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MAJOR CONNECTORS

MAJOR CONNECTORS

It is defined as A part of a removable partial denture which connects the components on one side of the arch to the components on the opposite side of the arch GPT. CLASSIFIED AS MANDIBULAR MAJOR CONNECTORS

MAXILLARY MAJOR CONNECTORS

GENERAL IDEAL REQUIREMENTS FOR MAXILLARY AND MANDIBULAR MAJOR CONNECTORS

Rigidity:It should be rigid enough to uniformly distribute the occlusal forces acting on any portion of the prosthesis without undergoing distortion. It should provide cross-arch stability. It should provide vertical support and protect soft tissues. It should provide indirect retention whenever required. It should be comfortable to the patient. It should not allow any food accumulation. It should be self-cleansing.

DESIGN CONSIDERATIONS FOR ALL MAJOR CONNECTORS

Intentional relief: its border should be 6mm away from gingival margins in the maxillary arch to avoid any injury to marginal gingiva. In the mandible the border is placed 3mm away from the marginal gingiva,if not possible it is extended across the marginal gingiva as a lingual plate. The borders of the major connector should be parallel to the gingival margins. The metal framework should cross the gingival margin only at right angles. The part of the framework adjoining the tooth surface should be hidden in the embrasures to avoid discomfort.

The borders should be rounded to avoid interference to the tongue. It should be symmetrical and should cross the palate in a straight line. The anterior border of the maxillary major connector should end in the valley of the rugae and should never lie on the crest of the rugae. The major connector should not extend over the bony prominences like tori.

MAXILLARY MAJOR CONNECTORS

Additional requirements for maxillary major connectors : A beading should be provided at the borders to obtain better adaptation and prevent entry of food particles,it is created by making a 0.5-1mm groove on the master cast,the beading should thin out as it approaches the gingival margins. Relief is given in cases of palatal tori or a prominent mid palatine suture.

TYPES OF MAXILLARY MAJOR CONNECTOR1. Single posterior palatal bar 2. Palatal strap 3. Single broad palatal major connector or palatal plate type major connector 4. Double or anteroposterior palatal bar 5. Horseshoe or U-shaped connector 6. Closed horseshoe or anteroposterior palatal strap 7. Complete palate

SINGLE POSTERIOR PALATAL BAR

It is a bar running across the palate,with a narrow half oval cross section,which is thickest at the centre. Indication : For interim partial denture. Disadvantages : 1.Poor bony support from the hard palate due to narrow antero-posterior width. 2.It cant b used anterior to the premolar region due to interference to the tongue. 3.Can be used only when 1 or 2 teeth are to be replaced on each side due to poor vertical support. 4.It can be used only in Kennedy s class III cases wherein teeth capable of bearing the load should be present both anterior and posterior to the edentulous space.

PALATAL STRAP

It comprises of a wide,thin band of metal plate that runs across the palate. It should be atleast 8mm wide for adequate rigidity This strap extends over 3 planes namely: - Vault or horizontal plane. - Right and Left lateral slopes of the palate. Indications : - Unilateral distal extension partial denture. - Bilateral short span edentulous spaces in a tooth supported prosthesis. Advantages : - Good resistance with minimum volume of metal.

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Excellent resistance against bending and twisting forces. Increases patient comfort as very thin metal is present. Enhanced retention d/t increased cohesion and adhesion. Good indirect retention against dislodgment by sticky foods or gravity in an anterior direction. Disadvantages : large palatal coverage. posterior border should end before the junction of hard and soft palate to avoid discomfort. the strap cant be placed across a prominent median suture. can cause papillary hyperplasia.

PALATAL PLATE TYPE MAJOR CONNECTOR

It has a thin broad contoured palatal coverage,it is broader than a palatal strap. Indications : Class I cases with little vertical ridge resorption. Cases with V or U shaped palate. Cases with strong abutments. Cases with more than six remaining anterior teeth. Advantages : Good retention d/t presence of interfacial surface tension. Good vertical support. Surface configurations d/t very thin metal provide natural feel. Disadvantages : can cause papillary hyperplasia.

ANTERO-POSTERIOR OR DOUBLE PALATAL BAR MAJOR CONNECTOR

It is a combination of an anterior palatal strap and a posterior palatal bar. The anterior strap is narrower than a conventional palatal strap. The margins of the strap should lie on the valley and not on the crest of the rugae. Posterior bar is half oval. The strap and the bar are connected by two longitudinal elements along the lateral slopes of palate giving a circular configuration which provides rigidity. Anterior strap lies in 3 planes,this also contributes to the rigidity of the prosthesis.

