Minor Connectors and Indirect Retainer

A unit of partial denture which connects other components (direct

retainer, indirect retainer, denture base) to the major connector

Minor Connector

On maxillary arch the coverage of the distal extension base must extend to the?

Pterygomaxillary Notch

On the mandibular arch the denture base must cover the

Retromolar pad

Functions of Minor Connectors

1. Provide unification, rigidity, and stress distribution by transferring stresses from the major connector to other parts of the partial denture and from partial denture to the abutment teeth

2. Act as a bracing elements through contact with guiding planes opposing the retentive arms

3. Maintain a path of insertion via contact with guiding planes

Types of Minor Connectors

1. Minor connectors that join clasp assemblies to major connectors

2. Minor connectors that join indirect retainers to major connectors

3. Minor connectors that join denture bases to major connectors

4. Minor connectors that serve as approach arms for bar-type clasps

(1) Minor Connectors that Join Clasp Assemblies to Major Connectors

1. Must be ____

2. Must have _________ to ensure rigidity

3. Must be positioned so they do ________ the oral tissues

   1. Should be located on the embrasures

4. Should be ____ buccolingually, but ___ mesiodistally

   1. Para kasya sa embrasure

5. Should never be positioned on the ___________ surface of a tooth where its bulk will be evident

(1) Minor Connectors that Join Clasp Assemblies to Major Connectors

• Must be rigid

• Must have sufficient bulk to ensure rigidity

• Must be positioned so they do not irritate the oral tissues

  • Should be located on the embrasures

• Should be broad buccolingually, but thin mesiodistally

  • Para kasya sa embrasure

• Should never be positioned on the convex lingual surface of a tooth where its bulk will be evident

2) Minor Connectors that Join Indirect Retainers or Auxiliary Rests to Major Connectors

● Should form __________ with the corresponding major connectors, but junctions should be _______ to prevent stress concentration

● The juncture to the major connector should be ______

2) Minor Connectors that Join Indirect Retainers or Auxiliary Rests to Major Connectors

● Should form right angles with the corresponding major connectors, but junctions should be gently curved to prevent stress concentration

● The juncture to the major connector should be rounded

All of your RPD components should be rounded EXCEPT for your ?

retentive arm and major connector on distal extension area.

(3) Minor Connectors that Serve as Approach Arms for Vertical Projection / Bar-type Clasps

• Approaches the tooth from an__________ rather than from an occlusal direction

  • Occlusal direction – _______

  • Apical direction – _______

• The approach arm should display a ____, even taper from its origin to its terminus

• Must not cross a ____________

(3) Minor Connectors that Serve as Approach Arms for Vertical Projection / Bar-type Clasps

• Approaches the tooth from an apical direction rather than from an occlusal direction

  • Occlusal direction – suprabulge

  • Apical direction – infrabulge

• The approach arm should display a smooth, even taper from its origin to its terminus

• Must not cross a soft tissue undercut

(4) Minor Connectors that Join Denture Bases to Major Connectors

● Must be _________ to anchor a denture base to the removable partial denture framework

● Must be rigid enough to __________and displacement

● Must provide _______ interference

(4) Minor Connectors that Join Denture Bases to Major Connectors

● Must be strong enough to anchor a denture base to the removable partial denture framework

● Must be rigid enough to resist fracture and displacement

● Must provide minimal interference

Coverage of the Denture Base Retaining Element (DBRE)

In the Maxillary arch, a distal extension base must extend the ____________ and should cover the _________

must extend the entire length of the ridge and should cover the tuberosity

Coverage of the Denture Base Retaining Element (DBRE)

In the mandibular arch, the minor connector should extend ___________ of the ___________

Two thirds the length of the edentulous ridge

Types of Denture Base Retaining Element (DBRE)

1. Lattice

2. Mesh

3. Pinhead

Consists of longitudinal and transverse struts that form a ladder-like network

Lattice

Position of the lattice on Maxillary: One longitudinal strut should be positioned ______ to the_____. The border of the major connector generally will act as the __________

Maxillary longitudinal strut placement:

• Buccal to the ridge crest

• Second longitudinal strut

Position of the lattice on Mandibular: One longitudinal strut should be positioned ______ to the __________ and the other ________ to the ________

Mandibular longitudinal strut placement:

• Buccal to the ridge crest

• Lingual to the ridge crest

Positioning of a longitudinal strut along ______________ must be avoided (interfere with setting of artificial teeth, fracture of denture base)

The crest of the ridge(must be buccal to avoid interference with the pontics)

Transverse struts also must be positioned to facilitate the placement of?

Artificial teeth

Minimum sizes when creating boxes that is formed by the longitudinal and transverse strur

5mm

DBRE used whenever multiple teeth are to be replaced

Lattice and Mesh

• Provides the strongest attachment of acrylic resin to the removable partial denture framework

Lattice

A mesh minor connector may be compared to a ?

rigid metallic screen

Disadvantages of Mesh

● Difficulty during the packing of acrylic resin

● May interfere with the arrangement of prosthetic teeth

Often used in conjunction with metal denture bases.

Pinhead

Other terms for Pinhead

• Bead

• Nailhead

• Wire

DBRE that Should be limited to short-span, tooth-supported applications in patients with well healed ridges.

Pinhead

Pinhead should only be limited to

• Limited to short-span

• Limited to short-span, tooth-supported applications in patients with well healed ridges.

Type of DBRE Indicated If mesiodistal space and occlusogingival space is limited.

Pinhead

Advantages of Pinhead

Related to improved hygiene and enhanced thermal stimulation.

