1. Materials for Inlays, Onlays, Crowns and Bridges
Chapter 7
DAE/DHE 203

2. Review: Inlay – indirect restoration; occlusal surface excluding cusps
Onlay – indirect restoration; occlusal surface plus cusp(s)

3. Review: Crown – usually covers the clinical crown of the natural tooth
Can create “¾ crowns”
Bridge – replaces missing tooth/teeth
Abutment vs. Pontic
Cantilever, Maryland

4. Review:
Cantilever Bridge
Maryland Bridge

5. Materials for Indirect Restorations:
Dental Ceramics – Porcelains
Composites
Metals

6. Uses for Dental Ceramics:
Crowns (Anterior – “jackets”)
Veneers
Fused to metal for crowns & bridges
Denture teeth
Inlays & Onlays
All-porcelain crowns & bridges (without metal substructure)

7. Characteristics of Ceramics:
High melting point
Low thermal & electrical conductivity
High compressive strength & stiffness
Low tensile strength
Brittle (low toughness – able to fracture)
Excellent esthetics
Great biocompatibility
I am starting with the end of the chapter first. We will discuss metals last and merge into the next section, which is about how metal restorations are fabricated. This section begins on page 158 of your text.

8. The Composition of Ceramics:
Metal oxide compounds
Building block of ceramics = silica
Silicon dioxide molecule (SiO2)
Can be amorphous or crystalline arrangement
Components mined from the earth
Porcelains are white & translucent ceramics

9. Composition of Dental Porcelains:
Three Main Components:
Feldspar – % (potassium-aluminum silicate)
Quartz – (silica)
Kaolin Clay – 3 –5 % (aluminum silicate)
Plus:
glass modifiers
leucite – strengthens & toughens; raises the coefficient of thermal expansion
pigments (metallic oxides) – color
fluorescing agents
Leucite has been added to give strength to porcelains in HIGH-stress areas.

10. Types of Porcelain: High-fusing: Fuses at 1300-1350° C
Used for denture teeth
Highest strength & stability
Medium-fusing:
Fuses at ° C
Used for all-ceramic restoratives
Low-fusing:
Fuses at ° C
Used for PFM restorations
1300 degrees Celcius is the same as about 2375 degrees Fahrenheit
Low-Fusing – this porcelain is created to fuse at a lower temperature to protect the metal substructure of the PFM – the higher temperatures will exceed the melting point of the alloys used in the PFM.

11. Properties of Porcelains:
Great hardness
Excellent wear resistance
Can rapidly abrade tooth enamel
Not ductile – very stiff (compressive & tensile strength)
Able to fracture; brittle
Often used to veneer metals (PFM)
Especially in stress-bearing areas (posterior)
Shrinkage occurs upon firing

12. Preparation of Porcelain:
Powders of quartz, feldspar, clay are blended
Powder mixed with Water
“Dentin” or Core Layer is painted onto die or metallic framework
Excess water removed from mixture thru brushing or vibration of die – packs particles
Placed in oven to “sinter” (heated below fusion point)
particles begin to coalesce (not melted)
water is removed
die is cooled

13. Preparation of Porcelain:
“Enamel” is painted onto porcelain core
Die is fired; cooled
Stains are painted onto outer surface
Final high-temperature firing – “glaze” finish
Cooled slowly
Metals used as substructure must have similar coefficients of thermal expansion as the porcelain to avoid in cracking porcelain

14. Preparation of Porcelain:

15. Porcelain-Fused-to-Metal:
Advantages:
Strong core
Supports porcelain
Best for high-stress areas
Easy “seating” – cementation
Less expensive than all-ceramic
Disadvantages:
Esthetics not Perfect
Not as translucent
Metallic margin
Ions may discolor porcelain
Porcelain may fracture from metal

16. All-Ceramic Restorations:
Superior esthetics
All-ceramics made of reinforced porcelains
Added glass, alumina, leucite, magnesia, or zirconia
Change in composition to allow for better resistance to cracking
Video

17. CAD-CAM system: Milled porcelain restorations
“CAD” – computer-aided design
“CAM” – computer-assisted machining
“CEREC” – by Sirona
Use porcelain blocks, milled in the office
One-appointment indirect restorations
Expensive start-up cost
Show Patterson catalog – page 149+ blocks of porcelain for milling

