06. major connectors

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Major Connectors

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

Requirements of a Major Connector Rigidity Functions as one unit

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 Non-Interference with Tissues Should not enter undercut areas avoid by changing path of insertion or by using blockout

Non-Interference With Tissues Avoid terminating on: Free gingival margin Cross abruptly at 90o Relief is used to minimize impingement

(Fig 2-17, Stewart's)

Non-Interference With Tissues Avoid terminating on: Hard structures such as the midpalatal suture or mandibular tori Place relief

Non-Interference With Tissues Avoid terminating on: Lingual frenum & the movable soft palate Soft tissue movements must also be allowed Careful intraoral exam

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

Unobtrusive Smooth transition from connector to denture base - butt joint

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

(Fig 2-21, Stewart's)

Mandibular Major Connectors Lingual Bar Lingual Plate Continuous Bar

Mandibular Major Connectors Lingual Bar Most common in mandibe Use whenever possible

Mandibular Major Connectors Lingual Bar Shape Flat on tissue side Convex or tear-drop on tongue side (1/2 pear shape, with thin edge toward teeth)

(Fig 2-35, Stewart's)

Mandibular Major Connectors Lingual Bar Size Occluso-gingival width = 4 to 6 mm Thickness = l.5 to 2 mm

Inferior Border Mandible Patient lifts tongue Activates floor of mouth Measure from tip of probe to free gingival margin

Inferior Border Mandible Record values in chart, transfer to cast

Lingual Bar Position Superior border l.5-2.0 mm or more below FGM As far from gingival margin as possible

(Fig 2-15, Stewart's)

Potential Impingement Anterior major connector moves toward tissue as the posterior portion is loaded Space needed more when ridge is less vertical

(Fig 2-33, Stewart's)

Mandibular Major Connector Relief Eliminates impingement Wax spacer (relief) placed under major connector one thickness of 30 gauge wax

Lingual Plate (Linguoplate) Lingual bar with extension over cingula of anterior teeth Use where a lingual bar cannot be used

Lingual Plate Indications Potential Impingement from lingual bar High floor of the mouth Prominent lingual frenum Lingual tori

Lingual Plate Rest at each end of lingual plate Prevents forces being directed facially Easier denture tooth addition than bar

Lingual Plate Variations May show through embrasures

(Fig 2-41 & 43, Stewart's)

Continuous Bar Retainer(Kennedy Bar, Double Lingual Bar)

Lingual bar with secondary bar above cingula Secondary bar acts as indirect retainer

Continuous Bar Retainer Potential food trap between two bars Normally avoid

Maxillary Major Connectors Anterior-Posterior Palatal Strap Full Palatal Strap Palatal Strap Anterior Palatal Strap

Maxillary Major Connectors Terminate 4.0 mm or more from free gingival margin when possible

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

Anterior-Posterior Palatal Bar A narrow (A-P) variation of anteriorposterior palatal strap Double palatal bar connector Requires greater bulk for rigidity

Anterior-Posterior Palatal Bar More objectionable to the patient Strap connectors provide greater distribution of stresses

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

Full Palatal Plate Abutments are periodontally involved Maximum stress distribution Flabby tissue Shallow palatal vault

Full Palatal Plate Greater stability and stress distribution Not used with torus Increases retention

Full Palatal Plate Connector should: Be fabricated of uniformly thin metal Have accurate anatomic reproduction of the ruggae improves strength and rigidity

Full Palatal Plate Connector should: Cover same area as complete denture posteriorly Have large surface area of mucosal contact improves potential for retention

Full Palatal Plate Generally of cast metal Acrylic resin used in interim prostheses

Palatal Strap Usually use for Class III & IV cases Wide anterio-posteriorly

Palatal Bar Dont use Narrow anterio-posteriorly Thick occluso-gingivally Palatal bar objectionable due to bulk

(Fig 2-24, Stewart's)

Palatal Strap (or Bar) Never use in cases involving distal extensions or replacement of anterior teeth since it must be made bulky for rigidity Relief may be required over bony midline Not used with torus

Anterior Palatal Plate(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

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

Flexes, impinging on soft tissue

Unilateral RPD Dangerous Avoid aspiration

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