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Dental Materials - Lecture 2 - Metals, Alloys, Ceramics, etc
Dental Materials - Lecture 2 - Metals, Alloys, Ceramics, and Polymers
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10/20/2011

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Cards

Term
Overview of the stages in evidence based practice
Definition

Identify clinical problem -->

 

Produce a focused question -->

 

Search for evidence -->

 

Make sense of the evidence -->  (reject if poor)

 

Act on the findings -->

 

Evaluate the impact on practice

Term
List types of dental alloys and give composition
Definition

Noble

  • High noble
    • Noble metal content > 60 wt%
    • Gold > 40 wt%

  • Noble
    • Noble metal content > 25 wt%

Predominately Base

  • Noble metal content < 25 wt%

 

Term
List the 4 types of Dental Alloys and their Yield Strength and Elongation %
Definition

Type I:  Soft - low stress applications, inlays

  • YS < 140 MPa; elongation 35%

Type II:  Medium - moderate stress, inlays and onlays

  • YS 140-200 MPa; elongation 28/10%

Type III:  Hard - high stress, crowns, short-span FPD

  • YS 200-340 MPa; elongation 12%

Type IV:  Extra-hard - very high stress, long span FPD, RPD

  • YS > 340 MPa; elongation 10%

 

 

 

 

 

 

Term
FGC vs PFM Alloys
Definition

PFM alloys have:

  • Higher melting pt (1150-1200 C) than FGC alloys (950-1000 C)

  • Slightly higher elastic limit (450-1100 MPa) than FGC alloys (200-520 MPa)

  • Higher hardness (VHN=180-260) than FGC alloys (VHN=120-150)

PFM alloys are more difficult to cast

 

Term
List Some Base Metal Dental Alloys and their common uses.
Definition

Titanium and Titanium alloy (Ti or Ti-Al-V or Ti-Mo)

  • Crown and bridges and partials - cast
  • Orthodontic wires
  • Endodontic instruments
  • Implants

Stainless Steel (Fe-C-Cr-Ni)

  • Pre-formed crowns - wrought
  • Ortho wires and brackets
  • Endo instruments

Cobalt-Chromium (Co-Cr)

  • Partial denture framework - cast
  • Ortho archwires - wrought

Nickel-Chromium (Ni-Cr)

  • Partial denture framework - cast
  • PFM crowns and bridges - cast

 

 

 

Term
List some physical properties of Titanium
Definition
  • Low elongation - does not burnish
  • High yield strength - very strong
  • Higher elastic modulus - rigid - 2x that of gold
  • Specific gravity - light weight
  • High melting point ~1400C
  • High hardness:  resistant to scratches and polishing (30% harder than IV gold)
Term
Define ceramic
Definition
Any of various hard, brittle, heat- and corrosion resisitant materials made by shaping and then firing a nonmetalllic mineral, as clay, at a high temperature
Term
Define glass
Definition
Any of a large class of materials with highly variable mechanical and optical properties that solidfy from the molten state without crystallization, are generally transparent or translucent, and are regarded physically as supercooled liquids rather than true solids.
Term
define glass-ceramic
Definition
any of a variety of materials which are initially formed as glasses, and subsequently heat-treated to induce crystal formation and growth
Term
define porcelain
Definition
a hard, white, translucent ceramic made by firing a pure clay and then glazing with variously colored fusible materials.
Term

Metal-Ceramics:

Advantages vs Disadvantages

 

Definition

Advantages:

  • Max strength and predictability
  • FPD applications
  • Soldering possibilty
  • Established technique
  • Relatively low start-up cost

Disadvantages:

  • Excessive tooth reduction
  • High opacity
  • Diminished translucency
  • Waxing and casting required
  • Thermal compatibility essential

 

Term
List current metal ceramic systems and applications
Definition

Feldspathic Porcelains - metal ceramic/resin bonded

  1. Resin bonded inlays, onlays, and veneers

Slip cast- reinforced ceramic cores

  1. Inceram/Spinell- glass infiltrated
  2. Zirconium

Pressable ceramics- reinforced ceramic cores

  1. Empress/Empress 2- Leucite/Apatite glass
  2. OPC, Etc- Sintered

CAD/CAM

  1. Procera- pure alumina core
  2. Cerac, Cercon, Etc

 

 

 

Term
List uses for high, low and medium fusing porcelain.
Definition

High fusing porcelain

  • harder than enamel by 30%; high wear resistances;
  • Uses:  denture teeth, buccall aspects of bridges

Low fusing porcelain

  • Uses:  veneer for metal in PFM restorations

Medium fusing porcelain

  • Uses: for anterior procelain jacket crown

 

 

Term
All-ceramic restorations:  general indications
Definition

-Inlays/onlays

-Laminated veneers

-Full crowns (anterior and posterior ?)

