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Fixed Prosthodontics

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Fixed Prosthodontics

• Specialty that deals with replacement of missing teeth or parts of teeth with extensive restorations

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Purpose

• Restores masticatory function

• Improves aesthetics and often self-esteem

• Improves speech

• Promotes good oral hygiene

• Prevents further movement of teeth because of support of prostheses

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Advantages of a Fixed Prosthesis

• Aesthetic

• Secure in mouth

• Restores function for many years

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Patient Considerations

• Complete medical and dental history

• Examination of the intra- and extraoral tissues

• Radiographs

• Impressions for study models (diagnostic casts)

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Patient Considerations

• Intraoral photographs taken with intraoral camera

• Extraoral photographs

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Candidates for Fixed Prostheses

• Must have motivation to maintain prostheses

• Must have healthy supportive tissues

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Case Presentation

• Provide treatment choices to patient

• Review costs and insurance coverage

• Discuss number of appointments required

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Types of Fixed Prostheses

• Indirect restoration

– Fabricated in dental laboratory

– Examples include:• Crowns and bridges• Veneers• Inlays and onlays

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Types of Fixed Prostheses

• Direct restoration

– Restoration placed directly on tooth at appointment

– Examples include• Direct resin veneers

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Indirect Restorations

• Impressions taken and sent to lab

• Temporary restoration is fabricated and placed

• Fixed prostheses fabricated in lab

• Restoration cemented in mouth at second appointment

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Crowns

• Anatomically shaped and fitted to tooth

• Covers teeth with extensive decay or breakdown

• Placed when there is no longer enough tooth structure to retain a filling

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Types of Fixed Crowns

• Full-cast crown– Covers entire coronal surface of tooth

• Partial crown– Cast restoration that covers three or more

surfaces of a tooth– Facial surface is left intact

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Porcelain Fused to Metal (PFM)

Full porcelain crownPorcelain fused to

metal crown

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Three-Quarter Gold Crown

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Inlays and Onlays: Cast Restorations

• Inlays– Restoration placed within tooth – Covers area between cusps in middle of

tooth and proximal surfaces involved

• Onlays– Include cusp ridges of tooth

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Inlays and Onlays

Gold onlay restoration on mandibular first molar

Gold inlay restoration

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Bridges

• Restoration that spans the space of one or more missing teeth

• Requires coverage of one or more adjacent teeth

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Components of a Bridge

• Abutments– Teeth on either side of a missing tooth that

provide support to which the fabricated tooth (pontic) can attach

• Pontic– Portion of bridge that replaces missing

tooth

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Bridges and Abutments

(A) Three unit bridge abutments, points, and retainers

Missing tooth

Tissue

Abutments (prepared teeth)

Fixed bridge

Retainers

Pontic

Porcelain-fused-to-metal bridge

(A)

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Bridges and Abutments

(B) Maryland bridge

(B)

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Veneers

• Types – Direct resin veneers– Indirect resin veneers– Porcelain veneers

• Advantages– Natural in appearance– Requires minimal tooth reduction

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Types of Materials Used for Fixed Prosthetics

• Alginate impression material• Bite registration materials• Retraction cord• Final impression material• Temporary cement• Bonding agent• Permanent cement

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Types of Materials Used for Fixed Prostheses

• Gold casting alloys– Gold used in crowns, inlays, and onlays is

not pure gold • Combination of metals known as an alloy• Platinum, palladium, tin, and iron

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Tooth-Colored Cast Restorations

• Porcelain– Used for inlays and bonded veneers– Porcelain fused to metal crowns and

bridges– Porcelain crowns

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Tooth-Colored Cast Restorations

• Composite resin– Used for inlays, onlays, and veneers– Stronger than direct composite restorations– Bonded in place

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Cad/Cam Restorative Systems

• Becoming more common

• Allows metal-free, tooth-colored restorations to be fabricated in one appointment

• Inlays, onlays, crowns, and veneers

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Cad/Cam Restorative Systems• No unpleasant impressions

• No need for temporaries

• Less reduction of healthy tooth structure

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CEREC (Chairside Economical Restorations of Aesthetic Ceramics)

• Switzerland — 1980

• Several factors to consider – Time investment to train staff – Large financial investment– Computer familiarity

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Basic Steps of CEREC Restoration

• Patient is seated and anesthetized

• Ceramic shade is selected

• Ceramic tooth prepared

• Prep coated with reflective powder

• Camera prepared optical impression

• Restoration designed from CEREC data

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Basic Steps of CEREC Restoration

