Connectors –in fpd/ dentistry schools

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INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

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Connectors are those parts of a fixed
partial denture orsplint that join the
individual Retainers and Pontics
together.
 Usually this is accomplished with
-"Rigid connectors” although
nonrigid connectors are used
occasionally.
 The latterare usually indicated
when it is impossible to prepare a
common path of insertion forthe
abutment preparations foran FPDwww.indiandentalacademy.com

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CONNECTOR
The portion of an FPDthat unites the
retainer(s) and pontic(s).
RIGIDCONNECTOR
A cast, soldered, orfused union between
the retainer(s) and pontic(s).
NON RIGIDCONNECTOR
Any connectorthat permits limited
movement between otherwise
independent members of an FPD.www.indiandentalacademy.com

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RIGID CONNECTORS
Rigid connections in metal can be
made by casting, soldering, or
welding.
Cast connectors
 are shaped in wax as part of a
multiunit wax pattern.
Cast connectors are convenient and
minimize the numberof stepswww.indiandentalacademy.com

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The fit of the individual
retainers may be
adversely affected
because distortion more
easily results when a
multiunit wax pattern is
removed from the die
system.

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Soldered connectors
involve the use of an
intermediate metal alloy whose
melting temperature is lowerthan
that of the parent metal
The parts being joined are not
melted during soldering but must
be thoroughly wettable by
liquefied solder.

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Dirt orsurface oxides on
the connectorsurfaces can
reduce wetting and
impede successful
soldering; forexample,
the soldermay melt but
will not flow into the
soldering gap.

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WeldingWelding
is anothermethod of rigidly
joining metal parts.
Here the connection is created
by melting adjacent surfaces
with heat orpressure.
A fillermetal whose melting
temperature is about the same
as that of the parent metal can
be used during welding.www.indiandentalacademy.com

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In industrial metalworking, a
distinction is made between soldering,
in which the fillermetal has a melting
point below 450 º C (842º F), and
brazing, in which the fillerhas a
melting point above 450 º C
Rigid connections in dentistry are
generally fabricated above 450 º C,
but the process has almost always
been referred to in the dental literature
as soldering.
 A proposed international standard
uses the term brazing.www.indiandentalacademy.com

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NONRIGID CONNECTORSNONRIGID CONNECTORS
Nonrigid connectors are indicated when it is
not possible to prepare two abutments for
an FPDwith a common path of placement.
Segmenting the design of large, complex
FPDs into shortercomponents that are
easierto replace orrepairindividually is
advisable.
This can be helpful if there is uncertainty
about an abutment's prognosis.
If the abutment fails, only a portion of the
FPDmay need to be remade.www.indiandentalacademy.com

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In the mandibulararch, nonrigid
connectors are indicated when a complex
FPDconsists of anteriorand posterior
segments.
 During the mandibularopening and
closing stroke, the mandible flexes
mediolaterally.'
 Rigid fixed partial dentures have been
shown to inhibit mandibularflexure, and
extensive splints have been shown to
flex during forced opening
The associated stresses can cause
dislodgment of complex FPDs.
Segmenting complex mandibularFPDswww.indiandentalacademy.com

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Nonrigidconnectors aregenerated
throughincorporationof prefabricated
inserts inthewaxpatternorthrough
custommillingprocedures afterthefirst
castinghas beenobtained.
 Thesecondpartis thencustom-fittedto
themilledretainerandcast.
Theyareoftenmadewithprefabricated
plastic patterns.
 Theretainers arethencastseparately
andfittedtoeachotherinmetal.www.indiandentalacademy.com

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CONNECTOR DESIGN
The size, shape, and position of
connectors all influence the success
of the prosthesis.
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 overtime.www.indiandentalacademy.com

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Adequate access (i.e., embrasure
space) must be available fororal
hygiene aids cervical to the connector
If a connectoris too large
incisocervically, hygiene is impeded
and overtime periodontal failure will
occurForesthetic FPDs, a large
connectororinappropriate shaping of
the individual retainers may result in
display of the metal connector.

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TYPES OF CONNECTORS
RIGIDCONNECTORS
Rigid connectors must be
shaped and incorporated into
the wax pattern afterthe
individual retainers and
pontics have been completed
to final contourbut before
reflowing of the margins forwww.indiandentalacademy.com

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Cast Connectors
Connectors to be cast are also waxed
on the mastercast before reflowing
and investing of the pattern.
The presence of a cast connector
makes the pattern somewhat more
awkward.
Access to the proximal margin is
impeded, and the pattern cannot be
held proximally during removal from

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Restricting cast connectors
to complete coverage
restorations is therefore
advisable, which can be
gripped buccolingually.
Partial-coverage wax
patterns are easily distorted
when they are part of a
single-cast FPD.www.indiandentalacademy.com

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Soldered Connectors.
 As with cast connectors,
connectors to be soldered are waxed
to final shape but are then sectioned
with a thin ribbon saw therefore,
when the components are cast, the
surfaces to be joined will be flat,
parallel, and a controlled distance
apart.
 This allows accurate soldering
with a minimum of distortion.www.indiandentalacademy.com

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Molten solderwill flow
toward the location where
the temperature is highest.
In metal, the two flat
surfaces previously created
in wax retain heat,
ensuring that the highest
temperature is in the

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Soldering Gap Width.
As gap width increases,
soldering accuracy decreases .
 Extremely small gap widths
can prevent propersolderflow
and lead to an incomplete or
weak joint.

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An even soldering gap of
about 0.25 mm is
recommended.
If a connectorarea has an
uneven soldering gap width,
obtaining a connectorof
adequate cross-sectional
dimension without resulting
distortion is more difficultwww.indiandentalacademy.com

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Loop Connectors
Although they are rarely used,
loop connectors are sometimes
required when an existing
diastema is to be maintained in a
planned fixed prosthesis.
The connectorconsists of a loop on
the lingual aspect of the prosthesis
that connects adjacent retainers
and/orpontics.

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The loop may be cast from
sprue wax that is circularin
cross section orshaped from a
platinum-goldpalladium (Pt-
Au-Pd) alloy wire.
Meticulous design is
important so that plaque
control will not be impeded

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NON RIGID CONNECTORS
The design of nonrigid
connectors that are
incorporated in the wax
pattern stage consists of a
mortise (also referred to as the
female component) prepared
within the contours of the
retainerand a tenon (male)
attached to the ponticwww.indiandentalacademy.com

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The mortise is usually
placed on the distal aspect
of the anteriorretainer.
Accurate alignment of the
dovetail orcylindrically
shaped mortise is critical; it
must parallel the path of
withdrawal of the distal
retainerwww.indiandentalacademy.com

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Paralleling is normally
accomplished with a dental
surveyor.
When aligning the cast, the
path of placement of the
retainerthat will be
contiguous with the tenon is
identified.

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The mortise in the other
retaineris then shaped so its
path of insertion permits
concurrent seating of the tenon
and its corresponding retainer.
 The mortise can be prepared
freehand in the wax pattern or
with a precision milling
machine.

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Anotherapproachis to
useprefabricatedplastic
components forthemorti
andtenonof anonrigid
connector

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As analternative, aspecial
mandrelcanbeembeddedin
thewaxpatternandthe
abutmentretainercanbecast,
withrefinementof thefemale
componentas necessary; the
malekeyis thenfabricatedof
autopolymerizingacrylic resin
andattachedtothepontic.

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Connectors –in fpd/ dentistry schools

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