18. “CEREC®” System:

19. “CEREC” System:
Video

20. “Procera®” Lab uses computer stylus to measure die
Data is transferred to a lab where an aluminum oxide core is fabricated through milling
Core is sent back to lab for porcelain finish
No metal substructure
Video

21. “Procera”

22. “Cerpress®” Ceramic core made of “pressable” ceramic
Used in “lost wax” technique
Ceramic is heated and pressed into mold space
Porcelain is applied to core
Bonded to tooth with composite bonding adhesives

23. “Cerpress”

24. Composite Inlay Restorations:
Intended for very large Class I or II restorations
Applied directly or indirectly
Reduces concern of polymerization shrinkage and marginal leakage
Composite restoration fully cured outside of mouth
Similar to direct composite materials

25. Direct Composite Restoration:
The tooth is prepared
The prep-site is lined with a lubricant
The composite is placed and cured (but not etched, bonded!)
Remove the composite filling and finish cure
The restoration is cemented into prep at same appointment

26. Indirect Composite Restoration:
After tooth is prepped, an impression is taken
A provisional filling material is placed
The impression is sent to lab
Lab fabricates the restoration from composite material onto the die
The restoration is cured fully
The inlay is seated with composite cement at 2nd appointment

27. Other Indirect Composites:
Composite materials are also being used for crowns, bridges, veneers, and onlays
Fabricated in the lab
“Sinfony”, Targis/Vectris”, “belleGlass”
Allow for conservative prep designs
Have great esthetics
Use etch, bonding agent & resin cement

28. Uses for Metals: Full metallic crowns, bridges Inlays, onlays
Substructure for PFM’s
Substructure/framework for partial dentures
Temporary crowns (prefabricated)

29. Properties of Metals: Composed of metallic elements (80 pure metals)
High thermal & electrical conductivity
High ductility, opacity & luster
High strength, high melting points
Crystalline arrangement of atoms
Various types of metals can be created by “alloying” metals
Mixing 2 or more metals
Dental alloys must be resistant to corrosion

30. Forming Metal Objects:
Metal is relatively stable when in a solid state
To mold metal, it must be heated beyond its melting range
Except the use of mercury in dental amalgam!
When cooled, metal forms a crystalline solid
Casting – heating metal and pouring it into a mold where it solidifies into a specific shape
A “lost-wax technique” is used to create the mold space for the metal

31. ALLOYS: Alloys have advantages over pure metals alone:
Stronger
Harder
Easier to fabricate
Less expensive
Alloys are formed when metallic atoms are dissolved within the atoms and crystals of another metal

32. Dental Alloy Requirements:
Strong & hard enough to withstand occlusal forces
Biologically compatible
High resistance to corrosion & tarnish
Easy to cast
Not cost-prohibitive to use

33. Alloy Composition: Noble Metals – “Precious” Metals
Gold (Au) *
Platinum (Pt) *
Palladium (Pd) *
Iridium, Ruthenium, Niobium, Osmium
Resistant to corrosion and tarnish
Gold was the first metal successfully used
copper & silver added to enhance it

34. Gold Alloys: Gold is a soft metal Less gold in alloy improves strength
ADA-approved classes based on properties of alloy
Mixed with platinum, palladium, copper & silver
Gold alloys are expensive
ADA Classes – Type I & II = softer alloys; used for inlays; Type III = hard alloys; used for crown & bridge; Type IV = extra hard for partial denture frames
Since golds are expensive, alternative alloys have been used.
Golds give excellent thin, margins and some providers still prefer it for some restorations. In fact, a new PFM has emerged which fuses porcelain to gold for the strength of a metal core but with the better esthetics that a gold core can give over a base metal alloy – this is an expensive alternative that some dentists are choosing again – “Captek” (Show picture)

35. Porcelain-Fused-to-Metal Alloys:
Silver found to discolor porcelain
Palladium added to alloy eliminates discoloration and adds strength
Base Metal Alloys – most popular for PFM’s
Contain NO noble metals – “Non-Precious”
Corrosion prevention by surface oxide layer formed by Chromium content
Primary metal is Nickel
Allergen (10% women, 1% men)
Carcinogen?
Video
Base Metal Alloys are also known as “NON-Precious”