• Milling machine mills restoration

• Restoration tried in position and adjusted

• Restoration bonded in place

• Polishing

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Role of the Laboratory Technician

• Fabricates custom trays

• Pours impressions

• Articulates models (casts)

• Prepares wax patterns

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Role of the Laboratory Technician

• Invests and casts gold alloy restorations

• Prepares porcelain and PFM crowns

• Fabricates prosthesis according to dentist’s request

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Role of the Dental Assistant• Provide patient education

• Prepare treatment room

• Take preoperative X-ray

• Make preliminary impressions and bite registration

• Select shade

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Role of the Dental Assistant

• Assist at chairside

• Place and remove temporary crowns

• Remove cement

• Pour impressions

• Fabricate custom trays

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Fabrication of the Prosthesis in the Dental Laboratory• Pouring alginate impression of the

opposing arch in plaster

• Pouring final impression to make a master mold and die

• Creating a wax pattern on the die

• Investing and preparing wax pattern for casting

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Fabrication of the Prosthesis in the Dental Laboratory• Casting the die once invested material

and metal are heated

• Casting the crown in gold alloy

• Painting porcelain on the crown and curing

• Finishing and polishing

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Crown Preparation Appointment

• Administer anesthetic

• Make preliminary impressions and bite registration

• Remove decay

• Using a diamond bur, reduce tooth structure

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Crown Preparation Appointment

• Place retraction cord

• Take master impression

• Fabricate temporary crown

• Reschedule patient for delivery of crown

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Crown Preparation Tray

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Shade Selection

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Materials Used to Take the Bite Registration

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Types of Preparations

• Examples of cavity margin on preparation-chamfer, shoulder, and shoulder with beveled edge

• Pins placed in a prepared tooth for support and retention

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Types of Preparations

Chamfer preparation

Shoulder preparation

Beveled shoulder preparation

Preparation at gingiva margin

Crown

Prepared tooth

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Gingival Retraction Techniques

• Placing retraction cord around the prepared tooth

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Master Impression

• Dental assistant receives syringe with light-bodied impression material and transfers tray with medium- to heavy-bodied impression material to dentist

• Final impression

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Master Impression

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Try-in Appointment

• Remove temporary crown

• Remove excess cement

• Try-in crown

• Adjust contacts and occlusion if needed

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Try-in Appointment

• Line inside of crown with cement

• Place crown on tooth and have patient close on bite stick

• Remove excess cement from margins

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Retention Techniques• Required when there has been

extensive tooth loss due to the following:– Decay– Fractures– Broken tooth structure

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Retention Techniques

• Core buildups– Provide retention for crown– Performed on vital teeth

• Retention pins– Used to enhance core buildup– Available in kits with various sizes and

tools

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Pin Placement

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Core Post Placement• A core post in place in a nonvital tooth

Crown

Core buildup

Apical seal of root canal

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Tooth with Core Post, Core Buildup, and Pins

Core buildup

Core post

Crown

Pins

Natural tooth structure

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Vital Tooth

• Pins inserted into enamel

• Buildup material then surrounds pins

• Examples of materials used:– Amalgam– Composite – Silver alloy/glass ionomer

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Nonvital Tooth

• Portion of gutta percha is removed for coronal pulp region

• Post cemented into canal

• Core buildup material placed around post

• Buildup prepped for crown

• Master impressions are taken

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Implant Retainer Prosthesis

• Can be placed after six months

• Attach to post or screw

• May be a crown or part of a bridge

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Maintenance of Fixed Prosthodontics

• Part of patient’s daily routine

• Aids can be used to clean bridgework

• Should be removed routinely and thoroughly cleaned

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Advanced Chairside Functions

• Gingival retraction– Ensures an impression with clear margins– Retracts tissue horizontally to allow room

for impression material– Displaces tissue vertically to completely

expose margin

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Types of Gingival Retraction

• Mechanical – Placed in sulcus of healthy gingiva– No drugs or chemicals used– Left in place for 10-15 minutes

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Types of Gingival Retraction

• Retraction Systems– Silicone placed to displace tissue– Prevents bleeding and creepage

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Types of Gingival Retraction

• Chemical retraction – Impregnated cord is used– Topical solution is used– Know the contraindications

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Types of Gingival Retraction

• Surgical retraction– Dentist removes tissue with surgical knife– Electrosurgery unit may also be used