Other forms of removable partial denture

1. Prof. Amal F. Kaddah

3. Other Forms of Removable Partial Denture
Dr. Amal Fathy Kaddah
Professor of Prosthodontic
Faculty of Dentistry
Cairo University

4. When you realize you've made a mistake, take
immediate steps to correct it.

5. Removable Partial Dentures (RPDs)
• Metallic Removable Partial Denture
• Acrylic Temporary Removable Partial
Denture
• Other Forms of Removable Partial Denture

6. I. Unilateral RPD
II. Swing-lock RPD
III. Overlay partial denture (R P overdentures)
IV. Implant supported RPDs
V. Attachments for RPDs
VI. Fixed-Removable partial dentures.
VII. Esthetic design of RPDs
VIII.Prototyping technologies that are used to fabricate
dental prostheses
Other forms of removable partial denture

7. VII- Esthetic design of RPDs
1. Rotational path of insertion
2. I bar
3. R L S
4. MGR clasp Design
5. Hidden Clasp/ Twin Flex/Saddle Lock
6. EthetiClasp TM
7. Equipoise
8. Virginia RP (Cu-sil Partial Denture. gasket retention systems.)

8. 9. Flexible Removable Partial Dentures
10. Tooth coloured occlusal approaching clasps (‘invisible’
clasps (optiflex)
11.Other alternatives
ABonding composite to clasp arm
Anodizing clasp arm
12. Precision & Semi-Precision Attachments for Removable
Partial Dentures

9. VIII. Prototyping technologies that are
used to fabricate dental prostheses
1. Stereolithography
2. Laminated object manufacturing
3. Solid ground Curing
4. Fusion Deposition Modelling
5. Selective Electron beam melting
6. 3D inkjet Printing
7. Laser powder forming techniques
a. SLS - Selective Laser
b.SLM – Selective Laser Melting

10. Tooth and Tissue Supported RPD Tooth Supported RPD
Metallic Removable Partial Denture

11. Types of Temporary RPDs
A. Interim Removable Partial Denture (RPD)
B. Transitional RPD
C. Treatment RPD
D. Immediate RPD
*Tissue Supported RPD

12. Other Forms of Removable
Partial Denture

13. CONTENTS
I. UNILATERAL RPD
II.SWING-LOCK RPD
III.OVERLAY REMOVALE PARTIAL DENTURE
IV.IMPLANT SUPPORTED RPDs
V.ATTACHMENTS FOR RPDs
VI.FIXED-REMOVABLE PARTIAL DENTURES
VII.ESTHETIC CLASPING PARTIAL DENTURES

14. Should be used with caution, as the
chance of the denture becoming
dislodged and aspirated is too great
I- UNILATERAL REMOVABLE PARTIAL DENTURES

15. Bilateral RPD Unilateral RPD
(Removable Bridge)
Which restore missing teeth and
extended on both sides of the
dental arch

16. * Long clinical crown of abutment tooth
*Buccal and lingual surfaces of the
abutment tooth must be parallel to
resist tipping forces
*Retentive undercuts should be available on
both the buccal and lingual surfaces of each
abutment
UNILATERAL REMOVABLE PARTIAL DENTURES

17. X
Unilateral RPD
(Removable Bridge)

18.  Which has extensions into undercuts on
the labial surfaces of the teeth.
II- THE SWING-LOCK RPD

19. It consists of a labial/buccal retaining bar,
hinged at one end and locked with a latch
at the other, together with
The swing-lock RPD
a reciprocating lingual
plate to gain a maximum
retention and stability.

20. The bar incorporate rigid struts or an
acrylic veneer which make prosthesis
immobile.
The swing-lock RPD

21. A labial acrylic veneer

22. INDICATIONS
 Missing key abutment
 Reduced bone support

23.  Gingival recession

24. The retching ( gagging)
Patient
Maxillofacial defects

25. CONTRINDICATIONS
Poor oral hygiene
High smile line
Soft-tissue limitations
Certain malocclusion
Alveolar limitations

26. •The denture can be particularly
helpful where the remaining
natural teeth offer very little
undercut for conventional clasp
retention.
Advantages

27. • The “gate” can carry a labial acrylic veneer. This
veneer can be used to improve the appearance
when a considerable amount of root surface has
been exposed following periodontal surgery.
Advantages

28. Disadvantage
As this type of denture covers a
considerable amount of gingival
margin, the standard of plaque
control must be high.

