Max major

DEFINITION

It is the unit of the RPD to which all other parts are directly or indirectly attached.

The chief functions of a major connector include:

1.unification of the major parts of the prosthesis. 2. distribution of the applied force throughout the arch to selected teeth and tissue. 3. and minimization of torque to the teeth ( cross-arch stability ).

Functions of a Major Connector

Unification Partial denture acts as one unit Connects various parts

Functions of a Major Connector

Stress Distribution Distributes functional loads to both teeth &mucosa

Functions of a Major Connector

Cross-Arch Stabilization (Counterleverage) Bracing elements on one side of the arch providing stability to the other

Location

1.Major connectors should be away from 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. 5. Major connectors should be located and /or relieved to prevent impingement of tissue because the distal extension denture rotates in function.

*The gingival tissue must have an unrestricted superficial blood supply to remain healthy

*Structurally the tissue covering the palate is well suitable for placement of the connector because of the presence of firm submucosal connective tissue and an adequate, deep blood supply, Excepted in the palatal torus and median palatal suture area.

Requirements of Major Connector 1.Rigidity

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. therefore rigidity provides cross-arch stability through the principle of broad distribution of stress

To Increase Rigidity Use a more rigid alloy Chrome-cobalt > gold alloys; cast > wrought Shape 1/2 round > 1/2 pear shaped > flat bars

To Increase Rigidity

Increase the bulk as the length increases Corrugate linguo-plate or rugae areas

Requirements of Major Connector

2.Non-Interference with the Soft Tissues It does not interfere with the tongue and not impinge on oral tissue when the restoration is placed, removed, or rotates in function . Avoid terminating on Free gingival margin

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3.Minimize Food Impaction

Locate margins away from the FGM Eliminate "traps" or large concavities where food can collect

4. a major connector must promote patient comfort

Smooth transition from connector to denture base - butt joint

promote patient comfort

Line angles and edges should be smooth and rounded Borders should not interfere with speech

Relief

Mandibular major connectors should be located and/or relieved to prevent impingement of tissue because the distal extension denture rotates in function. Except for a palatal torus or prominent median palatal suture area, maxillary connectors ordinarily require no relief.


Maxillary Major Connectors1. Single Palatal Bar2. Single Palatal Strap3. Combination Anterior & Posterior Palatal Straps4. Palatal plate-type connector 5. U – shaped Palatal Connector6. Anterior-posterior palatal bars

1. Single palatal bar

Bar: less than 8 mm in widthStrap more than 8 mm in width
Indication :(Single Palatal Bar) Only in short span Kennedy class III At present time the single palatal bar is used as an interim partial denture until a more definitive treatment can be done for the patient. Contraindication: it should not be placed anterior to the second premolar because its bulk produce noticeable discomfort and severe interference with the tongue. it should never be used in a distal extension situation and when anterior teeth require replacement.

Single Palatal Bar

Don’t usePalatal bar objectionable due to bulk

2. Single palatal strap

Single Palatal Strap
Strap should be 8mm wide or approximately as wide as the combined width of a maxillary premolar and first molar. Confined within an area bounded by the four principal rests

Single Palatal Strap

Usually use for Class III


Single palatal strap Indication:Bilateral edentulous spaces of short span in a tooth -supported restoration.it is preferable to the palatal bar for posterior tooth supported cases. However, other connectors should be chosen if there is a large torus or if many teeth are being replaced.

Single palatal strap

Characteristics and Location (1) Anterior border follows the valleys between rugae as nearly as possible at right angles to median suture line. (2) Posterior border at right angle to median suture line. (3) Strap should be 8 mm wide or approximately as wide as the combined width of a maxillary premolar and first molar. (4) Confined within an area bounded by the four principal rests


Advantages : 1.because the strap is located in three planes ( vault of the palate , the lateral slopes of the palate and the anterior slope of the palate) , it offers great resistance to bending and twisting forces. 2. because the palatal strap is strong , it can be kept thin, thus increasing patient comfort. 3. retention of partial denture through the forces of adhesion and cohesion is increased by the intimate contact between the metal and soft tissue. 4. the increased tissue coverage helps distribute applied stresses over a larger area.


