CONNECTORS IN FPD- Dr Soumya

1. CONNECTORS IN FPD
DR SOWMYA BALAKRISHNAN
READER
DEPARTMENT OF PROSTHODONTICS

2. CONNECTORS
A connector is that portion of the fixed
partial denture that unites the retainer(s)
and the pontic(s).

3. Types of connectors
• Fixed partial denture connectors can be broadly divided into two types:
Fixed – fixed
Fixed – movable
Fixed – removable
Rigid connectors
Cast connectors
Soldered connectors
Loop connectors
Nonrigid connectors
Tenon-mortise connectors
Split pontic connector
Cross-pin and wing connector

4. • 1. Fixed-fixed:
• Connectors on both sides of the pontic are rigid with no scope for any
movement.
• The connector is either soldered to the pontic and the retainer or all the
components are cast as a single piece .

5. • 2. Fixed-movable:
• One of the connectors of the FPD assembly is nonrigid ( it is called so
because it allows some movement between the pontic and abutment)
and is made of a precision or semiprecision attachment which allows
some vertical movement .
• Normally indicated in case of a pier abutment, tilted abutments or
periodontally weak abutments.

6. • 3. Fixed-removable:
• Developed by Dr James Andrews and is
called ‘Andrews Bridge’.
• The fixed portion consists of two
abutment retainers adjacent to an
edentulous space splinted by a bar. The
retainers attached to the bar are
cemented on the abutments .
• The removable portion consists of the
artificial teeth (pontics) and a denture
flange with a sleeve which clips onto the
bar .

7. • It has an advantage of flexibility in
placing denture teeth as well as the
stabilizing qualities of a fixed
prosthesis.
• Indicated for patients with extensive
supporting tissue (bone) loss.
Replacing the teeth for such patients
with a conventional FPD will result
in unaesthetically long pontics with
no lip support.
• Also indicated with long edentulous
spans.

8. Rigid connectors
• These connectors do not allow any
movement and are indicated when the
entire masticatory load is to be
transferred onto the abutments.
• They can be directly cast as a part of a
multiunit fixed partial denture, or
different units can be joined together by
means of soldering.

9. • • A loop connector is used in case an existing diastema is to be maintained in
the fixed partial denture . It is mainly cast and care should be taken that the
tissue contour is followed during the fabrication of the wax pattern of the
connector .

10. • • Design: The size, shape, and position of rigid connectors all influence the
success of the prosthesis. An ideal connector will enhance ease of cleansing,
should have adequate strength and be aesthetically acceptable.

11. Nonrigid connectors
• Connectors allow limited movement between the retainer and the
pontic and have little amount of flexibility.

12. • Indications:
• ○ When a parallel path of insertion cannot be achieved in the preparations.
• ○ Pier abutment.
• ○ Periodontally unfavourable abutments to reduce the amount of stress to the
tooth. Here, it is called stress breaker.
• Types:
• Almost all of them will consist of a male and a corresponding female
component.
• The shape and configuration of the male and female differ to accommodate the
movement between the pontic and the retainer required.

13. • Tenon-mortise connector:
• The tenon (male component) is attached to the pontic and the mortise (female
component) is attached to the retainer.
• Their alignment must be parallel to the path of placement.
• They can be made free hand or milled or prefabricated plastic patterns can be
used.

14. • Split pontic connector is used in
case of pier abutment situations where
a minimal amount of movement is
required to maintain abutment health.
• The pontic is split into mesial and
distal halves, which are attached to
their respective retainers.
• A shoe/key is incorporated into the
mesial half and the keyway in the
distal half. This assembly engages
when the FPD is seated in position

15. • Cross-pin and wing connectors
are similar to the split pontic connector
and are used for tilted abutments.
• The wing is attached to the distal
retainer, which is cemented first and
pontic to the mesial retainer

16. SPECIAL
CONSIDERATIONS
• Pier abutment Definition: A natural tooth located between
terminal abutments that serve to support a fixed or a removable
prosthesis (GPT8).
• It is also called ‘intermediate abutment’ .

17. • In this situation, if a five-unit rigid FPD is planned by using all the
natural teeth adjacent to the edentulous areas as abutments, forces
are transmitted to terminal retainers as a result of the intermediate
abutment (pier) acting as fulcrum, causing failure (loosening) of a
weaker retainer (anterior).

18. • Some times tension between the terminal retainers and their
respective abutments rather than a pier fulcrum caused intrusion of
the weaker abutment which lead to failure (loosening) of a weaker
retainer (anterior) .These loosened castings will cause marginal
leakage and secondary caries.

19. • Hence physiologic tooth movements, arch position of the abutments
and a disparity in the retentive capacity of the retainer can make a rigid
connector in a five-unit fixed prosthesis, a less ideal treatment of choice
in case of pier abutments. The use of a nonrigid connector has been
advocated to overcome this problem.
• It is a broken stress mechanical union of retainer and pontic, the
movement in it is enough to prevent the transfer of stress from the
segment being loaded to the rest of FPD. It consists of a T - shaped key
attached to the pontic, and a dovetail key way placed within a retainer.

20. • The location of this device is important. It is usually placed on the
middle abutment, since placement on the terminal abutments could
result in pontic acting as a lever arm.
• The key way should be placed within the distal contour of pier
abutment and key, on the mesial side of distal pontic. This seats the key
more solidly into the keyway as forces usually are mesially directed
due to the mesial inclination of posterior teeth.

21. • Cantilever fixed partial dentures
• Definition: A fixed dental prosthesis in which the pontic is cantilevered,
i.e. is retained and supported only on one end by one or more
abutments (GPT8).
• In a conventional FPD supported by abutment on either side of
edentulous space, forces on the pontic are distributed evenly to both
the abutments.

22. • In a cantilever FPD, forces applied to the pontic tend to depress and
tip the pontic. This is a potentially destructive design with the lever
arm created by the pontic .
• Prospective abutment teeth for cantilever FPDs should satisfy the
following requirements:
• ○ Lengthy roots with favourable configuration.
• ○ Long clinical crowns.
• ○ Good crown root ratios.
• ○ Healthy periodontium.
• ○ Should be used to replace only one tooth.

23. • Indications:
• 1. Missing maxillary lateral incisors using canine for support. ○ There
should be no occlusal contact on the lateral incisor pontic in centric
and eccentric relations.
• ○ A distal rest prepared on the central incisor will support a mesial
extension from the lateral pontic to prevent rotation.
• 2. Missing first premolar using II premolar and I molar as abutments.

24. • 3. Missing I molars when there is no distal abutment, using I and II
premolar as abutments.
• ○ Pontic should be similar in size to a premolar.
• ○ Only light occlusal contact on pontic with no contact in eccentric.
• ○ Pontic should possess maximum occlusogingival height.
• 4. Periodontally compromised teeth as they have extremely long
clinical crowns.
• 5. Pier abutment situations.

25. • Canine replacement fixed partial dentures
• Replacing canine with a fixed partial denture is often
difficult as the canine lies outside the interabutment axis ,
the fulcrum line is labial to the arch circumference. Hence,
the abutments are subjected to increased stresses.

26. • The prospective abutments are the lateral incisor, weakest tooth in the
arch and the first premolar, weakest posterior tooth.
• The forces acting on the maxillary canine act outward, labially,
subjecting it to a greater stress, as compared to the mandibular canine
where the forces act lingually.