In one study, the modified squared and index techniques generated more accurate casts than the squared techniques. It is postulated that the more retentive element of a square impression coping could lead to better entrapment of the impression material, resulting in less discrepancy. evaluated the accuracy of three impression coping designs and found that casts retrieved from transfer impressions with nonmodified copings and those with airborne-particle abraded adhesive-coated copings were statistically less accurate than casts from square impression copings splinted with autopolymerizing acrylic resin. However, Liou and colleagues showed that surface treatment of copings did not lead to increased accuracy. found improved precision of the impression when adhesive-coated copings were used.
They may be modified by treatment with airborne-particle abrasion or impression adhesives. Several modifications have been proposed to enhance the retention of impression copings. Therefore, to produce an accurate impression, familiarity with coping designs and geometry is required. There are variations in implant impression coping shapes and designs, depending on the implant system and the components designed by the manufacturer of a particular system. Other influences include the direction of removal of the tray in relation to the implants’ axis, the number and parallelism of the implants, the degree of undercuts present, and the depth of implant position. The accuracy may be influenced by the impression material selected as well as the technique, coping design, shape, type of impression tray, implant numbers, implant angulations, and the operator’s skill. The implant in this case was well placed and the implant margin was supragingival and the snap-on fit well (rotated on the implant prior to inserting the second stabilizing component fully into the implant).In implant prosthodontics, an accurate impression is critical in constructing a precise prosthesis. Note: I have used snap-on transfers before and some could have even been a Straumann implant without trouble. The portion of the impression coping that fits into the implant seems shallower than those of other brands of implants I have used and didn’t seem to be as stable when I was trying to position it prior to screwing it in. However I found the metal coping not to be as stable when placed into the implant as I am accustomed to with other internal connection implants that I have used.
I managed to get an accurate impression and the crown seated well. Next I used a metal closed tray impression coping. However the crown that was made was rotated and would not seat. I inserted the implant replica into the plastic implant transfer components and everything seemed solid. I retook the impression with a new plastic snap on and heavy body impression material. I found the Straumann plastic snap-on impression copings inaccurate.Īfter the first impression I attached the implant replica to the plastic components in the impression and the implant replica rotated slightly. I just completed a case of a 46 implant (lower right first molar) with limited access. Has anyone had either good or bad experiences trying to take an impression of Straumann tissue level implants using Straumann impression copings?
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