Before VPS impression materials, we used alginate for partial dentures and rubber base for complete dentures. But those days were over once we were introduced to VPS. It was great to use accurate materials without needing custom trays, and we appreciated the fact that they had no offensive smell or taste.
Today, the standard of care in dentistry is to use VPS or polyether impression materials for crown and bridge procedures, dentures, and partials. VPS (addition silicone) is user-friendly with predictable handling, a pleasant taste, and a somewhat hydrophilic property when a sufficient surfactant is incorporated in the formulation. Polyether handles just as well and is more hydrophilic.
Both VPS and polyether impression materials are capable of providing highly accurate impressions with good tear strength. They are thixotrophic, which leads to good handling properties. They have a good working time and a reasonable setting time, whether the clinician is impressing just 1 or 2 crowns or an entire arch, round-house case.
Since VPS and polyether impression materials are accurate, the problems with missed impressions, however rare, are generally because of inadequate preparations, retraction, moisture control, application, or a combination of any of those. The key to successful impressioning is developing a systematic technique that yields consistent results.
It is important to prepare the tooth or teeth with smooth consistent margins that follow the gingival contour. Retraction with cord, clay, electrosurgery, or a laser is also important. Once this is accomplished, it is time to make the impression with a VPS or polyether impression material that is not injected beyond its working time and not removed from the mouth prior to its setting time.
If these steps are incorporated into a system that can be predictably reproduced, impressioning can be a stress-free procedure for both the clinician and the patient. When the clinician develops a systematic technique using VPS impression materials, he finds great, highly accurate results.
Although it has been a few years since my days as a dental student, I still find myself using VPS impression materials' "the good stuff."
Christopher A. Hooper, DDS is a Dental Product Shopper Editorial Advisory Board member and has a private practice in Virgnia Beach, VA.