Transcript Major Connectors

Major Connectors
Dr Deeksha Arya
Associate Professor
Department of prosthodontics
BDS III year
RPD Lecture
Timing- 12-1 PM
Components of a typical removable
partial dentures• 1. Major connectors
• 2. Minor connectors
• 3. Rests
• 4. Direct retainers
• 5. Stabilizing or reciprocal components (as parts of
a clasp assembly)
• 6. Indirect retainers (if the prosthesis has distal extension
bases)
• 7. One or more bases, each supporting one to several
replacement teeth
• The chief functions of a major connector include
• unification of the major parts of the prosthesis,
• distribution of the applied force throughout the arch to
selected teeth and tissue, and
• minimization of torque to the teeth.
This component also provides the cross-arch stability to help
resist displacement by functional stresses.
Location
• 1.Major connectors should be free of movable tissue.
• 2. Impingement of gingival tissue should be avoided.
• 3. Bony and soft tissue prominences should be avoided during
placement and removal.
• 4. Relief should be provided beneath a major connector to
prevent its settling into areas of possible interference, such as
inoperable tori or elevated median palatal sutures.
• Major connectors should be located and/or relieved
to prevent impingement of tissue because the distal
extension denture rotates in function.
DEFINITION

A MAJOR CONNECTOR IS THE COMPONENT OF
THE PARTIAL DENTURE THAT CONNECTS THE PARTS
OF THE PROSTHESIS LOCATED ON ONE SIDE OF THE
ARCH WITH THOSE ON THE OPPOSITE SIDE.

It is that unit of the partial denture to which all other
parts are directly or indirectly attached
CONTENTS
Function of the major connector
Desirable characteristics of major connector
Types of major connector
Steps in designing major connector
Metarial used for major connector
Factors affecting the selection of major connector
DESIRABLE CHARACTERISTICS OF MAJOR CONNECTORS
1. Rigid
2. Compatible with oral tissues
3. Does not interfere with and is not irritating to the tongue
4. Does not substantially alter the natural contour of the palatal vault.
5. Does not impinge on oral tissues
6. Covers no more tissue than is absolutely necessary
7. Does not contribute to the retention or trapping of food particles .
8. Contribute to the support of the prosthesis.
TYPES OF MAJOR CONNECTOR
SIX BASIC TYPES OF MAXILLARY MAJOR CONNECTORS ARE
CONSIDERED:
1. SINGLE PALATAL BAR
2. SINGLE PALATAL STRAP
3. U-SHAPED PALATAL CONNECTOR
4. ANTERIOR-POSTERIOR PALATAL BAR
5. COMBINATION ANTERIOR AND POSTERIOR PALATAL
STRAP-TYPE CONNECTOR
6. PALATAL PLATE-TYPE CONNECTOR
SINGLE PALATAL BAR
A palatal connector component of less than 8 mm in width is referred
to as a bar.
It is narrow half – oval with its thickest point at the centre
A partial denture made with a single palatal bar is often either too
thin and flexible or too bulky and objectionable to the patient's
tongue
INDICATION
Limited to replacing one or two teeth on each side of arch and placed no
further anteriorly than the second premolar position.
Perhaps the only indication for its use is as an interim partial denture until
a more definitive treatment can be considered.
CONTRAINDICATION
 In distal extension situation
 when anterior teeth are to be replaced
DISADVANTAGES
 Most difficult for the patient to adjust as to maintain the degree
of rigidity it has to be made bulky.
 Due its narrow anterior-posterior width it derives little vertical
support from the bony palate and must be therefore supported
positively by rests on the remaining natural teeth.
SINGLE PALATAL STRAP
It consists of a wide thin barel of metal that crosses the palate in
an unobtrusive manner.
 It should not be less than 8mm wide or its rigidity maybe
compromised.
It can be relatively narrow for small tooth supported prosthesis or
wider for larger edentulous spaces requiring support
ADVANTAGES
 Because the palatal strap is located in three planes it offers great
resistance to bending and twisting forces.
Distribution of stress over a broad area.
Retention of the partial denture is enhanced by the intimate contact
between the metal and soft tissue.
The strap also contributes some indirect retention.
DISADVANTAGES
The patient may complain of excessive palatal coverage.
Another possible disadvantage is an adverse soft tissue reaction in
the form of papillary hyperplasia.
INDICATIONS
Used only when 1 or 2 teeth are being replaced on either side.