29. III- OVERLAY REMOVABLE PARTIAL DENTURE
• Any removable dental prosthesis constructed over one
or more remaining natural teeth, roots of natural teeth,
and/or dental implants, providing additional support,
stability & retention
= Overlay denture,
= Overlay prosthesis,
= Superimposed prosthesis

30. • The endodontically treated abutment is prepared by
removing the clinical crown few millimeters above the
free gingival margin to create a dome-shaped
preparation with a lightly chamfered margin extending
slightly subgingivally.

32.  Metal coping is made and
cemented over the
abutments.
 The removable partial
overdenture is then completed
in the usual manner.

33. 1- Preservation of the alveolar ridge
Advantages of Overdentures
• Improved occlusal stress distribution.
• Edentulous mouth Bone loss of
6.6mm in 7 years.
• Dentate mouth Bone loss of 0.8 mm in
7 years.
TallgreenA , Acta Odontol Scand 24: 195-239, 1966.

34. 2- Preservation of the remaining teeth
3- Preservation of proprioceptive
response:
Enhance neuromuscular control,
occlusal awareness and biting force.

35. 4.Improved Crown to Root ratio (C/R)
5.Support and Stability.
6.Controlled Retention through the use of
attachments
7.Increase the patient acceptance and
Psychological Benefits
8.Convertibility
9.Conventional dental procedures

36. Disadvantages of Overdentures
Gingival irritation
1. Covering the gingival margins
• Periodontal breakdown of the abutment teeth.
2. Caries susceptibility
3. Bony undercuts
Limitation of the path of insertion
Esthetic, Pain or retention Problems

37. 4. Inadequate reduction of the
abutment teeth may cause:
 Increased vertical dimension.
 Encroachment of the interocclusal
distance.
 Esthetics

38. Interference with proper
setting up of teeth
Fracture of artificial teeth
Fracture of the denture base

39. 5. Expense and Time consuming
6. Bulkier
7. Removable Prosthesis

40. Types of over-Dentures
Tooth supported over-dentures.
Implant supported over- denture.
Overdentures can be classified into 2 categories,
depending on the types of abutment providing support

41. 1. Definitive over-denture
2. Interim and transitional over-dentures
3. Immediate over-denture
4. Attachment retained over-denture
Types of tooth supported Over-dentures
This type of overdenture overlies natural tooth
structures

42. Definitive over-denture
Conventional partial over-denture
Constructed over 1 or more abutment teeth
Could be made entirely of
acrylic resin or in conjunction
with metal bases

43. Interim and transition overdentures
• Temporary RPDs Used for patients in transition or
preparation phase until permanent overdenture
constructed
• Patient old partial denture can be modified & used by
extending the denture & add new artificial teeth using
self cure acrylic resin

44. Immediate overdenture
• Constructed prior to preparation of
abutment teeth & ready for insertion after
preparation& reduction
• It enhances patient’s ability & adaptability to
wear dentures

45. Attachment retained over-denture
 Constructed with an incorporated attachment to
improve retention
 More expensive & more time for construction
Indicated for patient with good oral hygiene & low
caries index
 The abutment teeth should have good periodontal
condition & adequate bone support

46. I V- IMPLANT SUPPORTED RPDs
Lack of adequate support (tooth/soft tissue)
results in displacement of bilateral and
unilateral distal extension removable partial
dentures.
Placement of implants is one option for
managing this problem
Distal implants effectively convert a
Kennedy Class I or II denture to a Kennedy
Class III denture.

47. • This type of over denture gains support from
both the dental implants and intraoral tissues
• Implant-supported overdenture provides better
stability of prosthesis and reduce bone
resorption

48. Completed overlay RPD
• Implant-assisted overlay partial denture provides
favorable biomechanics and also offers optimal
esthetics for lip/cheek support and replace hard and
soft tissue

49. Why Implants and RPD in this patient?
• Implants were in grafted bone
• Implant/restoration ratio unfavorable
• Facilitate support, stability, retention
• Implants, teeth, mucosa
• Esthetic considerations

50. V- Attachments for RPDs
1. Attachment retained Partial denture
2. Attachment retained Partial over-denture
Classification of attachments based on their
location and Design:

51. 1) Stud Attachments.
2) Magnetic Attachments.
3) Telescopic design
4) Bar attachments.
1- Attachment retained Partial denture
1) Intracoronal stud attachments.
2) Extracoronal stud attachments
2- Attachment retained over-denture

52. a) Rigid attachment Doesn’t allow movement of
denture base, provide adequate retention.
May induce more torque on abutment.
b) Resilient attachment designed to permit
some controlled movements of the
denture base, during functional loading.
Induces less torque on abutments.
Resilient attachment
Rigid attachment
Classification of attachments based on their
movement and function:

