MAJOR CONNECTORS

Presented by, Silpa Abraham

Ist year MDS

INTRODUCTION

The designing of RPD varies according to the type of support and also it is easier for dentist to convey information to lab. To understand designing of RPD, knowledge about components is a must.Each component of a removable partial denture has a name descriptive of function.

COMPONENTS OF RPD

MAJOR CONNECTORS

• A major connector is that part of a partial removable dental prosthesis that joins the components on one side of the arch to those on the opposite side.

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Therefore, all components ae attached to the major connector either directly or indirectly.

REQUIREMENTSRigidity

Protection of associated soft tissues

Provide means for obtaining indirect retention where

indicatedProvide means for placement of

one or more denture basesPromote patient comfort

FUNCTIONS

Unification of major parts of the prosthesis

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

Minimise torque to teeth

CROSS-ARCH STABILITY

• Resistance against dislodging or rotational forces obtained by using a partial removable dental prosthesis design that uses natural teeth on the opposite side of the dental arch from the edentulous space to assist in stabilization.

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FEATURES

Principle of leverage

Limits movement

possibilities by acting as

counteracting lever

Important in distal extension

cases

MAXILLARY MAJOR CONNECTORS

SIX BASIC TYPES

OF MAXILLARY

MAJOR CONNECTORS

Single

Palatal

Bar

Single

Palatal

Strap

Anteroposterior

palatal

bar

Anteroposterior palat

al strap

horse-shoe palat

al connector

Palatal plate type/comple

te palate

PALATAL BAR

• Narrow half oval• Thickest point at the center• Bar is curved; no sharp angles

If used,• Limited to short span Class III applications• Placement not anterior to second premolar

Advantages And Disadvantages:Was one of the most widely usedToday primarily for interim applications

BulkyNarrow antero-posterior widthNearly all support from rests

PALATAL STRAP

• most versatile• Wide band metal with thin cross-sectional area• Anteroposterior dimension <8mm• Width of the strap increases with increase in length of

edentulous span• Rigidity ; support from hard palate

• Wider strap resembles complete palate major connector• Indicated in cases of bilateral posterior short edentulous

spaces • Not suitable for anterior teeth replacements with distal

extension• Objectionable bulk: rigid, resist torque,adequate vertical

support & horizontal stabilization

Advantages And DisadvantagesExcessive palatal coverage;improper positioning strap bordersPapillary hyperplasia

Resistance to bending and twisting forces:L beam principleInherently strong, relatively thin, little interference with tongue actionIncreased tissue coverage

ANTEROPOSTERIOR PALATAL BAR

• Palatal bar+palatal strap• Anterior palatal strap and posterior palatal bar• Both joined by flat longitudinal elements• Effect of circle: rigid• L-beam effect

Advantages and Disadvantages:RigidityMaybe used when support is not a major considerationUsed in patients with tori which cannot be removed

Uncomfortable Bulk and contourLittle support from hard palateContraindicated in patients with reduced periodontal support

ANTEROPOSTERIOR PALATAL STRAP

• Structurally rigid• Most used maxillary partial denture application• Indicated :

• Numerous teeth to be replaced• Palatal tori present

• Width:8mm, thin in cross section• Palatal border smooth & gentle

• If no anterior teeth to be replaced, strap most posterior position

• Appropriate placement: ↓ interference with speech, patient comfort

• Open area:20x15mm• Anterior and posterior components joined by longitudinal

connectors on either side-square or rectangular frame-strength

• Flexure practically non-existent

Advantages and Disadvantages:

- Rigid:derives support from hardpalate-Corrrugated rugae: strength-Structural encirclement-L beam effect

-Interference with phonetics-Irrritation to tongue: extensive borders

HORSESHOE CONNECTOR

• Thin band of metal running along the lingual surfaces of the remaining teeth

• Extension:6-8mm along palatal tissues• Medial border: junction of horizontal and vertical slopes of

the palate• ↑ border extension- ↑ rigidity• Symmetry to be displayed• All borders gently curved & smooth

Advantages and Disadvantages:

-1˚ use: several anterior teeth missing-Reasonably strong-Indicated for cases with tori or other bony prominences -Lack of rigidity:flexible

-Doesnot provide support , impingement of underlying tissue-Bulky-Gingival irritation and periodontal damage

PALATAL PLATE TYPE CONNECTOR

• Thin, broad, contoured palatal coverage used as maxillary major connector & covering half or more of hardpalate

