Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.

‫م‬

Minor Connectors
Minor connectors are those components that serve as the
connecting link between the major connector or the base of a removable
partial denture and the other components of the prosthesis, such as the
clasp assembly, indirect retainers, occlusal rests, or cingulum rests.
It arises from major connector thus joining major connector to these
units. In addition to the joining function, the portion of denture
framework by which the denture base is attached, is the minor
connector.
Like the major connector, the minor connector must have sufficient
bulk to be rigid; otherwise the transfer of functional stresses to the
supporting teeth and tissue will not be effective. At the same time, the
bulk of the minor connector should not be objectionable.
The primary function of a minor connector is to join the remaining
components of a removable partial denture to the major connector.
Minor connectors also are responsible for distribution of applied
forces to the supporting teeth and oral tissues. Therefore, rigidity is an
essential characteristic of all minor connectors. The broad distribution of
forces prevents any one tooth or any one portion of an edentulous ridge
from bearing a destructive amount of stress. In contrast, bending or
deformation of a minor connector may result in stress concentration and
damage to the supporting teeth and soft tissues.
Functions of minor connectors
1. Join the denture parts to major connector.
2. Transfers functional stress to the abutment teeth.

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

This is a (prosthesis-to-abutment function) of the minor

connector. 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 through occlusal rests. The minor
connectors arising from a rigid major connector make possible this
transfer of functional stress throughout the dental arch.

3.Transfers the effects of the retainers, rests, and stabilizing

components throughout the prosthesis.
This is an (abutment-to-prosthesis function) of the minor
connector. Thus forces applied on one portion of the denture maybe
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 rigidity of the major
connector.
4. Provide unification and rigidity
5. It might help in retention and stability of the prosthesis.
6. Through its connection to the guiding plane; it helps as a bracing
element.
7. Share in the path of insertion and removal maintenance.
8. Gridwork (framework) minor connectors that connect the denture
base and teeth to the major connector.

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

There are five types of minor connectors on location and

function:
1. Embrasures Minor connectors placed into embrasures
between two adjacent teeth.
A minor connector that contacts the axial surface of an abutment
should not be located on a convex surface. Instead it should be located in
an embrasure (Fig.1), Therefore these connectors should be somewhat
triangular shaped in cross section to minimize intrusion into the tongue
or vestibular spaces, while still providing adequate bulk for rigidity
where it will be least noticeable to the tongue. It should be thickest
toward the lingual surface, tapering toward the contact area (Fig.2 and
3). Therefore the minor connectors should be positioned in lingual
embrasures to disguise their bulk and promote patient comfort.
It should 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.
When the minor connector cross the free gingival area must be
relieved in order not impinge the tissue.
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 a minor connector contacts tooth surfaces on either side of
the embrasure in which it lies, it should be swing back to join the major
connector in a rounded right angle in order to increase gingival
exposure. This avoids sharp angles, which could hinder tongue
movement, eliminates spaces that could trap food, and prevent stress
concentration (Figure.4 and 5).

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

Minor connectors should be located at least 5mm from other vertical

components.
Ideally, a minor connector should not contact the teeth gingival to
the height contour. If a minor connector fits tightly against an abutment
below the height of contour, this wedging can result in increased tooth
mobility. Alternatively, it may be difficult to seat or unseat the
framework.
Due to contact interproximal guiding planes thus helping to
determine the path of placement of the RPD.

2. Proximal minor connector:

Proximal minor connectors contact an abutment tooth adjacent to
an edentulous space. Proximal minor connectors are usually term
proximal plates but are sometimes call guiding plates.
Minor connectors originating from the gridwork in an
edentulous area usually take the form of vertical metal plates (proximal
plates) that make broad contact with prepared guiding planes. These
proximal plates may or may not terminate in an occlusal rest, depending
on the partial denture design. Therefore the proximal minor connector
may be present in connected part of a direct retainer assembly or as a
separate entity. The plate is shifted slightly towards the lingual to
increase rigidity, enhance reciprocation and improve esthetic. The
proximal minor connector should be broad buccolingually to provide
strength but thin mesiodistally to minimize encroachment on the saddle
area, this shape makes it easier to place a prosthetic tooth in a natural
position (Fig.6 and 7).

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

3. Surface minor connectors

Surface minor connectors are located on the lingual surface of incisors
and canines. They connect lingual rests to the major connector. Their
junction with the major connector is a rounded right angle and they taper
toward the occlusal (incisal). The lateral borders extend into the
proximal embrasures to hide these edge from the tongue (Fig8 and 9).

4.minor connectors that serve as an approach arm for a vertical

projection or bar-type clasp.
Approach arms for bar – type clasps are the only minor
connectors that are not required to be rigid (Fig.10). These components
support direct retainers (clasps) and therefore must exhibit some degree
of flexibility.
A minor connector of this type approaches the tooth from an
apical direction rather than from an occlusal direction. The approach arm
should display a smooth, even taper from its origin to its terminus. It
must not cross a soft tissue undercut, and for this reason its use is
contraindicated in some instances.

