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MANDIBULAR MAJOR CONNECTOR

Dr. shanai M.

The following is a list of the different types of mandibular major connectors

1. Lingual bar
The lingual bar and the liguoplate are the most common major connectors used in mandibular removable partial dentures.
• Located above moving tissue but as far below the gingival tissue as possible
• The superior border should be tapered toward the gingival tissue superiorly with its greatest bulk at the inferior border, resulting in a contour that is a half-pear shape.
• A rounded border will not impinge on the lingual tissue when the denture bases rotate inferiorly under occlusal loads.
• The inferior border of a lingual mandibular major connector must be located free
from the floor of the mouth. Yet at the same time,
it must be located as far inferiorly as possible to
avoid interference with the resting tongue and
trapping of food substances when they are introduced
Into the mouth

Indication

The lingual bar should be used for mandibular RPD where sufficient space exists between the slightly elevated alveolar lingual sulcus and the lingual gingival tissue (more than 8 mm)

CHARACTERISTIC AND LOCATION

• Half-pear shaped with bulkiest portion inferiorly.
• Superior border tapered to soft tissue
• Superior border located at least 4 mm inferior to gingival margins and farther if possible
• Inferior border located at the determined height of alveolar lingual sulcus when the patient ´s tongue is slightly elevated.

Methods that may be used to determine the relative height of the floor of the mouth

At least two clinically acceptable methods may be used to determine the relative height of the floor of the mouth and locate the inferior border of a lingual mandibular major connector.
1- measure the height of the floor of the mouth in relation to the lingual gingival margin of adjacent teeth with a periodontal prob
when these measurements are taken, the tip of the patient´s tongue should just lightly touch the vermilion border of upper lip.
Recording these measurements permits their transfer to both diagnostic and master cast.
2. Use an individualized impression tray which lingual borders are 3 mm short of the elevated floor of the mouth, and then use an impression material that will permit the impression to be accurately molded as the patient licks lips








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.

It may be flexible if poorly constructed.

Rigidity is less compared to a well constructed lingual plate.

Lingual Plate (Linguoplate)

The linguoplate is lingual bar with superior border extending upwards to contact cingula of anterior teeth and lingual surfaces of involved posterior teeth at their height of contour

The indications for the use of a linguoplate

• Less than 8 mm between the marginal gingiva and the activated lingual frenum and of the mouth.
• In Class I situations in which the residual ridges have undergone excessive vertical resorption.
• For stabilizing periodontally weakened teeth, splinting with linguoplate can be of some value when used with definite rests on sound adjacent teeth.
• When the future replacement of one or more incisor teeth will be facilitated by the addition of retention loops to an existing linguoplate.


Characteristics and location
1. Half-pear shaped with bulkiest portion inferiorly located.
2.Thin metal apron extending superiorly to contact cingula of anterior teeth and height of contour of posterior teeth
3.Apron extend interproximally to height contact points ( i.e., closing interproximal spaces).
4. Scalloped contour of apron as dictated by interproximal blockout.
5. The superior border should be knife edge and contoured to intimately contact lingual surface above the cingula.
6. Inferior border at the ascertained height of the alveolar lingual sulcus when the patient´s tongue is slightly elevated.
7. Close inter proximal space to level of contact points.







The linguoplate dose not in itself serve as an indirect retainer. When indirect retention is required, definite rests must be provided for this purpose. Both the linguoplate and the cingulum bar ideally should have a terminal rest at each end, regardless of the need for indirect retention. However, when indirect retainers are necessary, these rests may also serve as terminal rests for the linguoplate.

