CHAPTER 5: MINOR CONNECTORS

Minor connectors

are the connecting link between the major connector or base of a removable partial denture and other prosthesis components

They may be continuous with some other part of the denture, such as an occlusal rest at one end of a linguoplate

The portion of a partial denture framework that supports the clasp and the occlusal rest

Those portions of a removable partial denture frame- work that retain the denture bases

When dental implants are placed, modifications can be required in the denture base retaining minor connector

contacts the guiding plane surfaces of the abutment teeth, whether as a connected part of a direct retainer assembly or as a separate entity

rigidity is an essential characteristics of this connector

the broad distribution of forces prevents any one tooth or any portion of an edentulous ridge from bearing a destructive amount of stress

Modifications for anterior implants to enhance retention

must consider retentive device bulk and connection requirements

For implants placed more distal for support purposes

space for embedding an attachment housing within the denture base is required

2 functions of minor connectors

serves as a connecting link between the major connector or the base of a rpd and the other components

transfers occlusal forces from prosthesis to abutment and abutment to prosthesis

prosthesis-to-abutment function of the minor connector

Transfers functional stress to the abutment teeth

Occlusal forces applied to the artificial teeth are transmitted through the base to the underlying ridge tissue if that base is primarily tissue supported

Occlusal forces applied to the artificial teeth are also transferred to abutment teeth via occlusal rests.

Minor connectors from a rigid major connector facilitate this transfer of functional stress throughout the dental arch

abutment-to-prosthesis function of the minor connector

Transfers the effects of the retainers, rests, and stabilizing components throughout the prosthesis

Thus forces applied on one portion of the denture may be resisted by other components placed elsewhere in the arch for that purpose.

A stabilizing component on one side of the arch may be placed to resist horizontal forces that originate on the opposite side.

This is possible only because of the transferring effect of the minor connector, which supports that stabilizing component, and the rigid- ity of the major connector.

form and location of minor connector

must be rigid and not objectionable to transfer functional stresses to supporting teeth and tissue

should be located in an embrasure and not on a convex surface, least noticeable to the tongue, and conform to the interdental embrasure

passing vertically from the major connector so that the gingival crossing is abrupt and covers as little of the gingival tissue as possible

should be thickest toward the lingual surface, tapering toward the contact area

provides intimate tissue contact, preventing food from dislodging the prosthesis

The deepest part of the interdental embrasure should have been blocked out to avoid interference during placement and removal, and to avoid any wedging effect on the contacted teeth.

when it contacts tooth surfaces on either side of the embrasure, it should be tapered to the teeth to avoid sharp angles and trap food, hinder tongue movement

must be wide enough for optimal use of guiding plane

Tapered to tooth below clasp origin — when forming a clasp arm

Tapered to knife-edge full length of buccal aspect — if no clasp arm is formed

Minor Connector Guidelines

(1) WHEN A MINOR CONNECTOR CONTACTS TOOTH SURFACE ON EITHER SIDE OF THE EMBRASURE IN WHICH IT LIES, IT SHOULD BE TAPERED TO THE TEETH, THIS AVOIDS SHARP ANGLES WHICH COULD HINDER TONGUE MOVEMENT

(2) CONTACTS THE AXIAL SURFACE OF AN ABUTMENT THAT SHOULD NOT BE LOCATED ON A CONVEX SURFACE

(3) LOÇATED IN AN EMBRASURE WHERE IT WILL BE LEAST NOTICEABLE TO THE TONGUE

(4) PASSING VERTICALLY FROM THE MAJOR CONNECTOR SO THAT IHE GINGIVAL CROSSING IS ABRUPT AND COVERS AS LITTLE OF THE GINGIVAL TISSUE AS POSSIBLE

(5) IN AN EMBRASURE SPACE, THE MINOR CONNECTOR IS TAPERED TO THE TOOTH TO AVOID BULK AND TO ACCOMMODATE THE TONGUE

(6) SUFFICIENT BULK TO BE RIGID YET THE BULK OF THE MINOR CONNECTOR SHOULD NOT BE OBJECTIONABLE

(7) A MINOR CONNECTOR THAT CONTACTS THE GUIDING PLANE CAN BE CONNECTED PART OF A DIRECT RETAINER ASSEMBLY OR AS A SEPARATE ENTITY ALONE

Modification of Removable Partial Denture Minor Connector

Proposed for maxillary arch application

Minor connector located in lingual surface of maxillary abutment tooth

Reduces gingival tissue coverage

Enhances partial denture guidance during insertion and removal

Increases stabilization against horizontal and rotational forces

Location may encroach on tongue space, creating food entrapment space

Requires careful application.