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Indications : when anterior and posterior abutment teeth are widely separated. cases with large inoperable palatal tori. patient who wants to avoid complete palatal coverage. long edentulous span in Class II modification 1 arch. Class IV conditions. Advantages : rigid and strong with limited soft tissue coverage. Disadvantages : limited support from palate. uncomfortable d/t multiple borders,provides interference to the tongue.

HORSESHOE OR U-SHAPED MAJOR CONNECTORIt is U-shaped running along the arch,it has a thin metal band running along lingual surface of posterior teeth,anteriorly it becomes more like a thin plate that covers the cingula of the teeth. The posterior border extends 6-8mm onto the palatal tissue,the entire surface and the borders should be smooth and gently rounded. Indication : - used when many teeth are to be replaced. - used in presence of tori extending to the posterior border of the hard palate or a prominent median suture. - excessive overbite of the anterior teeth.

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Advantages : reasonably strong. has moderate indirect retention and support. Disadvantages : it tends to straighten when vertical forces are applied on either one or both ends,hence cant be used for distal extension denture bases. greater bulk is required to avoid flexing of the major connector causing patient discomfort.

ANTERO-POSTERIOR PALATAL STRAP OR CLOSED HORSE SHOE MAJOR CONNECTORSimilar to U-shaped major connector but a strap of metal extends between the two open ends of the horseshoe,centre of palate is left uncovered. Differs from a double palatal bar in that the posterior strap is a thin plate. Indications : - used when numerous teeth are to be replaced and a torus is present. - it is used in cases with Kennedy s ClassI and ClassII cases with anterior tooth replacement.

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Advantages : rigid due to a circular configuration. additional strength and a circulard/t L-beam effect and a circular configuration. greater support from palate. Disadvantages : interference with phonetics,annoyance to tongue and discomfort.

COMPLETE PALATE

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This major connector covers the entire palate. Anterior border should be 6mm away from the gingival margin or extend upto the cingula of anterior teeth,posterior border should extend to the junction of hard and soft palate. Indications : when many posterior teeth are replaced. in cases where anterior teeth are to be replaced along with a Kennedy s classI condition. In cases with flat ridges and shallow vaults where high stability is required. for patients with well developed muscles of mastication or presence of all mandibular teeth. in cleft palate cases with a narrow steep vault.

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Advantages : best rigidity and support. gives better perception. Disadvantages : soft tissue reactions like inflammation and hyperplasia interference with phonetics.

MANDIBULAR MAJOR CONNECTORSTYPES : 1. LINGUAL BAR 2. LINGUAL PLATE 3. DOUBLE LINGUAL BAR 4. SUBLINGUAL BAR 5. MANDIBULAR CINGULUM BAR 6. LABIAL BAR DESIGN CONSIDERATIONS : - They are longer and narrower than the palatal connector d/t the interference from the tongue. - Relief is given in all the cases.

1. LINGUAL BAR :It is the most commonly used mandibular major connector. It is half pear-shaped in cross section with the thickest portion placed inferiorly. There must be a minimum 8mm vertical clearance from the floor of mouth,the upper border should have a 3mm clearance from the marginal gingiva. Minimum height of the major connector should be atleast 5mm. Should be placed as inferior as possible so that movement of the tongue is not restricted. Advantages: it is easy to fabricate. - it has mild contact with oral tissues and no contact with teeth

Disadvantages : - contraindicated in cases of tori. - in cases with limited vestibular depth,the bar will be thinned out and tends to flex.

LINGUAL PLATE :

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It is similar to the lingual bar but the superior border extends up to the cingulum of the lingual surface of the teeth. Superior border is scalloped and has an intimate contact with the teeth,this produces a knife edged margin. In cases with large embrasures and spacing,th superior border is made to dip down so that it is not visible externally. Indications : when most posterior teeth are lost and indirect retention is required. when remaining teeth are not periodontally sound.when there is no space for lingual bar. presence of inoperable mandibular tori. in cases with retrognathic jaw when 1 or more incisor teeth have to be replaced.

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Advantages : most rigid and stable. provides indirect retention when rests are provided on the pr

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