53. a)Precision Attachments
Ready made attachments (prefabricated from
milled alloys, made of precious metal)
b)Semiprecision Attachments
Fabricated in the dental laboratory
Classification of attachments based on their method of
fabrication and the tolerance of fit between the components

54. Precision Attachments
• They are Ready made attachments, their components
are machined in special alloys under precise tolerance.
• Box or key way
• Frictional Retention
• One path of insertion
• Allows minimal to no rotation
• The components are interchangeable
and usually easier to repair when necessary

55. • A precision attachment is prefabricated from
milled alloys, made of precious metal, and fit of
two working elements. They are generally
intracoronal and non-resilient..
Precision Attachments
• Precision attachment can be described
as a retainer used in fixed and removable
partial denture.

56. • Fabricated in the dental laboratory
• Economic benefits, easily fabrication
• Less intimate fit
• Principle to relieve stress
 Allows movement
 Resilient or stress releasing
• Lose stress distributing properties
Semiprecision Attachments

57. A. Intracoronal attachments
Precision
Non-Resilient
B. Extracoronal attachments
Precision / Semi-Precision
Resilient / Non-Resilient
1- Attachments retained Partial dentures
(Direct retainer Attachments)

58. Uses for Attachments Removable partial
dentures
•Esthetics
•Retention
•Function

59. • Metal receptacle (female part
=matrix) is incorporated entirely
within the contour of the crown.
A- Intracoronal attachments:
• Closely fitting component (Patrix = male part)
which is incorporated within the denture)
mates with the receptacle

60. Excessive tooth reduction and
compromised embrasures, which
result in oral hygiene and
periodontal situation problems.
In addition, all intracoronal attachments are
non-resilient.
A- Intracoronal attachments:
Crown

61. Female portion of the attachment is
within the crown

62. B- Extracoronal attachments
• All of their mechanism outside the contour of a
tooth.
Portion of attachment
outside of crown/retainer
contours (male or female)
Minimal tooth reduction is necessary

63. B- Extracoronal attachments

64. Portion of the crown outside the crown
abutment

65. Disadvantages
•Extra tooth preparation for intracoronal
attachment
•If insufficient reduction, Over-contoured
retainer

66. Contraindications
 Short clinical crowns
 Large pulps Dexterity problems
 Bruxers?

67. 2- Over-Denture Attachment
1- Stud Attachments.
2- Magnetic Attachments.
3- Bar attachments.
4- Telescopic retainers.
It could be in the form of:

68. Consists of a male (stud), usually
attached to metal coping cemented
over prepared abutment
and female (housing) embedded in
the fitting surface of overdenture
base.
1- Stud attachments

69. a- Intra-Radicular:
The stud is attached to the fitting surface of the
denture and the housing is incorporated in the
abutment. e.g : Zest Anchor
1- Stud attachment

70. b- Extra-Radicular:
The stud is attached to the metal coping cemented
over the prepared abutment, while the housing is
embedded in the fitting surface of the denture.
e.g : Ceka , Rotherman, Gerber
1- Stud attachment

71. Overdentures with stud attachments
Female housing is embedded in the fitting surface
of the acrylic overdenture.
1- Stud attachment

72. 1- Stud attachment

73. Examples of stud attachments
include:
•Ball and socket attachment
•O-rings attachment
•Extra-radicular attachment (ERA)
•Locator (self-aligning) attachment
1- Stud attachment

74. Ball attachment:
implant abutment while the socket (female
unit) is incorporated on the fitting surface of
the overdenture
1- Stud attachment
• This is the simplest system,
consisting of a ball and a socket.
• The ball (male unit) is made on the

75. This system consists of a metal
abutment analogue and a metal O-ring
fitted with silicone ring.
O-rings (ball type)attachment:
Note: Implants must
parallel to one another
O- ring
1- Stud attachment

76. • Favorable stress distribution patterns (ball type only)
• Minimize the risk of implant loss secondary to implant
overload
• " Simple to use "
• Less initial cost than a
tissue bar
O-rings (ball type)attachment:
1- Stud attachment

77. •This system is deemed most suitable
for parallel implant abutments.
Extra-radicular attachment (ERA):
Male Color Code:
Black fabrication male
White final male with light retention
Orange final male with moderate retention
Blue oversize male with heavy retention
Grey oversize male with very heavy retention
Yellow extra oversized male with more retention than grey
Red extra oversized male with more retention than yellow
1- Stud attachment