Artificial Tooth Placement and Minor Connector Design

The majority of the minor connector should be towards the lingual aspect of the abutment tooth to ensure sufficient bulk without affecting the placement of the artificial tooth

The artificial tooth should contact the abutment tooth with only a thin layer of metal intervening buccally

The minor connector should lie in the interdental embrasure, similar to between two natural teeth

Minor connectors should be completely embedded within the denture base, with strong butt-type joints without appreciable bulk

Angles formed at connector junctions should not exceed 90 degrees for the strongest mechanical connection

An open latticework or ladder design is preferred, made using preformed wax strips

Minor connectors for mandibular distal extension base should extend posteriorly about two-thirds the length of the edentulous ridge and have elements on both lingual and buccal surfaces

A means to attach acrylic-resin individualized trays to the mandibular framework should be arranged when the framework pattern is being developed

In an embrasure space, the minor connector is tapered to the tooth to avoid bulk and to accommodate the tongue.

minor connector that contacts the guiding plane

Part of a clasp assembly, either separate or connected to the lingual stabilizing portion

Contacts the guiding plane about half the distance between adjacent buccal and lingual cusps of the abutment tooth

Extends gingivally, contacting an area of the abutment from the marginal ridge to two-thirds the length of the enamel crown

Viewed from above, it is triangular, with the apex located buccally and the base lingually

Less interference with adjacent artificial tooth arrangement.

Tissue Stops

are integral parts of minor connectors designed for retention of acrylic-resin bases

They pro- vide stability to the framework during the stages of transfer and processing.

They prevent distortion of the framework during acrylic- resin processing procedures

can engage buccal and lingual slopes of the residual ridge for stabil- ity

Altered cast impressions often require tissue stops to be augmented.

Autopolymerizing acrylic resin can be used to achieve this

Minor connector retains acrylic-resin denture base

Distal to terminal abutment, it establishes a definitive finishing index tissue stop for the acrylic-resin base.

FUNCTION(S of tissue stop

(1) PROVIDE STABILITY TO THE FRAMEWORK DURING THE STAGES OF TRANSFER AND PROCESSING

(2) PREVENTING DISTORTION OF THE FRAMEWORK DURING ACRYLIC-RESIN PROCESSING PROCEDURE

finishing Index Tissue Stop

Similar to a tissue stop but serves a different function.

Located distal to the terminal abutment and is a continuation of the minor connector contacting the guiding plane.

Purpose is to establish a definitive finishing index tissue stop for the acrylic resin base after processing

Finishing Line

The ideal location is at the junction of major and minor connectors at palatal finishing lines should be located 2mm medial from an imaginary line that would contact the lingual surfaces missing posterior teeth

should not be greater than 90 degrees, somewhat undercut

The medial extent of the minor connector depends on the lateral extent of the major palatal connector

its location should be based on restoration of the natural palatal shape, considering the location of replacement teeth

Equal consideration should be given to the junction of minor connectors and bar-type direct retainer arms

These junctions are 90-degree butt-type joints and should follow base contour and clasp length guidelines.

consequence when finishing line is located too far medially

the natural contour of the palate will be altered by the thickness of the junction and the acrylic resin supporting the artificial teeth

consequence when finishing line is located too far buccally

it will be most difficult to create a natural contour of the acrylic resin on the lingual surface of the artificial teeth

Tissue Reaction to Metallic Parts of Removable Partial Dentures

Controversy surrounds tissue reactions to partial denture coverage, especially in marginal gingiva and broad tissue contact areas

Pressure from lack of support, inadequate hygiene measures, and prolonged prosthesis use can cause tissue reactions

Settling of the denture can result from loss of tooth and/or tissue support, causing pressure elsewhere in the arch

Excessive pressure must be avoided when oral tissue must be covered or crossed by partial denture elements

Lack of hygiene measures can result in tissue reactions due to accumulation of food debris and bacteria

Maintaining cleanliness of the tissue surface of the prosthesis is another hygiene concern

Prosthesis wear can exacerbate untoward tissue reaction, leading to inflammation and breakdown of the epithelial barrier