In CLASS III situations
Need for palatal support is minimal
CONTRAINDICATION
 Anterior replacements with distal extension bases.
U-SHAPED PALATAL CONNECTOR
It consists of thin band of metal running along posterior teeth and
extending onto the palatal tissues for 6-8mm.
The borders of the horseshoe connector must either be 6 mm from the
gingival margin or extend onto the lingual surfaces of the teeth.
The borders should also be placed in the valleys of the rugae.
The lateral palatal borders should be at the junction of the horizontal and
vertical slopes of the palate.
The rigidity can be increased by extending the borders slightly onto
the horizontal palate surface.
INDICATIONS
•Can be in case of a large inoperable tori
•When several anterior teeth are to be replaced.
•In case of patients with exaggerated gag reflex.
•When periodontically weakened anterior teeth need some stabilizing
support.
DISADVANTAGES
Its lack of rigidity allows lateral flexure under occlusal forces… induce
torque or direct lateral force to abutment teeth.
Bulk to enhance rigidity results in increased thickness in areas that are
a hindrance to the tongue.
ANTERIOR AND POSTERIOR PALATAL BAR-TYPE
CONNECTORS
 The flat anterior bar is narrower than the palatal strap…borders are
positioned in the valleys between the rugae.
The posterior bar is half-oval, similar to the single posterior palatal bar
connector but less bulky.
The two bars are joined by flat longitudinal elements on each side of the
lateral slopes of the palate providing an L beam effect
INDICATIONS
when support is not a major consideration and when the anterior and
posterior abutments are widely separated.
Presence of torus palatinus.
The patient's mental attitude: the a-p bar may be used as a compromise
for the patient who strongly objects to the greater bulk or area coverage of
the full palatal connector.
CONTRAINDICATIONS
In reduced periodontal support of the remaining teeth that necessitates
additional support from the palate.
ADVANTAGES
The main advantage is its rigidity. In comparison to the amount of
soft tissue coverage, it is by far the most rigid maxillary major
connector
DISADVANTAGES
it is frequently uncomfortable.
Derive very little support from the palate.
May interfere with speech- especially the anterior bar.
ANTERIOR AND POSTERIOR PALATAL STRAP-TYPE
CONNECTOR
A posterior palatal strap should be flat and a minimum of 8 mm wide.
 Posterior palatal connectors should be located as far posteriorly as
possible to avoid interference with the tongue
INDICATIONS
Kennedy’s Class I and CLASS II arches.
CLASS II modifications I arches.
Class IV arches.
In case of inoperable tori.
DISADVANTAGES
Even though the metal over thin rugae area may be thinner than in
some other major connectors, interference with phonetics may occur in
some patients.
In addition, the extensive length of borders may cause discomfort to the
tongue
PALATAL PLATE-TYPE CONNECTOR
The full palate connector should be thin, with the natural anatomy of
the palate reproduced ..
The anterior border must be kept 6 mm from the marginal gingiva or
must cover the cingula of the anterior teeth.
 The posterior border of the complete palate normally extends to the
juncture of the soft and hard palate.
The posterior border can be fabricated of either metal or acrylic resin.
If it is made of metal, the border must be precisely established,
because if overextended it will quickly induce soreness, and the
metal is difficult to alter satisfactorily.
A slight bead should be provided in the metal by lightly
scraping the refractory cast, prior to forming the wax pattern for
the framework.
The acrylic resin border is preferred when maximum adhesion
and atmospheric seal is needed
ADVANTAGES
It reproduces the anatomic contours properly.
uniform thickness and the thermal conductivity of the metal are readily
acceptable to the tongue and underlying tissues.
DISADVANTAGES
Adverse soft tissue reaction in the form of inflammation or hyperplasia
may occur
Problems with phonetics may occasionally occur
INDICATIONS
CLASS I AND CLASS II arches
When the last remaining abutment tooth on either side of a Class I arch is
the canine or first premolar tooth,
In individuals with a full complement of mandibular teeth
When flat or flabby ridges or a shallow vault is present.
Cleft palate patients
CONTRAINDICATION
Presence of tori which cannot be surgically removed a full palatal
coverage cannot be given.
DESIGN OF MAXILLARY MAJOR
CONNECTORS

In 1953 blatterfein described a systematic
approach to designing maxillary major connectors.
STEP 1: OUTLINE OF PRIMARY BEARING
Areas. The primary bearing areas are those that
will be covered by the denture base(s)
STEP 2: OUTLINE OF NONBEARING AREAS.