78. Completed overlay RPD
• White-colored (the least amount of retention) ERA were
used on the implants.
• Support, stability, and retention are achieved
• Support provided by the positive occlusal and cingulum
rests and the full palatal coverage
Extra-radicular attachment (ERA):

79. It is usually indicated when the implant
abutments are non-parallel to each other
1- Stud attachment
Locator (self-aligning) attachment:

80. *Can be used in cases of limited inter-arch space.
*Can accommodate inter implant angulations up
to 40°.
1- Stud attachment
Locator (self-aligning) attachment:

81.  Provides dual retention, one is mechanical and
another is frictional.
 The nylon male head is slightly oversized than its
female component which provides frictional fit.
1- Stud attachment
Locator (self-aligning) attachment:

82. The outer margin of attachment engages the shallow undercut
area on abutment to provide outer mechanical attachment.
Locator (self-aligning) attachment:
1- Stud attachment

83. *They cannot be used in cases where
rigid restoration is required.
*Regular replacement of male nylon
part due to constant wear and tear.
Disadvantages of using locator attachments:
1- Stud attachment
Locator (self-aligning) attachment:

84. 2- Magnetic attachments
 Small, strong mini magnets
 One of poles cemented in a prepared
cavity in endodontically treated
abutment & the other attached to
denture base

85. Maxillary and mandibular removable overlay
dentures using magnetic attachments

86. Dental magnet placed on abutment
keepers ready to be cured to the denture

87. A Kennedy class II defect dentine was restored by
a magnetic attachment- supported RPD

88. 3- Bar attachment
A bar contoured to connect abutment teeth
together, run parallel & overlie residual ridge
Provide support & retention for overdenture
& splint abutment teeth
Bars may be in form of preformed metal or
plastic

89. A- Bar units
Rigidly fixed to copings, don’t allow any
movement between bar & sleeve
Transmits occlusal stresses totally to
abutments “tooth born”

90. B- Bar joints
Resilient attachments allowing movement
between bar & sleeve
Support provided by both residual ridge &
abutment teeth “tooth tissue born”

91. Bar attachment
Sleeve
Clip, into which
the bar will slot
Bar

92. • The application of computer-aided design and
computer-aided manufacturing (CAD/CAM) in the
fabrication of the overdenture framework
simplifies the laboratory process of the implant
prostheses.
CADCAM-Bar

93. • The CAD/CAM System was utilized to produce a
lightweight titanium overdenture bar with locator
attachments.
CADCAM-Bar

94. • The digital workflow of
CAD/CAM milled implant
overdenture bar allows us
to avoid numerous
technical steps and
possibility of casting errors
involved in the conventional
casting of such bars.
CADCAM-Bar

95. 4- Telescopic Overdenture
“Telescopic Overdenture”= Milled
primary copings with parallel walls and
the denture has secondary copings.
Retention is gained from friction due to the
parallel walls of the primary copings and
the precise fit of the secondary copings, full
extension of flanges is not critical.

96. Gold or metallic cast Copings and
telescopic crowns are a method of
improving overdenture retention.
These may be conical crowns (semi-
parallel wall) with a friction
adaptation at the marginal area of the
abutment or Milled crowns for larger
areas and parallel surfaces.

97. Friction retention is more
commonly used in exclusively
tooth-supported overdentures that
are not supported by soft tissue.

98. VI- FIXED-REMOVABLE PARTIAL DENTURE
The replacement of missing teeth
and restoration of alveolar contour.
Situations of trauma and cleft lip
and palate, and after the surgical
excision of pathoses.
 Reduction of the surrounding volume of hard
and soft tissues is even more pronounced

99. Andrew's bridge system: an
aesthetic and functional
option for rehabilitation of
compromised maxillary
anterior dentition

100. • The Andrews fixed dental prosthesis was
first introduced in 1976 by James Andrews,
• Consisted of a bar soldered to retainers at
each end onto which a denture is clipped.

101. - Extensive alveolar bone loss
- Median diastema
- Unfavorable skeletal
relationships
INDICATIONS

103. Precision attachments can be used in conjunction
with other conventional means of retention for
removable prostheses
Gold crowns have been placed on
the molar teeth incorporating rest
seats, guide planes and undercuts to
achieve support, stability and
conventional retention. Retention is
achieved anteriorly using a precision
attachment on the upper left lateral
incisor root.

