#Alginate impression making full#

There were no available data on the suitable accuracy of casts used for building cobalt chromium removable dentures. In this study, the accuracy of casts made for building cobalt chromium removable partial dentures was evaluated. They investigated the accuracy between the dies and the crown. Peters et al reported that inaccuracy up to 78 μm and 50 μm, respectively are acceptable. There is no universal standard for clinically acceptable changes of hydrocolloid impression materials. However, if the impression could be stored for a reasonable time prior to pouring, this would be an advantage to irreversible hydrocolloid users in the management of their practices. Previous studies that evaluated the accuracy and dimensional stability of irreversible hydrocolloid impression material demonstrated the necessity of immediate pouring of the material or as soon as possible after removal from the mouth. Four different storage times (12, 25, 45 and 60 minutes) were tested. The group selection was based on a pilot study method. The remaining impressions were stored under 100% humid condition and two different temperatures refrigerator temperature (4☌, SD=1 group A) and room temperature (23☌, SD=1 group B). The first group (control group) was poured immediately after taken.

#Alginate impression making full#

Two-hundred seventy impressions were taken under full standard condition and classified into nine groups, each including 30 impressions. All the procedures were carried out in the same condition. The alginate powder was stored at 23☌ (SD=1) and 50% (SD=10) relative humidity in a temperature controlled-room for three days. Three stainless steel studs, welded to the tray with two holes on the horizontal parts, and two guiding pins on the fixed base were engaged into the holes to maintain the tray in a fixed and stable position. The head of each cylinder was well-rounded and the die position was in the second left and right molars and 10 mm distance from the midline of centrals. On the maxillary dentiform, three die cylinders (6 mm height and 6 mm diameter) were fixed. The base is a quadrangular block on which three pins are entirely engaged into three holes on the maxillary dentiform. The aim of this study was to verify the dimensional stability of one alginate-based impression material named Super (Iralgin, Golchai Co., Tehran, Iran) stored in a 100% relative humidity environment poured immediately and stored after specific periods. If it were safe to store the impressions for up to 30 minutes without clinically significant distortion, this would be an advantage to irreversible hydrocolloid users in the management of their practices. The results showed that if the irreversible hydrocolloid was poured within 15 min, it could be used as a final impression material. The impressions were poured at 15 min, 30 min, one hr and three hrs after impression making. Jamani et al investigated the best storage condition and time for pouring irreversible hydrocolloid impression material. They concluded that immediate pouring made the most accurate cast. Storing of the impressions was carried out at different times as 10 min, 30 min, one hr and 24 hrs before pouring. Cohen et al studied the dimensional stability of three different irreversible hydrocolloid impression materials under five different storage conditions. Past studies have shown that these impressions between 0 and 12 minutes are necessary to maintain clinically acceptable accuracy. Several investigations have studied the dimensional stability of alginate-based impression, and different tests have been developed for analyzing this property. Therefore, whether or not irreversible hydrocolloid impression materials are accurate enough for restorative and prosthetic dental use is in question. Irreversible hydrocolloid impression material has dimensional changes as a result of synergists or evaporation of water when exposed to air. An impression material must have dimensional stability to cause the overall success of the cast made from it.