Making Accurate Detailed Impressions – Part 1
By: Frank J. Milnar, DDS, AAACD
This article originally appeared in Inside Dentistry.
Taking impressions is a critical step in creating quality restorations. Pressure, astringency, and time are the key elements needed to create the proper environment for taking a good impression. There are well over 40+ brands of impression materials offered by nearly 30 different companies—most are very similar.1 It can be overwhelming and confusing to understand and select the right material types and properties for your clinical use.2
NoCord VPS Impressioning System (Centrix, www.CentrixNoCordVPS.com) is the first material that is truly different. The newest impression material in the market, NoCord VPS brings all three critical areas into play. It is an impressioning system that retracts the tissue, stops bleeding, and takes an accurate impression all in one step. It is able to do this because it incorporates the astringent within the NoCord™ Wash Material (Centrix) and combines it with NoCord™ MegaBody® Tray Material (Centrix) to help create the force (pressure) for retraction and hemostasis. The purpose of this article is to introduce a new class of impression material that takes advantage of these properties, while maintaining the accuracy and stability benefits of a vinyl polysiloxane.
Here is a typical case that one may run into during an average day in the dental office.
A 34-year-old patient presented with decay and discoloration from ferrous contamination under an all ceramic e.max crown (Ivoclar Vivadent) on No. 14 (Figure 1). The patient was given a local anesthetic using Anutra's buffered anesthetic system. Before removing the crown, an Access Blue® (Centrix) quick set impression was made in order to make a temporary restoration. The crown was removed by sectioning it in half using an 850-814-ML diamond (Diatech). After the sectioned crown was removed, the tooth was re-prepared by removing the decay and stain using an 850-814-ML diamond and H32.31.012 diamond (Brasseler USA). The defects in the tooth were filled with the core paste and were finally finished with a final modified chamfer using 850-814.10ML (Diatech).
As a result of extensive subgingival decay on the distal, there was excessive bleeding (Figure 2). Centrix NoCord VPS was indicated as our final impression. NoCord Wash Material can be used by itself where there is minimal bleeding because of its astringent property. Simply wash and dry the preparation before using NoCord VPS to achieve an accurate impression with gingival retraction. In instances such as this, it may be necessary to control excessive bleeding by using additional hemostatic methods such as GingiTrac™ (Centrix) (Figure 3).
TheraCal LC, a light-cured, resin-modified calcium silicate was placed as a liner. It is ideal for direct and indirect pulp capping and as a protective base/liner.
The final steps in making an accurate impression will be addressed in our next blog.
1. Cowie RR. Understanding impression materials and techniques. Dent Today. 2007;26(3):108, 110-111.
2. Brown RL. An elastomeric impression material breakthrough. Dent Today. 2009;28(10):118, 120.