prosthodontics session 2

Question 1

addition reaction silicone elastomer (VPS or PVS)

Answer 1

1) highly accurate, used as impression material in dentistry
2) manufactured as two liquids

Question 2

PVS reaction

Answer 2

1) P’CH = CH2 + R3Si H => R’CH2 - CHSi R3

Question 3

tray should?

Answer 3

1) remain in place under load
2) not be too tight

Question 4

border molding

Answer 4

1) extends the impression tray to the functional limits of the vestibule
- this is what a vestibule looks like when smiling, talking, eating

Question 5

silicone spray applied directly to the typodont

Answer 5

1) paint PVS adhesive on tray borders
2) and allow it to dry
3) inject impression material onto all tray borders
4) inject material directly into typodont vestibules

Question 6

seat the tray

Answer 6

1) drill single vent hole in anterior palate (2-3 mm)
2) inject monolayer of medium wash into tray, and brush some onto the typodont
3) you will see some show throughs
4) work quickly less than 2 mins
- final impression thickness should be <3mm
5) small voids should be ok <10mm
- redo if >10 mm
- you can also use wax to fill small voids

Question 7

polysulfide imrpession material

Answer 7

1) polysulfide polymer (mercaptan: active group is - SH), filler, plasticizer
2) catalyst: lead dioxide, filler, plasticizer
- 4-5 min working time
- mix equal lengths
3) HAVE to pour only once within a few hours
4) smells like rotton eggs

Question 8

prosthetic final impression criteria

Answer 8

1) clear details
2) read it yourself

Question 9

making model

Answer 9

1) note sticky wax place circumferentially around the impression (3mm from periphery)
2) then put rope wax around the impression and sear it
3) then you can see the edges of your impression free to be captured by the stone
4) make box wax and seal that
- must measure 10 mm above the tongue block out

Question 10

lower impression are complicated by tongue space

Answer 10

1) fill it with VPS before removing impression

Question 11

pour model

Answer 11

1) separate in one hour from the impression
2) >10mm, land area 3 mm wide, vestibules 3 mm deep

Question 12

seal on upper dentures

Answer 12

1) posterior palatal seal
- look for clinical junction between moving and non moving tissue
2) hamular notch, fovea (or make a mark where the mirror depresses, or ask them to go AAAA, or hold their nose and swell up their nose with air)

Question 13

develop post dam

Answer 13

1) modify it so there is some retention and engagement into the soft palate

Question 14

vibrating line

Answer 14

1) RIGHT at the end of the attached tissue
2) should not move if they go AAAA