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Biomaterials > All Ceramic > Flashcards

All Ceramic Flashcards

1
Q

main reasons to use all ceramics

A
  1. esthetics
    - translucent
  2. color stability
  3. material stability
  4. biocompatibility
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2
Q

biggest problem

A

brittle

- dont deform under stress all that much before they catastrophically fracture

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3
Q

isse with biocompatbility that is over come with all ceramics

A

mercury free and metal free

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4
Q

empress is an example of?

A

low strenght PRESSABLE

- and because of properties it is used more in the anterior

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5
Q

pressable ceramic examples

A 
empress
OPC
Cerpress
Finesse
Microstar 
Bitapress
Cergo 
Fortress
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6
Q

improve ceramics through?

A

MICROSTRUCTURE
- through increase in crystal content

  • Decreasing the size/ crystal size

network – interconnected materials

phase change – “tranformation toughening”

translucency - chemistry and crystal composition

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7
Q

empress aka?

flexural strenght and % crystals and dimension

A

leucite glass ceramic

45% crystal at 10-15 microns with 120 MPa flexural stregth

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8
Q

emax aka?

flexural strenght and % crystals and dimension

A

lithium disilicate

70% crystal at 2-7 microns with 380 MPa flexural strength

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9
Q

Celtra press vs emax and implicaiton

A

emax= lithium disilicate

celtra press = lithium silicate - reduced crystal size down to /5 microns so improved fracture resistance with 10% wt zirconia reinforced

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10
Q

*how are esthetics improved with all ceramics?

A

MORE TRANSLUCENT

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11
Q

CAD/ CAM stands for?

A

Computer Aided Design/ Computer Aided Machining

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12
Q

what is subtractive and what is additive in CAD/CAM components

A

subtractive –> milling

additive -> printing

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13
Q

components of CAD/CAM that can affect accuracy

A

scanner system

bur size

feed rate – milling speed

materials – need to be resistant to damage

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14
Q

bur size in milling machines?

A

smaller – more accurate

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15
Q

two types of chair side cameras

A
  1. cerec AC bluecam

2. CEREC omnicam

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16
Q

resolution

A

ability to distinguish between two points

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17
Q

shorter wavelength?

A

HIGHER RESOLUTION

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18
Q

wavelenght in bluecam

A

.4 microns - very small

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19
Q

T/F resolution increases as wavelength decreases?

A

TRUE

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20
Q

major differences between omni scan and blue scan

A

omni = no powder and color

  • VIDEO
  • more technique sensitive

blue cam - powder /no color

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21
Q

why use CAD/CAM

A

reliable and reproducible *

design 
- virtual 
FABRICATION
material
- NOVEL, GOOD CLINICAN RESULTS

FABRICATION TIME

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22
Q

implants are placed how? very general and number one rule

A

restoration driven

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23
Q

virtually integrated patient?

A

what we are trying to get to

  • incooporate a virtual facebow, etc
  • virtual articulator
  • basically all scans and movements into one
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24
Q

TI base restoration options

A
  1. screw retained full contour one piece

2. screw retained custom abutments with seperate bonded crown

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25
Q

crew retained custom abutments with separate bonded crown features

A

flexibility in material combinations / esthetics

  • compensation for mis-alignment
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26
Q

features of screw retained full contour

how many pieces?

A

one piece

  • less steps’
  • high load bearing capacity
  • cannot completely adjust for mis-aligned implants
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27
Q

monolithic material definition

A

formed or composed of material without joints or seams

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28
Q

monolithic material examples

A
  1. feldspathic porcelain
  2. glass ceramic
  3. composite resin
  4. full contour zirconia
  5. interpentratingi phase ceramic
  6. metals
29
Q

Q: according to Dr. Giordano the most famous monolith is

A

A: in 2001: a space odyssey

30
Q

two examples of poly-crystalline ceramics

A
  1. alumina

2. zirconia

31
Q

most dominant material used for CAD/CAM?

A

Zirconia (at 76%)

followed by lithium dislicate with 14%

32
Q

minimum requirement for four unit posterior with ceramic?

A

800 MPa

33
Q

minimum requirement for three unit in posterior with ceramics?

A

650/ 700 MPa

34
Q

anterior bridge strength requirement

A

450 MPa

35
Q

anterior cemented crowns or posterior cemented crowns strenght requirement

A

360 MPa?

36
Q

bonded anterior or posterior crowns strenght requirement

A

130 MPa

37
Q

human tooth MPa?