-Anterior three-unit bridges ?

-Posterior three-unit bridges ??

 

Term

All-ceramic restorations:

Advantages

Definition

-excellent esthetics

-high hardness* (wear resistance)

-compatible with periodontal tissues

-thermal insulator

-high compressive strength

Term

All-ceramic restorations:

Disadvantages

Definition

-marginal adaptation is inferior to that obtained with cast metal restorations

 

-more tooth structure removed than PFM

 

-May cause wear to antagonist enamel (esp high firing porcelain)

 

-Low fracture resistance*

Term
define anisotropic
Definition
Term

(1)  "dental composite" has what particulate in polymer resin matrix?

 

(2)  List the things that direct performance or behavior of composite/layered structures

Definition

(1) 

ceramic

 

(2) 

-The constituents selected

-How much of each material (Vol. %)

-The materials' interface

-The materials' design (position, orientation, etc) 

 

Term

(1)  List the types of Post and core materials used

 

(2) what does the clinical studies say about the different materials for post and core?

 

(3) which materials does Dr Dyer recommend for p&c?

Definition

(1) Metal, ceramic, composite

 

(2)  No difference between traditional CPC, cast to post, cast prefab, and pre-fab followed for up to 10 years.

 

(3)  Metal - Ceramometal,

Composite - Metal (CoCr, Ti) prefab with particulate reinforced composite (PRC)

Term

(1)  List the materials available for fixed pros build-ups?

 

(2)  Evaluation of "best evidence"

 

(3)  Recommended materials

Definition

(1) 

Particulate reinforced composite (PRC)

-metal/polymer (Glass Ionomer)

-ceramic/polymer (Dimethacrylate)

Fiber-reinforced composite (FRC)

Metal matrix comp. - amalgam

 

(2)  GI composites < Dimethacrylate composites

 

(3) 

Particulate reinforced composite (PRC)

-ceramic/polymer (Dimethacrylate)

Metal matrix comp. - amalgam

Term

(1)  Clinical success rate of ceramic inlays (CEREC) at 4yrs

 

(2)  Indirect PRC inlays/onlays success rate at 4-6yrs

 

(3)  Average lifetime for Gold

 

(4)  Average lifetime for Amalgam

 

(5)  Average lifetime for PRC

Definition

(1)  97.4%

 

(2)  95%

 

(3)  20yrs

 

(4)  12-14yrs

 

(5)  7-8yrs

Term

Extracoronal restoration:

(1)  success rate of veneers

 

(2)  Success rate of ceramic crowns

 

(3)  Gold vs ceramic onlays

 

(4)  Recommendations

Definition

(1)  at 3 yrs, 92% success porcelain veneers, 74% acrylic

 

(2) (Procera, Empress) 90% success 7-10yrs (mostly anterior prostheses)

 

(3)  Gold onlay not statistically different than ceramic onlay at 7 yrs.

 

(4)  Metal - Type III Gold, Composite - PFM

Term

FPD:  Evaluation of best evidence.

 

(1)  Meta Analysis

 

(2)  Clinical Studies

 

(3)  Recommendations

Definition

(1)  66-75% success at 15 yrs (Gold and PFM)

 

(2)  InCeram Alumina 83% success at 10yrs

 

(3)  Metal - Type III Gold, Composite - PFM

Term

Provisional Prostheses:  Evaluation of best evidence.

 

(1)  Clinical Studies

 

(2)  Recommendations

Definition

(1) 

-Dimethacrylate based composites and PMMA similar in clinical performance.

-FRC > PRC in Provisional restorations

 

(2) 

-Polymer - PMMA

-Composite - PRC