A Modified One-step Putty-wash Impression

Technique

Yu-Jen Wu A. & Donovan T.E J Prosthet Dent 2007;98:245-

246

Literature demonstrates that optimum accuracy can be achieved with

Custom trays and Stock trays

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

PLASTICMETAL

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.

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.

Glenn E. Gordon et al. The effect of tray selection on the accuracy of elastomeric impression materials. J PROSTHET DENT 1990;63:12-5.

Custom trays produced dies that were more accurate overall when compared with those produced by stock trays.

Eames WB, Sieweke JC, Wallace GW, Rogers LB. Elastomeric impression

materials: effectof bulk on accuracy. J Prosthet Dent

1979;41:304.

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.

The putty-wash impression technique using an elastomeric impression material is a popular method.

Variations of the Putty-wash impression technique

1-step 2-step

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.

2-step technique

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.

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.

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.

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

Simultaneous / Squash Technique

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.

Pameijer CH. A one-step putty-wash impression technique utilizing vinyl polysiloxanes. Quintessence Int Dent Dig. 1983 Aug;14(8):861-3.

• Accuracy of impressions resulting from

the 1-step putty-wash technique is

controversial.

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.

• Some authors found that there was no difference in accuracy between techniques.

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.

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

eliminated.

1. Use the original diagnostic cast or cast

recovered from an impression of the diagnostic

provisional restorations to fabricate the

vacuum-formed spacer

PROCEDURE

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.

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.

4. Complete essential gingival

retraction procedures on prepared teeth.

5. Place the vacuum-formed spacer

intraorally and verify stability.

6. Make a transfer impression of the spacer

with high-viscosity putty impression

material in a stock tray.

7. Before the putty impression

material is polymerized, remove the

entire impression from the mouth

and gently remove the spacer from

the putty material.

8. Simultaneously wash the putty tray with light-bodied polyvinyl siloxane impression material to make the definitive impression.

• Thickness of light body is controlled

• Putty doesn't show up in critical areas

• Decreased chair side time

Increased Laboratory time

Additional material(resin sheets )

Adds Cost to the patient

Inhibit polymerization

Fewer Inherent voidsExtended essential working timeReduce waste

Auto mix System

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