prosthetic treatment- removable dentures, classes of defects

1. Removable partial dentures

2. REMOVABLE PROSTHODONTICS
• It is devoted to replacement of missing teeth & contigous tissues with
prosthesis designed to be removed by the wearer.
• It includes two disciplines: removable complete denture
prosthodontics and removable partial denture prosthodontics.
• A RPD may be extracoronal or intracoronal depending on what type
of retention is used to keep it in the mouth.

3. Definition and Overview
• A removable partial denture (RPD) is a denture for a partially
edentulous patient who desires to have replacement teeth for
functional or aesthetic reasons and who cannot have a bridge (a fixed
partial denture) for any reason, such as a lack of required teeth to
serve as support for a bridge (i.e. distal abutments) or financial
limitations.
• This type of prosthesis is referred to as a removable partial denture
because patients can remove and reinsert it when required without
professional help. Conversely, a "fixed" prosthesis can and should be
removed only by a dental professional.

4. COMMON TERMINOLOGIES USED IN RPD
• Appliance - It is a device worn by a patient in the course of treatment.
e.g. orthodontic appliance, surgical ,space maintainer.
• Abutment -“A tooth,a portion of a tooth ,or that portion of a dental
implant that serves to support & or retain a prosthesis.”
• Retainer- The fixation device ,or any form of attachment applied
directly to an abutment tooth & used for the fixation of a prosthesis,
is called retainer.

5. Partially edentulous conditions
• The patient's oral condition is categorized based on the remaining
dentition in a classification first proposed by Dr. Edward Kennedy in
1925.
• His classification consisted of four general outlines for partially
edentulous arches that can present within a patient, which then could
be treated with an RPD.
• When there is an edentulous space that is outside of the four
classifications, it is termed a modification space.
• The use of this classification allows for easier communication
between dental professionals, allows for easily visualization of the
arch, and distinguishes a tooth-borne or tissue-supported RPD.

6. Partially edentulous conditions
• Class I (bilateral free ended partially edentulous)
• Class II (unilateral free ended partially edentulous)
• Class III (unilateral bounded partially edentulous)
• Class IV (bilateral bounded anterior partially edentulous)

8. Class I
• RPDs are fabricated for people who are missing some or all of their
posterior teeth on both sides (left and right) in a single arch (either
mandibular or maxillary), and there are no teeth posterior to the
edentulous area.
• In other words, Class I RPDs clasp onto teeth that are more towards
the front of the mouth, while replacing the missing posterior teeth on
both sides with false denture teeth.
• The denture teeth are composed of either plastic or porcelain.

9. Class II
• RPDs are fabricated for people who are missing some or all of their
posterior teeth on one side (left or right) in a single arch, and there
are no teeth behind the edentulous area.
• Thus, Class II RPDs clasp onto teeth that are more towards the front
of the mouth, as well as on teeth that are more towards the back of
the mouth of the side on which teeth are not missing, while replacing
the missing more-back-of-the-mouth teeth on one side with false
denture teeth.

10. Class III
• RPDs are fabricated for people who are missing some teeth in such a
way that the edentulous area has teeth remaining both posterior and
anterior to it.
• Unlike Class I and Class II RPDs which are both tooth-and-tissue-borne
(meaning they both clasp onto teeth, as well as rest on the posterior
edentulous area for support), Class III RPDs are strictly tooth-borne,
which means they only clasp onto teeth and do not need to rest on
the tissue for added support.
• This makes Class III RPDs exceedingly more secure as per the three
rules of removable prostheses that will be mentioned later, namely:
support, stability and retention.

11. Class IV
• However, if the edentulous area described in the previous paragraph
crosses the anterior midline (that is, at least both central incisors are
missing), the RPD is classified as a Class IV RPD.
• By definition, a Kennedy Class IV RPD design will possess only one
edentulous area.

12. Designing partial dentures
• Prior to designing partial dentures a complete examination is
undertaken to assess the condition of remaining teeth. This may
involve radiographs, sensibility testing or other assessments.
• From this examination and assessment of occlusion (occlusal plane,
drifting, tilting of teeth and surveyed articulated casts) the designing
of partial dentures can begin.
• Information from previous dentures can be very useful in deciding
which features to keep the same and which features of the design to
change – in the hope of making an improvement.

