1. Fixed Prosthodontics Chapter 50 1
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2. Chapter 50 Lesson 50.1
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3. Learning Objectives Pronounce, define, and spell the Key Terms.
List indications and contraindications for a fixed prosthesis.
Identify the steps for a diagnostic workup.
Describe the differences among full crowns, inlays, onlays, and veneer crowns.
Describe the uses of porcelain for fixed prosthodontics.
Identify the components of a fixed bridge.
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4. Introduction
Fixed prosthodontics is the specialized area of dentistry devoted to the replacement of missing teeth with cast prostheses that are permanently cemented in place.
A prosthodontist is a dentist with an additional 3 years of specialized training.
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5. Indications for Fixed Prosthodontics
One or two adjacent teeth are missing in the same arch.
The supportive tissues are healthy.
Suitable abutment teeth are present.
The patient is in good health and wants the prosthesis placed.
The patient has the skills and motivation to maintain good oral hygiene.
Fixed prosthodontics is also known as “crown and bridge.”
Fixed prosthetics require good home care by the patient.
The supportive tissues must be healthy, because they will be supporting the bridge.
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6. Contraindications for Fixed Prosthodontics
The supportive tissues are diseased or missing.
Suitable abutment teeth are not present.
The patient is in poor health.
The patient is not motivated to have the prosthesis placed.
The patient has poor oral hygiene habits.
The patient cannot afford the treatment.
Would a patient with severe periodontal disease be good candidates for fixed prostheses? Why or why not?
If suitable abutment teeth are not present, what is another option for the patient? (Removable prosthesis or implants.)
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7. Types of Cast Restorations
Inlay
Covers a portion of the occlusal and proximal surface
Onlay
Covers proximal surfaces and most or all of the occlusal surface
Porcelain veneers
Thin shell-like covering placed to improve the appearance of anterior teeth.
(Cont’d)
Cast restorations are also known as indirect restorations.
They are fabricated outside the patient’s mouth, in a dental laboratory.
Where is the proximal surface?
Why can’t veneers be placed on posterior teeth?
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8. Fig. 50-1 Inlay cast restoration.
An inlay involves the proximal surface and only a portion of the occlusal surface.
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9. Fig. 50-2 Onlay cast restoration.
An onlay involves the proximal surface and most or all of the occlusal surface.
Cusp tips are involved.
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10. Fig A and B Porcelain veneers placed to cover hypocalcification defects. (From Roberson T, et al: Sturdevant’s art and science of operative dentistry, ed 4, St Louis, 2002, Mosby.) A B
Veneers are placed to cover defects such as hypocalcification and intrinsic stains.
What is an intrinsic stain? (A stain that comes from the inside.)
An opaquer may be used to block out any underlying color or structural defects.
The cement used for veneers may also be shaded to enhance the color match.
What is the best lighting for shade selection?
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11. Types of Cast Restorations
(Cont’d)
Full crown
Completely covers the anatomic crown of an individual tooth
Three-quarter crown
Covers the anatomic crown of a tooth except for the facial portion
Porcelain Fused to Metal (PFM) crown
Full metal crown with outer surfaces covered with a veneer of porcelain.
Full crowns are used when a tooth has decay so severe that reconstruction cannot be performed with the use of a direct restoration.
The facial surface is not involved in the preparation of three-quarter crowns; this technique is not commonly used.
With a PFM, porcelain is added for aesthetic reasons and matched to natural teeth.
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12. Fig. 50-8 Anterior PFM crown.
Which anterior tooth might this be? (Canine.)
The metal “ring” is healthier for the gum tissue because it is not as “bulky” as the porcelain fused to metal.
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13. Types of Cast Restorations
(Cont’d)
Porcelain jacket crown
Constructed as a thin metal shell covered by layers of porcelain
Fixed bridge
A prosthesis for missing teeth within the same arch
Resin-bonded bridge
Also known as a Maryland bridge, with winglike extensions coming from the proximal sides
A porcelain jacket crown is a very thin metal shell covered by layers of porcelain to resemble the shading and translucence of the enamel of a natural tooth.
A fixed bridge contains a series of two or more units and is cemented permanently in place.
Winglike extensions of the resin-bonded bridge are bonded onto the lingual surfaces of the teeth adjacent to the missing tooth.
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14. Fig. 50-9 PFM anterior fixed bridge.
How many units are involved in this bridge?
What are the components of the bridge? (Two pontics, two abutments.)
Which teeth are being replaced?
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15. Fig. 50-11 Resin-bonded bridge.
This is an example of a Maryland bridge.
Wings are bonded onto the lingual surfaces of the adjacent teeth.
Would a Maryland bridge be placed on the posterior teeth? Why or why not?
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16. Chapter 50 Lesson 50.2
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17. Learning Objectives
Describe the preparation and placement of a cast crown.
Discuss the uses of core buildups, pins, and posts in crown retention.
Describe the use of retraction cord before a final impression is taken.
Demonstrate the placement and removal of gingival retraction cord.
(Cont’d)
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18. Learning Objectives
(Cont’d)
Describe the function of provisional coverage for a crown or fixed bridge.
Assist in the preparation procedure of an indirect restoration.
Assist in the cementation procedure of an indirect restoration.
