Major and Minor Connectors Flashcards by Rodwan Halimi

What is a major connector?

Rigid structure that joins the components on one side of the arch with those on the opposite side.

All other RPD components are either directly or indirectly attached to it.

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What is the function of the major connected in an RPD?

Union of RPD components

Distribution of applied force throughout the arch to selected teeth and tissues

Minimization of torque to individual teeth

Control prosthesis movement (Cross-arch stability)

Assist indirect retention

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Why should a major connector be rigid?

A flexible major connector would cause damage to hard and soft tissues.

It would allow forces to be concentrated on individual teeth and segments of residual ridges resulting in tooth mobility and loss, bone resorption leading to decreased support for associated denture bases.

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Why should a major connector be in a favourable location?

To avoid impingement of gingival tissues (gingival margin)

Avoid tori and soft tissue prominences

Relief beneath major connector in areas of possible interferences

To be free of movable tissue

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What are the important features of a major connector?

Rigidity

Favourable location

Rounded angles

Borders of major connector far from the gingival margin

Maintain the natural contour of subadjacent structures

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How far should the major connector be from the gingival margin?

Mandible = 3 - 4 mm

Maxilla = 5 - 6 mm

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What are the features of good major connectors?

Intimate contact of major connector and palatal mucosa improve retention and stability.

Lower the periodontal support the greater the palatal coverage.

The wider the major connector the thinner it can be the narrower it is the thicker it should be.

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What are the types of majjor connectors?

Single palatal strap

Antierior-posterior strap or palatal plate

U-shaped palatal corridor

Broad palatal strap or palatal plate

Single palatal bar

Anterior-posterior palatal bar

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When is a single palatal strap used?

Class III +/- mod (no anterior mod)

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What are the design features of the single palatal strap?

Thin for tongue comfort but wide (>=8mm) enough for rigidity

Anterior border should follow the valleys but avoid cutting across the rugae

Anterior and posterior borders cross the suture line at right angles

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When is an anterior-posterior palatal strap used?

Class II, III with anterior mod, IV

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What are the design features of an anterior-posterior palatal strap?

Flat and at least 8mm wide

Posterior strap should be anterior to the hard/soft palate limit

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When should the anterior-posterior palatal strap be avoided?

Inoperable torus extending to soft palate

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When is a U-shaped palatal connector used?

Inoperable large palatal torus

Common with class IV

Significant gag reflex

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What are the problems with the U-shaped palatal connector design?

Poorest design for rigidity

Bulk is often required where tongue space is needed (the most freedom is required in the rugae zone)

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When is palatal plate or gull palatal coverage used?

Few remaining teeth such as only the anterior arrangement

Teeth with poor prognosis

Long, flat residual ridges

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What are the design features of a single palatal bar?

Narrow

Cross-section is a half-oval shape

< 8mm in width

Class III with small edentulous area

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What are the single palatal bar disadvantages?

Bulky - Discomfort, not to be placed anterior to the 2nd PM

Low vertical support

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Where is the single palatal bar placed?

Anterior: located in the area of palatal rugae

Median: Behind palatal rugae (ideal)

Posterior: Placed in the limit hard-soft palate

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What is an anterior-posterior palatal bar?

Combination of anterior and posterior bars. Anterior bar is more flat.

Has 2 longitudinal elements connecting the anterior bar to the posterior bar.

Replaces many teeth.

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Why are anterior-posterior palatal bars used? What makes them not a good idea to use?

Used when torus is present. They are good at minimizing soft tissue coverage and to provide rigidity.

Not very comfortable so avoid using.

What maxillary major connector should be used for a mouth with weak periodontal support of remaining teeth?

More of the palate should be covered: Palatal strap/complete palate indicated.

If remaining teeth have adequate periodontal support which maxillary major connector should be used?

Palatal strap

Anteroposterior palatal bar

For long span distal extension where rigidity critical what should be used as a maxillary major connector?

Anteroposterior strap

Complete palate

Which maxillary major connector should be used for anterior teeth replacement?

Anteroposterior palatal strap Horseshoe Complete palate

Which maxillary major connector is used if the torus is present?

