shammasm, intro to dentures, removable prosthodontics, rpd

2. Designing of removable
partial denture

3. Learning outcomes
1. List the differences between two
main types of RPD’s.
2. Explain the design sequence.
3. Describe step by step procedure
for designing RPD.
4. Explain the different color codes
for designing RPD.

4. Replace what is missing and
also preserve remaining tissues

5.  The objective of partial denture
designing can be thought of as
the control of denture
movement while not exceeding
the physiological tolerance of
the oral structures.

6. Differentiation Between Two Main
Types of Removable Partial
Dentures

7. Class I and II Class III
The
manner
in which
each is
supporte
d
Derive their
primary support
from tissues
underlying the
base and
secondary support
from the abutment
teeth
Derives all
of its
support
from the
abutment
teeth

9. Class I and II Class III
The
method of
impressio
n making
Dual
impression/
functional
impression
Anatomic
impression

10. Class I and
II
Class III
The need for
some kind of
indirect
retention
Needed
(because it
rotates about a
fulcrum)
Not needed

11. Class I
and II
Class III
The use of
a base
material
that can be
relined to
compensat
e for tissue
changes.
Acrylic-
resin is
generally
used as a
base
material for
distal
extension
bases.
Metal bases are
more frequently
used in tooth-
supported
restorations,
because relining
is not as likely to
be necessary.

13. Class I and II Class III
Requirement
s for direct
retention
a combination
clasp could be used
because it is a
combination of cast
and wrought
materials
incorporated into one
direct retainer, RPI,
RPA
Akers,
Embrasure,
Ring clasp

17. Design Sequence
 Path of insertion
 Rests
 Major connector
 Minor connectors
 Direct retainers
 Indirect retainers

18. Rests
Occlusal rests Premolars and
molars
Cingulum rests Maxillary canines
Incisal rests Mandibular canines
Interproximal
occlusal rests
On the dentulous
side
Extended occlusal
rests
Mesially tipped
molars

19. Kennedy Class III
Place rests adjacent to edentulous
space (both ends).
Exceptions:
Teeth incapable of providing adequate
support, poor crown/root ratio, or
uncorrectable periodontal disease.
If abutment tooth has improper
anatomy for the indicated rest.

20. Place rests adjacent to
edentulous space

21. Kennedy Class I & II
Mesial rest preferred
Distal rest preferred when:
abutment is rotated
plunger cusp/heavy centric contact on
mesial
large restoration on mesial

22.  If the rest is placed
on the distal of the
tooth adjacent to the
edentulous area,
when a posterior
force is applied the
tooth is tipped
towards the
edentulous area,

23.  which opens the
proximal contacts
between teeth
and moves the
tooth causing
mobility and bone
loss.

25.  When the rest is placed
mesially (away from the
edentulous area), the
force tends to move the
tooth towards the
adjacent tooth mesially.
 Thus the adjacent tooth
absorbs some of the
forces of occlusion.

26. Distal Extension-base RPD-Rest Position
Distal rest Mesial rest

27.  A tooth is better able to tolerate
vertically directed forces than
horizontal forces.

28. kratochalkboard1.2.wmv

29.  If the rest is placed on the distal side
of the abutment near the edentulous
area, the forces are not vertical but
almost horizontal in the region just
next to the abutment.

30.  As you move the rest anteriorly, the
forces are directed more favorably in
a more vertical direction in relation to
the edentulous area.

31. Major Connectors
 Assess tori, height of floor of
mouth, frenal attachments,
which may affect major
connector choice.

32. Mandibular Major Connectors
Lingual bar Whenever possible (8 mm space)
Linguoplate High frenum, floor of mouth less
than 8 mm, resorption of ridges
Want to stabilize teeth,
May need to add teeth to RPD
Want to avoid torus
Sublingual
bar
When the height of the floor of the
mouth in relation to the free
gingival margins will be less than
6 mm.