Disadvantages: *the patient may complain of excessive palatal coverage. *adverse soft tissue reaction in the form of papillary hyperplasia this is due to: denture wearing 24 hours daily poor oral hygiene lack of patient instructions

3. Combination anterior and posterior palatal strap type connector

Anterior-Posterior Palatal Strap
Maximum rigidity Minimum bulk Use in most cases Especially torus palatinus

. Combination anterior and posterior palatal strap type connector

Indications for Use ( 1) Class I and II arches in which excellent abutment and residual ridge support exists. (2) Long edentulous spans in Class III,modification 1 arches. (3) Class IV arches in which anterior teeth must be replaced with a removable partial denture. (4) Inoperable palatal tori that do not extend posteriorly to the junction of the hard and soft palates.


Characteristics and location (1) Parallelogram shaped and open in center portion . (2) Relatively broad (8 to 10 mm) anterior and posterior palatal straps. (3) lateral palatal straps (7 to 9 mm) narrow and parallel to curve of arch; minimum of 6 mm from gingival crevices of remaining teeth. (4) Anterior palatal strap: anterior border not placed farther anteriorly than anterior rests and never closer than 6 mm lingual gingival crevice (5) Posterior palatal connector: posterior border located at junction of hard and soft palates and at right angles to median palatal suture and extended to hamular notch area(s)

Anteroposreior palatal strap

Advantages:
1.It is rigid 2.It provide good support to the partial denture. Disadvantages: May be not accepted by some patients due to multiple borders and coverage to the rugae area

PALATAL MAJOR CONNECTOR

COMPLETE PALATAL COVERAGE MAJOR CONNECTOR

6.The complete palatal plate

Indications: (1) In most situations in which only some or all anterior teeth remain. (2) Class II arch with a large posterior modification space and some missing anterior teeth. (3) Class I arch with one to four premolars and some or all anterior teeth remaining, and abutment support is poor and cannot otherwise be enhanced; residual ridges have undergone extreme vertical resorption; direct retention is difficult to obtain. (4) In the absence of a torus.

Complete Palatal Plate

Maximum tissue support Connector of choice in long distal extension cases Six or less anterior teeth remain

Complete Palatal Plate

Advantages:
1.It offers maximum rigidity support and retention to the partial denture. 2.It is made in a uniform thin metal plate, which reproduce anatomic contour of the palate and feel natural to the patient. Disadvantages: 1.Often cannot be used in the presence of a palatal torus. 2.Complete palatal coverage may alter taste and tactile sensation.


. U-SHAPED PALATAL MAJOR CONNECTOR

U-SHAPED PALATAL MAJOR CONNECTOR

Too flexible Allows movement at the posterior Traumatic to the residual ridge Use only where torus prohibits other connectors

Flexes, impinging on soft tissue

This connector should be used only in those situations in which inoperable tori extend to the posterior limit of the hard palate.The U-shaped palatal major connector is the least favorable design of all palatal major connectors ,because it lacks the rigidity 
U-SHAPED PALATAL MAJOR CONNECTOR

(U-Shaped or "Horse-Shoe" Palatal Connector)

Poor connector Never use unless absolutely necessary Requires bulk in the rugae area (where the tongue requires freedom) for rigidity


Combination Anterior-posterior palatal bar Structurally, this combination of major connector exhibits many of the same disadvantages as the single palatal bar To be sufficiently rigid and to provide the needed support and stability, these connectors could be too bulky and could interfere with tongue function.

Anterior-Posterior Palatal Bar

Requires greater bulk for rigidity More objectionable to the patient


Beading of the Maxillary Cast Beading is a term used to denote the scribing of a shallow groove on the maxillary master cast outlining the palatal major connector exclusive of rugae areas The purposes of beading are as follows: 1. To transfer the major connector design to the investment cast 2. To provide a visible finishing line for the casting 3. To ensure intimate tissue contact of the major connector with selected palatal tissue Beading is readily accomplished by using an appropriate instrument, such as a cleoid carver. Care must be exercised to create a groove not in excess of 0.5 mm in width or depth.

Review of indications for maxillary major connectors