The nonbearing areas are the lingual gingival
tissues within 5 to 6 mm of the remaining teeth,
hard areas of the medial palatal raphe (including
tori), and palatal tissues posterior to the vibrating
line.
STEP 3: OUTLINE OF CONNECTOR AREAS.
STEP 4: SELECTION OF CONNECTOR TYPE
Connectors must have a maximum of rigidity to distribute
stress bilaterally.
 Connectors should be of minimum bulk
When edentulous areas are located anteriorly, the use of
only a posterior strap is not recommended.
 By the same token, when only posterior edentulous
areas are present, the use of only an anterior strap is not
recommended.
The need for indirect retention influences the outline of
the major connector.
STEP 5: UNIFICATION. After selection of the type of
major connector, the denture base areas and connectors
are joined.

 MATERIALS USED FOR MAJOR CONNECTORS
 THE VARIOUS ALLOYS THAT CAN BE USED IN CONSTRUCTING
REMOVABLE PARTIAL DENTURE FRAMEWORK ARE:
1.TYPE IV GOLD ALLOY
2.NICKEL CHROMIUM
3.COBALT-CHROMIUM
4.CO- CR- NI
5.TITANIUM AND ITS ALLOYS
FACTORS AFFECTING SELECTION OF THE MAXILLARY
CONNECTOR
RIGIDITY
THE PRESENCE OF PALATAL TORI
THE NEED FOR ANTERIOR TOOTH REPLACEMENT
THE REQUIREMENT FOR INDIRECT RETENTION
THE NEED TO STABILIZE WEAKENED TEETH
PHONETIC CONSIDERATIONS
THE MENTAL ATTITUDE OF THE PATIENT
MANDIBULAR MAJOR
CONNECTORS
Contents
 Introduction
 Definition
 Desirable characteristics of major connectors.
 Criteria for selection of mandibular major
connectors.
 Structural requirements of mandibular major
connectors.
 Types of mandibular major connectors.
 Lingual bar major connector.
 Sublingual bar major connector.
 Double lingual bar or Kennedy bar major
connector.
 Cingulum bar or continuous bar major connector.
 Linguoplate major connector.
 Labial bar major connector.
 Hinged continuous bar major connector.
 Design of mandibular major connector.
 Materials used for major connector.
 Summary and Conclusion.
 References.
“No component of a Removable Partial Denture
should be added arbitrarily or conventionally.
Each component should be added for a good
reason and to serve a definite purpose”.
- Mc Cracken
Introduction
• Choosing one of the possible procedures for restoring partially
edentulous arch involves border line decisions.
• If the relationship between the biologic behaviour of the oral
structures and the mechanical influence of the denture is
recognized we can provide a partial denture…..
• The major connector may be compared with the frame of an
automobile or with the foundation of the building.
• Major connector must be rigid……….
• It is the dentists responsibility to ensure appropriate design
and fabrication.
Definition
• A major connector is the component of the
partial denture that connects the parts of the
prosthesis located on one side of the arch with
those on the opposite side.
• It is that unit of the partial denture to which
all other parts are directly or indirectly
attached.
Desirable characteristics of major connectors
• The major connector should be rigid to
effectively distribute stress…
• Impingement of free gingival margin should
be avoided.
• Borders of major connector should run
parallel to the gingival margin of teeth.
• Adequate rests must be provided for the
major connector.
• Should not create food traps.
• Should not cause discomfort to the tissues.
• Should not alter the natural contour of the
palatal vault or the lingual surface of the
lower alveolar ridge.
• Should be non-interfering and nonirritating to the tongue.
• Should not interfere with speech and
phonetics.
• Should not cover more tissue than
absolutely necessary.
• Should be made of a material compatible
with the oral tissues.
Criteria for selection of mandibular major
connector
• Although the maxillary connector is able to contribute
substantially to support the prosthesis, the mandibular
connector has the very limited capacity for support. Indirect
retention is needed to stabilize the mandibular partial
denture.
– The requirement of indirect retention.
– Horizontal stability and stress distribution.
– Anatomical considerations.
– Periodontal considerations.
– Esthetic considerations.
– Patient comfort.
Structural requirements for
mandibular major connectors
• Most of the mandibular major connectors are
long and relatively narrow because of space
limitation caused by the height of the floor of
the mouth, position of lingual frenum.
• For these reasons considerations must be
given to maintain rigidity of the connector
without making it so bulky.
