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. Any backordered items will be shown on your shipping confirmation email and on your invoice.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. Please note that final inventory status is not determined until an order is submitted it is rare but possible that a product shown as "in stock" on our website is out of stock when you submit your order. These orders typically ship out from the manufacturer in a few days.ĭiscontinued: This item has been discontinued and is no longer available for sale. These orders typically ship out of our warehouse in approximately 7-10 business days.ĭirect from mfg: We will arrange to have the item shipped to you directly from the manufacturer. Special order: We do not stock this item, but we will happily place a special order to get it for you. You can call 80 or email to inquire about an expected delivery. If an item on promotion is backordered at time of order, the purchase will qualify for free goods if the order is placed prior to the promotion's expiration date. Partially in stock: We have at least one of the item you requested in stock, but the rest of the items will be on backorder for approximately 7-10 business days.īackordered: If an item is backordered, it will generally ship out of our warehouse in approximately 7-10 business days, unless there are delays from our vendors. We maintain an inventory of the vast majority of the items we sell 98% of items are shipped same-day straight out of our warehouse. In stock: The item is on our shelves and ready to ship.
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