5. Gridwork(framework) minor connectorsthat connect the

denture base and teeth to the major connector.
Minor connector that covers the edentulous area to join denture
base to major connector should be completely embedded within the
denture base.
These minor connectors must be strong enough to anchor a
denture base to the removable partial denture framework. They must be
rigid enough to resist fracture. In addition, these components must be

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

thin to provide minimal interference with the arrangement of artificial

teeth.
minor connector for mandibular distal extension base should extend
posteriorly about two thirds the length of the edentulous ridge. This
provides adequate support and retention for the associated resin base
(Fig.11). such design will not only add strength to the denture base but
also may minimize distortion of cured base from its inherent strains
caused by processing.
Minor connectors for maxillary distal extension denture bases
should extend the entire length of the residual ridge and should cover the
tuberosity (Fig.12).

Several types of denture base retention minor connectors:

1. Mesh construction
2. Latticework construction (open construction, or ladder type).
3. Bead, loops, posts, or nail-head minor connectors (metal base).
1. The mesh type tends to be flatter(thin), with more potential rigidity.
Conversely the mesh has been shown to provide less retention for the
acrylic if the openings are too small ,Increased pressure is needed to
force resin through the small holes in the minor connector. Insufficient
packing pressure may result in inadequate resin penetration and a weak
attachment to the framework. Studies have shown that the smaller the
openings in this minor connector, the weaker the attachment (Fig.13).
2. The lattice type can be used whenever multiple teeth are to be
replaced. It has superior retentive potential to acrylic resin, but can
interfere with the setting of teeth, if the struts are made too thick or

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

poorly positioned. This type can be relined easily after ridge resorption
(Fig.14).
The major difference between retentive mesh and retentive lattice is
the size of the openings. Retentive mesh has small openings while
retentive lattice has much larger openings.

Relief
Adequate mechanical retention of the denture base resinis gained
by providing relief under the minor connector gridwork (mesh type or
Lattice type) to allow the acrylic resin to flow under the gridwork. To
allow for this space, relief wax is placed on the cast in the edentulous
areas prior to making a refractory cast (for fabricating the framework).
Usually one thickness of baseplate wax is sufficient (about 1 mm of
relief). After the framework has been waxed and cast on the refractory
model and returned to the master cast, the space provided by the relief
wax is available for the mechanical retention of the acrylic resin.
Relief under the gridwork should not be started immediately
adjacent to the abutment tooth but should begin 1.5 - 2 mm from the
abutment tooth. This will create a metal to tissue contact immediately
adjacent to the tooth. A metal surface is preferable since it wears less,
and is less porous, thus facilitating hygiene (Fig.15 and 16).
3. Bead, loops, or nail head minor connectors: it fits directly on the
ridge, therefore no relief is provided for this type of minor connector.
The primary advantage of a metal base is related to improved
hygiene and thermal stimulation ( better soft tissue response to metal).
Disadvantages include difficulty in adjusting and relining cast
metal bases. Furthermore, the attachment of resin is relatively weak
(Fig.17 and 18).
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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

These minor connector should be limited to short-span, tooth-

supported applications in patients with well healed ridges.

Finishing line
It is the junction of minor connector that join denture base to major
connector.
The finishing line junction with the major connector should take the
form of an angle not greater than 90 degrees, therefore being somewhat
undercut.
A minor connector that supports an acrylic resin denture base must
be joined to the major connector with sufficient bulk to avoid fracture.
The minor connector must be joined to the major connector in angle
not greater than 90° (butt-joints), to ensure rigidity of acrylic denture
base and to help lock the acrylic resin to the major connector. The
acrylic resin denture base must join the major connector in a smooth,
even fashion. Any irregularity or step between the two surface will
irritate the tongue (Fig.23).
Because acrylic resin gains its strength with increasing bulk, it
should not be finished to a thin edge. If this is attempted, the material
may chip or fracture. This can create unhygienic and potentially
irritating conditions. Ideally, a butt joint should be provided so the
acrylic resin can blend evenly with the major connector(Fig.22).
The medial extent of the minor connector depends on the lateral
extent of the major palatal connector.
If the 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 (Fig.24), when the palatal

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

contours are restored, enhancing speech and contributing to a natural

feeling for the patient.
If, the 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.
The location of the finishing line at the junction of the major and
minor connectors should be based on restoration of the natural palatal
shape, with consideration given to the location of the replacement teeth.
The junction of the major and minor connectors at palatal finishing
lines should be located 2mm medial from an imaginary line that would
contact lingual surface of missing posterior teeth (Fig.21).
Extension of the finishing line to the area of the pterygomaxillary
notch provides for attachment of the border portion of the resin base
through butt-type joint the pterygomaxillary notch (arrows in Fig.25).
Equal consideration must 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 the guidelines for base contour
and clasp length (Fig.26).

Function of finishing line:

1. A finishing line creates a definite limit to the plastic of the denture
base, in this way the plastic ends in a bulk of material. Thin areas of
plastic are weak and subjected to fracture.
2. undercut finishing line provides mechanical retention for plastic
denture base.
3. finishing line provides a smooth transitional from the plastic base to
the removable partial denture metal framework.
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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

If finishing line is located on the outer surface of major connector, it

is called external finishing line (Fig.20). If finishing line is located on
the inner or tissue surface of major connector, it is called internal
finishing line (Fig.19).

