acrylic partial dentures

1. TEMPORARY ACRYLIC
PARTIAL DENTURES
DR VEENA PAUL
DEPT.OF PROSTHODONTICS

2. An acrylic partial denture (APD) is one of the options
available for replacing missing teeth and is also the
most cost effective treatment option

3. One of the disadvantages of APD’s is its poor strength.
Dentists and dental technicians tend to design and construct acrylic
partial dentures with little or no tooth support.
This can have a detrimental effect on the surrounding hard as well as
soft tissue.

4. Generally not considered a permanent treatment option for
replacing missing teeth.
• The provision of metal-based removable partial dentures,
fixed partial prostheses or implant supported prostheses to
replace missing teeth is considered to be more permanent
treatment solutions.

5. In many less affluent societies, APD’s are commonly used in
private practice as permanent prostheses owing to the cost-effectiveness
of the material – acrylic – used as a major connector, as well as low cost
laboratory procedures involved in the construction of this partial
denture.
In a National Health Survey conducted over a 9 -year period (1992 to
2001) in the UK, it was found that for every metal-based partial
denture constructed, five APD’s were made.

6. A metal-based partial denture constructed in private practice will cost
the patient in the region upto Rs5000, whereas an APD will cost in the
region of Rs1000 to Rs2000.
APD’s thus offer a cheaper alternative to metal-based partial dentures
as it is relatively easy to construct in the laboratory, it is easier to repair
and reline and wrought wire components can be added to the
framework for retention and support.

7. susceptibility to fracture-- usually compensated for
by increasing the bulk of the material - potential of
traumatizing the soft tissues as well as periodontal tissues.

8. All removable partial dentures should utilize the
existing teeth for support and retention as teeth have a much
better response to loading when compared to soft tissue and bone.
This is easily achievable with the metal-based partial denture as the
entire denture is cast as one and support and retention gained from
rests and clasps extending from the major connector

9. For an APD to be tooth-supported, additional material such as
stainless steel rests and clasps have to be added to the acrylic
major connector. There is no chemical bond between stainless
steel and acrylic and clinically this can present itself as a weak
area which is prone to fracture.
However, with proper patient selection, optimal clinical and
laboratory procedures, the disadvantages of APD’s can be
minimized.
The design of the removable partial denture is more important
than the material to be used for its construction.

12. Every designed an upper mucosa-borne denture for bounded
saddles and with specific features such as gingival margin relief and
clasps distally to provide horizontal stability
This design however, cannot be applied to all acrylic partial denture patients as
it requires bounded saddles and patients do not necessarily present with these
criteria.

13. Potential disadvantages of acrylic partial
dentures
• Acrylic due to its nature is a porous material and thus has an
increased area for plaque accumulation.
• Upper APD’s appear to have a better prognosis mainly due
to the larger surface area that is covered-repeated review
regimens advised else tissue damage

14. Poor laboratory technique:
Should block out unwanted undercuts and interdental spaces on the
master model (pour a duplicate cast and process the denture on the
duplicate cast. )
Failure to block out these unwanted undercuts usually lead to problems in
seating the denture with the dentist adjusting the acrylic and
inevitably grinding away too much of the acrylic and thus
compromising the acceptability of the denture.

15. as a space between the denture and
the abutment teeth with subsequent trauma to gingival tissues

16. Lower APDs present an additional problem:
the surface area is
much smaller compared to an upper
denture and there can be
no relief of gingival margins.
The acrylic major connector has to cover all
the abutment surfaces to provide additional
strength to the acrylic.
Support must be gained from the
remaining teeth otherwise the denture will
tend to “sink” into the tissues with a
resultant stripping of the gingivae

17. PRINCIPLES IN ACRYLIC PARTIAL DENTURE
DESIGN AND CONSTRUCTION
Surveying the diagnostic cast
The casts should be articulated to assist with the designing of the
dentures.
Design sheets with the appropriate design for the APD must
accompany the study casts to the laboratory

18. The same principles as for the
design of the metal-based
partial denture are applied
when designing an APD.
These include:
• the edentulous areas / saddles
• support
• retention
• reciprocation
• connector
• horizontal stability

19. • Every removable
partial prosthesis
should be tooth
supported
(Kennedy Class III and
IV) or tooth-and-
mucosa supported
(Kennedy Class I and
II), but never only
mucosa–supported

20. Retention is gained from the abutment teeth and can be passive
(depending on a long and single path of insertion) or active
(wrought clasps engaging undercuts on abutment teeth).
For any prosthesis to be retentive it requires a single long path of
insertion and this is usually determined by the edentulous
saddles and the degree of parallel surfaces that can be obtained
on the abutment surfaces.

21. • Guiding planes are 2 or more parallel surfaces prepared on the
abutment teeth which can be used to limit the path of insertion and
improve the stability of a removable prosthesis.
• Guiding planes must have a minimum length of 3 mm to provide
adequate passive retention

26. THANK YOU..