Sometimes a linguoplate is indicated as the major connector of choice even though the choice even though the anterior teeth are quit spaced and the patient strenuously objects to metal showing through the spaces. The linguoplate can then be constructed so that the metal will not show through the spaced anterior teeth. This is a modification of the linguplate and is named interrupted linguoplate. The rigidity of the major connector is not greatly altered. However, such a design may be as much as food trap as the continuous bar type of major connector

Sublingual bar

A sublingual bar is 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 the superior border of the bar at least 4mm below the free gingival margin. The bar shape remains essentially the same as that of a lingual bar, but placement is inferior and posterior to the usual placement of a lingual bare, lying over and parallel to the anterior floor of the mouth

Sublingual bar

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.
Interferance with elevation of the floor of the mouth during functional movements

Lingual Bar with Cingulum Bar (Continuous bar )

This type of bar consists of lingual bar with another bar crossing the lingual surfaces of lower anterior teeth located on slightly above the cingula of anterior teeth
Indication of use
1. when a linguoplatate is indicated but the axial alignment of anterior teeth is such blockout of interproximal undercuts would be required.
When wide diastemata exist between mandibular anterior teeth and a linuoplate would oblectionably display metal in frontal view
Characteristics and location
1.Conventionally shaped and located same as lingual bar component when possible.
2. thin, narrow (3mm) metal strap located on cingula of anterior teeth, scalloped to follow interproximal embrasures with inferior and superior borders tapered to tooth surfaces
3. originates bilaterally from incisal, lingual, or occlusal rests of adjacent princible abutments


Cingulum Bar (Continuous Bar)
When a linguoplate is the major connector of choice, but the axial alignment of the anterior teeth is such that excessive blockout of interproximal undercuts must be made, a cingulum bar may be considered.
Indication of use
1. Height of activated lingual frenum and floor of the mouth at the same level as marginal gingiva.
2. Inoperable tori or exostoses at the same level as the marginal gingiva.
3. Severely undercut lingual alveolus
4. Concern that a major connector traversing the gingival sulcus will cause a periodontal problem.
5. Considerable gingival recession

Cingulum Bar (Continuous Bar)

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.


Labial Bar
in only a few situations does extreme lingual inclination of the remaining lower premolar and incisor teeth prevent the use of a lingual bar major connector. With the use of conservative mouth preparations in the form of recontouring and blockout, a lingual major connector can almost always be used. Lingually inclined teeth sometimes may have to be reshaped by means of crowns. Although the use of a labial major connector may benecessary in rare instances, this should be avoided by resorting to necessary mouth preparations rather than by accepting a condition that is otherwise correctable

Labial Bar

The same applies to the use of a labial bar when a mandibular torus interferes with placement of a lingual bar. Unless surgery is definitely contraindicated, interfering mandibular tori should be removed so that the use of a labial bar connector may be avoided.
Indications:
1. Lingually inclined teeth preventing the use of a lingual mandibular major connector.
2. Lingual tori or exostoses which can not be removed surgically, avoided in the RPD design
3. A lingual major connector can not be used because of the slope or undercut of the lingual alveolus.

Labial Bar

Characteristics and location
1.Half-pear shaped with bulkiest portion inferiorly located on the buccal aspect.
2.Superior border tapered to soft tissue and 4mm inferior to labial gingival margins.
3.Inferior border located in the labial buccal vestibule; at the junction of attached & mobile mucosa.

A modification to the linguoplate is the hinged continuous labial bar. This concept is incorporated in the Swing-Lock* design, which consists of a labial or buccal bar that is connected to the major connector by a hinge at one end and a latch at the other end
Support is provided by multiple rests on the remaining natural teeth. Stabilization and reciprocation are provided by a linguoplate that contacts the remaining teeth and are supplemented by the labial bar with its retentive struts. Retention is provided by a bar type of retentive clasp with arms projecting from the labial or buccal bar and contacting the infrabulge areas on the labial surfaces of the teeth.





Use of the Swing-Lock concept would seem primarily indicated when the following conditions are present:
1. Missing key abutments.
2. Unfavorable tooth contours.
3. Unfavorable soft tissue contours
4. Teeth with questionable prognoses
contraindications
to the use of this hinged labial bar concept are apparent. The most obvious is poor oral hygiene or lack of motivation for plaque control by the patient. Other contraindications include the presence of a shallow buccal or labial vestibule or a high frenal attachment.