• The slope of the lingual tissue and tissue that
slope towards tongue requires relief.
Types of major connector
• Lingual bar major connector.
• Sublingual bar major connector.
• Lingual bar with cingulum bar major
connector (continuous bar).
• Cingulum bar (continuous bar) major
connector.
• Linguoplate major connector.
• Labial bar major connector.
• Hinged continuous labial bar.
Lingual bar major connector
 The basic form of a mandibular major connector is
a half-pear shape, located above moving tissue but
as far below the gingival tissue as possible.
 Advantages:
 Lingual bar connector has minimal tissue coverage
and has minimal contact with oral tissues.
 It does not contact the teeth, so decalcification of
the tooth surface is minimized.
 Disadvantages:
 It may be flexible if poorly constructed.
 Rigidity is less compared to a well constructed lingual
plate.
 Indications:
 It should be used for mandibular removal partial
denture where sufficient space exists between
the slightly elevated alveolar lingual sulcus and
lingual gingival tissues.
 Contraindications:
 Inoperable lingual tori.
 Highly attached lingual frenum.
 Interferences to elevation of the floor of the
mouth during functional movements.
Characteristics and location
• Half-pear shaped with bulkiest portion
inferiorly located.
• Superior border tapered to soft tissue.
• Superior border located atleast 4mm inferior
to gingival margins.
• Inferior border located at the ascertained
height of the alveolar lingual sulcus when the
patients tongue is slightly elevated.
• Availability of space for connector is one of the important
factor to be considered. Atleast 8mm of vertical space
between the active tissues of the floor of the mouth and
the gingival margins of the teeth is required.
• There are two clinically acceptable methods to determine
relative height of the floor of the mouth to locate the
inferior border of the major connector.
 First method: Patients tongue should
touch the vermillion border of the upper
lip and measurements were made in
relation to the lingual gingival margins of
the adjacent teeth using a periodontal
probe. The readings are transferred to the
master cast.
 Second method: This method uses an
individualized impression trays having its
lingual border 3mm short of the elevated
floor of the mouth is molded with an
impression material during functional
movements of tongue.
Blockout and relief of master cast
• All tissue undercuts parallel to path of placement.
• An additional thickness of 32-gauge wax when the
lingual surface of the alveolar ridge is either undercut or
parallel to the path of placement.
• No relief is necessary when the lingual surface slopes
inferiorly and posteriorly.
• One thickness of base plate wax over basal seat areas.
 Waxing specifications
 Six-gauge, half-pear shaped
wax form reinforced by 22-24
gauge sheet wax adapted to
the design width.
 Long bar require more bulk
than short bar.
 Finishing lines
 Butt joints with minor
connectors for retention of
denture bases.
Z. Ben-Ur, S. Matalon, I. Aviv and H.S. Cardash (J.P.D. 1989)
Conducted a study to check the rigidity of five lingual bar type
mandibular major connectors with different cross-sections a
micrometer microscope and a system of pulley and weights
were used and torsion forces were measured to compare
rigidity. They concluded that the lingual bar type with halfpear shaped cross section showed the highest degree of
rigidity. Among the conventional lingual bars the wide
semielliptical bar showed the highest degree of rigidity and
narrow semielliptical bar was most flexible.
Zee Ben-Ur, Eitan Mijiritsky, Colin Gorfil, and Tamar Brosh
(J.P.D. 1999)
Conducted a study to investigate the design and crosssectional shape of major connectors most favorably
influencing rigidity and flexibility. Five lingual bar major
connectors of different cross-sectional forms were cast in
chrome-cobalt alloy. Vertical and horizontal forces were
applied to each point while the opposite side was gripped in
Instron. They concluded that the half-pear shaped crosssection proved to be the most rigid major connector.
Anthony K. Kaires (J.P.D. 1958)
Conducted a study using Electronic means to know the effect
of partial denture design on functional force distribution in a
mandibular bilateral distal extension denture as it is related
to the supporting tissues and also to determine what effect
the variations of partial denture designs has on masticatory
performance. They concluded that the effect of partial
denture design on masticatory performance did not reveal
any significant relationship. Generally they stated that a rigid
design is more desirable than a flexible one in withstanding
horizontal stresses.
Linguoplate mandibular major connector
• If the rectangular space
bounded by the lingual bar, the
anterior tooth contacts and
cingula, and the bordering
minor connectors is filled in, a
lingual plate results.
