enamic

Question 1

what is enamic
% what by volume?
what is it not

Answer 1

INTERCONNECTED NETWORK

• CERAMIC 75%
• POLYMER 25%(BY VOLUME)
• interconnected network of polymer and ceramic

NOT a composite resin
NOT a conventional ceramic

Question 2

think of what when see inter-connected network?

Answer 2

ENAMIC

- this will be a test question

Question 3

occlusal reduction needed for enamic

Answer 3

1

70 - translucency

inlay/onlay / crown / implant restoration

Question 4

*penetrating phase materials like enamic will resist crack propagation due to?

Answer 4

THE INTERCONNECTED CERAMIC AND POLYMER PHASES

Question 5

occlusal reduction needed for e. max

Answer 5

1.5

Question 6

downfall to zirconia

Answer 6

easy to make so might not all be as good

Question 7

implication of temperature on structure for zirconia

Answer 7

different phases / crystal structure at different temperatures

Monolithic - largest at room temp.

Tetragonal - intermediate at 1170 degrees celcius

Cubic - smallest at 2370 degrees celcius

Question 8

*pure zirconia with no added stabilizers is useful in?

Answer 8

for paint pigments and polishing materials

not really good at pure – sand at pure

Question 9

zirconium? vs zirconia?

Answer 9

zirconia is the oxidized version of zirconium (zirconium is metal and now it is not)

Question 10

when is zironia partially stable at room temp? what form? how?

Answer 10

adding yttris by 3-5%

• tetragonal –PARTIALLY STABLE AT ROOM TEMP

Question 11

when is zirconia fully stable?

Answer 11

cubic zirconia

Question 12

describe transformation toughening with zirconia

Answer 12

basically though stress application
- go from tetragonal (yttria partially stable zirconia )– to monolithic

3% volume increase

Question 13

warping is a result of?

Answer 13

non-uniform density in the zirconia blocks

Question 14

Zirconia FDA standard?

USA ADA?

Answer 14

only FDA 510 K

usa ADA - #131 - machinable zirconia blanks

Question 15

zirconia must meet which standards?

Answer 15

1. density is equal throughout
2. shrinkage factor can be accurately measured
3. furnace – sintering schedule

Question 16

implication of sintering too long

Answer 16

more translucent – BUT BIG crystals – cubic crystals and becomes weaker

Question 17

• highly stabilized zirconia resists crack propagation by which type of crystal transformation?

Answer 17

tetragonal –> monolithic

intermediate size to larger size

Question 18

how to make zirocnia more translucent

Answer 18

add yttria – more cubic

3- 5 %
3% is original

Question 19

effects of surface treatments on strenth of various zirconia?

Answer 19

the more sand blasted / treated the surface – got higher failure rate (especially in the higher translucent ones)

Question 20

as translucency increases what happens to crystal size?

Answer 20

also increases

• so less resistant
• yttria increases

Question 21

implication of yttria increasing?

Answer 21

weakening

Question 22

occlusal reduction needed gfor zirconia?

high translucency zirconia? ultra translucency zirconia?

Answer 22

normal - .8

high - ,8

ultra - 1.0

Question 23

concerns with monlithic full contour zirconia

Answer 23

1. enamel wear
2. occlusal adjustment
   - weaken zirconia
3. zirconia degredation

Question 24

after 1 year started seeing degradation why?

Answer 24

because the glaze was wearing off

- but if you POLISH it before glaze - this can be avoided more

Question 25

elevation in the surface due to?

Answer 25

transformed surface under stress from tetragonal to monoclinic -- because monclinic due to its structure being higher

Question 26

why should ALL restorations be polished?

Answer 26

because stains and glaze wear off over time

Question 27

glaze applied to ceramics tends to last?

Answer 27

about 3 years

Question 28

what to do with full contour zirconia before insert? with lab? what if chairside?

Answer 28

lab - polish the zirconia and then apply the glaze if chairside - check restoration and opposing dentition annually grind into zirconia -- ideally polish and re-glaze grind into the zirconia intra-orally -- with ZR wheels, paste, water spraay, LOW SPEED

Question 29

Does zirconia have low thermal conduction? implication?

Answer 29

YES -- could lead to fracture

Question 30

why do ceramic resotrations fail?

Answer 30

INDEQUATE PREPARATION - too thin - not enough load bearing capacity then SHARP ANGLES - concentrates stress fracture sites IMPROPER FABRIICATION - Not following directions - sub standard materials - excessive adjustment - incorrect polishing (surface was left ground with diamond burs) POOR BONDING TECHNIQUE MATERIAL SELECTION - inadequate properties for clinical - canine- molars - need more high stress