major and minor connectors

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Major and Minor Connectors Major Connectors: connecting the parts of the prosthesis located on one side of the arch with those on the opposite side, all parts of RPD attached. Requirement of major connectors 1) Rigidity: Stress applied to any portion of RPD should be effectively distributed. 2) Provide Protection of soft tissue: Maxillary: 6mm away from gingival crevice Mandibular: 3mm away from gingival crevice 3) provide indirect retention: crossing the hard palate in both 4) provide means to connect of denture bases: 50) provide patient comfort: Preventing food entrapment and providing self-cleansing Anteriorborder of maxillary connectors should end in the valleys between rugae crests. Margins should not cross bony or soft tissue prominences (tori). MAXILLARY MAJOR CONNECTORS Beading: O.5·1.0mm on the master casts PURPOSE: 1) Provides marginal seal. 2) Preventsfood debris from collecting under major connectors. 3) Provides technician finish line. 4) Increases denture strength. 1) Single palatal bar: The palatal bar should be limited for the use of Kennedy Class III cases. It is rarely used. The main disadvantage is its bulkiness. 2) Palatal strap: 8mmwide at least Advantages: a. Because the palatal strap is inherently strong, it can be kept relatively thin. b. less interference with tongue, more likely to be accepted by patient. c. the increased tissue coverage helps distribute applied stresses over a larger area. Disadvantage: a. Patient might complained about the palatal coverage. b. Might cause papillary hyperplasia c. might not be suitable for long, bilateral distal extension cases 3) Anteroposterior bars: the combination of an anterior

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Page 1: Major and Minor connectors

Major and Minor Connectors

Major Connectors: connecting the parts of the prosthesis locatedon one side of the arch with those on the opposite side, all parts ofRPD attached.Requirement of major connectors1) Rigidity: Stress applied to any portion of RPD should be

effectively distributed.2) Provide Protection of soft tissue:

Maxillary: 6mm away from gingival creviceMandibular: 3mm away from gingival crevice

3) provide indirect retention: crossing the hard palate in both4) provide means to connect of denture bases:50) provide patient comfort: Preventing food entrapment andproviding self-cleansing Anteriorborder of maxillary connectors

should end in the valleys between rugae crests. Margins should notcross bony or soft tissue prominences (tori).

MAXILLARY MAJOR CONNECTORSBeading: O.5·1.0mm on the master castsPURPOSE:

1) Provides marginal seal.2) Prevents food debris from collecting under major connectors.3) Provides technician finish line.4) Increases denture strength.

1) Single palatal bar:The palatal bar should be limited for the use of Kennedy Class IIIcases. It is rarely used.The main disadvantage is its bulkiness.

2) Palatal strap: 8mmwide at leastAdvantages:a. Because the palatal strap is inherently strong, it can be keptrelatively thin.b. less interference with tongue, more likely to be accepted bypatient.c. the increased tissue coverage helps distribute applied stressesover a larger area.Disadvantage:a. Patient might complained about the palatal coverage.b. Might cause papillary hyperplasiac. might not be suitable for long, bilateral distal extension cases

3) Anteroposterior bars: the combination of an anterior

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Page 2: Major and Minor connectors

6} Complete palate: can be All acrylic resin, combination

metal and acrylic resin, all metal.Advantages:a) provides proper posterior palatal sealb) provides the best stabilization in shallow vault or flabby ridgec) good for the transition to complete dentured) all-metal palate enhances the transfer of the temperature changesDisadvantages:a) inflammation and hyperplasia may happen because of extensive soft tissue coverageb) may have phonetic problems

strap and a posterior barAdvantages:a. rigid,b. The two bars, lying in different planes, produce a structurally

strong L4beam effect.c. Might be used for patient with mid palatal torus.Disadvantage:a. The anteroposterior palatal bar is frequently uncomfortable.

The bulk and contour of the connector may be bothersome tothe tongue and may interfere with phonetics.

b. Limited contact with the palatal tissues, the anteroposteriorpalatal bar derives little support from the bony palate.

c. Contraindicated in patients with reduced periodontal support.

