• REFER TEXT BOOK : Mc. CRACKEN
Dr. Praveen Srikantachary
15-02-2015
Contents
• Introduction
• Classification of various components
• Details of each components.
INTRODUCTION
• When using a prosthesis that can be removed from the mouth, the prosthesis
must extend to both sides of the arch. This enables direction of functional
forces to supporting teeth and tissue for optimum stability.
• It is through this cross-arch tooth contact, which is at some distance from
the functional force, that optimum resistance can be achieved. This is most
effective when a rigid major connector joins the portion of the prosthesis
receiving the function to selected regions throughout the arch
Components of a typical RPD
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
Occlusal
rest
Major
connector
Direct retainer
Minor
connector
Reciprocal arm
MAJOR CONNECTOR
• 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.
• This component also provides the cross-arch stability to help resist
displacement by functional stresses
Types of Major connector
Maxillary
Mandibular
1.Single posterior palatal
bar.
1.Lingual bar, sublingual bar.
2.Palatal strap
2.Lingual plate.
3.Anteroposterior/Double
Palatal bar.
3.CINGULAM bar.
4.Horse shoe shaped
connector.
5.Closed horse shoe /
anteroposterior palatal
strap.
6.Complete palate
4.Labial bar.
5. Lingual bar with cingulam
bar
IDEAL REQUIREMENTS OF THE MAJOR CONNECTOR
It should be rigid.
Should provide vertical support (Maxilla),
for the RPD.
It should not impinge on free gingival margin
and other soft tissues.
Should provide indirect retention when needed
(Mandible).
The borders should parallel to the mean
marginal gingival line and if any crossover it
should be at right angle.
Should enable to place the denture bases
where required.
Should not allow food lodgment beneath it.
Should be comfortable to the patient.
The borders should be as innocuous to the
tongue as possible.
Should be made with a material, which IS
biocompatible.
The borders are terminated in the valleys of
the rugae.
MINOR CONNECTORS
• DEFINITION
• A minor connector is defined as the connecting link between the major
connector or base of a removable partial denture and other units of
prosthesis such as clasps, indirect retainers and occlusal rests. GPT 8
TYPES
1. Minor connector that joins clasps assemblies to major connectors.
2. Minor connectors that joins indirect retainers or auxiliary rests to major
connector.
3. Minor connectors that joins denture bases to major connectors.
IDEAL REQUIREMENTS
1. must be RIGID- as they support active components of RPD
2. must have SUFFICIENT BULK to ensure rigidity
3. must be positioned so that they do not irritate the oral tissues.
LOCATION
Minor connectors located on proximal surfaces of teeth adjacent to edentulous
areas should be broad buccolingually and thin mesiodistally
RESTS: DEFINITION
• A projection or attachment, usually on the side of an object –(GPT 8).
• The components of a removable partial denture that serve primarily to
transfer forces occurring against the prosthesis down the long axis of the
abutment teeth are called rests. (- Stewart)
• Any unit of a partial denture that rests on a tooth surface to provide vertical
support is called rest. (McCracken’s)
REST SEAT
• The prepared recess in a tooth or restoration created to receive the occlusal,
incisal, cingulum or lingual rests. (GPT 8)
• The prepared surface of a tooth or fixed restoration into which a rest fits.
(Stewart)
CLASSIFICATION :
I.
a) Primary rest
b) Secondary / Auxillary rest
II. According to location :
Anterior / Posterior
III. According to surface :
Occlusal
IV. a) Intracoronal
b) Extracoronal
Incisal
Lingual / cingulum
Onlay
Interproximal
Internal
DIRECT RETAINERS
• DIRECT RETAINER- that component of a partial removable dental
prosthesis used to retain or prevent dislodgement, consisting of a clasp
assembly or precision attachment. (GPT 8)
• The components of a removable partial denture that engage abutments and
resist dislodging forces are called direct retainers (stewart).
Components of a clasp assembly..
•
•
•
•
Retentive arm
Reciprocal arm
Rest
One or more minor connectors
Requirements of a clasp assembly
•
•
•
•
•
•
Retention
Support
Stability
Reciprocation
Encirclement
Passivity
Classification
• Retentive clasp assemblies
1. Circumferential or Aker’s or suprabulge
2. BAR type or vertical projection or infrabulge or Roach clasp
INDIRECT RETAINERS
• “ It is the part of RPD that assists the direct retainers in preventing
displacement of distal exension denture bases by functioning through lever
action on the opposite side of the fulcrum line ”
FULCRUM LINE
• It is an imaginary line passing through teeth and direct retainers, around
which the denture rotates slightly when subjected to various forces directed
toward or away from the residual ridges
• More than one fulcrum line may be present for one RPD
• Depends on direction and location of force
TYPES OF INDIRECT RETAINERS
•
•
•
•
•
Auxillary Occlusal rest
Canine extension from Occlusal rest
Canine rest
Continuous bar retainers & Linguoplates
RUGAE support
DENTURE BASES
• The denture base supports the artificial teeth and consequently receives the
functional forces from occlusion and transfers functional forces to
supporting oral structures.
• This function is most critical for the distal extension prosthesis, as functional
stability and comfort often relate directly to the ability for this transfer
offerees to occur without undue movement.
• PROVIDE cosmetic effect of the replacement, particularly when techniques
are used for tinting and reproducing natural-looking contours.
• Adhesion and cohesion are effective when there is perfect apposition of the
impression surface of the denture to the mucous membrane surfaces. These
forces lose their effectiveness if any horizontal displacement of the dentures
breaks the continuity of this contact.
• Atmospheric pressure is effective primarily as a rescue force when extreme
dislodging forces are applied to the denture.
• It depends on a perfect border seal to keep the pressure applied on only one
side of the denture.