A modified one-step putty-wash impression technique

Abstract

aClinical Instructor, Chang Gung Memorial Hospital, Chang Gung University College of Medicine. bProfessor, School of Dentistry, University of North Carolina. (J Prosthet Dent 2007;98:245-246) Although the literature demonstrates that optimum accuracy can be achieved with custom trays and stock trays,1-4 the putty-wash impression technique using an elastomeric impression material is a popular method. Two variations of the putty-wash impression technique are commonly used, the 2-step and 1-step.5 With the 2-step technique, a preliminary preoperative putty impression is made and, subsequently, “washed” with low viscosity material after tooth preparation. In terms of the 2-step puttywash impression technique, several methods are described for control of the bulk of the wash material,6-8 which is essential for fabricating accurate stone dies. With the 1-step procedure, low viscosity impression material is injected around the prepared tooth or teeth, and then the putty impression material is immediately placed intraorally and the materials polymerize simultaneously. Accuracy of impressions resulting from the 1-step putty-wash technique is controversial. Some authors found that there was no difference in accuracy between techniques,5,9-11 while others criticized several potential disadvantages with this approach. These disadvantages include lack of control of the bulk of wash material and the high risk of capturing portions of the prepared margin in putty material rather than lower viscosity material.12 Most putty viscosity materials have inadequate fine detail reproduction for this purpose. 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 unfavorable impression results. Using this technique, the limitations of using 1-step putty-wash impression can be eliminated.