Connectors are parts of a fixed partial denture that join the retainers and pontics. There are two main types - rigid and non-rigid. Rigid connectors can be made through casting, soldering, welding or milling. Soldering involves joining metal components using a filler metal with a lower melting point. Proper design of connectors is important for strength, hygiene, and esthetics. Connector size, shape, and position must allow for adequate strength and plaque removal.

1. Connectors For Fixed
Partial Dentures

2. Parts of the bridge
•Retainers
•Pontic
•Connector

4. Fixed Partial Denture
Component Parts
1- Retainers
2- Pontic
3- Connectors

5. Definition
Types
Design
Soldering
Welding

6. Connectors are those parts of a fixed partial
denture (FPD) that join the individual retainers
and pontics together

7. I. Rigid connectors
II. Nonrigid connectors

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1- RIGID CONNECTORS
Rigid connections in Metal can be made by casting,
soldering, or welding.
Porcelain connectors
Loop connectors
Milled connectors

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Rigid connectors can be done by
Casting
Soldering
Welding
Milling
Rigid connectors must be shaped and incorporated into the wax
pattern after the individual retainers and pontics have been
completed to final contour

10.  a. Cast Connectors
They are shaped in wax as part of a multiunit wax
pattern (one-piece casting)
 Convenient, minimizing laboratory steps
 Liability to distortion during wax pattern
removal from the cast
 Restricted to simple restorations
I. Rigid Connectors

12. b. Soldered connectors
Soldering involves the joining of metal components by the
use of a filler metal or solder alloy having a lower melting
temperature than the parts to be joined
The parts being joined are not melted during soldering but
must be thoroughly wettable by liquefied solder
I. Rigid Connectors

14. Welding depends on melting adjacent surfaces
with heat or pressure. Sometimes a filler metal
whose melting temperature is about the same as
that of the parent metal can be used

16. Soldering: filler metal has a melting point below 450°
C
Brazing: filler metal has a melting point above 450° C

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Dental Brazing

18. b. Soldered connectors
 Connectors to be soldered are waxed to final shape
and then sectioned with a thin ribbon saw
 The surfaces to be joined should be flat and parallel
 An even gap width of 0.25 mm is recommended
 Cleanliness of the surfaces is very important to allow
good wetting by the solder alloy
I. Rigid connectors

20. c. Loop Connectors
 Required when an existing diastema is to be
maintained in a fixed prosthesis
 The connector consists of a loop on the lingual
aspect of the prosthesis connecting adjacent
retainers and/or pontics.
 Meticulous design is important to allow proper
hygiene
I. Rigid connectors

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PORCELAIN CONNECTORS

23. II. Nonrigid Connectors
Indicated when it is not possible to prepare abutments
for an FPD with a common path of insertion
Complex, large FPDs can be segmented into shorter
components to minimize the induced stresses
The design consists of a mortise (female component)
prepared within the contours of the retainer and a tenon
(male) attached to the pontic

24.  The non-rigid connector could be either of the precision type or non-
precision type. The precision type involves a female part prepared
within the contour of the retainer, and a male part attached to the
pontic and fitting into the female part.
 The non-precision type could be in the form of occlusal rest,
subocclusal rest or lingual rest.

26. 1-Connectors must be sufficiently large to prevent distortion or fracture
during function but not too large; otherwise, they will interfere with
effective plaque control and contribute to periodontal breakdown by time.
2-Adequate access (i.e., embrasure space) must be available for oral hygiene
aids cervical to the connector.
3-For esthetic FPDs, a large connector or inappropriate shaping of the
individual retainers may result in display of the metal connector ,which
may compromise the appearance of the restoration.

27. 4-The tissue surface of connectors is curved faciolingually to facilitate cleansing. In
a buccolingual cross section, most connectors have a somewhat elliptical shape.
5-The connectors should occupy the normal anatomic interproximal contact areas
because encroaching on the buccal, gingival, or lingual embrasure restricts
access. However, to improve appearance without significantly affecting plaque
control, anterior connectors are normally placed toward the lingual.

