Practical Points of View for Removable Partial Denture Copyright (c) Dr. Myint Kyaw Thu Department of Prosthodontics University of Dental Medicine, Yangon

1. PRACTICAL POINTS OF VIEW
FOR REMOVABLE PARTIAL
DENTURE
MYINT KYAW THU
B.D.S., M.D.Sc.,(Prosthodontics)
Department of Prosthodontics, UDMY
1

2. CLASSIFICATION OF
REMOVABLE PARTIAL
DENTURES
2

3. REMOVABLE PARTIAL DENTURE
CLASSIFICATION
KENNEDY CLASSIFICATION SYSTEM
CLASS I - Bilateral Posterior Edentulous Areas
CLASS II - Unilateral Posterior Edentulous Area
CLASS III - Unilateral or Bilateral Edentulous Area(s)
Bounded by Remaining Tooth/Teeth
CLASS IV - Single Edentulous Area Anterior to
Remaining Teeth and Crossing the Midline
3

4. KENNEDY CLASSIFICATION SYSTEM RULES
(Proposed by Dr. O.C. Applegate)
1. Classification follows all mouth preparations including extractions
2. Edentulous areas with no teeth replacements are not considered
3. Third molars are not considered unless present or being replaced
4. Additional edentulous areas are “modification spaces”
a. Anterior space - A
b. Posterior space - P
5. Class I or II situations take precedence over IV situations
6. A Class III situation takes precedence over a Class IV situation
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5. KENNEDY CLASS I
CLASS I - Bilateral Posterior Edentulous Areas
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6. KENNEDY CLASS II
CLASS II - Unilateral Posterior Edentulous Area
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7. CLASSIFICATION WITH MODIFICATION AREAS
CLASS II-P
CLASS II-A-2P
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8. KENNEDY CLASS III
CLASS III - Unilateral or Bilateral Edentulous Area(s) bounded by Remaining Tooth/Teeth
UNILATERAL
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9. KENNEDY CLASS III
BILATERAL
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10. KENNEDY CLASS IV
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11. COMPONENTS OF
REMOVABLE PARTIAL
DENTURES
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12. REMOVABLE PARTIAL DENTURE
COMPONENT PARTS
 Occlusal Rest
 Major Connector
 Minor Connector
 Direct Retainer
 Indirect Retainer (Mainly for Class I and II RPD)
 Saddle (Base)
 Replaced Teeth
12

13. OCCLUSAL REST
- Transfers stress to the abutment tooth
- Resists movement of the prosthesis in a cervical direction
-Stabilizes the retentive arm in the proper position
Less than 90 degree
angle to make rest seat
“positive”
Marginal ridge lowered to
allow sufficient thickness
without creating an occlusal
interference.
Deepest portion of rest seat;
deeper than reduced
marginal ridge area
13

14. MAJOR CONNECTOR
Definition:
“The part of a removable partial denture that joins the
components on one side of the arch to those on the opposite
side.”
MANDIBULAR
MAJOR CONNECTORS
- Lingual Bar
- Labial Bar
- Lingual Plate
MAXILLARY
MAJOR CONNECTORS
- Complete (or modified) Palatal Plate
- Anteroposterior Palatal Strap/Bar
- Anterior Palatal Strap
14

15. 1. LINGUAL BAR - Six gauge half-
pear shape approximately 4 mm in
height with superior border at least
3mm from fgm’s.
MANDIBULAR MAJOR CONNECTORS
7mm
The bar is pear shaped in cross
section with the thickest part along
the inferior border.
2. LINGUAL PLATE – Used when
fgm to floor of mouth is less than 7mm,
or when anteriors are mobile and their
longevity is questionable.
Superior border is placed at the
junction of incisal and middle
thirds.
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16. LABIAL BAR -
Form and Usage: Same as the lingual bar but placed buccally (labially)
due to severe lingual inclination of the remaining teeth
Labial Bar Labial Bar
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17. MAXILLARY MAJOR CONNECTORS
-Wide application to all classifications, but mostly to Cl I and II.
- Provides maximum support as plate rests on tissue (as do all maxillary major
connectors.)
- Contraindicated where tori are present.
COMPLETE PALATAL
PLATE
MODIFIED PALATAL
PLATE
Anterior border ends in valley of rugae
not less than 6mm from fgm
Posterior border must not impinge
upon movable tissue
17

