3. Numerous studies have compared
accuracy of polyvinyl siloxane
impressions made with custom tray and
stock trays.
Custom Tray Stock Tray
•PMM TRAY
•PVS PUTTY TRAY
•PHOTO CURE BISACRYL RESIN
PLASTIC
METAL
PMM trays should be fabricated 24 hours in
advance to insure stability.
Donovan TE, Chee WW. A review of contemporary
impression materials & techniques . Dent Clin North Am
2004;48:445-70.
4. Metal and rigid plastic stock
trays give greater accuracy in the
putty/wash silicone twin mix
impression technique compared
with flexible plastic ones for crown
and bridge work.
Those using the latter should be
aware of their shortcoming in this
respect.
Carrotte PV et al. The influence of the impression tray on
the accuracy of impressions for crown and bridge work--
an investigation and review. Br Dent J. 1998 Dec 12-
26;185(11-12):580-5.
5. Custom trays produced dies that
were more accurate overall when
compared with those produced by
stock trays.
Glenn E. Gordon et al. The effect of tray
selection on the accuracy of elastomeric
impression materials.
J PROSTHET DENT 1990;63:12-5.
6. Elastomeric impressions are most
accurate when used with a cross
sectional thickness of
approximately 2 mm. This
thickness is optimally provided
with a custom tray.
Eames WB, Sieweke JC, Wallace GW,
Rogers LB. Elastomeric impression
materials: effect
of bulk on accuracy. J Prosthet Dent
1979;41:304.
9. 2-step technique
First a preliminary pre-operative
putty impression is made
(to customize the tray)
Then subsequently it is "washed"
or “relined” with low viscosity
material after tooth preparation.
10. In terms of the 2-step putty-wash
impression technique, several
methods are described for control of
the bulk of the wash material,
which is essential for fabricating
accurate stone dies.
11. Base Plate Wax Spacer
Polyethylene Wax Spacer
Monzavi A, Siadat H. Use of wax spacers for putty-wash
impression of implant snapon impression copings. J
Prosthet Dent 2005;93:494.
12. Vacuum formed resin spacers
Wu AY, Donovan TE. The use of vacuum-formed resin
sheets as spacers for putty-wash impressions. J Prosthet
Dent 2007;97:54-5.
13. Relieved putty impression
Scalpel
Flame bur
Vented (2 holes to direct the wash)
Leendert Boksman. The Hydraulic & Hydrophobic
Impression Technique:Facts Based on the Research
Literature
14. With the 1-step procedure , low viscosity
impression material is injected around the
prepared tooth or teeth
then the putty impression material is
immediately placed intra orally and the
materials polymerize simultaneously.
Simultaneous / Squash Technique
Pameijer CH. A one-step putty-wash impression technique
utilizing vinyl polysiloxanes. Quintessence Int Dent Dig. 1983
Aug;14(8):861-3.
15. • Accuracy of impressions resulting from
the 1-step putty-wash technique is
controversial.
16. • Some authors found that there was
no difference in accuracy between
techniques.
Idris B, Houston F, Claffey N. Comparison of the
dimensional accuracy of one- and two-step techniques with
the use of putty/ wash addition silicone impression
materials.
J Prosthet Dent 1995;74:535-41.
17. Others criticized several
potential disadvantages with
this approach.
Impossible to control the thickness
of light body
Usually portions of prepared
margins are captured in the putty
(putty materials are essentially
deficient in their ability to record
marginal details) Donovan TE, Chee WW. A review of contemporary
impression materials & techniques . Dent Clin North Am
2004;48:445-70.
18. This article describes a modified 1-step
putty-wash technique using vacuum-formed
resin sheets as spacers to control the
wash bulk and minimize the chance of
unfavourable impression results.
Using this technique, the limitations of
using1-step putty-wash impression can be
19. PROCEDURE
1. Use the original diagnostic cast or cast
recovered from an impression of the diagnostic
provisional restorations to fabricate the
vacuum-formed spacer
20. 2. Place the cast and a 5 x 5-inch sheet
of 0.08-inch-thick soft clear ethyl vinyl
acetate on a single-chambered vacuum-forming
machine.
Heat until a 0.5-inch droop develops, and
then vacuum form the spacer on the cast.
21. 3. Do not prepare
occlusal stops because
they interfere with
the removal of the
spacer from the putty.
• Trim the spacer to
cover approximately 2
to 3 mm of marginal
gingiva on the buccal
and lingual surfaces
of the teeth.
22. 4. Complete essential gingival
retraction procedures on prepared teeth.
5. Place the vacuum-formed spacer
intraorally and verify stability.
23. 6. Make a transfer impression of the spacer
with high-viscosity putty impression
material in a stock tray.
24. 7. Before the putty impression
material is polymerized, remove the
entire impression from the mouth
and gently remove the spacer from
the putty material.
25. 8. Simultaneously wash the putty
tray with light-bodied polyvinyl
siloxane impression material to
make the definitive impression.
26.
27.
28. • Thickness of light body is
controlled
• Putty doesn't show up in critical
areas
• Decreased chair side time
32. Auto mix System
Fewer Inherent voids
Extended essential working time
Reduce waste
33. Adhesion of impression material to
tray
All impression materials shrink
slightly upon setting resulting
in smaller die
With proper tray adhesive (7 to
15 min), impression material
shrinks towards the tray
during setting resulting in
slightly larger die which is
preferable to a smaller one