28. Connector Design
Size
 They should be sufficiently large to withstand stresses
and prevent distortion or fracture during function
 If small failure
 If too large small embrasures hygiene is
impeded

30. Shape
 Tissue surface should be highly polished and curved
faciolingually to facilitate cleansing
 Mesiodistally, it is shaped to create smooth transition
from one component to the other
 Buccolingually elliptical in shape to provide strength

32. Position
Connectors are normally placed towards the lingual to
improve appearance without affecting plaque control

35. Connectors For Fixed
Partial Dentures

36. Parts of the bridge
•Retainers
•Pontic
•Connector

38. Fixed Partial Denture
Component Parts
1- Retainers
2- Pontic
3- Connectors

39. Definition
Types
Design
Soldering
Welding

40. Joining components of fixed partial dentures
Building up proximal contacts
Repairing casting voids or broken joints

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Factors affecting solder joint strength
1- Soldering Gap Width.
2- Solder Alloy
Types
Solder's main requirement
3-Soldering flux and antiflux
4- Soldering Investment
5-Heat source

42. Soldering gap width
As Soldering gap width increases soldering
accuracy decreases.
Extremely small gap widths can prevent proper
solder flow and lead to an incomplete or weak
joint.
An even soldering gap of about 0.25 mm is
recommended.

43. Material Science
Solder
Flux and antiflux
Soldering investment

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Solder's main requirement
 They should have lower fusion temperature than
the parent alloy (about 80-100°less).
 They should have high tarnish and corrosion
resistance
 Flow freely
 They should have high strength property
 They should be non pitting
 They should have color match

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Solder Alloy
Types
Fineness
Karat
pre-ceramic or post-ceramic solders

46. Solder
 Gold solders are classified by
fineness and by karat
 Fineness is the proportion of pure
gold in 1000 parts of alloy
 Karat refers to the gold content of
the casting per 24 parts of the alloy

47. Solder
Modern casting alloys are metallurgically
complex they need specially
formulated solders
Group I: Traditional gold solders
Group II: special solders

48. Solder
Pre-ceramic solders:
High fusing solders flow well above the fusion range of
porcelain
Post-ceramic solders:
They flow below the pyroplastic range of porcelain

49. Soldering All-Metal FPDs
Type III and type IV gold retainers are
soldered with gold solders of 615 to
650 fineness

50. Soldering Metal-Ceramic FPDs
Allows for the try-in step and any necessary
adjustments can be made
Sag can be a problem with high-gold content
ceramic alloys
Necessary when regular gold is combined in an
FPD with metal-ceramic units
All porcelain construction steps must be
completed before soldering

52. Soldering flux
It is applied on a metal surface to remove oxides or prevent their
formation
The solder will be then free to wet and spread over the clean
metal surface

53. Types of fluxes
For gold alloys: borax glass because of its affinity
to copper oxides. Soldering flux formula is borax
glass (55 parts), boric acid (35 parts), and silica (10
parts).
For base metal alloys: fluoride fluxes to dissolve
stable oxides of chromium, cobalt and nickel

54. Soldering Antiflux
Used to limit the spreading of the solder alloy. It is
placed on the casting before flux application
Graphite pencil
Iron oxide (rouge)

55. Soldering investment
Similar in composition to casting investments
High strength
Should withstand heat without cracking
Quartz investments are better than cristoballites
because of lower thermal expansion

56. Heat sources
Torch soldering
Oven soldering
Infrared soldering
Laser welding

57. Torch soldering
Low heat soldering: gas-air
torch
High heat soldering: gas-
oxygen torch

58. Reducing portion of the flame is used to prevent
oxidation
Flame is never concentrated in one area but kept
in constant motion for even heat distribution
Maximum visibility, accessibility and control
Torch soldering

60. Oven soldering
Can be done under vacuum or in air inside a
porcelain furnace
A piece of solder is placed at the joint space and the
casting and solder are heated simultaneously

61. Vacuum firing is not needed for soldering gold alloys
Air firing is preferred with post-ceramic soldering. With
vacuum, there is chance for drawing entrapped gases to
the surface of glazed porcelain
Provides uniform heating and accurate temperature
control
Oven soldering

62. Infrared soldering
 Can be used for low-fusing
connectors as well as pre-ceramic
soldered joints
 Infrared source produces
concentrated heating by optically
collecting infrared energy and
directing it to the connector area

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Investment soldering techniques
Free-hand soldering technique:
Is used for building up of deficient proximal
contacts or contours or to repair casting
voids in a single unit restoration.
Investment soldering technique:
Is used for assembling components of a
fixed partial denture.

