The two-step putty and wash impression technique with a spacer medium is an important technique to master. Many associate it primarily with fixed prosthodontics. However, it has an important role to play in many aspects of orthodontic practice. This technique can lead to more accurate stone dies.1 This is extremely pertinent for orthodontists involved in prescribing and making orthodontic aligners and custom-made fixed appliances using impressions. Furthermore, this technique is useful for cases where palatal temporary anchorage devices are being used. Additionally, this technique can produce accurate models that may be required for cases requiring a multidisciplinary orthodontic–restorative approach.
Step 1. Preparation is key, assemble all the equipment you need. This includes: a lab bag, scissors, disposable mirror and scalpel, PVS heavy-bodied silicone and light-bodied silicone.Step 2. Line the impression tray with an impression tray adhesive.Step 3. Use the impression tray as a template to cut out the correct sized spacer. A lab bag is a more than suitable material if no spacer foil is available.Step 4. Mix the heavy-bodied PVS material and place in impression tray.Step 5. Place the spacer on top of the PVS material so that it covers the entire arch and therefore will act as a barrier between the teeth and the material.Step 6.
(a) Fully seat the impression and remove after a few seconds. While the impression material is still not fully set use the side and end of the mirror to smooth the inner lining of the impression with the spacer in situ. (b) Then, gently remove the spacer material being careful not to distort the material and continue to smooth the inner areas of the impression. This will remove any drag marks or uneven surfaces and make space for the light-bodied material.Step 7. Ensure the teeth are fully dried and isolated prior to commencing with the next stage. Place the light-bodied silicone into both buccal sulcus and the impression tray and fully seat the impression – this is the second and final stage of the technique.Step 8. Once set, remove the impression and inspect for any defects, air-blows or drag marks.Step 9. Trim the impression of any unwanted excess material with the scalpel.Step 10. Repeat the same process for the opposing arch.
