frame work design for metal ceramics

Question 1

what are the goals of framework design

Answer 1

even thickness of porcelain
Proper porcelain-metal interface
Good connector design
Optimally placed occlusal contacts

Question 2

how can you get metal to bond to glass

Answer 2

glass adheres to clean, gas-free metal if covered with adherent oxide and temperature raised to where oxide is partially dissolves into the glass

Question 3

why would there be an adhesive failure at porcelain metal interface

Answer 3

OXide layer is missing

Question 4

why would there be an adhesive failure at metal oxide-metal interface

Answer 4

contaminated metal

Question 5

why would there be an adhesive failure at porcelain-metal oxide interface

Answer 5

Contaminated metal oxide

Question 6

how would there be a cohesive failure in porcelain

Answer 6

Maximum strength exceeded

Question 7

why would there be a cohesive failure in metal oxide

Answer 7

Excesive oxidation

Question 8

why would there be a cohesive failure in metal

Answer 8

Doesn’t happen

Question 9

what does framework design determine

Answer 9

Occlusal contact location

Question 10

where should the occlusal contact be

Answer 10

Opposing tooth should contact metal with 1.5mm from junction on excursive path

Question 11

where should centric stop be located

Answer 11

1.5mm from the metal ceramic junction

Question 12

why should the centric stop be located 1.5mm from the metal ceramic junction

Answer 12

Prevent porcelain fracture from deformation of the metal

Question 13

what should you do minimize wear if vertical overlap must be minimal

Answer 13

Ceramic against ceramic

Question 14

should metal be extended to the incisal edge

Answer 14

No

Question 15

why shouldn’t metal be extended to the incisal edge

Answer 15

metal flexure or burnishing in function will cause porcelain fracture

Question 16

what design should the connector have for framework design

Answer 16

Tresle design with it centric on porcelain

Question 17

how large should connects be

Answer 17

Greater than 2.5 x2.5mm

Question 18

what should posterior occlusion be in

Answer 18

MEtal or porcelain, but metal cusps should be in metal fossa

Question 19

what should the proximal contacts be in

Answer 19

Metal or in porcelain

Question 20

what is easier to add if deficient porcelain or metal

Answer 20

Porcelain easier to add if deficient/more esthetic on anterior

Question 21

what should the proximal contact be in for posterior areas

Answer 21

both in metal or in porcelain

Question 22

what should surround ear attachment for a parital

Answer 22

Surrounded by at least 1.0mm of metal to prevent flexure in function

Question 23

what are the mechanical properties of porcelain

Answer 23

Weak in tension and strong in compression

Question 24

how do you increase the compression bonding of the PFM

Answer 24

greater porcelain wrap around increases compression bonding and strength

Question 25

how should the porcelain metal junction look

Answer 25

A butt joint of 90 degrees or slightly greater

Question 26

where should sharp edges exist in the porcelain bearing surface

Answer 26

no sharp edges, all rounded in the internal and external areas of the porcelain bearing surface

Question 27

how thick should the coping be

Answer 27

.5mm thick, or thicker to support the porcelain

Question 28

what should the interproximal contact be made in

Answer 28

Metal or porcelain

Question 29

why should marginal ridges be supported

Answer 29

So as to not break under compression

Question 30

how large should you leave proximal ares

Answer 30

Enough for connectors or post soldering

Question 31

whats one of the first things you should do when making an FPD

Answer 31

full wax-up

Question 32

why should you do a full wax up

Answer 32

To create an incisal guide table to protect posteriors and do the lingual convity of the teeth

Question 33

where should the metal be for a pfm FPD

Answer 33

behind the contacts

Question 34

what material touches the tissue in the pontif

Answer 34

Porcelain

Question 35

how do you make the metal good to receive porcelain in a FPD

Answer 35

cook at high temp to create oxide layer

Question 36

what is the shit metal sometimes used for the coping

Answer 36

Ni-Cr

Question 37

what does too much porcelain on one side of the tooth lead to

Answer 37

Cohesive failure

Question 38

what in occlusion should you check before preping a tooth

Answer 38

The contact to know where to make room for contours

Question 39

what design creates strength

Answer 39

Tressel design