This is a presentation on "Indirect retainer & minor connectors" in RPD. We often find this topic a little bit confusing. So, here I wanted to summarize the whole topic in a nutshell. Hopefully, you will find it interesting to have all the information in a concise way.

1. WELCOME

2. WEEKLY SEMINAR
OF
DEPT. OF PROSTHODONTICS
TOPIC: INDIRECT RETAINERS & MINOR CONNECTORS IN RPD
PRESENTED BY-
DR. MD. IRFANUR RAHMAN, BDS
DHAKA DENTAL COLLEGE & HOSPITAL

3. SUPERVISEDBY-
Dr. Syed Faruque Shihab
Associate Professor
Head of the Department
Department of Prosthodontics
Dhaka Dental College & Hospital

4. CONTENTS
Parts of a RPD
What is indirect retainers
Concept of fulcrum line
Factors influencing the effectiveness of indirect retainer
Characteristics of an indirect retainer
Auxiliary functions of an indirect retainer
Forms of indirect retainers
What is minor connector
Functions of minor connectors
Form & location of minor connectors
Finishing lines of minor connector

5. COMPONENTS OF A TYPICAL RPD
1. Major connectors
2. Minor connectors
3. Rests
4. Direct retainers
5. Clasp assembly
6. Indirect retainer
7. Denture base

6. WHAT IS INDIRECT RETAINER
The component of a partial removable dental prosthesis that
assists the direct retainer (s) in preventing displacement of the
distal extension denture base by functioning through lever
action on the opposite side of the fulcrum line when the
denture base moves away from the tissues in pure rotation
around the fulcrum line. (GPT)

7. INDICATIONOF INDIRECT RETAINER
• Used in Kennedy class I & class II RPD
• Used in tooth-tissue supported RPD

8. CONCEPT OF FULCRUMLINE
An axis which passes through the two most posterior rests closest to
the edentulous space around which a denture tends to rotate in
function.

9. TYPES OF FULCRUMLINE
Retentive fulcrum line: An imaginary line connecting retentive
points of clasp arms, around which denture tend to rotate when
subjected to forces such as the pull of sticky food.

10. TYPES OF FULCRUM LINE
Stabilizing fulcrum line: An imaginary line connecting occlusal
rests, around which line the denture tends to rotate under
masticatory force.

11. LOCATIONOF FULCRUMLINES FOR DIFFERENTCLASSES OF RPD
Kennedy class I Kennedy class II

12. LOCATIONOF FULCRUMLINES FOR DIFFERENTCLASSES OF RPD
Kennedy class III Kennedy class IV

13. FACTORS INFLUENCING THE EFFECTIVENESS OF INDIRECT
RETAINER
1. The rest of the primary abutments must be held in place by effective direct
retainers & binding of proximal plates. Thus rotation around an axis occur, which
subsequently activates indirect retainer.
2. Distance from the fulcrum line-
a) Length of the distal extension base
b) Location of the fulcrum line
c) Distance of the indirect retainer from fulcrum line
3. Rigidity of the connectors supporting the indirect retainers
4. Effectiveness of supporting tooth

14. CHARACTERISTICS OF AN INDIRECT RETAINER
Assist the direct retainer in resisting movement of the partial denture in
an occlusal direction around the fulcrum line.
Usually consist of a rest & minor connector.
Provide additional bracing or stabilization against horizontal movement.
Provide an auxiliary rest for support of the major connector.
Reduce anterior-posterior tilting (rocking) leverages on principle
abutment.
Significant aid in determining need of a reline in an extension base RPD.
Placed as far away as possible from fulcrum line.

15. FUNCTIONS OF INDIRECT RETAINER
Primary function:
Indirect retainer shifts the fulcrum line away from the point of application
of force, thereby counteracting the lifting force & stabilizing the denture.
Auxiliary function:
• Reduces the anteroposterior tilting leverages on the principal
abutments, particularly when an isolated tooth is being used as an
abutment.
• Helps in stabilization

16. FUNCTIONS OF INDIRECT RETAINER
Auxiliary function:
• Act as auxiliary guiding plane.
• May act as an auxiliary rest to support a portion of major connector.
• May provide an indication to reline an extension base.
• Act as a third point of reference to orient the RPD.

17. FORMS OF INDIRECT RETAINERS
• Auxiliary occlusal rest
• Canine rest
• Canine extensions from occlusal rest
• Cingulum bars & linguoplate
• Modification areas
• Rugae support

18. FORMS OF INDIRECT RETAINERS
Auxiliary occlusal rest Canine rest
Canine extensions from occlusal
rest

19. FORMS OF INDIRECT RETAINERS
Cingulum bars & linguoplate
Rugae support

20. WHAT IS MINOR CONNECTOR
Components that serve as the connecting link between major
connector or base of a removable partial denture and other
components of the prosthesis such as the clasp assembly, indirect
retainers, occlusal rests, or cingulum rests are known as minor
connectors.

21. FUNCTIONS OF MINOR CONNECTOR
• Joins the units of prosthesis and denture base to the major connector.
• Transfers functional stress to the abutment teeth.
• Transfers the effects of the retainers, rests and stabilizing components throughout
the prosthesis.
• Retains the base to the metal frame.

22. CLASSIFICATION OF MINOR CONNECTOR
• Clasp assembly minor connector
• Approach arm minor connector
• Indirect retainer/ auxiliary arm minor connector
• Denture base minor connector

23. FORM& LOCATION OF MINOR CONNECTORS
Like major connector, minor connector should have sufficient bulk to
be rigid.
Too bulk → irritation
Minor connector that connects the axial surface of an abutment
should not be located in the convexity of the tooth instead should be
in an embrasure.
Should make an abrupt joint with major connector.
Abrupt joint → minimal tissue contact → minimal Irritation
Should be thickest toward the convex surface and tapering toward the
contact area.

24. FORM& LOCATION OF MINOR CONNECTORS
Tapering toward the tooth → minimal space between tooth an minor
connector →minimal chance of food impaction
Tapering toward the tooth → minimal sharp angles → minimal tongue
irritation

25. FORM& LOCATION OF MINOR CONNECTORS
Deepest part of interdental embrasure should be blocked out to
avoid interference during placement & removal.
Minor connector must be wide enough that the guiding plane can be
used to fullest advantage.
When an artificial tooth will be placed against a proximal minor
connector, the minor connector’s greatest bulk should be toward the
lingual aspect of the abutment tooth.

26. FINISHLINE OF MINOR CONNECTOR
Types-
Internal finish line
External finish line

27. FINISHING LINES OF MINOR CONNECTOR
1. Finishing line junction with major connector should not be
greater than 900.
2. If finish line is located far too medially, natural contour of palate
can be altered by thickness of acrylic resin.
3. On the other hand, too far buccally placed finish line will not
produce natural contour of the acrylic resin on the lingual surface
of the artificial teeth.

28. FINISHING LINES OF MINOR CONNECTOR

29. FINISHING LINES OF MINOR CONNECTOR