Identify home-care instructions for a patient with a permanent fixed prosthesis.
Identify the role of the laboratory technician.
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19. Overview of a Fixed Prosthodontic Procedure
Shade selection
A shade guide contains samples of all available shades used to match the natural tooth color.
Moisture helps achieve a more accurate match.
Use natural sunlight.
Record the shade on the patient record and on the laboratory prescription.
(Cont’d)
Shade selection should be performed before anesthetic is administered.
Unfortunately, there are times when the initial shade selection does not match at the final appointment. Reselection of a shade must be done.
Some dental labs have the patient come to the lab for a custom shade.
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20. Overview of a Fixed Prosthodontic Procedure
(Cont’d)
Tooth preparation
The tooth is prepared for the cast restoration to slide into place and to be able to withstand the forces of occlusion.
Rotary instruments are used to reduce the height and contour of the tooth.
Hand-cutting and rotary instruments are used to prepare the gingival margins.
The gingival margins are designed to provide a smooth junction of the edge of the restoration to the tooth.
What is a bevel?
What is a chamfer?
What is a shoulder?
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21. Overview of a Fixed Prosthodontic Procedure
(Cont’d)
Retention aids
These provide additional support for the crown if the tooth is extensively decayed or fractured or has been endodontically treated.
Core buildup
Pin retention
Post-and-core
Pins are placed before the core buildup.
Post-and-core can only be used on teeth that have been endodontically treated.
A cast post is made from an acrylic pattern and fabricated by a dental lab technician.
Not all teeth require pin retention for a core buildup.
What material is used for a core buildup?
What is a prefabricated post made of? (Titanium and titanium alloys.)
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22. Overview of a Fixed Prosthodontic Procedure
(Cont’d)
Gingival retraction and tissue management
The cord temporarily displaces the gingival tissue and widens the gingival sulcus so that impression material can flow around all parts of the preparation.
Nonimpregnated
Impregnated
Gingival retraction cords come in a variety of sizes (thicknesses). They are available twisted, untwisted, and braided.
Impregnated cords contain a vasoconstrictor.
What is a vasoconstrictor?
What medical conditions would contraindicate the use of impregnated retraction cord?
A hemostatic solution is used to control bleeding.
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23. Procedure 50-1 Position the cord around the tooth preparation.
Retraction cord is positioned around the prepared tooth.
Transfer is performed with the use of cotton pliers.
Packing is easier when the tissues are dry.
Typically, hemostatic solution is placed after the cord has been successfully packed, but sometimes bleeding needs to be controlled before placement of the cord or as the cord is being placed.
Some cords come presoaked in a hemostatic agent.
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24. Overview of a Fixed Prosthodontic Procedure
(Cont’d)
Final impression
Elastomeric impression materials are used to create an extremely accurate impression.
Light-bodied material is mixed and applied around the prepared tooth.
Heavy-bodied material is mixed and loaded into a tray to be seated on the quadrant or arch.
The final impression must be accurate to prevent the dental laboratory technicians from fabricating the restoration according to an inaccurate impression (which will require additional appointments for the patient).
Always ask the dentist which type of elastomeric material will be used for the final impression. Dentists usually use one to three types of material (one or two for crown and bridge impressions and one for denture impressions).
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25. Overview of a Fixed Prosthodontic Procedure
(Cont’d)
Bite registration
Provides the laboratory technician with a reproduction of a patient’s bite and opposing arch registration for designing the anatomic structures of the fixed prosthetic
Open bite
Closed bite
Why is it necessary to obtain a bite registration? (To show the dental laboratory technicians the relationship between the arches.)
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26. Overview of a Fixed Prosthodontic Procedure
(Cont’d)
Provisional coverage
Used for patient comfort from tooth preparation to final cementation of the fixed prosthetic
Reduces sensitivity and discomfort
Maintains function and aesthetics
Protects the margins
Prevents shifting
The temporary is made to last long enough for the dental laboratory technicians to fabricate the permanent restoration.
Good contact and occlusion are important in the fabrication of a provisional restoration.
What might happen if the provisional temporary does not have good contact with the adjacent teeth? (Drifting.)
What are the postoperative instructions for care of the provisional temporary?
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27. Delivery
When the casting has been fitted and is acceptable, the dentist cements the casting.
Permanent cementation
Temporary cementation
The shade should be checked before cementation.
The cement is placed on the inside of the restoration and transferred to the dentist for placement.
What types of cement are used?
Why would the restoration be cemented temporarily?
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28. Home-Care Instructions for the Patient with a Fixed Prosthesis
Good home care is essential to the maintenance of a fixed prosthesis.
A fixed prosthesis and its supporting tissues must be brushed carefully every day.
A bridge threader is used to thread dental floss under the pontic and into the sulcus at both abutments of a bridge.
Fixed prosthetics must be taken care of just as normal teeth are.
If symptoms do not subside, the patient should be instructed to contact the office immediately.
Is it normal for a patient to experience slight temperature sensitivity after the crown has been placed?
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29. Laboratory Prescription
The laboratory prescription is a detailed and precise written order from the dentist to the laboratory technician bearing the description of the restoration to be fabricated.
Lab slips may be filled out by the dental assistant.
Always have the dentist check the slip before sending it out to the dental laboratory.
The slip should be filled out completely.
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