently and after meals. Candidal
infection for those patients is very common for two reasons: 1)
poor oral hygiene. 2) Or if the denture is ill-fitting. And most of
the time combined (both of them).we can notice this infection
on the hard palate.




                                                                      9
-The acrylic has low impact strength and may fracture.

-Bone resorption if mucosally or dually-supported and frequent
relining may be required. After bone resorption there will be a
space between the denture and the bone leading to more
movement and more damage. The best solution is to reline in
which we add acrylic on the fitting surface of the prosthesis.

-Bulky if compared with fixed prosthesis, and so uncomfortable
for new wearers. As we noticed in RPD we fulfill the hard
palate to replace missing lateral. In contrast, in fixed prosthesis
it is very tiny.


-Some patients complain of reduced thermal sensation with
upper RPD covering the palate. When you eat a piece of cake
thermal and taste expansion will be reduced.

-Better to be removed at night for tissue re-adaptation. Most of
fungal infections occur in patients that wear their RPD 24 hours
(^_^).



Slide 16: Treatment options for partially edentulous patients

What are the treatment options for partially edentulous patients?
There are 4 options.

1) NO treatment
2) RPD
3) FPD
4) implant-supported prosthesis (fixed, removable).




                                                                  10
   Hint: implant doesn't mean fixed prosthesis only.




Each one of these 4 options is suitable. So, it is not necessary to
follow this sequence. For example: if we have two patients and
both of them with missing laterals. As a treatment option for the
first patient we decide to do RPD. And for the other we decide
to do a bridge depending on many factors that we will talk about
them later.

Slide 17: **veeeeeeeeeeeeeeeery important slide

What are the steps involved in construction of removable partial
dentures? (Metal-acrylic and acrylic only).
-Metal-acrylic which is metal framework.
Acrylic only which is acrylic RPD.




                                                                 11
Now we will talk about acrylic RPD only, and metal acrylic we
will talk about it later.

    Data from history and                         Mount casts on articulator
     oral examination*                            analysis of diagnostic casts

*(Dr. mentioned: after that
 We take
a primary                    Treatment plan*
impression.
 So, what
type of material                Designing RPD
 should we use?
 Only alginate. Keep in
your mind that impression
 compound can't be
 used for edentulous patients).
                                                        Acrylic only RPD*
        Metal acrylic RPD

          Tooth modifications                          final impressions


          Final impressions                     jaw relations (if needed)*


         Try-in metal framework                          try-in of RPD*


          Jaw relations                                 insertion of RPD


          Try-in of RPD



         Insertion of RPD


                                       Review




                                                                        12
* (Dr. explained according to treatment plan:




             This sequence may be changed. Sometimes
             you need treatment planning for mounted
             models & sometimes you can do treatment
             planning without mounted model. Example:
             patient with missing lateral doesn't need
             mounted model in comparison to patient with
             multiple missing teeth & supra eruption of
             some teeth, we can't plan the case in patient's
             mouth because we might need more than two
             hours. Also we can't see from behind the
             teeth. So, we mount the model. Then do
             treatment plan & decide is it acrylic RPD or
             metal RPD).




*(Dr. explained according to acrylic RPD: in some cases we need special
tray and final impression. in other cases final impression is enough. For
instance: if the patient with missing lateral, primary impression is
enough).

*(Dr. explained according to jaw relations: in some cases you can
articulate the models without need for the record block because we have
remaining teeth and it is not as in complete denture).

*(Dr. explained according to try-in of RPD: also it depends on the case.
if the patient with missing lateral no need for try-in. but, if all anterior
teeth are missing in this patient you need to do try-in).




                                                                           13
Slide 18: Provisional/temporary RPDs

We have 3 types of PROVISIONAL RPDs:
1) Interim RPD
2) Transitional RPD
3) Treatment RPD
*Does interim RPD means acrylic partial denture? No, it can be
metal not only acrylic.

