Major Connectors

transcript

Major ConnectorsPresented by : Apurva Thampi

Contents Introduction Major connectors Role of major connectors Types of maxillary major connectors

Review of indicationsSteps in Designing

Types of Mandibular major connectorsReview of indicationsSteps in Designing

Recent advances Conclusion References

IntroductionName of components – descriptive of

function

Components

Major connectors

Minor connector

Direct retainer

Indirect retainer

Denture base

Major connectorsA major connector joins the components of the removable partial denture from one side of the arch to the opposite side

Role of major connectors

Be rigidProtect the associated soft tissueProvide means for obtaining indirect

retentionProvide a means of placement of denture

basePromote patient comfortSelf cleansing

Rigidity :

Permits broad distribution of forces

Protect soft tissue:

Maxillary connector – 6mm from marginal gingiva

Mandibular connector – 3mm from marginal gingiva

Provide means of indirect retention:

By use of indirect retainers, rotation around the fulcrum

line can be prevented

Promote patient comfort:

Edges should be contoured

Major connector is based on the principle of leverage

It will limit movement possibilities by acting as a counter-acting lever

CROSS-ARCH STABILITY

Major connector

maxillary

mandib

Requirements of maxillary major connectors

Borders – 6mm from gingival marginsAnterior border should blend with the

palatal anatomyBorders should cross the margins at right

anglesPalatal strap – 8mm wideOpen central connectors – medial borders

should be located at the junction of horizontal and vertical surfaces

Thickness of the plate should be uniformBorders should be gently curvedIntaglio surface should not be highly

polished

Types of Maxillary major connectors

• Palatal bar• Palatal strap• Antero-posterior palatal bar• Horse-shoe shaped• Antero-posterior palatal

strap• Complete palate

6 types of maxillary

major connector

Palatal bar

Narrow, half ovalThickest point at the centreGentle curved and should not form an

Indications class III (short span)

application

*Palatal bar has few advantages and should be avoided

*Bulky – causes discomfort to the patient*Narrow antero-posterior width

Advantage/Disadvantage

Palatal strap

Most versatileBand of metal with a thin cross-sectional

dimensionA-P dimension should not be less than

Width should be increased with the length of the edentulous span

Indication Kennedy’s class II

*Increased resistance to bending and twisting forces*can be kept thin*little interference with normal tongue action*increased tissue coverage

*Excessive palatal coverage* Anterior border should be positioned posterior to rugae* Prone to papillary hyperplasia

Antero-posterior palatal bar

Palatal bar + palatal strap2 bars joined by a flat longitudinal

element

*Rigid*Minimises soft tissue coverage*Provides exceptional resistance to deformation

*Uncomfortable*Bulky*Derives little support from bony tissue*Contraindication – reduced periodontal support

Horse shoe connector

Consists of a thin band of metalLingual surface of remaining teeth to

palatal tissue – 6-8 mmShould be symmetrical – equal height

on both sides

*Strong connector*Derives some vertical support from tissues of hard palate*Designed to avoid bony prominences

Tendency to deformDoes not provide cross-arch stabilisationShould be considered only if more rigid connectors cannot be used

Horse shoe major connector has a tendency toFlex or deform. Hence it is not a good connector When cross arch stabilization in required.

Antero-posterior palatal strap

Maximum usageEach strap – 8mm width, thin cross-

sectionBorders – 6mm from gingival marginPosterior strap should not contact

soft palate

*Derives good support from hard tissues*L-beam effect – increases resistance to flexure

+Extensive length of borders may cause irritation to the tongue

Complete palate

Provides ultimate rigidity and supportMaximum tissue coverageMust be kept 6mm away from

gingival marginsMechanical seal – presence of bead

line along posterior border

ADVANTAGESAll posterior teeth to be replacedRemaining teeth are periodontally

compromisedProvides vertical supportPermits force distribution to the teeth as

well as the tissuesComfortable Coverage of multiple planes – L beam

effect

DISADVANTAGESAdverse soft tissue reaction may occur

– soft tissue hyperplasia – poor oral hygiene and prolonged periods of denture wearing

Indications

Case Type of major connector

Weak periodontal support Wide palatal strap or complete palate

Adequate periodontal support Palatal strap or A-P palatal strap

Long-span distal extension A-P palatal strap or complete palate

Anterior teeth to be replaced A-P palatal strap, complete palate or horseshoe major connector

Presence of torus A-P palatal strap, A-P palatal bar, horse shoe connector

Design of maxillary major connectors

: Outline primary stress

bearing areas

Outline non beari

ng areas

Outline of connector area

Selection of connector type

Unification

Requirements of mandibular major connectors

Rigid without being bulkyMust not impinge on the movable

floor of the mouthRelief required between the rigid

metal connector and underlying tissues

Types of mandibular major connectors

•Lingual bar•Lingual plate•Double lingual bar•Labial bar

4 types of

mandibular major connect

Lingual bar

Most frequently usedCross-section – half pear shapedBroadest portion near the floor of the

mouth8mm space between gingival margin

and floor of the mouthPresence of mandibular tori –

surgical removal

*Minimal contact with remaining teeth*Simple design*Decreased plaque accumulation*Increased soft tissue stimulation