104. the female ‘clip’
attachment is
embedded into the fit
surface of the denture
This tooth has been root treated and prepared for a
cast post and diaphragm onto which is soldered the
male component of a Rothermann type precision
attachment;

105. VII- ESTHETIC DESIGN OF RPDs

106. Alternatives to the circumferential clasp
1. Rotational Path
2. I Bar
1. RLS
2. MGR
5. Saddle-Lock ®
6. EsthetiClaspTM
7. Equipoise®
8. Gaskets
VII- ESTHETIC DESIGN OF RPDs

107. 9. Flexible (polystyrene/ valplast)
10.Tooth coloured occlusal approaching
clasps (‘invisible’ clasps (optiflex)
11.Other alternatives
 Bonding composite to clasp arm
 Anodizing clasp arm
12. Precision & Semi-Precision Removable
Partial Dentures

108. 1. Rotational Path Partial Dentures
Dual Path of Insertion Partial Dentures
• Conventional
– All rests seat simultaneously
• Rotational Path
– Insertion sequence
• First segment containing rotational
center
• Second segment rotated into final seat
Conventional Vs Rotational Path RPD

109. 1- Elimination of clasps on one side of RPD
Rotational Path RPD
Objectives
3- Esthetic and Appearance
2- Create Guiding planes and retentive areas

110. Place rigid element into undercut
Rotate other end into place
(clasps)
Rotational Path RPD
1- Elimination of clasps on one side of RPD

111. Place in Undercut, Rotate Clasp into Place

112. Diagrammatic representation of seating of the
RPD framework, eliminating anterior clasps.
[From Jacobson: JPD 1994; 71:271-7].
a = long anterior rest
acting as the rotational
center for insertion of
RPD.

113. RPD rotated in position. No anterior clasp.
a = minor connector relieved following the
curve of insertion.
b = Minor connector providing retention

115. Large deep rests to provide
support, reciprocation
Reciprocation from adjacent
teeth
No rigid elements in undercut
Principles

116. Conventional versus Rotational Path

117. Guide planes in addition to Esthetic they
provide retention and effective in
stabilizing weakened teeth
2- Create Guiding planes and retentive areas

118. A cast in a tilted
relationship
represents a path of
placement toward
the side of the cast
that is tilted upward

119. Without guiding planes, Clasps designed are ineffective when
restoration is subject to dislodging forces in occlusal direction

120. Undercuts may affect appearance when anterior
teeth are to be replaced Mesial undercuts on teeth
adjacent to saddle ; bony undercut labially
Cast tilting may reduce anterior spaces and
reduce blocking out of labial undercut
3- Esthetic and Appearance

121. Undercut on the mesial aspects of the abutment teeth >>
if the RPD is constructed with this vertical path of insertion >>
Unsightly gaps between the saddle and the abutment teeth gingival
to the contact point >> Giving the cast a posterior tilt >> avoid
these gaps >> better appearance
This unsightly gap can be avoided by giving the cast a posterior tilt

122. BY POSTERIOR TILT THIS
UNSIGHTLY GAPS CAN BE
AVOIDED
By rotational path of insertion

123. Path of insertion is marked on
the cast using parallel lines
Minimal anterior spacing is
achieved with an upwards and
backwards path of insertion

124. How is problem of interference
overcome ?
•Avoidance - changing path of insertion
• Elimination - modify teeth (or bone ?)
• Exploitation - sectional dentures
- Surgery to remove interfering structures
- Contouring the tooth surface

125. For example, if a bony undercut is present labially , insertion
of a flanged denture along a path at right angles to the
occlusal plane will only be possible if the flange stands away
from the mucosa or is finished short of the undercut . This
can result in poor retention and appearance

126. Posterior tilt f the cast, thus the path of insertion is
parallel to the labial surface of the ridge. Thus, it is
possible to insert a flange that fits the ridge accurately

127. Undercut Alveolar Ridges The labial
undercut here is a source of ‘interference’

129. 2. I bar
• Mesial occlusal rest
• Distal guide plane with proximal plate
• Buccal bar clasp
• Less visible than a circumferential clasp

130. 3. RLS Clasp
 Mesio-occlusal Rest,
 A distolingual L-bar direct retainer
 Distobucca Stabilizer
Advantages:
• Reduces torque on the abutment tooth.
• Clasp disengagement as the distal
extension base moves tissue-ward in
function
Hiding Denture Clasp

131. The design of clasp for a distal
extension RPD that helps preserve both
3. RLS Clasp
the abutment teeth and
the tissues of the
edentulous ridge is
described.

