Classification of RPD

4.  We will discuss today
 Classification systems
 And
 Components of removable partial denture

5. Prime purpose :
 To enable dentist to clearly communicate to a listener.
 Helps to create order from the many number of
possible combinations of missing teeth and edentulous
spaces.
 An aid in learning of the fundamentals of design

6. Need for classification:
 To formulate a good treatment plan.
 To anticipate the difficulties common to occur for that particular
design.
 To communicate with a professional about a case.
 To design the denture according to the occlusal load usually
expected for a particular group.

7.  Requirements of a Classification:
 Allow visualization of type of partially edentulous arches that
is being considered.

8.  Requirements of a Classification:
 Allow differentiation between
tooth supported and tooth-tissue supported RPDs

9.  Requirements of a Classification:
 Serve as a guide to the type of design to be used.
 Be universally accepted.

10.  Various classification systems:
 Cummer
 Kennedy’s
 Applegate-Kennedy
 Bailyn
 Neurohr
 Mauk
 Friedman
 Godfrey
 Skinner
 ACP classification (American College of Prosthodontics)

11.  Craddock Classification:
 Class 1: if the denture is supported by teeth.
 Class 2: if the denture is supported by mucosa.
 Class 3: if the denture is supported by both
the teeth and mucosa.

12.  Cummer’s classification system Proposed By
CUMMER in 1920.
 Cummer stated:
 “ For working purposes all the cases may be made to
fall into 4 simple classes, which have as their basis the
choice of number and position of the direct retainer”.

13.  Class I – DIAGONAL:
 2 diagonally opposite teeth are chosen as abutment teeth for
the attachment of direct retainer.
 Class II –DIAMETRIC:
 2 diametrically opposite teeth are chosen as abutment teeth for
the attachment of the direct retainers

14.  Class III –UNILATERAL:
 one or more teeth on the same side are chosen as abutment
teeth for the attachment of the direct retainers.


15.  Class IV –MULTILATERAL:
 Three or more teeth are chosen as abutment teeth for the
attachment of the direct retainers.
 The teeth are disposed in a triangular or quadrilateral
relationship

16.  Most widely used method of classification
 Proposed in 1923 by Dr. Edward Kennedy of New
York.
 It is based on the relationship of the edentulous spaces
to the abutment teeth.

17.  Class I:
 Bilateral edentulous areas located posterior to the
remaining natural teeth.
 Class II:
 Unilateral edentulous area located posterior to the
remaining natural teeth.

18.  Class III
 Unilateral edentulous area with natural teeth both
anterior and posterior to it.
 Class IV
 Single, bilateral edentulous area located anterior to the
remaining natural teeth.

19.  Applegate’s 8 Rules:
 Rule 1:
 Classification should follow rather than precede
extractions that might alter the original classification.
 Rule 2:
 If the third molar is missing and not to be replaced it is not
considered in the classification.

20. Rule 3:
 If the third molar is present and is to be used as an
abutment, it is considered in the classification.
 Rule 4:
 If the second molar is missing not to be replaced that is the
opposing second molar is also missing and is not
considered in the classification.

21.  Applegate’s 8 Rules:
 Rule 5:
 The most posterior edentulous area or areas always
determines the classification.
 Rule 6:
 Edentulous areas other than those determining the
classification are referred to as the modification spaces and
are designated by their number.

22.  Applegate 8 Rules:
 Rule 7:
 The extent of the modification is not considered, only
the number of additional edentulous areas.
 Rule 8:
 There can be no modification areas in class IV arches.
Because any edentulous area lying posterior to the
single bilateral area determines the classification.

24. Partial Denture Components

25.  Means of Retention
 Means of Reciprocation
/ Bracing
 Means of Support
 Means of Connection

26. MEANS OF RETENTION

27. Definition:
“The quality inherent in the prosthesis to resist the
force of gravity, the adhesiveness of food and the
forces associated with the removal of prosthesis”

28. Definition:
The component that engages an abutment tooth and
in so doing resists dislodging forces applied to a
removable partial denture is called direct retainer.