Patients often neglect to remove partial dentures often, leading to changes in living tissues

Clinical experience shows that tissue coverage is not detrimental to oral tissue health when pressure, cleanliness, and time are controlled

components of removable partial denture

directly attached to the major connector

indirectly attached to the major connector

directly attached to the major connector

the components dont need a connecting link in order to be attached towards the major connector

ex: metallic denture bases and minor connector

indirectly attached to the major connector

these components need a connector in order to be attached towards the major connector

ex: rest, direct retainer, indirect retainer, acrylic denture bases

OPEN LATTICE FRAMEWORK

PORTION OF DENTRE FRAMEWORK BY WHICH ACRYLIC RESIN DENTURE BASES ARE ATTACHED

MADE BY USING 12 GAUGE HALF ROUND AND 18 GAUGE ROUND WAX STRIPS

THE LATTICE FRAMEWORK'S THICKNESS IS ELEVATED BY 1.5MM EACH CONSUMING AN INTER RIDGE DISTANCE OF 3.0MM. T

HE MANDIBULAR'S RETROMOLAR PAD IS ALSO AN ELEVATED LANDMARK AND IF THE FRAMEWORK COVERS THIS, IT WILL APPROXIMATE THE MAXILLARY TUBEROSITY AND SPACE BECOMES TOO LIMITER FOR THE PLACEMENT OF MOLAR PONTICS.

THE ELEVATED PART OF THE RETROMOLAR PAD AND THE ASCENDING RADIUS SHOULD BE AVOIDED TO ALLOW PROPER PLACEMENT OF MOLAR PONTICS

MAXILLARY OPEN LATTICE ON DISTAL EXTENSION

SHOULD EXTEND THE ENTIrE LENGTH OF THE RESIDUAL RIDGE AND SHOULD BE OF A LADDERLIKE AND LOOP DESIGN

MANDIBULAR OPEN LATTICE ON DISTAL EXTENSION

THE MINOR CONNECTOR FOR THE MANDIBULAR DISTAL EXTENSION BASE SHOULD EXTEND POSTERIORlY ABOUT 2/3RD THE LENGTH OF THE EDENTULOUS RIDGE

Indications of Mesh type

LIMITED OCCLUSOCERVICAL CLEARANCE FROM THE OPPOSING DENTITION

SUPRAERUPTED OPPOSING TOOTH

DIFFICULTY IN PLACING THE PONTICS TO SATISFY IDEAL OCCLUSION FOR THE PATIENT

consequence of bending or deformation of a minor connector

may result in stress concentration and damage to the supporting teeth and soft tissues

categories of minor connector

minor connectors that join clasp assemblies to major connectors

minor connectors that join indirect retainers or auxiliary rests to major connectors

minor connectors that join denture bases to major connectors

minor connectors that serve as approach arms for vertical projection / bar-type clasp

minor connectors that join clasp assemblies to major connectors

Connects the clasp (retentive + reciprocal parts) to the major connector.

Used whenever a direct retainer (clasp) is needed to hold the denture in place.

minor connectors that join indirect retainers or auxiliary rests to major connectors

Transfers forces from indirect retainers / auxiliary rests to the major connector

Used when indirect retention or extra support (auxiliary rests) is needed to prevent denture rotation

minor connectors that join denture bases to major connectors

Provides attachment for the denture base and artificial teeth to the major connector

Used in tooth-supported and distal extension RPDs to carry acrylic base and teeth.

minor connectors that serve as approach arms for vertical projection / bar-type clasp

Acts as the pathway or arm that brings the bar clasp from the gingival direction to engage the undercut.

Used specifically with bar clasps (I-bar, T-bar, modified T-bar)

lattice framework on MX

a distal extension base must extend into the pterygomaxillary notch

this is to provide appropriate mechanical support for the denture base, the minor connector should extend beyond the most prominent portion of the tuberosity (arrow)

lattice framework on MN

a distal extension base must cover the retromolar pad

this is to provide appropriate mechanical support, the minor connector should extend be two-thirds the length of the edentulous ridge

mesh construction

Provides a lattice or grid where acrylic resin can lock in

Most common method to attach denture base and artificial teeth.

bead, nailhead, or wire construction

Provides mechanical retention for acrylic by beads, nailhead-shaped projections, or wires embedded in resin.

Used when space is limited or when mesh can’t be used.