132. 4. MGR Clasp Design
Mesial Groove Reciprocation
• Retention:
– 19 gage round W.W. I bar
– Retentive dimple at distal buccal
• Reciprocation
– Mesial groove/rest
• Distal proximal plate

133. distal facial I-bar
(wrought wire 19
ga.) Mesial
Groove
Reciprocation
shallow rest
Lingual view

137. 5. Saddle-Lock ® - hidden clasp
r = retainer that emerges from
denture base to engage the
undercut on the proximal tooth
surfaces.
b = bracing arm
p = proximal minor connector
with relief space to allow
flexure of the retainer.

138. Saddle-Lock ® - hidden clasp
• Advantages
– Esthetics
• Limitations
– No metal horizontal shoe
extension
– Short retentive arm
– Adjustment access

139. • Utilizes proximal
undercuts
• Encircles tooth 181°
L clasp
C clasp
6. EsthetiClasp TM

140. • L-Clasp
– Clasp arm extending from
lingual minor connector
– Independent reciprocal rest
– L > rigidity than C
EsthetiClasp TM

141. C-Clasp
– Modified back-action clasp
– Rest incorporated in clasp
– C > flex than L
EsthetiClasp TM

142. 7. Equipoise RPD System
• Esthetic retentive concept for distal extension
situations
• Rests placed away from edentulous
span
• 1mm vertical inter-proximal reduction
between abutment and adjacent tooth
Proposed by J.J. Goodman

143. Equipoise Lingual back-action
clasp reciprocated
Minimal facial clasp
display.1mm

144. Labial view of a different RPD with an equipoise
clasp on tooth 22, satisfying the aesthetics as the
clasp assembly is inconspicuous

145. • Optional Bu-Li retentive
groove at mid and
gingival third junction
on distal surface of
abutment tooth
Equipoise RPD
System

146. Occlusal view of the clasps placed on the
13 and the 24 as part of a Kennedy class
IV RPD.
Equipoise Clasp:

147. Equipoise® - Critique
• Caries susceptible preparation
• Mesial proximal plate torque
• Minimal Stress release
• Potential loss of proximal space (Greater
preparation)
• Requires greater surveillance
• Kennedy Class III situations
• Visible metal mesial embrasure display

148. •Cu-Sil is a tissue-
bearing appliance
featuring a soft
elastomeric gasket
8- Cu-Sil® PARTIAL OVERDENTURES
Gasket Retention Systems

149. •It clasps the neck of each
natural tooth, sealing out
food and fluids, cushioning
and splinting each natural
tooth from the hard denture
base.
8- Cu-Sil® PARTIAL OVERDENTURES
Gasket Retention Systems

150. 8- Cu-Sil® PARTIAL OVERDENTURES
Gasket Retention Systems
• It helps prevent tooth loss and
improves the prognosis of loose,
mobile, isolated, elongated or
periodontally involved
abutments by eliminating wear,
stress and torque.

151. It is a denture with holes, lined by a gasket of
silicone rubber, the holes thus providing space for
remaining natural teeth to emerge into the oral cavity
through the denture
8- Cu-Sil® PARTIAL OVERDENTURES
Gasket Retention Systems

152.  It is an acrylic tissue-bearing appliance
featuring a soft elastomeric gasket which
clasps the neck of each natural tooth,
 Sealing out food and fluids, and
cushioning and splinting each natural
tooth from the hard denture base.
8. Gasket Retention Systems(Cu-sil)

153.  Cu-Sil – Elastomeric
 No clasps
 Silicone gasket around teeth
 Retaining their very few remaining teeth.
8. Gasket Retention Systems(Cu-sil)

154.  Flexite/Valplast –Thermoplastic
 Compensates for lost bone/gingival height
8. Gasket Retention Systems(Cu-sil)

155.  It is an innovative approach to
preserve the few remaining
natural teeth
 Cu-sil denture is the simplest
RPD, No special impression
techniques or materials are
required.
8. Gasket Retention Systems(Cu-sil)

156.  It is a practical alternative to overdentures
 It can be used for roofless uppers and free
end partials where tooth contour is
insufficient to cast clasps.
 It improves the prognosis of loose, mobile
isolated elongated or periodontally involved
abutments
8. Gasket Retention Systems(Cu-sil)

157. Mechanical undercut of the remaining natural teeth
was examined with the help of a surveyor and blocked
out using dental plaster.
8. Gasket Retention Systems(Cu-sil)

158. It is an excellent option for the patients who
want to replace their missing teeth while
retaining their very few remaining teeth.
8. Gasket Retention Systems(Cu-sil)

159.  Preserving the remaining natural teeth
and have a positive effect on retention
and stability of dentures.
8. Gasket Retention Systems(Cu-sil)
 It gives the patient
psychological satisfaction
of retaining the natural
teeth.

