rpd major connectors

RPDMajor Connectors

Definition

A component of partial denture that connects parts of partial removable prosthesis at one side of arch with those on opposite side.

It’s a unit to which all other parts are attached directly or indirectly.

Functions Unification : * partial denture acts

as one unit * connects various

parts Stress 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 .

Requirements Rigidity : - 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

Types Bar shaped : It is long, narrow, and thick. In cross section bars are ½ round, ½ oval

or ½ 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 Connectors Lingual Bar Lingual Plate Sublingual 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 lingually• interfering lingual tori• high attachment of lingual frenum• interference 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 frenum lingual tori the 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 Connectors

Whenever 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 Strap Palatal plate-type connector Single palatal strap U-shaped palatal connector (Anterior

Palatal Strap) Single palatal bar Anterior-posterior palatal bar

Anterior-Posterior Palatal Strap :

maximum rigidity - minimum bulk used 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 palate Maximum tissue support Connector of choice in long distal

extension cases Six or less anterior teeth remain Greater stability and stress distribution Not used with torus Increases 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

Forms :

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.

Indications :

Abutments are periodontally involved Maximum stress distribution is needed Flabby 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 necessary requires bulk in the rugae area (where the

tongue requires freedom) for rigidity too flexible

allows movement at the posterior traumatic to the residual ridge use 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 We’am Faroun

Done By :

Third year Dental students at AQU