S) Anteroposterior palatal strapThe A-P palatal strap connector is a structurally rigid connector thatmay be used in most maxillary partial denture applications. It isparticularly indicated when numerous teeth are to be replaced and when a torus is present.

Advantages:

a. The corrugated contour over the rugae adds strength without adding thickness.

b. The structural encirclement produced by the A4P straps contributes to the rigidity.

c. The shape of this connector also provides a definite L4beam effect.

Disadvantages:a. Interference with phonetics may occur in some patients.b. the extensive length of borders may cause irritation to the tongue.

4) Horseshoe, or U-Shaped major connectorAdvantages:a. used when several anterior teeth are being replaced

b. used in the presence of a hard median suture line or aninoperable torus

Disadvantages:a. a poor choice for distal extension partial denture. When verticalforce is applied to one or both ends of a horseshoe major connector,there is a tendency for the connector to flex or deform.

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Page 3: Major and Minor connectors

Structural requirements for maxillary major connectors

1. The borders must be placed a minimum of 6 mm from gingival margins or extended ontothe lingual surfaces of the teeth. The location is determined by the need for support,stabilization, and/or oral hygiene.

2. Relief is normally not required under maxillary major connectors.3. Borders that extend onto the anterior palate should blend with the palatal anatomy. This

may be accomplished by positioning borders on the appropriate slopes of the rugae.4. The anterior and posterior elements of an anteroposterior palatal strap should be at least 8

mm wide The posterior strap should be located in the farthest posterior position possiblewithout contacting the movable soft palate.

5. All borders should taper slightly toward the underlying soft tissues.6. Both anterior and posterior borders should cross the maxillary midline at right angles, never

diagonally.7. For those major connectors that present open central areas, the medial borders should be

positioned at the junctions of the horizontal and vertical surfaces of the palate. For gentlycurved palates, the proper locations must be approximated. Appropriate placement isnecessary to minimize patient awareness and potential discomfort.

8. Thickness of the metal should be uniform throughout the palate.9. Borders of the metal framework should be gently curved, never angular.10. The metal should be smooth but not highly polished on the tissue surface (ie, intaglio).11. All borders that contact soft tissues should display bead lines. The bead lines should become

less distinct as they approach the gingival margins of the teeth.

Indications for maxillary major connectors

1. If the periodontal support of the remaining teeth is weak, more of the palate should becovered. A wide palatal strap or a complete palate is indicated.

2. If the remaining teeth have adequate periodontal support and little additional support isneeded, a palatal strap or anteroposterior palatal bar may be used.

3. For long4 span distal extension bases where rigidity is critical, an anteroposterior palatalstrap or complete palate is indicated.

4. When anterior teeth must be replaced, an anteroposterior palatal strap, complete palate,or horseshoe major connector may be used. The final selection must be based onmodifying factors such as number and location of missing posterior teeth, periodontalsupport of remaining teeth, and type of opposing occlusion.

5. If a torus is present and is not to be removed, an anteroposterior palatal strap,anteroposterior palatal bar, or horseshoe major connector may be used. Final selectionmust be based on modifying factors.

6. A horseshoe connector should be used very sparingly. Flexure of this major connector maypermit the concentration of forces upon individual teeth or localized segments of themaxillary arch.

7. A palatal bar is rarely indicated.

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Page 4: Major and Minor connectors

MANDIBULAR MAJOR CONNECTORS

The main differences between the maxillary and mandibularmajor connectors is the supporting structures. The palatalcoverage provides great support to the maxillary RPD. On theother hand, relief must be routinely provided between themandibular major connector and the soft tissue. Relief preventsthe margins of the major connector from lacerating the sensitivelingual mucosa as a result ofthis movement. No bead linesshould be used with the mandibular major connectors.