160.  Future add-ons and relines are possible.
 The Cu-sil like denture can serve as conventional
full denture if the patient later loses all the natural
teeth.
 Cu-sil dentures serve as a solution for lone
standing or very few remaining teeth present in the
dental arch.
 No need of endodontic procedures
8. Gasket Retention Systems(Cu-sil)

161. Cu-Sil
Bitem
8. Gasket Retention Systems(Cu-sil)
• Limitations
– Hygiene
– Caries potential and Perio risk
– Liner lifespan
– Deterioration
•Bond
•Elasticity
•Yeast

162. Difficult to adjust, polish
Tend to tear, rough surface
8. Gasket Retention Systems(Cu-sil)

163. 9- FLEXIBLE (POLYSTYRENE/ VALPLAST)
• Biocompatible nylon and
thermoplastic resin-flexibility and
stability.
• Color, shape and design of valplast
partials blend with natural
appearance of gingiva making
prostheses nearly invisible.

164. FLEXIBLE (POLYSTYRENE/VALPLAST)
• Strength of valplast resin doesn’t require a metal
framework-eliminates metallic taste.
• Enables partial to be fabricated thin enough with non
metallic clasps.

165. Polymethylene clasps are alternative to metal clasps
10. Tooth coloured occlusal approaching clasps
‘Invisible’ Clasps (Optiflex)
Non-metal, White
Opti•Flex Coating applied to metal clasps
Thick, white, ugly clasp?
Porous (plaque)
Fatigue
Bulky (comfort)

166.  Bonding composite to clasp arm
 Anodizing clasp arm
11- Other alternatives

167. 12. Precision & Semi-Precision RPDs
Partial overdenture Extracoronal attachments

169. Summary - Esthetic Clasps
• Retention location
• Components
• Preparation
• Lab support
• Colour

170. 1. Stereolithography
2. Laminated object manufacturing
3. Solid ground Curing
4. Fusion Deposition Modelling
5. Selective Electron beam melting
6. 3D inkjet Printing
7. Laser powder forming techniques
a. SLS - Selective Laser
b. SLM – Selective Laser Melting
VIII- Prototyping technologies that are
used to fabricate dental prostheses

171. Stereolithography (SLA)
• Fabrication of surgical drilling guide templates,
• Constructing customized implants for cranioplasty
• Construction of the orbital floor
• Surgical guide for implant placements
• For temporary crowns and bridges and creating wax patterns.
SLA [Stereolithography] is regarded as the first Rapid prototyping process and was
developed in the late 1980s. (Torabi et al., 2014)
The various applications of SLA in dentistry includes:
The layer thickness for SLA printed models is 50-150 micro meters. Layer build
thickness of the material is about 0.05 to 0.2mm (plane resolution) and minimum
vertical platform movement is about 0.0017mm. (Chia and Wu, 2015 , Abduo et al., 2014)

172. Fused Deposition Modelling (FDM):
• Fused Deposition Modelling or Fused filament Fabrication
was developed by S. Scott Crump in the late 1980s.
• Printed wax patterns and fixed bridges
• Based on the principle of use
of a ceramic paste which is
coiled as a filament or wire.
FDM filament

173. Fused Deposition Modelling (FDM):
• The layer thickness of the Fusion deposited material is about
0.178 and 0.356mm for the extruded thermoplastic material.
(Zandparsa, 2014)
• Used to build material models in
layer by layer fashion.
• This technique is applied in the
fabrication of Thermoplastic resins
for the fabrication of wax pattern
frameworks.
Thermoplastic pattern

174. Selective Electron Beam Melting:
•Selective Electron Beam melting
(SEBM) manufactures parts by
melting metal powder in layers by
means of high vacuum electron
beam.

175. • Electrons are used rather than lights so the
materials printed are fully dense, void free
and extremely strong when compared to
other techniques.
•SEBM is employed in creation of highly
porous Titanium Implants for Maxillofacial
customized reconstructions. (Van Noort, 2012))

176. Laser Powder forming techniques
• This technology is classified into two types based on the
material used:
1- Selective Laser Melting and
2- Selective Laser Sintering
The terms SLS is used to describe fabrication of pattern from
ceramics or polymers whereas SLM is used to describe the
fabrication of pattern from metals. (Abduo et al., 2014)

177. Laser Powder forming techniques
•This technique uses laser
on a fine layer of powder
to create a melted metal
pool so that the powder
particles fuse together.
Laser melting

178. The various materials used to
create prostheses include:
• Titanium and its alloys,
• Cobalt chromium alloys
(Van Noort, 2012; Abduo et al., 2014)
Laser melting
Laser Powder forming techniques

179. Prosthodontics Applications
1. Removable Dental Prostheses
Fabrication of removable partial denture frameworks.
2. Fixed Dental Prostheses (crowns and bridges )
3. Craniofacial Prostheses
4. Implants.