*If care is not taken, frame work may not be rigid*Too thin or too flexible – concentration of potentially destructive forces on individual teeth

Lingual plate

Half pear shaped – this solid piece of metal extending from superior border to lingual surfaces of teeth

Lingual border as low as possible - avoid interferences with functional movements

Plate must completely close the interproximal surfaces

Superior border is knife-edged to avoid “ledging”

Open embrasures or widely spaced teeth – modification – “step back”

Metal should cross gingival margins at right angles

To ensure rigidity – inferior border should be made thicker

“Ledging” occurs when metal margins are thick or linear

and provides unnatural contours

“Step back” modification requires the superior border

of the plate to cover the cingulum of the individual

*Exceptional rigidity – des not interfere with functional movements*Stabilize periodontally weak teeth*May provide additional indirect retention*If mandibular tori cannot be removed, adequate relief should be provided

*Extensive coverage – decalcification of enamel*Irritation of tissues in patients with poor oral hygiene

Double lingual bar

Lingual bar + lingual plateUpper and lower borders are similar

to lingual plateNo continuous metal sheetUpper bar – half oval cross-section

(2-3 mm height and 1mm thickness)Two bars should be connected by

rigid minor connectors

Rests should be placed at each end of the bar – no further posterior than 1st premolar

*Effectively extends indirect retention in an anterior direction*Free flow of saliva – marginal gingiva stimulation

Tendency to trap debrisUncomfortable – multiple borders and thickness

Labial bar

Runs across mucosa on facial surface

Half pear shapedLonger than lingual barHeight and thickness must be greaterSuccessful treatment very limited

SWING LOCK MODIFICATIONLabial component does not serve as

major connectorHinge at one end and locking device on

the otherPermits RPD to reach inaccessible

undercuts

Considered when remaining major connectors cannot be used

*Patient acceptance is poor-uncomfortable*Bulk distorts the lower lip*Labial vestibule not deep enough to accommodate a rigid connector without encroaching on the gingival margins

Indications

Tooth supported RPD Lingual bar

Insufficient room between floor of mouth and gingival margins

Lingual plate

Anterior teeth with reduced periodontal support

Lingual plate

Anterior teeth with reduced periodontal support and large interproximal spaces

Double lingual bar

Replacement of all mandibular posteriors

Lingual plate

Design of mandibular major connectors

I – outline basal seat area on the diagnostic cast

II – outline inferior border of major connnector

III – outline superior border of Major connector

IV – unification

Acrylic dentures Recent advances Conclusion References

Acrylic dentures

Most commonly usedIndicated when the life of the denture

is expected to be lessOr if relining may be necessaryWeaker and less rigid than the metal

alloys - more likely to flex or fracture during function.

Connectors -J. C. Davenport, R.M.Basker, J. R. Heath, J. P. Ralph, PO. Glantz, and P. Hammond (BDJ)

INDICATIONSDuring the phase or rapid bone

resorption after tooth lossWhen remaining teeth have poor

prognosis, and an extraction and replacement is expected

Interim dentureIn growing individuals

Design for the replacement of one or two anterior teeth in youngpeople is the 'spoon' denture. It reduces gingival margin coverage to aminimum, but a potential hazard is the risk of inhalation or ingestion.

A more stable and therefore more widely applicable design is themodified spoon denture. Here one has the choice of relying on frictionalcontact between the connector and the palatal surfaces of some of theposterior teeth, or of adding wrought wire clasps.

Another acceptable design is the 'Every' denture which can be used for

restoring multiple bounded edentulous areas in the maxillary jaw.

Acrylic RPDs in the mandible often lack tooth-support makingtissue damage highly probable. Such RPDs should thereforebe avoided whenever possible.Connectors -J. C. Davenport, R.M.Basker, J. R. Heath, J. P. Ralph, PO. Glantz,

and P. Hammond (BDJ)

Acrylic dentures Recent advances Conclusion References

Recent advances

Recent work has shown that CAD/CAM/RP technologies can be successfully applied to the fabrication of RPD alloy frameworks

RPD framework using PEEK

To conclude….

Bibliography

McCracken’s removable partial prosthodontics – 12th edition

Stewarts removable partial prosthodontics – 4th edition

Partial dentures – John osborne and George Lammie – 4th edition

Use of CAD/CAM technology to fabricate a removable partial denture framework (R. J. Williams, BA, PhD,a Richard Bibb, BSc, PhD,b Dominic Eggbeer, BSc,c and John Collis, BDS) (JPD)

Thank you!!

Major Connectors

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