54b7New Microsoft Office Power Point Presentation

RETAINERS IN FIXED PARTIAL DENTURES

Submitted by-Apoorva sharmaintern

RETAINERS- The part of a fixed partial denture which unites the abutment to the remainder of the restoration.

Retainers with pontics

Abutment

Bridge

IDEAL RETAINER

Should cause least amount of destruction to the abutment

least destroys the outline form of the tooth

Marginal line should be Finished with great accuracy

Rigidity – withstand the requisite

load Functional adaptation and

protect the tooth against its fracture

Least destroys the cervical marginal ridge

Positioned margins at less susceptible to caries or recurrence of caries

Preparation should be made without trauma to the pulp or surrounding tissue

Accurate complement to the lost tooth structure

Cleansable esthetic

TYPE OF RETAINERS-1. based on the tooth coverage- full veneer crown partial veneer crown conservative retainers telescopic retainers2. Based on material being used- all metal retainers metal ceramic retainers all ceramic retainers all acrylic retainers

FULL VENEER CROWN- These retainers cover all the five

surfaces of the abutment Most retentive Ideal retainers Design can resist masticatory forces in

all direction

Disadvantages- Extensive tooth preparation

Gingival decay is prevalent

Reduced strength

PARTIAL VENEER CROWN- Preferred over full veneer crown Require less tooth reduction Guides for coronal contours Embrasure forms are pre-established

ADVANTAGES – - conservative tooth preparation - improved periodontal health as limited

contact between margin of restoration and gingiva

- marginal fit can be easily veryfied - unveneered portion of tooth can be

used for electric pulp testing DISADVANTAGES – - lacks retention - some display of metal

TYPES OF PARTIAL VENEER RETAINERS

1.Proximal boxes

2.Seven eight crowns

3.Reverse three quarter crown

4.Proximal half crown

1 Posterior three quarter crowns

2 anterior three quarter crown

3 pin modified three quarter crown

CONSERVATIVE RETAINERS- Require minimal tooth reduction Acid etching These dentures do not accept heavy

loads Indicated for anterior teeth Have a small metallic extension

which are designed to be luted directly onto the lingual surface of the abutment tooth using resin cement

RESIN BONDED FPD-

Missing anterior teeth

Retainer with wings

Wings bonded to the lingual surface of the abutment teeth

Advantages- - non invasive to dentine - conservative preparation - reduced cost and chair side time - decreased tissue irritation –

supragingival margins Disadvantages- - plaque accumulation - bulky contours may be intolerable to

some patients - not ideal for replacing more than

one tooth

TYPES- Rochette bridge Maryland bridge Castmesh fixed partial denture

Virginia bridge.

ROCHETTE BRIDGE - Wing like retainer - Funnel shaped perforations MARYLAND BRIDGES - Mechanical retention - microporosities present on the tissue surface

of the retainer created by etching CASTMESH FPD - nylon mesh is placed on the tissue surface of

the retainer wax pattern to create the microporosities

- doesn’t require acid etching VIRGINIA BRIDGE - utilizes lost salt technique to create voids in

the cast metal retainer - this provides mechanical retention

TELESCOPIC RETAINERS These are used when path of

insertion of the fixed partial denture does not coincide with the long axis of the abutment tooth

Indicated in tilted abutment The design involves the fabrication of

two copings Primary coping Secondary coping

Primary coping- functions to modify the morphology

of the tooth helps to change the path of insertion Secondary coping- designed to fit over the primary

coping along the new path of insertion

thus accurate parallelism of the

copings is necessary

ALL METAL RETAINERS-

Either can be partial or full veneer crowns

Strong enough even in thin sections

Advantages – - strength - high retentive qualities Disadvantages- - large amount of tooth reduction - adverse effects on tissues - vitality test not readily feasible - anesthetic – display of metal

PREPARATION- reduction- - non centric cusp – 1mm - centric cusp – 1.5mm margin- - chamfer – allows 0.5mm thickness

METAL CERAMIC RETAINERS-

They require more tooth reduction Can be fabricated over full veneer

crown or partial veneer crown

Advantages – - superior esthetics as compared

to complete cast crowns Disadvantages- - removal of substantial tooth

structure - subject to fracture - shade selection is difficult

PREPARATION- Incisal reduction – - 2mm Occlusal reduction – - 1.5 – 2mm - 1.5mm – for metal coverage - 2mm – for metal with ceramic veneer Margins- - facial surface- shoulder - lingual surface- chamfer Shoulder must extend at least 1mm

lingual to proximal contact area.

ALL CERAMIC RETAINERS- May be fabricated as full or partial

veneer crown Require maximum tooth reduction Porcelain requires sufficient bulk for

adequate strength

Advantages- - esthetically unsurpassed - good tissue response even with

subgingival margins Disadvantages- - reduced strength - least conservative - brittle –tend to fracture

PREPARATION- Incisal reduction- - 1.5 – 2mm clearance -this enables cosmetically pleasing

restoration -provides adequate strength Facial reduction- -1mm clearance Lingual reduction- -1mm clearance Margin- -shoulder preparation – 90 degree angle

ALL ACRYLIC RETAINERS-

Used for long term temporary fixed partial dentures

Not indicated for permanent restorations

OCCLUSAL ELEMENTS- Proper occlusal anatomy Definite cusp, ridges, grooves. The lingual surfaces of anterior teeth

have a definite concave surface. Incisal edge of anterior teeth are

rounded

DISTRIBUTION OF OCCLUSAL LOADS- Stress of occlusion in unworn teeth fall

very near the long axis. On worn teeth stress are spread over

wide and more dangerous area.

Unworn teeth Worn teeth

Forces directed along the long axis of the tooth.

Oblique forces.Causes destruction of the periodontium

CRITERIA OF SELECTING TYPE OF RETAINER- Abutment teeth are aligned parallel to

one another – full veneer crown can be given

Partial veneer crown are preferred for non carious abutments or abutments with large restorations but intact facial or buccal surfaces.

Endodontically treated tooth may have to be restored with core post before designing the retainer

APPEARANCE- Full veneer crown show superior

esthetics to partial veneer crown Anterior restoration – all ceramics Best to retain facial or buccal

surfaces of natural teeth as they provide best esthetics

In case with inadequate pontic space full coverage restoration can be designed for better appearance

Thank you