180. Removable Dental Prostheses fabricated
by digital printing
The digitization of Dental process,
which summarizes the 3d Printing, Is
the beginning to deliver great
accuracy in Removable
prosthodontics.

181. The various manufacturing materials
used in Layered Manufacturing includes
• Cobalt Chromium,
• Titanium and its alloys,
• Polymethyl Methacrylate,
• PEEK,
• Photopolymerising resins,
• Polycarbonate and
• Nylon (polyamides).

182. The first documentation of a CAD
designed fit framework was in 2009,
(Bohnenkamp, 2014) from which
various techniques have been
described for fabricating removable
partial denture frameworks.

183. RPD frame works uses SLM
technology for creating patterns, in
which material is built layer by layer
and the size of this thin layer is of 20
micro meters.
(Van Noort, 2012)

184. Moreover the shape of the powder
particles need to be spherical or
equiangular in order to create smooth,
dense, homogenous surface
properties with good hardness and
corrosion resistance. (Peek Devin2014)

185. • SLM fabricated Cobalt Chromium frameworks
showed better accuracy surface properties
Co-Cr Frameworks Accuracy and fit of SLM fabricated frameworks

186. The nickel free and beryllium
free cobalt chromium alloys
are the material of choice for
allergic patients
Hems and Knott, 2014; Xin et al., 2013)

187. PEEK
• Light weight,
• Strong,
• Comfortable,
• The accurate digital design matches the patient’s individual anatomy
• Stable taste proprioception because it is metal free,
• No thermal or electrical conductivity,
• Shock absorber during chewing and also
• The white colour of the framework gives and enhances better esthetics.
The advantage of using PEEK material as partial Denture
framework are:

188. •A modified PEEK material
containing 20% ceramic
fillers presents:
•High biocompatibility,
•Good mechanical and
chemical properties
PEEK Framework

189. • Modulus of elasticity is 4gpa which reduces
the stress transferred to the abutment and
also simulates bone.
• The mechanical property includes melting
point of 343 degree c, thermal conductivity
of about 0.25 wt/ tensile strength Mpa and
water sorption for 24 hrs is 0.1%.

190. Photopolymerising resin
• UV rays initiate the reaction and changes
the properties of photopolymers.
• The physical property of the material can
be changed from liquid to solid when the
photopolymers are exposed to UV light,

191. Photopolymerizing resin
• The light source initiates chemical
reaction, changes the structure,
modifies the chemical and
mechanical properties.
• In additive manufacturing Jetted
3d printers uses this polymer
liquid to fabricate prosthesis
Photopolymer resin framework

192. Overview of Fabrication of
Removable prostheses
The main objective for designing a RPD
framework includes:
1. Simplicity,
2. Esthetics,
3. Biomechanics and
4. Patient comfort.

193. The design fabrication of 3D Printing of
Removable partial Denture framework
includes basically four steps
1. The design process
2. Deciding the contour
3. Build-up of the tissue surface
4. Creating the polished surface
(Van Noort, 2012; Utela et al., 2008)

194. The design process
•The first step is scanning the data
Various methods of scanning are used
throughout dentistry including:
• Laser scanning
• Light scanning
The Design process

195. 1- The design process
• After optical scanning of the
master cast or impression or
the patient’s oral cavity
directly, various point clouds
are created which gives
surface and volume to the
3D model design
Optical scanning

196. 2- In the designed model,
electronic surveying is carried
out which paves way for
design of path of insertion and
desirable undercuts.

197. 3- After surveying the design,
fabrication of the shape of
the components of
removable partial denture
framework is carried out
using 3dimensional software.
Polishing of frameworks

198. 4- The next process is the
final process where
SLM fabricates the
metal framework from
the stl model data that
was fed to the
machine.
Polishing of frameworks

199. • The metal RPD framework were
built successfully and various
studies proved to show that the
3D printed frameworks had
better design and accuracy
when compared to the
traditional casting methods.
Polishing of frameworks

200.  The choice of the RPD design should be
based on biologic as well as mechanical
principles.
 The dentist responsible for the treatment
rendered must be able to justify the design
used for each case in keeping with these
principles.
Conclusion

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204. When you find a Dream inside your heart
Don't ever let it go