rpd major connectors
Post on 21-Apr-2017
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Definition A component of partial denture that connects parts of partial removable prosthesis at one side of arch with those on opposite side. Its a unit to which all other parts are attached directly or indirectly.
FunctionsUnification : * partial denture acts as one unit * connects various partsStress distribution : distributes functional loads to both teeth & mucosa
Cross arch stabilization(counterleverage) bracing elements on one side of the arch providing stability to the other .
RequirementsRigidity : - chrome-cobalt > gold alloys; cast > wrought - 1/2 round > 1/2 pear shaped > flat bars * to increase rigidity : - Increase the bulk as the length increases - corrugate linguoplate or rugae areas
Non Interference with soft tissues : - should not enter undercut areas * avoid by changing path of insertion * by using block out
- avoid terminating on free gingival margin * borders of maxillary connector should be placed a minimum of 6 mm away from and parallel to the gingival margins. * border of mandibular connector should be located a minimum of 4 mm below the gingival margin.
- avoid terminating on hard structures such as the mid palatal suture or mandibular tori. - avoid terminating on lingual frenum & the movable soft palate.
Minimize food impaction.Unobtrusive : - line angles and edges should be smooth and rounded - borders should not interfere with speech
TypesBar shaped : It is long, narrow, and thick. In cross section bars are round, oval or pear in shape. The thickness of a bar should be at least 6 gauge (4.11 mm) at its greatest dimension. The minimum width of a bar is 4 mm, but they must usually be wider than this for adequate rigidity.
Strap ( plate shaped ) : It is long, wide and thin. The width of a strap or plate varies from 6 -8 mm to the entire length of the palate. The thickest portion of straps or plates is 22 -24 gauge (0.64-0.51 mm).
Mandibular Major ConnectorsLingual BarLingual PlateSublingual bar Lingual bar with cingulum bar (continuous bar)Labial bar Swing lock design
Lingual Bar :
Most common in mandible (use whenever possible).Shape: flat on tissue side, convex or tear-drop on tongue side (1/2 pear shape, with thin edge toward teeth).Size : occluso-gingival width 4 to 6 mm, thickness l.5 to 2 mm.
Position: located above moving tissue but as far below the gingival tissue as possible (3-4 mm or more below FGM).* Patient lifts tongue activates floor of mouth : measure from tip of probe to free gingival margin or make impression with lifted tongue & measure on cast.* Eliminates impingement wax spacer (relief) placed under major connector.
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).Contraindications :remaining natural anterior teeth severely tilted linguallyinterfering lingual torihigh attachment of lingual frenuminterference with elevation of the floor of the mouth during functional movements (< 8 mm)
Lingual Plate :
Lingual bar with extension over cingulum of anterior teeth (used where a lingual bar cannot be used). Inferior border at the ascertained height of the alveolar lingual sulcus when the patient's tongue is slightly elevated. Rest at each end of lingual plate. It prevents forces being directed facially. Easier denture tooth addition than bar.
Indications :high floor of the mouth(< 8 mm)prominent lingual frenumlingual torithe residual ridges in Class I arch have undergone such vertical resorbtion that they will offer only minimal resistance to horizontal rotations of the denture through its bases.for using periodontally weakened teeth to furnish support to prosthesis and to help resist horizontal rotation of the distal extension type of denture (act as periodontal splint).
Mandibular Lingual Bar with Continuous Bar (Cingulum Bar)(Kennedy Bar, Double Lingual Bar)
Lingual bar with secondary bar on cingula of anterior teeth. Secondary bar acts as indirect retainer.
Indications :When a linguoplates otherwise indicated but the axial alignment of anterior teeth is such that excessive block out of interproximal undercuts would be required.When wide diastema exists between mandibular anterior teeth and a linguoplate would objectionably display metal in a frontal view.
Maxillary Major ConnectorsWhenever it is necessary for the palatal connector to make contact with the teeth for support, definite tooth supported by definite rest seats should be provided.Terminate 6.0 mm or more from free gingival margin when possible.
Anterior-Posterior Palatal StrapPalatal plate-type connector Single palatal strapU-shaped palatal connector (Anterior Palatal Strap)Single palatal barAnterior-posterior palatal bar
Anterior-Posterior Palatal Strap :
maximum rigidity - minimum bulkused in most cases - especially torus palatinus. Indications :Class I and II arches in which excellent abutment and residual ridge support exists, and direct retention can be made adequate without the need for indirect retention.
Long edentulous spans in Class II, modification 1 arches.Class IV arches.Inoperable palatal tori that do not extend posteriorly to the junction of the hard and soft palates.Contraindication : when there is an inoperable maxillary torus that extends posteriorly to the soft palate.
Anterior-Posterior Palatal Bar :
A narrow (A-P) variation of anterior-posterior palatal strap double palatal bar connector, requires greater bulk for rigidity.More objectionable to the patient. Strap connectors provide greater distribution of stresses.
Palatal Plate Type Connector :
Covers one half or more of the hard palateMaximum tissue supportConnector of choice in long distal extension casesSix or less anterior teeth remainGreater stability and stress distributionNot used with torusIncreases retention
Connector should :
be fabricated of uniformly thin metal have accurate anatomic reproduction of the rugae improves strength and rigidity cover same area as complete denture posteriorly have large surface area of mucosal contact improves potential for retention
A cast plate between two or more edentulous areas.A complete or partial cast plate that extends posteriorly to the junction of the hard and soft palate.An anterior palatal connector with a provision for extending an acrylic resin denture base posteriorly.
Abutments are periodontally involvedMaximum stress distribution is neededFlabby tissue Shallow palatal vault
Single Palatal Strap :
usually use for Class III & IV cases.should be 8mm wide or approximately as wide as the combined width of a maxillary premolar and first molar. confined within an area bounded by the four principal rests.never use in cases involving distal extensions since it must be made bulky for rigidity.relief may be required over bony midline. not used with torus.
Palatal Bar :
narrow anterio-posteriorly.thick occluso-gingivally. palatal bar objectionable due to bulk.
U-Shaped Palatal Connector Horse Shoe
poor connector never use unless absolutely necessaryrequires bulk in the rugae area (where the tongue requires freedom) for rigiditytoo flexible
allows movement at the posteriortraumatic to the residual ridgeuse only where torus prohibits other connector & extends to the posterior limit of the hard palate
References Chapter 5 Major and Minor Connectors, McCracken's Removable Partial Prosthodontics, 11th edition.
Under the supervision : DR. Nada najar
Ola Qatu Weam Faroun
Done By :Third year Dental students at AQU