![]() ![]() Soft-tissue contact was frequently observed in plastic trays, with an occasional tooth contact to the tray (Figures 2 and 3). Few metal trays were observed, even though the preceding evidence, as well as the anecdotal advice of many prominent clinicians, suggest they are more accurate. Maximum intercuspation can be visually verified by observing tooth-to-tooth contact anterior and posterior to the prepared tooth (Figure 1). Recent visits to 3 commercial labs in 3 different states in 3 different regions of the country showed that only about 40% of the 100 randomly selected dual-arch quadrant impressions were in maximum intercuspation. The 2 most common problems observed in commercial labs with dual-arch trays are tissue or tooth contact with the tray and failure to record maximum intercuspation. Photograph illustrating the difficulty in stabilizing a quadrant tray. CLINICIAN’S CHOICE metal Quad-Tray.įigure 6. ![]() Even soft-tissue contact with a plastic tray can cause the tray to distort.įigure 5. Tooth contact with the plastic tray leading to distortion of the final impression.įigure 4. Soft-tissue contact with the plastic tray leading to distortion of the final impression.įigure 3. Dual-arch impression that was correctly taken in maximum intercuspation shows tooth-to-tooth contact anterior and posterior to the prepared tooth.įigure 2. Rigid materials in metal trays were the most accurate, while monophase materials in plastic trays produced dies that were dramatically shorter.įigure 1. 1 Another study evaluated the effect of the viscosity of the impression materials in plastic and metal dual-arch trays.2 There were statistically significant differences noted in the accuracy of the dies. The conclusion was that they should only be used for single units, not when the terminal unit in the arch is being prepared. Evaluation of the 6 most popular plastic, disposable articulator systems used with dual-arch impressions found that with all systems, it was virtually impossible to maintain and repeat a centric occlusal position stop. This is further complicated by the fact that many commercial laboratories employ plastic, disposable articulators to use in the fabrication process, adding to the inaccuracies that can occur. When employed properly they can be used satisfactorily however, the overuse and abuse observed in commercial laboratories have frustrated both technicians and clinicians. ![]() Because of their ease of use, conservation of material, and elimination of the need for an opposing impression and bite registration, dual-arch quadrant impressions have become the overwhelming choice for most dentists. Laboratories estimate that about 85% of units are single crowns, and most of those are done with a dual-arch quadrant or triple tray. This article will attempt to clarify some of the areas of confusion regarding impression materials and techniques.Ĭonsider first the type of case that is being done. Confusion abounds and is further complicated by the omission from marketing literature of some information about PVS materials that is instrumental in using them and understanding how to get the best results from them. At least 43 different brands of polyvinyl siloxane impression materials are offered by at least 29 different companies. ![]() Unfortunately, there are a great many choices regarding the best tray to use (full-arch, quadrant, or dual-arch “triple” trays, stock or custom, plastic or metal trays) and regarding which technique is best (1- or 2-step putty/wash, heavy-body tray/wash, or monophase), and an even greater number of choices regarding which impression material to use to take the impression. The impression is the basic starting point for all laboratory procedures, as well as the basis for quality and cost-effective dentistry for the clinician. Table of Contents Be the best inspector you can be Details Reinventing High-definition Portable UT Built for All-level UT Inspectors Benefits Applications Want to see Gekko in action? Book a demo! Designed for the Field A Complete PAUT Portable Unit Portable & Robust Fast Connectivity Solution Water and Drop Test No Compromise on Performance Compatible With Most Accessories Streamlined Workflow Unique Features Exclusive Content Workshop Capture 3.There is no single procedure that a dentist can do, or any single procedure that a lab can do for the dentist, that will improve the final result of indirect restorations more than improving the quality of the impression. ![]()
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