Anteroposterior palatal strap Anteroposterior palatal bar Horseshoe

Why are palatal bars and horseshoe MMCs not used often?

Palatal bar rarely indicated due to less rigidity Horseshoe due to reduced rigidity

What are bead lines?

Lines at the borders of maxillary major connectors present to prevent collection of food particles under the major connector.

How do bead lines work?

They displace adjacent soft tissues to produce a mechanical seal.

Which forms of mandibular RPDs require Major connector relief and which don't?

Kennedy class III - teeth supported RPD - No relief or small relief needed. Kennedy class I, II, and IV - Moderate relief (around 1.5mm) No bead lines required

What are the requirements of a mandibular major connector?

Not invade floor of the mouth, lingual frenulum, and mandibular tori area. No bead lines required

What are the types of mandibular major connectors?

Lingual bar Lingual plate Sublingual bar Cingulum bar Double lingual bar Sublingual bar

What are the design features of a lingual bar?

Half-pear shape cross section Superior border tapered towards the gingival tissues superiorly Inferior border is the broadest portion Need at least 8mm from gingival margin to the floor of the mouth. (remember minimum height of 5mm and 3mm of gingival margin)

What are the design features of a lingual plate?

Thin metal sheet that adapts intimately to the cingulum

When is a lingual plate indicated?

Where the floor of the mouth is shallow or there is an inoperable torus (no space for lingual bar) High frenum attachment.

What are the advantages and disadvantages of a lingual plate?

Advantages: Good indirect retention Stabilize teeth with guarded prognosis Disadvantages: May irritate underlying soft tissues Caries when patient has poor oral hygiene

When is a cingulum bar used?

Only used if there is long enough clinical crowns and alternatives are not possible.

What are contraindications for a cingulum bar?

Retroclined anterior teeth Wide diastemas

What are the features of a lingual bar?

Lingual bar with a secondary bar above the cingulum Secondary bar acts as an indirect retainer

What are the advantages of a double lingual bar?

Expose most of the lingual surface of the teeth and the interproximal soft tissue Natural stimulation of gingival margins

What are the disadvantages of a double lingual bar?

Tendency to trap food debris (marked crowding leads to inaccurate adaptation) Irritation of the tongue (multiple borders)

What are the design features of a sublingual bar?

The sublingual bar is essentially a lingual bar by design but it is placed more posterior and inferior. Lying over and parallel to the anterior floor of the mouth Shallow floor of mouth or lingual undercuts Low frenulum attachment

What are the fucntions of minor connectors?

Join remaining components of RPD to the major connector (Clasp assemblies, indirect retainers, etc) Distribute applied forces to the supporting teeth and oral tissues, help reciprocation Join denture base to major connector

What are the primary attributes of a minor connector?

Rigid Form right angle with major connector Preferably located in interdental space Wider linguobuccal direction, narrow mesiodistal

What are the features of minor connectors that connect the denture bases to the major connector?

Gridwork Rigid No interference with artificial teeth Provide adequate support and retention for resin base: Maxilla covers tuberosity, mandible 2/3rds of edentulous ridge.

What is the cast stop?

Used in Kennedy class I and II free end saddles. Small area of minor connector contacting the master cast.

What is the function of the cast stop?

Prevents displacement or deformation of the metal framework during packing and processing of acrylic resin

What are internal and external finishing lines?

Resin-metal interfaces are referred to as finish lines. They function to help lock the acrylic to the major connector. Make the transition from the denture base and the framework

What is the function of the saddles?

Support artificial teeth and replace alveolar tissues Receive and distribute occlusal forces to supporting structures (Kennedy class I and II) Aid retention: Adhesion and cohesion. Stimulate underlying tissues of the residual ridge to prevent alveolar ridge atrophy. Prevent tooth migration Add cosmetic effect

What are the types of denture bases?

Metallic (eg CoCr) Acryllic

What are the advantages and disadvantages of metallic denture bases?

Adv: Thermal stimulus Resistance Easy to clean Less volume Disadv: Difficult to adjust Not able to reline Cost Weight

What are the advantages and disadvantages of acryllic?

Adv: Lighter Aesthetic Good adaptation Potential for future relining Disadv: Distortion No thermal stimulus Hygiene