INTRODUCTION: The topics to be covered today are:
 Components of a RAPD
 Major Connectors:

Types

Function

Indications for their use
COMPONENTS OF REMOVABLE PARTIAL DENTURES.
A removable alloy partial denture is made up of six structural elements, each of which
plays a role in restoring function and preserving the remaining oral structures. The six
structural units are:
1. Major connector.
2. Minor connector.
3. Rests.
4. Direct retainers.
5. Indirect retainers.
6. Denture base.
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Each component parts name is descriptive of its function and they are the same for
both the maxillary and the mandibular removable partial dentures.
MAJOR CONNECTOR.
Major connectors primary function is to unite the various structural elements of a
prosthesis. All other parts of the partial denture are attached to it either directly or
indirectly. The function of a maxillary major connector varies beyond this point to a
mandibular major connector.
The maxillary connector, in addition to the primary function contributes substantially to
the support of the prosthesis. The mandibular connector has a very limited capacity in
support, but may contribute to indirect retention.
Major connectors must posses the following five qualities:
1. Rigidity.
2. Provide vertical support and protection of the soft tissues.
3. Provides means of obtaining indirect retention where indicated.
4. Provide an opportunity of positioning the denture bases where needed.
5. Maintain patient comfort.
The first requirement of a major connector is rigidity. This allows stresses that are
applied to the partial denture to be distributed effectively over the entire supporting area,
including the teeth, underlying, bone and soft tissue. Other components of a partial
prosthesis can only be effective if the major connector is rigid. Flexibility allows forces to be
concentrated on individual teeth or edentulous ridges causing damage to those areas.
Major connectors must avoid impingement of the free gingival margin. The major
connector must never terminate on gingival tissue.
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In maxillary castings the border of the major connector should be at least 6mm to 8mm
from the gingival margin of the teeth and in the mandibular it should be at least 3mm from
the gingival margin.
Patient comfort should be a consideration when designing the major connector and food
traps must be avoided where possible.
The selection on a particular type of major connector will depend on the following:
Maxilla (a) The need for support.
(b) The number and location of teeth to be replaced.
(c) The number of clasps.
MAXILLARY MAJOR CONNECTORS.
A maxillary major connector should have a prepared seal along all borders that contacts soft
tissue (food line). This seal forms a beading that will slightly depress the soft tissue. The food
line (or seal) is scribed into the master cast to a depth of 1mm and width of approximately
1.5mm. The food line prevents food debris from collecting under the major connector. The
extra thickness provided by the seal enables the metal to be tapered into the tissue surface
without loss of strength. Usually, an intimate contact between the palatal soft tissue and the
connector is required so there is no relieving of the tissue.
It also provides a point where the casting should be finished.
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TYPES OF MAXILLARY MAJOR CONNECTORS.
The selection of any particular connector will depend on the need for support, the number
and location of teeth to be replaced and the number of clasps. Additional factors to be
considered are:
 The presence of palatal tori.
 The need for indirect retention.
 The need for stabilization of infirm teeth.
 Phonetic considerations.
 The mental attitude of the patient.
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There are six types of maxillary major connectors.
1. Single Posterior Palatal Bar.
Narrow, half-oval in shape with its thickest point at the centre. The bar is gently curved
and should not form a sharp angle at the junction with the denture base.
Indication for use.
Very limited use, usually when one or two teeth are missing on one side of the arch only.
Where there is minimal need for palatal support and minimal interference with
phonetics.
2. Palatal Strap.
Wide (minimum 8mm), thin band of metal that crosses the palate in an unobtrusive
manner.
Indication for use
Suitable for use when only one or two teeth are being replaced on either or both sides
of the arch, and the denture is to be tooth borne. There is minimal need for palatal
support but more than a palatal bar. Also there is minimal interference with phonetics
using this type of major connector.
3. Double Palatal Bar (A-P Bar).
Anterior portion is narrower than palatal strap. Posterior portion similar to single
posterior palatal bar. This configuration gives the effect of a circle.
Indication for use.
Used when the anterior and posterior abutments are widely separated and full palatal
coverage is not desirable e.g. tori palatinus. Offers very good rigidity.
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4. Horseshoe.
A thin band of metal running along the palatal surfaces of teeth and extending onto palate.
Indication for use.
There are three principle applications. When several anterior teeth are being replaced.
When a toris palatinus is present and does not allow for posterior coverage, or when
mobile anterior teeth require stabilizing.
5. Closed Horseshoe (Anterioposterior Palatal Strap).
Similar to horseshoe with palatal strap connecting both sides of the arch posteriorly.
Indication for use
Generally indicated when numerous teeth are to be replaced and when a toris palatinus
is present. When periodontaly weakened teeth require stabilizing. This is structurally
strong and rigid.
6. Complete Palate.
The posterior border extends to the junction of the soft and hard palate. It is similar to a
full denture, the difference being that it is made of an alloy instead of acrylic.
Indication for use
Indicated when all posterior teeth are to be replaced bilaterally. Also when anterior
teeth require replacement along with bilateral free-end saddles. When flat or mobile
ridges are present, the palate can offer stabilization for the prosthesis, if a patient has
well developed muscles of mastication and complete mandibular natural teeth, heavy
occlusal forces can be anticipated. A complete palate will offer support against vertical
displacement.
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OUTCOME
You should now be able to define and explain types, function and indications for use of
a maxillary major connector. Also you should be able to list the components of a
RAPD.
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