 Advantages:
 The linguoplate is a rigid mandibular major connector and it
provides more support and stabilization when compared to other
connectors.
 Can be used in stabilizing the periodontally-weakened teeth.
 When it is supported at each end by a rest it contributes to the
action of indirect retention.
 When properly contoured and fabricated, it will not cause
interference with tongue movements and will be more comfortable
to the patient.
 Disadvantages:
 It covers the tooth structure and the gingival tissue.
 The metal coverage of the free gingival tissue prevents physiological
stimulation and self-cleansing of these areas by saliva.
 Indications:
 It is indicated in cases where alveolar lingual sulcus so closely
approximates the lingual gingival crevices such as high lingual
frenum attachments.
 If residual ridges in Class I arch have undergone severe vertical
resorption that they will offer only minimal resistance to
horizontal rotation.
 It can be used to stabilize periodontally weakened teeth.
 When future replacement of one or more incisor teeth will be
facilitated by the addition of retention loops to an existing
linguoplate.
 Contraindications:
 In lingually inclined mandibular anterior teeth.
 Mandibular teeth with wide embrassures and diastema.
 Characteristics and location:
 Half-pear shaped with bulkiest
portion inferiorly located.
 Thin metal apron extending
superiorly to contact cingula of
anterior teeth and height of
contour of posterior teeth.
 Scalloped contour of apron as
dictated by interproximal blockout.
 The superior border finished to
continuous plane with contacted
teeth.
 Inferior border at the ascertained
height of the alveolar lingual sulcus
when patients tongue is elevated.
 Blockout and relief of master cast:
 All involved undercuts of contacted teeth parallel
to the path of placement.
 All involved gingival crevices.
 Lingual surface of alveolar ridge.
 Waxing specifications:
 Inferior border 6-gauge, half pear shaped wax
form reinforced with 24-gauge sheet wax.
 Apron 24-gauge sheet wax.
 Finishing lines:
 Butt-type joints.
Larry D. Campbell (J.P.D. 1977) conducted a study to
evaluate the multiple removable partial denture designs by
test patients. 8 major connector designs were evaluated
during speaking, chewing and swallowing and for general
comfort by 12 dentists. They concluded that the mandibular
lingual bar was chosen over the lingual plate by a 3:1 ratio.
Metal borders parallel to tongue movement were better
tolerated than those lying transverse. In general, patients
adapted best to major connectors that covered the least
amount of soft tissues.
 Kenneth R. McHenry, Owe E. Johansson (J.P.D. 1992)
conducted a clinical trial using the experimental
gingivitis model developed for periodontal clinical
research to evaluate the effect of removable partial
denture mandibular major connector design on
surrounding gingival tissues. A comparison between the
linguoplate (control) and cingulum bar (test) major
connectors were made at 7 day intervals for 21 days.
Results showed a greater increase in mean gingival
inflammation with the control than with the test
suggesting that cingulum bar has fewer detrimental
effects on gingival tissues than linguoplate.
Sublingual bar major connector:
A modification of the lingual bar that has been demonstrated to
be useful when the height of the floor of the mouth does not
allow placement of superior border of the connector at least 4mm below free gingival margin.
 Indications:
 The height of the floor of the mouth in relation to
the free gingival margin is less than 6mm.
 If it is desired to keep the free gingival margins of
anterior teeth exposed and there is inadequate
depth of the floor of the mouth.
 Contraindications:
 Lingually tilted remaining natural teeth.
 Inoperable lingual tori.
 High attached lingual frenum.
• Characteristics and Location:
– It is same as lingual bar except that the bulkiest
portion is located to the lingual and the
tapered portion is towards the labial.
– The superior border of the bar should be
atleast 3mm from the free gingival margin.
– Inferior border is located at the height of the
alveolar lingual surface.
• Blockout and relief of master cast:
– All tissue undercuts parallel to the path of
placement.
– Additional thickness of 32-gauge wax when the
lingual surface of alveolar ridges either
undercut or parallel to the path of placement.
• Waxing specifications:
– 6-gauge, half-pear shaped wax form reinforced
by 22-24 gauge sheet wax.
– Longer bar bulkier than shorter bar.
• Finishing lines:
– Butt-type joints.
 Karl A. Hansen and Donald J. Campbell (J.P.D. 1985)
conducted a study to evaluate patient acceptance of the
sublingual bar when compared with lingual plate major
connector and to determine the preferred design. They
concluded from the final data that the sublingual bar
compares favorably with the lingual plate in patient
acceptance and should be considered as a variable
design alternative when a lingual plate is not indicated.