29.  The clasp is a retainer in which a flexible arm
engages an external surface of an abutment
tooth in an undercut area cervical to the
greatest convexity of the tooth (height of
contour)

31.  1. RETENTIVE ARM
 2. RECEPROCATING ARM
 3. OCCLUSAL REST
 4. MINOR CONNECTOR

32.  1. RETENTIVE ARM
 The function of the retentive arm is to resist displacement on the
tooth, thus maintaining the prosthesis in its proper position.
 Terminal third is flexible
 Middle third has less flexibility
 The third that joins the body has no flexibility

33.  2. RECIPROCAL ARM
 It is placed on the tooth surface opposite the retentive arm.
 Its function is to counterbalance any stress generated against the
tooth by the retentive arm.
 It is rigid throughout its length.
 It provides horizontal stability, support
 and a limited amount of retention contact with tooth surface.
 The bracing arm provides resistance to horizontal forces exerted on a
tooth by the retentive clasp terminal during seating and unseating of
the prosthesis (reciprocation).

34. Definition:
 “The component of a
removable partial denture that
assists the direct retainer(s) in
preventing displacement of the
distal extension denture base
by functioning through lever
action on the side opposite of
the fulcrum line when the
denture base moves away from
the tissues in pure rotation
around the fulcrum line.”

35. FULCRUM LINES
•Definition:
Movement of the base AWAY from the ridge around an imaginary
line connecting the retentive clasp tips. (This is the axis relevant to
indirect retention.)

37. MEANS OF CONNECTION

38. Definition:
◦ “The component of the partial denture that connects the
parts of the prosthesis located on one side of the arch with
those on the opposite side.”
◦ GPT-2001

39.  3. MINOR CONNECTOR
 It joins the small components e.g. rests and clasps, to the
saddles or to the major connector.
 They also contribute to the functions of bracing and
reciprocation as in the RPI system.
 Other designated terms for it are truss arm, standard,
tail, tang, and upright.

40.  Those which:
 Join clasp to major connector
 Join indirect retainers or auxiliary rest to major
Connector
 Join denture base to major connector
 Serve as approach arms for bar- type clasp

41. Denture Base:
Which supports the teeth

42.  Unification and rigidity
 Stress distribution
 Bracing through contact
with guiding planes
 Maintain path of insertion

43.  4. OCCLUSAL REST
 It is positioned in a prepared recess on the tooth surface
and resist displacement of the clasp in a gingival
direction.
 Contributes to resistance to horizontal movement.

44. MEANS OF SUPPORT

45. ‹
‹WHY?
Increase masticatory efficiency

46. Support!
How?

47. “Any component of a partial denture on a tooth surface
that provides vertical support is called a rest”

48.  Portion of a tooth prepared to receive a rest

49.  2. Prevents denture base from moving cervically &
impinging gingiva

50. Major connector imbeds into tissue

54.  TYPES:

55.  TYPES:
 DIRECT RETAINERS:
 The component that engages an abutment
tooth and in so doing resists dislodging
forces applied to a removable partial denture
is called the direct retainer.

56.  TYPES:
 REST:
 The components of a removable partial denture that serve
primarily to transfer forces occurring against the prosthesis
down the long axis of the abutment teeth are called rests

57.  TYPES:
 INDIRECT RETAINERS:
 Which prevents the denture lifting across the
fulcrum line


58. Minor connector:
Which connects the major connector with
other component such as rest

59. 2-Intracoronal retainers (internal or precision
attachment):
 It consists of two units
 One is a female receptacle in a crown or inlay in the
abutment.
 Second part is a male insert attached to the partial
denture.
 The retention is derived by the frictional fit and wedging

60. 1-Intracoronal retainers types:
 1. Internal attachment
 2. External attachment
 3. Stud attachment
 4. Bar attachment