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. In implant prosthodontics, an accurate impression is critical in constructing a precise prosthesis. However, the high retentive coping design of the Osstem implant affected the accuracy in the open tray technique. The geometrical design of the impression copings did not affect the accuracy for either the open and closed tray techniques. The high retentive design of the Osstem system showed a statistically significant difference. No statistically significant differences between the two impression techniques in either parallel or nonparallel implants were observed. The horizontal and vertical discrepancies were measured and analyzed. Three custom-made acrylic resin models of three tested implant systems (Straumann®, SIC Invent®, and Osstem®) with diverse coping geometrical designs were evaluated in simulated cases of two parallel and two nonparallel implants. This in vitro study aimed to evaluate the effect of implant impression coping geometrical designs on the accuracy of open and closed impression techniques and in the parallel and nonparallel implant positions.
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