Mandibular lingual bar with cotninuous bar
(cingulum bar) or double lingual bar)
 This type of major connector is
also called “Kennedy bar” it
distribute stresses to all of the
teeth with which it comes in
contact there by reducing the
stresses to the underlying
tissues.
 It is also referred as “continuous
lingual clasp” major connector,
because of series of clasp arms
connected on the lingual
surfaces of lower anterior teeth.
 Advantages:
 The double lingual bar effectively extends indirect retention in an
anterior direction is supported by adequate rest.
 It also contributes to horizontal stabilization.
 It helps in minor amount of support to the prosthesis.
 The gingival tissues and inter-proximal embrassures are not covered
by the connector, which helps in free flow of saliva.
 Disadvantages:
 Patient may feel discomfort because it alters the normal position of
the tongue.
 If connector does not maintain intimate contact with tooth surface
there will be food entrapment.
• Indications:
– It is mainly used as a major connector
in periodontally treated anterior teeth
with wide inter-proximal embrassures.
– When linguoplate is contraindicated
due to poor axial alignment of anterior
teeth.
• Contraindications:
– In severely crowded anterior teeth.
 Characteristics and location:
 Shaped same as lingual bar.
 Thin narrow metal strap located on cingula of anterior teeth
scalloped to follow interproximal embrassures.
 Blockout and relief of master cast:
 Same as for lingual bar.
 No relief for continuous bar except blockout of interproximal
spaces.
 Waxing specifications:
 Same as lingual bar.
 Continuous bar pattern found by adapting two strips of 28-gauge
sheet wax over the cingula and into interproximal embrassures.
 Finishing lines:
 Butt joints.
 Mansuang, Hisashi, Takashi (I.J.P. 2001) conducted a
study to investigate the vibration characteristics of 3
different designs of mandibular major connectors in
vitro by observing model animation, decay rate and
maximum amplitude. Three removable partial denture
frameworks (lingual bar, Kennedy bar and lingual plate)
were studied. They concluded that all three designs
demonstrated no elastic deformation in terms of
vibration analysis a lingual bar demonstrated the
maximum decay rate indicating that it will dissipate the
energy through vibration faster than the other designs.
Hence the possibility of creating harmful effects to the
oral tissue is lesser.
Mandibular continuous bar (Cingulum bar)
 Improper axial alignment of the anterior teeth will necessitate
excessive blockout of interproximal undercuts. These types of cases
indicates continuous bar major connector.
 Contraindications:
 In lingually tilted anterior teeth.
 Wide diastema between mandibular anterior teeth.
 Characteristics and Location
 Thin narrow metal strap located on cingula of
anterior teeth, scalloped to follow interproximal
embrassures.
 Originates bilaterally from rests of the adjacent
principle abutments.
 Blockout and relief of master cast:
 No relief for cingulum bar except interproximal
spaces.
 Waxing specifications:
 A cingulum bar pattern formed by adapting two
strips of 28-gauge, 3mm wide over the cingula
and into interproximal embrassures.
 Finishing lines:
 Butt-type joint.
Mandibular labial bar major connector
 The labial bar has a limited application in cases where large
inoperable lingual tori and severely lingually inclined lower
anterior and premolars prevents the use of other mandibular
major connectors.
 Characteristics and Location:
 Half-pear shaped with bulkiest portion inferiorly
located on the labial or buccal aspect.
 Superior border tapered to soft tissue and 4mm
inferior to labial gingival margins.
 Inferior border located in the labial buccal
vestibule.
 Blockout and relief of master cast:
 All tissue undercuts parallel to path of placement
and when the labial surface is either undercut or
parallel to the path of placement.
 No relief if labial surface of alveolar ridge slopes
inferiorly.
• Waxing specifications:
– 6-gauge half-pear shaped wax form reinforced
with 22-24 gauge
– Long bar more bulkier than shorter bar.
– Minor connector joined with occlusal or other
superior components by a labial approach.
• Finishing line:
– Butt-type joints.
Hinged continuous labial bar
•
This type of major connector is the modification
of linguoplate which is incorporated in the
“Swing-lock” design consists of labial or buccal
bar i.e. connected to the major connector by
hinge on one end and latch at the other end.
•
Support provided by multiple rests on the
remaining natural teeth. Stabilization and
reciprocation provided by a lingual plate.