18. Used where torus precludes use of
palatal plate, provided a minimum of
5mm exists between the posterior
aspect of the torus and the vibrating
line.
Minimum width of 4mm
MAXILLARY MAJOR CONNECTORS
(MID)PALATAL STRAP
Used mainly in Cl III
situations – width of strap
varies to suit the clinical
situation.
ANTEROPOSTERIOR PALATAL STRAP
18

19. Usage:
- minor connector and rest
junction must be at least 1.5 mm
thick
- try to place interproximally
- joins major connector at a right
angle
- should be located at least 5 mm
from other vertical components
MINOR CONNECTOR
19

20. DIRECT RETAINER
Definition: “That component of a removable partial denture used
to retain and prevent dislodgment, consisting of a clasp assembly
or precision attachment.”
- Reciprocal Arm
-Occlusal Rest
- Retentive Arm
PARTS:
20

21. RETENTIVE ARM (CLASP) -
Retentive Surface Material:
Acceptable: enamel, gold, porcelain, composite
Not acceptable: amalgam, glass ionomer
Types of Clasps: (material)
Cast half-round
circumferential clasp on
a molar
Cast I-bar clasp on
a canine
Wrought wire (19 ga.) clasp
soldered to framework on a
premolar
Remote
soldered
or laser
welded
21

22. INDIRECT RETAINER
(Mainly for Class I and II RPD)
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.”
22

23. FULCRUM LINES
• Definition: FULCRUM LINE AXIS (sometimes referred to
just as FULCRUM LINE) An imaginary line, connecting the
most distal occlusal rests, around which a removable partial
denture tends to rotate towards the tissue under masticatory
forces
• Definition: RETENTIVE FULCRUM LINE AXIS –
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.)
23

24. INDIRECT RETAINER - Class I RPD Usage:
Primary fulcrum
line through most
distal rest seats
Ideally , a class I rpd has
two indirect retainers as
shown above; one for each
extension base
Practically, only one
indirect retainer is
needed for a class I rpd
as shown on the right
two pictures. Usually,
the site furthest from
the fulcrum line is
chosen.
Indirect retainers
24

25. INDIRECT RETAINER -
Class II RPD Usage:
Indirect retainer rest
seat; only one and on
the side opposite the
extension base
Primary fulcrum line
through most distal
rest seats
Indirect retainer rest seat Indirect retainer rest on tooth
#28; only a secondary rest seat
on the mesial of tooth #21 to
support the lingual plate major
connector
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26. DENTURE BASE - ACRYLIC
Usage:
- can be used in all rpd maxillary and mandibular classifications
- it can be relined if the edentulous ridge area changes
- attached to the rpd framework via meshwork
Meshwork wax-up on
mand. Rpd. It is
relieved off the ridge by
using 24 ga. wax during
block-out of the cast
prior to duplication and
waxing
Meshwork after
casting for a class
I mand.case
Cast meshwork for an
anterior modification
space
Acrylic base
attached to
meshwork -
note gray
shadowing of
meshwork
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27. DENTURE BASE - FINISH LINES
Definition: “The planned junction of different materials.”
Types: Internal (Acrylic bases only)
- Associated with the junction between the metal of the rpd framework and the acrylic
base material
- Formed by the 24 ga. relief wax used to provide space for the denture acrylic
24 ga. wax ~ 3mm
distal to tooth
24 ga. wax forming the internal
finish line
24 ga. wax forming the
internal finish line for a
modification space
27

28. DENTURE BASE - FINISH LINES
Types: Internal (Acrylic bases only)
Internal finish line in cast framework -note definite edge for acrylic material
junction
Acrylic base-framework
junction on finished rpd - it
should be a smooth transition
between the two
28

29. DENTURE BASE - FINISH LINES
Types: External (Acrylic and Metal bases)
External finish on mandibular
framework
External finish line on maxillary
framework
External finish line junction between acrylic and metal on a mandibular extension base, a
mandibular modification base, and a maxillary extension base - again there is a smooth transition
between the two. 29

30. REPLACED TEETH
Functions:
- Prevent migration of the remaining teeth
- Restore masticatory efficiency
- Retain proper interarch space
- Maintain esthetics of a normal facial contour
- Achieve distinct enunciation
Types of Material:
- Acrylic
- Porcelain
- Metal: gold and chrome 30

31. Work Authorization Form
A signed written order provided by the dentist to the
dental laboratory detailing the work to be performed
and specifying the materials to be used
(GPT-9, 2017)
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32. 32

33. 33

34. Sample Designs for Upper & Lower with
Different Types of Major Connector
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35. Mandibular RPD framework with lingual bar major connector
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36. Mandibular framework with linguo-plate major connector
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37. Mandibular RPD framework with a double lingual bar major connector
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38. The borders of a maxillary major connector should cross the palate at
right angles to the midline (solid line is correct, dotted line is incorrect)38