• Corrugated contours: uniform thickness and strength• Ultimate rigidity and support• Anterior border 6mm from marginal gingiva or covers

cingula of anterior teeth • Posteior border: junction of hard palate and soft palate

• Posterior palatal seal not used• Slight mechanical seal by beadline along posterior border• Contact with palate: retention• Palatal plate used in 3 ways

• When last remaining abutment on either side is either a canine or 1st premolar, excessive vertical resorption:palatal coverage

Can be used when all posteriors missing, periodontal compromised teethAnatomic contours producedL-beam effectAll metal connectors-enhances thermal conducticityResistant to colonization by candida

Soft tissue reactionsSoft tissue hyperplasia, poor oral hygiene, prolonged denture wear

MANDIBULAR MAJOR CONNECTORS

LINGUAL BAR

LINGUOPLATE

SUBLINGUAL BAR LINGUAL

BAR WITH

CINGULUM BAR

(CONTINUOUS BAR)

CINGULU

M BAR(CONTINUOUS

BAR)

LABIAL BAR

LINGUAL BAR

• Most frequently used• Indicated for all cases except insufficient space between marginal

gingiva and floor of the mouth• Half pear shaped• Broadest portion-inferior border, floor of the mouth• Additional rigidity: ↑ Thickness of wax Wax added to half pear ↑Height of bar

• Availability of space ;key factor• 8mm of vertical space ; 5mm minimum height and 3mm

between gingival margin and superior border• Clinical setting, available space measured using

periodontal probe• Another method: custom impression tray• Tori should be removed

Advantages and Disadvantages:SimpleMinimal contact with the remaining teeth and soft tissues↓ plaque accumulation, ↑ soft tissue stimulation

Improper waxing procedure or aggressive finishing of cast framework: thin and flexiblePermits concentration of forces upon teeth

LINGUOPLATE

• Half pear shaped with a thin, solid piece of metal from superior border

• Inferior border: as low as possible to floor of mouth• Inferior portion less bulky: no compromise in rigidity• Superior border: contact lingual surface of teeth above

cingulum.knife-edged:scalloped appearance• Complete closure of interproximal spaces upto contact points• Ledging effect

• Modification: stepback• Disadvantage:maynot be rigid: thicker inferior border• Rests located not far from 1st premolar

Advantages and Disadvatages:Indicated in:-Insufficient vertical space for lingual bar-remaining teeth periodontally compromised-Posterior teeth missing & need for additional indirect retentionExceptional rigidity Mandibular tori present

Decalcification of enamel surfaces & irritation of soft tissues: poor oral hygieneFood traps

SUBLINGUAL BAR

• Modification of lingual bar• When superior border cannot be placed 4mm below free gingival margin• Placement inferior and posterior than lingual bar• Lies over & parallel to anterior floor of the mouthContraindications:• Lingual tori• High attachment of lingual frenum• Interference with elevation of floor of mouth during function

CINGULUM BAR

• When linguoplate is the major connector of choice, but axial alignment of anterior teeth requires excessive blockout of interproximal undercuts.

• Located on or slightly above cingula of anterior teeth• When used alone , cingulum bar• When used along with lingual bar : LINGUAL BAR WITH CINGULUM BAR

LABIAL BAR

• Runs across the mucosa on facial surface of the mandibular arch

• Half pear in cross section• Height and thickness › lingual bar: rigidity• Indication: gross interference which prevents lingual bar• Modification : SWINGLOCK RPD

Advantages and Disadvantages:Patient acceptance poorDistorts lower lipLabial vestibule not deep enough to permit rigid material without encroaching gingival margins

Indicated when remaining teeth tipped so far lingually, when all other connectors ruled out

CONCLUSION

• Major connectors by uniting the other components of removable partial denture, act like a foundation bringing about bilateral distribution of forces which depends on the rigidity of the connector

• Although there are many variations in major connector, a thorough comprehension of all factors influencing the design will ead to best design for the patient.

REFERENCES

• Stewart’s clinical Removable partial prosthodontics, 4th edition• McCracken’s Removable partial prosthodontics, 12th edition• An atlas of Removable Partial Denture design,

Russell.J.Stratton/Frank J. Wiebett• Balvinder S Saluja, Divya Mittal.An overview of removable

partial denture.Indian Journal of Dental Sciences. • J. C Davenport et al.Connectors Bdj volume 190, no. 4, february

24 2001