Untitled Quiz

The impression tray is a device used to carry the impression material into the mouth, maintaining it in position during setting, and supporting it during removal from the mouth and when casting the impression.

An impression tray is typically made up of a body and a handle.

The body of an impression tray consists of a floor and flanges.

<p>False</p> Signup and view all the answers

<p>Impression trays should be strong and rigid to avoid distortion of the impression on removal.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>The tray confines the impression material, holds it in the correct position, and covers the entire area of the jaw needed for the impression.</p> Signup and view all the answers

<p>The flanges of the tray should reach the functional position of the sulci and frena, but not displace them when the impression is being taken.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>Impression trays are typically classified into two categories: stock trays and special/individual or custom trays.</p> Signup and view all the answers

<p>Stock impression trays are ready-made trays available in different shapes and sizes. They are supplied in small, medium, large and extra large sizes.</p> Signup and view all the answers

<p>The shape of the stock impression tray differs according to whether it is used for patients with a full set of teeth (dentulous), no teeth (edentulous), or partially missing teeth (partially edentulous).</p> Signup and view all the answers

<p>Stock trays designed for dentulous patients typically have flat floors, high flanges, and a handle in-line with the floor of the tray. They can be perforated, rim-lock trays or water-cooled trays.</p> Signup and view all the answers

<p>The rim-lock tray is often preferred for dentulous patients.</p> Signup and view all the answers

<p>Stock impression trays for edentulous patients typically have a round floor, short flanges, and a handle bent in an L-shape at a right angle to the floor.</p> Signup and view all the answers

<p>The stock tray for partially-edentulous patients has a combination of features. It typically has a flat floor and high flanges in the areas where there are teeth and a rounded floor and short flanges in the areas where there are no teeth.</p> Signup and view all the answers

<p>Stock trays are made from various materials, including nickel silver, stainless steel, aluminum tin or plastics.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>Stock trays are typically used for taking a preliminary impression of the mouth.</p> Signup and view all the answers

<p>The tray must be selected to conform nearly to the shape and size of the dental arch.</p> Signup and view all the answers

<p>Incorrect selection of the impression tray results in a distorted impression.</p> Signup and view all the answers

<p>Using a tray with long flanges can cause distortion of the oral vestibules, resulting in over-extended impressions.</p> Signup and view all the answers

<p>If a short tray is used, the impression material may not reach the entire area intended and could leave the tissues unsupported, potentially causing discomfort.</p> Signup and view all the answers

<p>Some dentists modify stock trays to improve their fit and to accommodate individual patients' unique mouth shapes and structures.</p> Signup and view all the answers

<p>Common modifications include bending the flanges to provide adequate space for impression material, or cutting the flanges to accommodate labial or buccal frena or to reduce over-extended flanges.</p> Signup and view all the answers

<p>A study cast is a positive reproduction of the form of a patient's upper or lower arch, made from a preliminary impression.</p> Signup and view all the answers

<p>The study cast is made from the preliminary impression taken with a stock tray, while the working cast is made from the final impression taken with a special/custom tray.</p> Signup and view all the answers

<p>A study cast is made by pouring a mixed plaster of paris into the preliminary impression.</p> Signup and view all the answers

<p>The plaster mixture is added to one end of the primary impression from the same area to avoid trapped air. Once the impression is filled, excess plaster is poured over a glass slab and the filled impression is carefully inverted over it. The plaster border is then smoothed and shaped with a spatula. After the plaster sets, the impression is removed, and the periphery of the cast is trimmed.</p> Signup and view all the answers