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Free-hand soldering technique:

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Investment soldering technique
Occlusal Soldering Index
Autopolymerizing Resin Soldering
Index .

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Investment soldering technique

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Investment soldering technique

69. Laser Welding
Laser welding is an autogenous welding technique
making use of the strong instantaneous thermal
effect of laser beam concentrated on a minute spot
Laser welding may be a practical way to join cast
titanium components

71. Advantages
Relative ease and time saving
Can be done directly on the cast
Less distortion, higher strength and reduced corrosion
Disadvantages
High cost and technique sensitive
Hazardous effects
Laser Welding

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Soldering defects and corrections:
 A prosthesis that fails to fit
 Lack of integrity
 Poor size or form
 Foreign body inclusion
 Joint fracture during testing
 Problems in post-ceramic
 Porcelain discoloration
 Localized surface roughness
 Porcelain cracking
 Loss of glaze

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Soldering defects and corrections:
A prosthesis that fails to fit:
Causes:
1- Failure to maintain proper relation between parts.
2- Improper heating of the assembly.
3- Improper proximal gap distance.
4- Presence of foreign materials (as investment) on the
fitting surface.
Treatment of the first three conditions is to break the
solder joint and reassemble the units.

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Soldering defects and corrections:
Lack of integrity:
Joints with pits or voids are not acceptable.
Small surface defects are reshaped if possible taking care
so as not to affect the size of the joint.
The presence of large void or internal porosity dictates
reinvesting the prosthesis and reflowing the joint and a
small amount of new solder should be added.

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Soldering defects and corrections:
Poor size or form:
Inadequate size of the joint affects its strength.
An undersized joint is corrected by reinvesting and
additional solder is added.
An oversized joint is corrected by grinding as it will
interfere with the proper oral hygiene measures.

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Soldering defects and corrections:
Foreign body inclusion:
Any foreign body inclusion should be removed and if
this result in undersized joint, reinvesting and
addition of new solder is done.
Joint fracture during testing:
This could be due to joint porosity due to improper
soldering technique. Resoldering is done after the
torn connector is smoothed.

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Soldering defects and corrections:
 Problems in post-ceramic:
 Besides the problems of high-heat soldering the following problems could occur in post-
ceramic soldering:
 Porcelain discoloration:
 It could be due to: excessive flux, contaminated furnace or direct contact of the flame with
porcelain near the solder joint.
 Localized surface roughness:
 It is often due to investment contacting the porcelain surface.
 Loss of glaze:
 Could be due to excessive flux or when phosphate-bonded investment is used as soldering
investment without protection of porcelain.
 Porcelain cracking:
 It could be due to very rapid heating or cooling.

80. Two schools exist regarding the need for restoration
of abutment teeth in fabricating a removable partial
denture.
Some authors prefer making removable appliances
with minimum of abutment preparation i.e. modify
the remaining natural dentition through
enamoplasty.
 Others point to the advantages of using cast
restoration on abutment teeth, claiming that the
masticatory and retentive forces can be directed
more favorably through them, in addition the use of
cast retainers, permits intracoronal rests which may
afford significant esthetics advantages and the
possibility of splinting of the abutment teeth.

81. Prerequisites for Success of RPD :
1- The framework
design :
The design should
allow the forces
developed during
placement, removal
and function to cause
least harm to the
remaining dentition.

82. 2- The denture base areas
Are shaped to avoid
interference with the
abutment retainer
during placement and
removal of denture.
Therefore the fixed
prosthesis determines
the denture base
configuration, rather
than vice versa.

83. 3- The rest of the removable partial denture (RPD) :
It should fit precisely into
corresponding rest seat
on the abutment
retainers, to reduce the
laterally directed forces,
so it must be spoon
shaped.

84. On anterior teeth a
cingulum rest seat
should resemble a V-
shaped groove
labiolingually to
prevent displacement

85. 4- The minor connectors
of (RPD) :
It should fit intimately
against the proximal
guide plane.
The guide planes should
be as long as possible
occluso- cervically and
should be as parallel as
possible to each other.

86. 5- The major connector :
It joins the contra lateral components of the
prosthesis. To provide bilateral bracing, it should
be rigid.

87. 6- Retentive arms :
They must flex rather than displace the
abutments laterally. When a clasp is in its normal
position with the removable partial denture fully
seated, it should fit in a passive manner against
the retainer.