35. Mandibular Major Connectors
Lingual bar with
cingulum bar
(Kennedy Bar,
Double Lingual
Bar)
When wide diastema exists
between mandibular
anterior teeth
Cingulum bar
(continuous bar)
Excessive block-out of
interproximal undercuts
(crowding of teeth)
Labial bar Malpositioned or lingually
inclined teeth and Large
mandibular tori

36. 1. Lingual bar
2. Sublingual bar
3. Cingulum bar (continuous bar)
4. Linguoplate
5. Lingual bar with cingulum bar

37. Maxillary Major Connectors
Single palatal
strap
Bilateral tooth-supported
prostheses
Combination
anterior and
posterior
palatal strap-
type connector
Class I and II arches,
Long edentulous spans in
Class II, modification 1
arches, Class IV arches,
Inoperable palatal tori
Palatal plate-
type connector
Some or all anterior
teeth remain

40. Maxillary Major Connectors
U-shaped
palatal
connector
When a large inoperable
palatal torus exists, and
occasionally when
several anterior teeth are
to be replaced
Single palatal
bar
-
Anterior–
posterior
palatal bars
-

41. U-shaped palatal connector

42. Lingual bar major connector should
be located at least 3-4 mm inferior
to gingival margins
3-4 mm

43. 6 mm
Palatal major connector should be
located at least 6 mm away from
gingival margins.

44. Minor Connectors
 Connects components to the major
connector:
 Direct retainer
 Indirect retainer
 Denture base

45.  Should be rigid
 Should be located in an
embrasure
 Should taper towards the contact
area

46. Between one minor connector and
the other minor connector - 4 mm
4 mm

47.  Should form a right angle with the
major connector
90o

48. DIRECT RETAINERS
Occlusally
approaching /
Suprabulge /
Circumferential/
Akers

49. DIRECT RETAINERS
 Gingivally approaching / Infrabulge /
Bar-type / Vertical projection
• I bar
• Y bar
• T bar
• Modified
T bar

50. • Modified T bar
• T bar

51. I-BAR
Y-BAR

53. Direct Retainers
Cl III
 Clasp of Choice: Akers
 Embrasure clasp: on
dentulous side
 Ring clasp: on single molar or
tilted molar

57.  Use stress releasing retainers
 More load transferred to residual
ridge
RPI RPA
Combination
Clasp
Direct Retainers
Cl I & II

60.  Clasp of Choice: RPI
 If can’t use I-bar: RPA
 High frenal attachment, soft tissue undercut,
shallow vestibule
 If can’t use mesial rest: Combination Clasp
 Restoration, heavy occlusion, rotated tooth
RPI RPA
Combination
Clasp

62. Number of Direct Retainers
 4 - Greatest amount of retention
 (e.g. Cl. III, mod 1)
 3 - Less retentive, (Class II)
 2 - Absolute minimum (Class I)

65. Indirect Retainers
 For Class I & II only
 Position on the opposite site of fulcrum
line
 Perpendicular and far from fulcrum line
 Canine and premolar usually
 Rest at each end of lingual plate

68.  FORM OF INDIRECT RETAINER
 Auxiliary occlusal rest
 Cingulum rest
 Incisal rest

69.  Step by step procedure for
designing

70. Drawing the Design
 Absolute Accuracy
 Technician to place elements in
proper position & proportions

71. Drawing the Design
 Absolute Accuracy
 Single clear lines
 No guessing involved

72. Armamentarium for survey &
design

73. Color codes
 Brown – metallic component
 Blue – acrylic resin portion
 Red – rest seat, areas of the teeth
to be prepared, relieved or
contoured, tripod marks
 Black – survey lines, soft tissue
undercuts, wrought wire clasp, type
of tooth.

74. Red color- To denote action

75. Black color – To place survey lines

76. Brown color - For metal frame work

77. Blue color - For acrylic resin

78.  No single design philosophy
can be considered "correct"
over all others. Variations are
possible as long as diagnostic
information and good
mechanical principles form the
basis for the design.