A

not significant but have great resistance to crack propagation

38
Q

T/F strength is static

A

NO – not static

39
Q

strength degradation through?

A

Stress
Fluids
Foods

cement breakdown

40
Q

*ceramic materials age in the mouth, mechanical properties usually?

A

DECREASE

- decrease over time

41
Q

what is the key to success in restorations?

A

adequate reduction / material thickness requirements maintained

42
Q

strenght measured in?

fracture resistance measured in?

A

strength – MPa

Fracture resistance – Newtons

43
Q

fracture resistance depends on

A

size and thickness

44
Q

ceramic vs concrete in reference to strength vs fracture resistance

A

ceramic – stronger (higher MPa) but concrete has higher load / fracture resistance

45
Q

processing implication

A

Processing is also a big factor in reliability/reproducibility in the materials that we’re using

LARGER DEFECTS IN FABRICATED (why CAD/CAM can be seen as an adbvantage)
- unavoidalble in fabricated / like hand built

46
Q

best polished cross section is seen in which processing?

A

BLOCK - due to the processing is better (vs. pressed or hand built)

47
Q

crystal re-inforced glass AKA

A

Dense porcelain blocks

48
Q

first successful monolithic?

A

Vita family

- MKII, Triluxe, real life, Feldspathic based

49
Q

Ivoclar Empres CAD based on?

A

Empress presable

  • 45% leucite crystal
  • improvements in microstructure
50
Q

first monolithic material

A

Vita MKII

-developed for Cerec I and used for over 30 years

51
Q

reduction you likely need for block materials

A

2mm

52
Q

describe VITA MKII

A

over 60 million restorations

  • feldspathic based
  • fine crystal reinforced (less than 10 microns)

clinical longevity as it resists intra-oral stresses and can be easily polished / glazed –> good finish

53
Q

flexural strenght of VITA MKII

A

130-160mpa

54
Q

challenge with blocks?

A

they are MONOCHROMATIC

  • need for enahnced esthetics
  • so solution would be multi-colored blocks
55
Q

gradual color change in a block would have what at top / enamel layer and what at bottom / cervical layer

A

top / enamel layer

  • low chroma
  • highest translucency

bottom / cervical layer

  • highest chroma
  • increased fluoresence

(middle/ body is regular chroma)

56
Q

featuers of Vita Triluxe forte?

A

four layers with gradual color change

57
Q

vita “real life” block aims to?

A

internal dentin and external enamel layer

- layered like a lab crown for improved esthetics

58
Q

minimum occlusal reduction for MKII empress? use?
translucency?
bonding?
type of material?

A
  1. 0 mm
    - use for inlay/ onlay/ crown

translucency is 70-80 and luted by bonding

feldspathic material

59
Q

how to form conventional glass ceramics

A

HEAT TREATMENT

- then crystals grow within the glass at the proper crystalizzation temperature

60
Q

temperature needed to go from metasilicate to disilicate

A

840 degrees celcius

must be held at this temperature long enoiugh to get crystallization

61
Q
  • class ceramic materials like emax require crystallization after machining ??
A

there might be over-crystallization if the temp is incorrect, tere migt be undercrystallization if the temperature is incorerect, the color might not be correct if the temperature is incorrect ALL OF THESE ARE TRUE!!!

62
Q

*color change that occurs when you heat treat the block? how?

A

blue/ purple –> to the tooth color

change in electronic status of some of the components - depending on the oxide you are using

63
Q

what happens if e.max crystallizatoin is not held at teperature for long enough?

A

needs to be held long enough at 840 degress celcius so you get crystallization

IF NOT YOU GET IMPROPER SHADE/ SOLUBLE

64
Q

use of emax

A

inlay, onlay,

65
Q

emax minimum occlusal reduction

A

1.0 - 1.5

66
Q

lithium SILICATE is pre-crystal? implication

A

yes – so it is a processing advnatage and does not need to be supported

67
Q

celtra-duo aka lithium silicate minimum thickness? translucency?
luting?

A

1.5

60 translucency

lute by bond

68
Q

emax minimum thickness? translucency?

luting?

A

1.0 but needs to be bonded

translucency - 60

69
Q

effect of glaze?

A

better mechanical properties

Biomaterials (16 decks)

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