39. The anterior border of a maxillary major connector should be hidden in
a valley between the rugae (solid line) and should never be placed
forward of the indirect retainers (dotted line) 39

40. Maxillary framework with a palatal strap major connector 40

41. An A-P palatal strap major connector
used to circumvent a torus that ends
more anterior to the junction of the hard
and soft palates
An A-P palatal strap used as the major
connector for a Kennedy Class II mod-1
41

42. An A-P palatal strap used as the major connector for a Kennedy Class III
RPD The palatal opening should be 15 mm or more in an
anteroposterior dimension 42

43. An A-P palatal strap major connector used to a Kennedy Class IV RPD43

44. A palatal plate major connector 44

45. A modified palatal plate major connector.
The posterior border may be located at
the solid or dotted line, depending on the
desirability of plating the molar and the
degree of rigidity and support required
A U-shaped major connector used to
circumvent a large inoperable torus
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46. SURVEYING
• Diagnostic procedure that analyzes the dimensional
relationships of the oral hard and soft tissues
• Must be accomplished in association with decisions regarding
the selection of abutments and the location of rests
• Essential component of RPD therapy
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47. Dental Surveyor
• A dental surveyor is used to determine the relative parallelism of
two or more surfaces of a cast of the dental arch
• A surveyor is used;
- to survey the diagnostic cast
- to contour wax patterns and crowns
- to place or form intracoronal retainers in crowns
- to survey the master cast prior to framework fabrication
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48. The dental surveyor:
• Stand base (B)
• Vertical support arm VSA/(fixed)
• Horizontal arm (HA)
• Movable vertical arm (MVA)
• Locking screw (LS)
• Chuck stylus (C)
• Table base (TB)
• Swivel coupling (SC)
• Mounting plat-form (MP)
48

49. Styli for the dental surveyor:
• Analyzing rod AR
• Carbon marker (CM) (In metal
sleeve)
• Undercut gauges (UG)
• Blade (B) for contouring wax
patterns
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50. Determining the path of insertion/dislodgement
• It is dependent upon;
- (1) potential guide surfaces
- (2) undercuts for direct retention
- (3) hard and soft tissue interferences and
- (4) esthetic considerations
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51. • Begin by attaching the diagnostic cast to the surveying table (ST)
• Orientate the mean occlusal plane parallel to the base of the surveyor stand
• Final orientation should seldom vary more than 10‘ from this position
• Place the analyzing rod in the chuck at the lower end of MVA
• Evaluate the positions of the proximal surfaces of abutments for parallelism
• Adjust the anteroposterior tilt of the cast until maximal parallelism is
obtained
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52. • Evaluate hard and soft tissue prominences and corresponding recesses
- that may interfere with insertion/removal of the rigid portions of the
metal frame-work or acrylic resin denture flanges
• After interferences have been located and analyzed;
- one of the following corrective procedures must be selected:
(1) maintain the established orientation of the cast and eliminate the
interferences by surgery and re-contouring of the involved teeth or
(2) avoid interferences by altering the tilt
52

53. Placing the survey line
After the orientation is established;
• Analyzing rod is replaced with a carbon marker and
• Height of hard and soft tissue contours is marked on the cast
• It is absolutely essential that survey lines be scribed by the side of the
carbon marker and not the tip
• If the tip touches the cast, erroneous and misleading information will be
produced
53

54. Tripoding the cast
• Tripoding is a procedure that records the tilt of the cast
• Practitioner or technician can reestablish - desired path of insertion/removal
• The carbon marker is placed in the chuck and the vertical arm is lowered
until the tip of the marker touches the cast at three widely separated points
• The arm is locked in position so that no vertical movement is possible
54

55. • A line 2 to 3 mm long is made at each of three points on the cast, and the
lines are circled in red
• Second method of tripoding is accomplished by drawing a vertical line on
three sides of the diagnostic cast
• Carbon marker or analyzing rod is lowered and placed against the side of the
cast
• A pencil is then used to draw a vertical line parallel to the marker or rod
• The procedure is repeated on two widely separated areas on other sides of
the cast
55

56. Three tripod marks (TM) should be widely
separated and must be made with the
vertical arm and the mounting table locked
in position
Drawing a vertical line (VL) parallel to the
side of the analyzing rod on three sides of the
cast The three lines should be as widely
separated as possible
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57. QUESTIONS
?????????
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