lecture 3 - components of rpd Flashcards
what are the components of rpd? (A-F)
A) Major Connector
B) Rests
C) Direct Retainer
D) Minor Connector
E ) Guide Plane
F ) Indirect Retainer
Resistance to removal from the tissues or teeth.
- Retention
Resistance to movement in a horizontal direction (anterior-posteriorly or mesio- laterally.
- Stability
Resistance to movement towards the tissues or teeth.
- Support
- The unit of a removable partial denture that connects the parts of one side of the dental arch to those of the other side.
- Its principal functions are to provide unification and rigidity to the denture.
Major Connector
- A unit of a partial denture that connects other components (i.e. direct retainer, indirect retainer, denture base, etc.) to the major connector.
- The principle functions of minor connectors are to provide unification and rigidity to the denture.
Minor Connector
A unit of a partial denture that provides retention against dislodging forces.
Direct Retainer
- A direct retainer is commonly called
a ‘______’ or ‘_______’ and is composed of four elements: _________________
clasp
clasp unit
a rest,
a retentive arm,
a reciprocal arm
a minor connector.
A unit of a Class I or II partial denture that prevents or resists movement or rotation of the base(s) away from the residual ridge.
Indirect Retainer
The indirect retainer is usually composed of one component, a ______
rest
- The unit of the denture that rests on the foundation tissues and to which prosthetics teeth are attached.
- Attaches the prosthetic teeth to the denture base retention minor connector which attaches the base to the major connector.
Denture Base
- Are artificial teeth used on a denture to substitute for natural teeth.
- By substituting for missing natural teeth, prosthetic teeth provide esthetics and masticatory functions.
Prosthetic Teeth
COMPONENTS OF A PARTIAL DENTURE (6)
1) Major Connector
2) Minor Connector
3) Direct Retainer
4) Indirect Retainer
5) Denture Base
6) Prosthetic Teeth
The unit of a removable partial denture that connects the various parts of the denture.
MAJOR CONNECTORS
what are the principal functions of major connectors?
unification
rigidity
Functions of a Major Connector (3)
- Unification
- Stress Distribution
- Cross-Arch Stabilization (Counter leverage)
A major connector unites all other components of a partial denture so that the partial denture acts as one unit.
UNIFICATION
– By unifying all elements of a partial denture the major connector can distribute functional loads to all abutment teeth, so that no one abutment is subjected to extreme loading.
STRESS DISTRIBUTION
– Unification of the direct retainers with the denture bases aids in distributing forces between both the teeth and the mucosa.
STRESS DISTRIBUTION
– By uniting one side of the arch to the other bracing elements on one side of the arch can aid in providing stability to the other. This can aid in dissipating twisting and torqueing forces.
CROSS-ARCH STABILIZATION (Counter-leverage)
– It is necessary to ensure that the partial denture functions as one unit.
– If the denture flexes, stress distribution and cross arch stabilization can be compromised since different portions of the denture can move independent of the others.
Rigidity
Major connectors should not enter into undercut areas unless tissue impingement can be avoided by changing the selected path of insertion or by using minor undercut blockout.
Non-Interference with the Soft Tissues
This can be minimized by locating the margins of the connectors at the prescribed distance from the free gingival margin and by taking care that the presence of minor connectors, clasp arms and major connectors does not create “traps” or large concavities where food can collect.
Food Impaction
– The margins of the major connector should have a smooth transition from connector to tissue so as to minimize the _________.
– All line angles and edges should be ______ and ______.
– Borders should not be placed in locations where they might interfere with speech.
– Bulk should be reduced enough so as not to interfere with speech or appearance, yet thick enough to ensure rigidity.
obtrusiveness
smooth and rounded
how to avoid tissue impingement? (2)
by changing the selected path of insertion
by using minor undercut blockout
Requirements of a Major Connector
- Rigidity
- Non-Interference with the Soft Tissues
- Food Impaction
- Unobtrusive
- This is the most commonly used mandibular major connector.
- It should be used whenever possible unless there are advantages that can be obtained from another major connector.
Lingual Bar
– flat on tissue side
– convex or tear-drop on tongue side
– 1/2 pear shape, with thin edge toward teeth.
Lingual Bar
occluso-gingival width of lingual bar
4mm
thickness of lingual bar
1.5 to 2mm
Lingual Bar:
– The inferior border should be as low as the ______________ and tissue reflections of the floor of the mouth will permit, as determined by observing functional movements of the tongue.
– The superior border should be
___________________. For hygienic reasons the superior border should still be kept as far from the gingival margin as possible.
lingual frenum
at least 3mm below the free gingival margin
- consists of a lingual bar plus an extension over the cingulum of anterior teeth.
- This mandibular major connector should only be considered in those rare instances where a lingual bar cannot be used.
Lingual Plate
Lingual Plate:
- Most often, this occurs when there is a __________ of the mouth, a prominent __________ or __________ that would be impinged upon by a lingual bar, if it was made with adequate height and distance from the free gingival margin.
- The lingual plate has also been advocated for extensive distal extension cases with ______________ (i.e. little resistance to horizontal rotational tendencies).
high floor
lingual frenum or lingual tori
severe vertical resorption of ridges
o A ________ or _______ area must be prepared at each end of the anterior segments of the lingual plate.
o This prevents excessive forces being directed facially by movements of the distal extension base.
o Any areas where the connector crosses the gingival tissue must be _______ to prevent impingement caused by the movement of the lingual plate.
vertical stop or rest
relieved
The connector consists of a lingual bar plus a secondary bar resting above the cingulum of the anterior teeth.
Continuous Bar Retainer / Kennedy Bar / Double Lingual Bar
The ____________ supposedly acts as an indirect retainer and performs a role in the horizontal stabilization of periodontally-involved teeth.
secondary bar
- The performance of these functions is questionable. Additionally, this major connector can create a food trap between the two bars.
- The use of this type of connector is not encouraged.
Continuous Bar Retainer / Kennedy Bar / Double Lingual Bar
Major connectors in the upper arch should terminate ___________ from the gingival crest tissues.
6.0 mm or more
- provides maximum rigidity and minimum bulk.
- The strength of this connector lies in the fact that the anterior and posterior sections are joined together by longitudinal connectors on either side.
- Each component braces the other against possible torque and flexure.
Anterior-Posterior Palatal Strap
- particularly indicated when maximum tissue support is required.
- In particular it should be the major connector of choice in long distal extension cases or where six or less anterior teeth remain.
Full Palatal Plate
- ______________ It should be selected where the primary abutments are periodontally involved, requiring maximum stress distribution.
- It should be fabricated of a uniformly thin metal plate with accurate anatomic reproduction of the ______ configuration (improves strength and rigidity). It should cover the same area as a complete denture posteriorly.
Full Palatal Plate
rugae
- The large surface area of contact with the mucosa improves the potential for retention (what type of connector is this?__________).
- Connectors of this type are generally of cast metal. However, an acrylic resin plate may be used in ___________.
Full Palatal Plate
interim prostheses
- This type of connector can be Wide (strap) or narrow (bar) depending upon its location or the need for strength or support of the denture.
Maxillary Major Connectors Palatal Strap (or Bar)
- It should only be used in tooth supported cases where no other connector can be used. It is usually objectionable due to its bulk. It should never be used in cases involving distal extensions or replacement of anterior teeth since it must be made to bulky for rigidity.
palatal bar
From a biomechanical standpoint, it is a poor connector and should never be used unless absolutely necessary. To be rigid, the horseshoe connector must have bulk in the rugae area where the tongue requires freedom.
Anterior Palatal Plate / U-Shaped / Horse-Shoe / Palatal Connector