Slide 19: Interim RPD

*Indications.
What does interim mean? Interim means provisional prosthesis
that can be replaced by another definitive prosthesis. Example:
if somebody has missing lateral and supposes that he is 17 years
old. As a first treatment option we put RPD- for 2-3 years- until
he becomes 20 years old. After that implant therapy will replace
it. In this case we use RPD as a temporary solution to be
replaced by another definitive prosthesis. By the way definitive
treatment can be another partial denture not necessarily implant.

*Materials. (Cold-cure acrylic/ heat-cure acrylic/acrylic &
metal). Most of the time, we use heat-cure acrylic.

*Clinical procedures. Exactly the same as I just mentioned
above. But, in cold cure or metal the steps are different from that
applied to the heat cured.

*Laboratory procedures. Include many steps:
Step 1: Classification of the models.
Step 2: Do survey to determine the desirable and undesirable
undercuts.
Step 3: Block out the undesirable undercuts.
Step 4: Wire binding and preparing the clasps.
Step 5: Setting of teeth.
Step 6: Denture base.
Or you can do the two last steps (5&6) together.

                                                                 14
After that you do processing (includes flasking, dewaxing,
packing, curing, deflasking, finishing and polishing).

Slide 20-22: -Refer to your slides to see the pictures.

Take this case for example: this is 21 years old female. She had
anterior bridge (fixed partial denture) when she was 16 years.
As you see in the picture there is a fracture in the ceramic. The
patient didn't like the color of her teeth and their level. So, the
bridge is defective, In addition to the endodontic problems that
she had. If we want to correct the deficiency we cut the bridge
and get rid off it. We can't leave our patient without teeth!!!!!.
Since, we need a provisional treatment (i.e. we need RPD as an
interim prosthesis that will be replaced by definitive one). So,
this is an interim RPD and after this she had two implants and a
bridge on these implant. (Here one tooth is added and another
one is extracted).This example is introduced to show you that
RPD is part of prosthodontic treatment, not considered as a part
of history.

Slide 23: Transitional RPD

 *Indications.
It means that the patient is in the process of being edentulous.
There are a lot of possibilities for patients that have transitional
RPD like: neglected mouth, poor oral hygiene, decayed teeth
and mobile teeth. To avoid the big psychological trauma/impact
of your patient you don't take all teeth out, although you know
the fate of these teeth is extraction. But, you do the process
slowly to reduce the psychological trauma. For example: if your
patient has extracted molars and the remaining teeth are from 5
to 5. Then you construct an acrylic denture and start to extract
the worst teeth that your patient complains about. And then add
a tooth every month until the patient has a complete denture
base. Finally you construct a new complete denture.
*Materials (heat-cure acrylic/acrylic & metal).


                                                                  15
*Clinical procedures.
*Laboratory procedures.
You should know how to add a tooth. (These procedures
described in chapter 19 in your book).

Slide 24: Treatment RPD

*Indications.
*Materials (acrylic & tissue conditioner).
Tissue conditioner is a very soft material & it still soft only for
one week. We put it on the fitting surface of the denture, In
order to recover the lesion (that caused by traumal infections).
These RPD called "treatment RPD", because we use it for
treatment purposes.
Just to know: soft acrylic considered as another material that can
be used.
*Clinical procedures.
*Laboratory procedures. The only difference is that you need
space for tissue conditioner. So, before you do the acrylic base
you add spacer. Same procedure that we do in the special tray in
which we use wax spacer and acrylic. When you remove the
wax spacer there will be a space for the impression material.
Here is the same concept; you add wax spacer and construct the
acrylic partial denture (can be cold-cure acrylic). After
construction you will remove the spacer. So, you will end up
with space in the partial denture and then add the tissue
conditioner and place it in patient's mouth.


                             Tooth-mucosa supported RPD




        Wish you all the best…& forgive me for any mistake…

                                      Done by: Fatina akel

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