13. Stages of partial denture design:
A systematic design process should be followed:
• the teeth to be replaced must be decided.
• the soft tissue to be replaced (flange) is then drawn.
• the major connector is selected from a list of options (the options available
will depend on the above assessment).
• retentive features of the denture must be decided – these may include
clasps, guide planes and indirect retention (often important in dentures
involving Kennedy Class 1 and Class 2 saddles).
• supportive features are then decided – these prevent the denture sinking
into the soft tissue; often the natural teeth can take some of the loading
(rest seats and connector coverage).

14. Stages of partial denture design:
However, this is not always possible. Support may thus be tooth-
borne, mucosal borne or a combination of tooth and mucosal borne.
• the denture should where possible have features that withstand
horizontal movement (bracing) and the clasps should have
appropriate reciprocation.
• the denture base material (usually acrylic or cobalt-chromium) and
materials of the various components must be selected.
• the hygiene of the prosthesis must be appropriate trying where
possible to minimise the soft tissues coverage.

15. Components of an RPD
Rather than lying entirely on the edentulous
ridge like complete dentures, removable partial
dentures possess clasps of cobalt-chrome or
titanium metal or plastic that "clip" onto the
remaining teeth, making the RPD more stable
and retentive.

16. Types
There are three basic types of partial dentures.
• The first is a cast removable partial denture, or “cast partial”, and
consists of a metal base that has acrylic teeth attached to it. Metal
clasps are the hook-like structures that help hold the removable
partial denture in place. Although the cast partial can be a bit
cumbersome, it has been used successfully for decades in the dental
profession.

17. Types
• The second type often referred to as a “flipper,” an acrylic removable partial
denture is generally considered less optimal than a cast metal partial. The main
reason is that the replacement teeth are set in a pink acrylic base that must be
thick and bulky to minimize the risks for breakage. A flipper is attached to your
natural teeth with metal clasps, which may be visible during talking and smiling.
Most people are able to speak and eat fairly normally with a flipper, but the
bulkiness can be aggravating. This is generally considered a temporary solution,
used as an interim device while a more permanent restoration is created.
However, flippers are the least expensive partials, and some people successfully
use them for years.

18. Types
• The third type is the "Valplast" or flexible partial denture, which is a nylon
thermoplastic material that has several advantages over the other two types of
partial dentures. The flexible partial dentures have no metal clasps and are very
light weight. The material is translucent, so the patients own gums show through,
giving a very natural appearance. Flexible partial dentures can be used to replace
many or few missing teeth, and can even be modified to replace a missing tooth
on only one side of the mouth, greatly enhancing its comfort. Valplast is an
option for people who are allergic to the acrylic found in other types of partial
dentures. Another great advantage is its resistance to breakage, as it is
surprisingly strong relative to its size and weight.

19. INDICATIONS FOR RPD
• Length of edentulous: RPD preferred for longer edentulous arches.
• Abutment tooth: When there is no tooth posterior to the edentulous
space to act as an abutment, a RPD is preferred.
• Periodontal support of remaining teeth: When it is poor RPD is
preferred because it requires less support from the abutment teeth.
• Cross arch stabilization: When a remaining teeth have to be stabilized
against lateral and anterior-posterior forces, a RPD is indicated.

20. INDICATIONS FOR RPD
• Excessive bone loss: In RPD, the artificial tooth can be positioned as per
the operators preferences and the denture base can be fabricated to
provide required support and aesthetics.
• Aesthetics: RPD provide better aesthetics because the denture base gives
the appearance of a natural tooth arising from the gingiva.
• Immediate tooth replacement after extraction
• Emotional problems: The appointment for removable partial denture is
shorter and less demanding to patient.
• Patient desires: Patient insist on RPD over FPD for the following reasons:
oTo avoid operative procedures on normal tooth.
o For economic reasons.

21. RPD IS GENERALLY PREFERRED IN THE
FOLLOWING CONDITIONS
• RPD IS GENERALLY PREFERRED IN THE FOLLOWING CONDITIONS:
• When more than 2 posterior teeth or 4 anterior teeth are missing.
• If the canine & two of its adjacent teeth are missing.
• When there is no distal abutment tooth.
• Presence of multiple edentulous spaces.
• If the teeth adjacent to edentulous spaces are tipped ,they cannot be used as an
abutment for a fixed prosthesis.
• If periodontally weakened teeth are present near the edentulous spaces.
• Teeth with short clinical crowns.
• Insufficient number of abutments
• Severe loss of tissue on the edentulous space.
• Old patients

22. Thank you!