Disadvantages of pinhead

• Difficulty in adjusting and relining cast metal bases.

• Attachment of resin is relatively weak

Created by removing a small square of relief wax where the posterior strut of the minor connector crosses the center of the ridge

Tissue Stops or Cast Stops

Tissue stops or cast stops is removing a small square of relief wax, what is the size of the square

2×2 mm

Tissue Stops or Cast Stops used to prevent or minimize what?

• Prevent or minimize bending/distortion of the minor connector during acrylic resin packing and processing

Anchored so the framework won’t move during placement of acrylic resin

Tissue stops or cast stops

Resin metal interfaces must be created on both the internal and external surfaces of the associated major connectors. These interfaces are referred to a?

Finish lines

Types of finish lines

External and Internal finish lines

Junction of metal and denture base/acrylic resin.

External and internal finish lines.

Formed as a result of relief wax placed on the edentulous ridges of a master cast prior to duplication

Internal Finish lines

The margins of the relief wax should be ____ and __________

Sharp and Well defined

Internal Finish Lines- Creates an_________ on the resultant refractory cast, that is necessary to create space for acrylic resin beneath open and mesh connectors, denture base with sufficient bulk to avoid ______ .

Internal Finish Lines- Creates an elevated area on the resultant refractory cast, that is necessary to create space for acrylic resin beneath open and mesh connectors, denture base with sufficient bulk to avoid fracture.

Must be sharp and should be slightly undercut to help lock the acrylic resin to the major connector.

External Finish Lines

Formed by the placement and carving of wax during framework fabrication. It should originate at the lingual extent of the rest seat and continue down the lingual aspect of the minor connector

External finish lines

External Finish Lines

• Should be ______ along its entire length.

• The contour of the external finish line should be ___________ of the major connector.

Well defined

Consistent with the contours

External Finish line
● Transition from the external finish line to a denture base should be _______ and________

smooth and flowing

A part of a removable partial denture that prevents rotational displacement of the denture about the rests of the principal abutment teeth.

Indirect retainer

Indirect retainer is a part of a RPD that prevents

prevents rotational displacement

The framework component that resists rotational displacement of an extension base away from the supporting tissues

Indirect retainers

discovered the effects of rotational movements

F. H. Balkwill 1880

the term fulcrum line to identify the primary axis of rotation

Prothero 1916

It is where the rotational forces are present. Indirect retainer is needed to counteract that forces.

Fulcrum line

Effects of Rotational Movement

• Denture base move away from the supporting tissues.

• Anterior segment of the major connector impinges upon the underlying soft tissues.

• Results in transmission of potentially destructive forces to the hard and soft tissues of the dental arch

Rationale of Indirect Retainers

• Reduce torquing leverages on the principle abutments.

• Contact of the indirect retainer’s minor connector with vertical tooth surface aids in stabilization against horizontal movement of the denture.

• Anterior teeth with indirect retainers are supported against lingual movement.

• Indirect retainers act as an auxiliary rests to support a portion of the major connector.

Forms of Indirect Retainer: CLICO

1. Occlusal Rest

2. Cingulum rest /Canine rest

3. Incisal Rest

4. Part of a major connector: Lingual Plate

5. Part of a direct retainer or Clasp Assembly

• Preferred component for indirect retention.

• Permits forces to be directed within the long axis of the corresponding abutment (location and orientation)

Occlusal Rest

Occlusal rest are usually placed on the?

Mesio-occlusal surface of a first premolar

Rest that is generally is limited to maxillary canines

Cingulum rest/Canine rest

esthetically objectionable and exhibit long approach arms that may transfer harmful tipping forces to abutments

Incisal Rest

Rest on the mandibular canine is called

Incisal rest

Lingual plate does not serve as an indirect retainer unless is adequately supported by ___________ , the lingual plate may enhance the efficiency of the indirect retainers

properly designed rests at each end

Part of the major connector the lingual plate - The indirect retainers are actually the terminal rests at either end that occur in the form of _________ or_________

Auxillary occlusal rest or canine rest

if the fulcrum line falls on the tooth next to the direct retainer do you need a separate indirect retainer?

No

FACTORS DETERMINING EFFECTIVENESS OF INDIRECT RETAINERS

1. The effectiveness of supporting tooth surface.

2. Identification of primary fulcrum line

3. Effectiveness of direct retainers(retentive arm)

4. Rigidity of the connector supporting the indirect retainer

5. Proper seating of the denture

Position of indirect retainers in properly prepared rest seats permits applied forces to be transmitted within the ?

long axis of the abutment

Identification of the primary fulcrum line

a. The ______ the distance between the fulcrum line and the indirect retainer, the more _______the Indirect retainer will be

b. the position of the indirect retainer should be _______ to—and as ___ from—the primary ______ line as is practical

Identification of the primary fulcrum line

a. The greater the distance between the fulcrum line and the indirect retainer, the more effective the Indirect retainer will be

b. the position of the indirect retainer should be perpendicular to—and as far from—the primary fulcrum line as is practical

This axis passes through rests of the most posterior abutment teeth. Used to know where to put the indirect retainer

Fulcrum Line

Where to put the end of the imaginary lines

Most posterior rest ( not the most posterior teeth)

An imaginary line around which a removable partial denture (RPD) tends to rotate when force is applied

Fulcrum line

PRINCIPLE OF DIRECT RETAINER

1. No force

2. Lifting force

3. Direct Retainer Present, No Indirect Retainer

4. Direct and Indirect Retainers Present