Retention is provided by bar type retentive clasp
arms projecting from the labial or buccal bar
and contacting the infrabulge areas on the labial
surfaces.
• Indications:
– Missing key abutments.
– Unfavorable tooth contour.
– Unfavorable soft tissue contours.
– Teeth with questionable prognosis.
• Contraindications:
– Poor oral hygiene.
– Shallow buccal labial vestibule.
– High frenal attachment.
Design of mandibular major connectors
 The basic principles of major
connector design includes:
 Step I-Outline the basal seat
areas on the diagnostic cast.
 Step II-Outline the inferior
border of the major connector.
 Step III-Outline the superior
border of the major connector.
 Step-IV-Connect the basal seat
area to the inferior and superior
borders of the major connector
and add minor connectors to
retain the acrylic resin base.
Materials used for Major connectors
• Various alloys that can be used in constructing
removable partial denture are:
– Type IV gold alloy.
– Nickel-chromium.
– Cobalt-chromium.
– Co-Cr-Ni.
– Titanium and its alloys.
• Base metal alloys have relatively high elastic modulus. This
property suggest that the thickness of partial denture
frameworks can be thinner than those of other metals.
• The ductility of titanium is greater than that of the others.
• Base metal alloys have higher hardness compared with
tooth enamel which causes in vivo wear.
• Alloys for partial denture frameworks have high melting
points and they exhibit high casting shrinkage with
potential for casting defects.
Summary
 Various major connector designs that can be useful in
the successful construction of a removable partial
denture has been discussed.
 For a tooth supported removable partial denture the lingual bar
is the suitable major connector.
 Long span edentulous ridges in which there is posterior
abutment and indirect retention is needed, the lingual plate is
indicated.
 When anterior teeth are periodontally treated and needs
support and stabilization, the lingual plate or double lingual bar
may be used.
 When the tissue of the floor of the mouth are active and <8mm
space available between tissue and marginal gingiva, a lingual
plate is preferred.
 Labial bar is rarely used.
Conclusion
• Major connectors by uniting the other components of a removable partial
dentures acts like a foundation bringing about bilateral distribution of
forces which depends on the rigidity of the connector.
• Utmost care should be taken to prevent a major connector from
interfering with normal functions or having any damaging effects to the
remaining oral structure.
• Although there are many variations in major connector, a thorough
comprehension of all factors influencing their design will lead to the best
design for each patient.
References
• McCracken’s Removable Partial Prosthodontics. A.B. Carr, G.P. McGivney,
D.T. Brown. 11th edition.
• Stewart’s Clinical Removable Partial Prosthodontics. Rodney D. Phoenix,
David R. Cagna, Charles F. DeFreest. 3rd edition.
• Removable partial prosthodontics. Ernest L. Miller, Joseph E. Grasso,
Second edition.
• Bert T. Cecconi : Lingual bar design. J.P.D. 1973; 29: 635-639.
• McCracken W.L. : Contemporary partial denture designs. J.P.D. 2004; 92:
409-417.
• Z. Ben-Ur, S. Matalon, I. Aviv : Rigidity of major connectors when
subjected to bending and torsion forces. J.P.D. 1989; 62: 557-562.
• David Henderson : Major connectors for mandibular removable
partial dentures: Design and function. J.P.D. 1973; 30: 530-549.
• Mansuang, Hisashi, Takashi : Rigidity of 3 different types of
mandibular major connector through vibratory observations. I.J.P.
2001; 14: 510-515.
• Carl A. Hansen, Donald J. Campbell : Clinical comparison of two-
mandibular major connector designs: The sublingual bar and the
lingual plate. J.P.D. 1985; 54: 805-808.
• Kenneth R. McHenry, Owe E. Johansson : Effect of removable partial
denture framework design on gingival inflammation – a clinical model.
J.P.D. 1992; 68: 799-803.
• Larry D. Campbell : Subjective reactions to major connector designs
for removable partial denture. J.P.D. 1977; 37: 507-515.
• Anthony K. Kaires : A study of partial denture design and masticatory
pressures in a mandibular bilateral distal extension case. J.P.D. 1958;
8: 340-350.
• Zeev Ben-Ur, Eitan Mijiritsky, Colin Gorfil : Stiffness to different
designs and cross section of maxillary and mandibular major
connectors of removable partial dentures. J.P.D. 1999; 81: 526-531.
Thank you