!l Lingual bar:a. half pear-shaped bar in cross-section, with the broadestportion at the inferior border of the barb) lingual bar Smm in height, the space between gingivalmargins and connector 3mm. There should be at least 8mm ofvertical space between the active tissue of the floor of themouth and the gingival margin of teeth. In the 2nd diagnosticdata collection visit, a periodontal probe should be used tomeasure the depth of lingual vestibule.c) lingual bar can rarely used over mandibular tori

Advantagesa. simpleb. minimal contact to oral tissuec. reduced plaque accumulationDisadvantages:needs certain thickness to keep rigid.

2) Lingual plate:Wide, thin half pear-shaped strap with a thin, solid plate of metalextending upward onto the lingual surfaces of teeth. Inferiorportion must have enough relief to prevent damaging soft tissue.Superior border must seal teeth embrasures to prevent foodimpaction.The superior border of a lingual plate must be contoured tointimately contact the lingual surfaces of the teeth above thecingula. In addition, the lingual plate must completely close theinterproximal spaces to the level of the contact points.When diastemata are present in between the mandibularanterior teeth, an interrupted lingual plate major connector canbe used to prevent metal showing. This type of design will causeplaque accumulation problems and also can reduce the rigidity ofmajor connector.The Iinguoplate does not in itself serve as an indirect retainer.When indirect retention is required, definite rests must beprovided for this purpose.

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Page 5: Major and Minor connectors

.,-+--

4) labial barVery rarely used.The only justification for using a labial bar is the presence of a grossuncorrectable interference that makes the placement of a lingualmajor connector impossible. Interierences that commonly lead to theselection of a labial bar are(1) malpositioned or lingually inclined teeth and(2) large mandibular tori that preclude the use of a lingual bar or lingual plate.

Advantages:

a. can be used as additional indirect retention(lingual plate itselfis not properly an indirect retainer]b. can be used as periodontal support and splinting.c. used when there is insufficient vertical space for lingual bard. used when there is mandibular toruse. used in bilateral distal extension RPD's with severe residualridge resorptionf. used when there is possibility of tooth loss requiringreplacement-lends itself to easy addition of a replacement toothg. it is the most rigid mandibular connector, providing moresupport and stabilizationDisadvantages:a. oral hygiene challenges, more plaque accumulation.b. more likely can cause soft tissue irritation.

3) Double lingual bar (lngual bar and continuouslingual clasp), or Kennedy barit is indicated when some degree of indirect retention is requiredbut there are large interproximal embrasuresAdvantages:a. provide proper indirect retentionb. improve horizontal stabilizationc. Because the gingival tissues and the interproximal embrasures arenot covered, a free flow of saliva is permitted and the marginalgingiva receives natural stimulation.Disadvantages:a. discomfort to the tongueb. entrapment of food debris

Indications for mandibular major connectors1. For a tooth-supported removable partial denture, the lingual bar normally is the mandibular

major connector of choice.2. When there is insufficient room between the floor of the mouth and the gingival margins « 8

mm), a lingual plate should be used. This major connector also is indicated for patients withlarge inoperable tori and patients with high lingual frenum attachments.

3. When the anterior teeth have reduced periodontal support and require stabilization, a lingual

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Page 6: Major and Minor connectors

plate is recommended.4. When the anterior teeth exhibit reduced periodontal support and large interproximal spaces, a

modified lingual plate (ie, step-back design) or double lingual bar should be used.5. When a removable partial denture will replace all mandibular posterior teeth, a lingual plate

should be used.6. A labial bar is rarely indicated.

MINOR CONNECTOR

1) Minor connector that join clasp to the majorconnector-

They connect to retentive clasp, rest to themajor connector

a) must be rigidb) must be placed in the embrasurebetween two teeth to provide sufficientbulk

2) Minor connectors that join indirect retainers orauxiliary rests to major connector

They should form a right angle with majorconnector, but the junction should be a gentlecurve rather than a sharp angular connector

3) Minor connectors that join the denture base tothe major connector

Open lattice work constructionMesh construction

Bead, wire, or nailhead retentionconnector

Attachment to major connector: Acrylicresin cannot be finished to a thin edge. Butt jointis necessary.

4) Minor connectors that serve as approach armfor vertical projection or bar-

type clasp

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