88.  The reciprocal arms, or reciprocal clasps, of
an RPD have two functions:
 they guide the prosthesis to place upon
insertion,
 and they support the abutments against
horizontal forces exerted by the flexing
retentive arms.
 They must contact the guide planes before the
retentive arms start to flex; so to protect the
periodontium.
Reciprocal arms:

89. Reciprocation
Guide the prosthesis
during insertion
Support abutment
against horizontal forces

90. Dental surveyor
Assess alignment of long axes of teeth that support
RPD
Determine the optimum path of insertion
Evaluate tissue undercut

93. There are some modifications that must be incorporated in the abutment preparation to be ready to support and
retain a removable partial denture.
Design of RPD

94. Occlusal rest
An adequate amount of tooth structure must be removed to allow for
minimum metal thickness of 1mm. in the area of an occlusal rest seat. The
rest seat must be at least 1mm. away from the metal porcelain junction.
The seat must be cut in the wax pattern after the cut back has been done for
porcelain veneering.

95. Min 1mm

96. Retention
As the retainers are usually subjected to
forces that tend to remove them during the
daily removal of the (RPD), retention
becomes even more important, so the use of
additional retentive features e.g. grooves,
pinholes and boxes are needed.
Additional tooth reduction will be needed if a
retainer must be under contoured to
accommodate for the non-retentive part of an
occlusally approaching clasp, to be positioned
as far gingivally as possible.

97. Careful planning is required when selecting the
path of withdrawal. Conventional crowns
generally should have a path of withdrawal
parallel to the long axis of the tooth, while the
(RPD) retainers must have another path of
insertion and removal than that of the crowns
Surfaces that have guide planes; reciprocal
planes and surfaces adjacent to the edentulous
area often need to be over prepared relative to
the ideal conservative technique used on
individual teeth when receiving crowns only.

98. Attachment

99. Attachment
A precision attachment is an accurately fitting interlocking device for fixing removable
restoration to the natural teeth. The removable restoration may be removable partial dentures
or removable bridge. The precision attachment is consisting of two components one
incorporated in the abutment while the other becoming part of (RPD).
Many names have been given to these components as male & female, patrix & matrix,
key & keyway.

100. The precision attachments may be:
1. Extra coronal attachments.
2. Intracoronal attachments.
3. Bars, studs and magnets.
The main advantage for their use is to enhance appearance
hence there is no need for the clasps.

101. Extracoronal Attachment
 Careful judgment is needed in deciding when to use them because
they place unfavorable stresses on the abutment teeth similar to those
exerted by a cantilever.
 They make oral hygiene more difficult.
 The attachment is built outside the abutment tooth i.e. in the
edentulous area. The female part is attached to the abutment while the
male part is incorporated in the (RPD).

102. Extracoronal Attachment

103. Intracoronal Attachment
In this type female portion is built into the coronal portion of the abutment.
The main advantage of the intracoronal type is that the occlusal forces that applied
through the device are close to the long axis of the abutment, so decrease their effect on
the abutment

104. Non-rigid connector
Non precision attachement
*Occlusal / cingulum rest

106. Non-rigid connector
* precision attachment

107. Intracoronal Attachment

108. Intracoronal Attachment

109. Intracoronal attachment with MCR
1mm

110. Bars, Studs and Magnet
Stud attachments and magnets are used to retain the over dentures. They are
incorporated in post-retained casting or implants. In these attachments the female part
is incorporated in the removable restoration while the male part is located into the
abutment, which is usually a non-vital tooth.
The bar-retained (RPD) or over denture can be very stable while bracing abutment
teeth. The bar should not be placed in contact with the edentulous ridge gingivally

115. Bars, Studs and Magnet

116. Bars, Studs and Magnet

117. Requirements of Ideal Precision
Attachment:
It should be small to preserve the remaining tooth
structure.
It should be strong.
It should be easily repairable.
It should be easily removed and cleaned by the
patient.
It should have high wear resistance.
It should place minimum stress on the abutment.

118. The main two situations that necessitate their use are:
1. To over come the problems of mal-alignment where it is impossible
to attain common path of insertion in two or more abutments. So the
pontic and one retainer have path of insertion while the other retainer
has another path of insertion and within it the precision attachment.
2. In cases with pier abutment to place minimum amount of stresses on
it.

119. Thank You