According to the position of the preparation margins, a decision regarding the use of a single- or double-cord technique should be made. A routine mapping of the sulcus and a proper selection of cords is mandatory. The intra-sulcular finishing line, which corresponds to the majority of clinical situations, demands proper gingival deflection in order to provide space for the impression material.Īn impression will be taken only in the conditions of complete health of the soft tissues. Regardless of the technique or material used, a major factor in the success of impression-making is gingival manipulation. Gingival manipulation and cords selection The double mix (putty and light or heavy and light) technique and the traditional two-step putty/wash technique will be described together with proper selection and use of retraction cords for soft tissue manipulation. Due to their optimal resistance to deformation, accuracy, good dimensional stability and tear resistance, PVS are still the material of choice for most dentists. The elastomeric impression materials used for accurate impression are most commonly polyvinyl siloxanes (PVS) and polyethers (PE). A perfect impression should capture, in an un-deformed manner, the entire configuration of the prepared tooth as well as some of the pristine tooth structure beyond the finishing line. A prerequisite for any long-lasting indirect restoration is a perfect marginal fit, which requires a precise impression.
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