Types finishing line:

1. vertical finishing line: it is the finishing line at the junction of ladder
area and major connector in free end extension cases (CL I and CL II) in
mandibular arch, and CL III or CL IV mandibular arch with labial bar
major connector (Fig.27,28, 29, and 30).
2. Horizontal finishing line: It is the junction of major connector and
ladder area and it extends horizontally forming an undercut area that
support acrylic resin that carrying artificial teeth, this type of finishing
line is detected in all maxillary partial denture cases and in CL III and
CL IV mandibular cases (Fig.31 and 32).

Tissue stop :
A small projection of metal at the distal end of an extension base
frame that contacts the cast and preventing distortion of the framework
during acrylic resin processing procedures. The provide stability to the
framework during the stages of transfer and processing (Fig.33,34, and
35). Tissue stops can engage buccal and lingual slopes of the residual
ridge for stability.
When the denture is flasked for processing, only the gridwork is left
exposed after the wax removal. If there is no “tissue stop”, the
framework can be bend or displaced during the pressure packing of the
mold with stiff doughy acrylic resin. If this occurs, the framework could
resume its normal shape after deflasking, and the denture would

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 Lecture 4, minor connectors Prosthodontics ‫ ﻋﻣر زﯾﻧواﻟﺗﺣو‬.‫م‬

subsequently lift off the tissue. Rocking of the denture base and clasp
apparatus would result, and the occlusion would be high (Fig.36).
Another integral part of the minor connector designed to retain the
acrylic resin denture base is similar to a tissue stop but serves a different
purpose. It is located distal to the terminal abutment and is a
continuation of the minor connector contacting the guiding plane. Its
purpose is to establish a definitive finishing index tissue stop for the
acrylic resin base after processing (Fig.33).

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 Fig.1 Embrasures Minor connectors placed into embrasures between two adjacent teeth.

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 Fig.3 Minor connector crossing gingival margin vertical, and
connected with major connector at right angle
Fig.2 In an embrasure space, the minor
connector is tapered to the tooth to avoid
bulk and to accommodate the tongue.

Fig.4 mesial and distal minor connectors and proximal plates

adjacent to the edentulous areas should be swing back to join Fig.5 Junctions of major and minor connectors should be
the major connector in a rounded acute angle. round and gently curved (arrows).

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 Fig.7 A minor connector that joins a clasp assembly to the major
Fig.6 A minor connector (arrow) that joins a clasp assembly connector must be broad buccolingually, but thin mesiodistally.
to the associated major connector. This allows the minor connector to be strong, yet does not
interfere with prosthetic tooth placement.

Fig.8 Surface minor connectors Fig.9 Surface minor connectors

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 Fig.10 A minor connector (arrow) that serves as the Fig.11 minor connector for mandibular distal extension
approach arm for a bar-type clasp. base should extend posteriorly about two thirds the
length of the edentulous ridge.

Fig.12 Minor connectors for maxillary distal

extension denture bases should extend the
entire length of the residual ridge Fig.13 Mesh type minor connector

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 Fig.15 Relief under the gridwork should not be started immediately
Fig.14 Latticework ,ladder type minor connector adjacent to the abutment tooth but should begin 1.5 - 2 mm from the
abutment tooth.

Fig.16 Relief under the gridwork minor connector.

Fig.17 nail head minor connectors

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 Fig.19 A butt joint should be used to join acrylic resin and metal
Fig.18 bead minor connector. components at the internal surface of a removable partial denture. Each
internal finish line should display an angle of 90 degrees.

Fig.20 External finish lines should be slightly less than 90

Fig.21 the external finish line should follow an arc
degrees. This results in improved mechanical retention for established by the lingual surfaces of the remaining teeth.
acrylic resin components.

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 External finish line

Internal finish line

Fig.22 Internal and external finish line

Fig.23 External finish line, junction between acrylic and major connector.

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 Correct Incorrect

Fig.24 Junction of the major connector and the minor connector at palatal finishing lines should be located 2 mm medial from an
imaginary line that would contact the lingual surfaces of missing posterior teeth. The finish line on the right is too far toward
midline of the palate. The natural contours of the palate will be altered.

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 Fig.26 The junctions of minor connectors and bar arm are 90-degree butt-type
Fig.25Extension of the finishing line to the area of
joints and should follow the guidelines for base contour and clasp length.
the pterygomaxillary notch provides a butt-type joint
for attachment of the border portion of the resin base
through the pterygomaxillary notch (arrows).

Fig.27 Vertical finish line CLI Fig.28 Vertical finish line in labial bar major connector

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 Fig.29 Vertical finish line, external surface Fig.30 vertical finish line, internal surface

Fig.31 Horizontal finishing line.

Fig.32 Horizontal finishing line.

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 Fig.33 Tissue stop

Fig.34 Tissue stop Fig.35 Tissue stop

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 Fig.36 framework can be bent or displaced during the pressure packing. When
there is no tissue stoper.

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