Shade taking, impressions, wax up

Question 1

What are the problems with selecting a shade?

Answer 1

Your colour perception
Lighting conditions
Translucency of tooth

Question 2

What are the 3 steps for using a 3D shade guide?

Answer 2

Increase in value accross, increase in chroma going down

1. Determine value - work accross using only ‘m’ shades - these all have the same hue
2. Determine chroma - 3 levels, select the right chroma within the value group
3. Determine hue - look at the L & R adjacent to the chosen ‘m’ see if more yellow (L) or red (R)

Question 3

What does a diagnostic wax up allow planning and communication of?

Answer 3

Aesthetics 
Occlusion 
Tooth reduction
Restoration type 
Restoration design 
Treatment plan

Question 4

How are the wax-ups articulated?

Answer 4

Trim the model
Locate together in correct occlusal position
Articulate - simple hinge glue-on

Question 5

Why is building up wax expensive?

Answer 5

Skilled and time consuming

Question 6

What may you use a duplicate to produce?

Answer 6

Stent to allow direct build-ups to be carried out

Question 7

What are the different impression materials that can be used?

Answer 7

Silicones: addition or condensation cured

Also Polyethers, polysulphides and reversible hydrocolloids

Question 8

What are addition-cured silicones available in?

Answer 8

putty
Medium
Light
Ultra-light

Question 9

What are the problems with silicones?

Answer 9

Control of dimensional stability
Flow of material into surface detail
Control of material in the tray/mouth

Question 10

What are the properties of the different silicones dependent on?

Answer 10

The amount of filler

Question 11

What are the properties if have high filler content, what are the properties if have low filler content?

Answer 11

High filler content - food dimensional stability, easy to control, poor surface detail
Low filler content - poor dimensional stability, good surface detail

Question 12

What is the solution for using silicones?

Answer 12

Use 2 bulk materials: putty/heavy bodied material for bulk, wash/light bodies material for detail
Or use a custom tray to support medium-bodied material

Question 13

What is the twin-mix technique?

Answer 13

Putty in tray and light bodied around the teeth

Question 14

What is the 2-stage technique?

Answer 14

Putty impression remove from mouth
Cut away detail of teeth and large undercuts
Now fill in with light bodied material and re-seat impression

Question 15

What is the 2-stage technique with a spacer?

Answer 15

Take an impression using putty with a spacer
Once, set remove the impression and discard spacer
Remove any large undercuts with scalpel
Fill the space with the low viscosity material and re-seat the impression
Once set, remove the completed impression

Question 16

What does the monophase technique involve?

Answer 16

Stock or special trat

Question 17

What are the technical considerations with imps?

Answer 17

Air blows
Drag
Complete impression
Rigidity of material - problem for technichians - if in thin section then will not be able to flex enough to get out or if engages in undercut then will break when try to remove