In vitro comparison of the accuracy of four intraoral scanners and three conventional impression methods for two neighboring implants.

PURPOSE: To determine whether the accuracy of two-implant model impressions taken with optical scanners was inferior to that of those taken with elastomeric materials. MATERIALS AND METHODS: Impressions of a resin reference model with two almost parallel implants were taken using three elastomeric impressions (closed tray technique, open tray nonsplinted technique and open tray splinted technique) and scanned with four optical scanners (CEREC Omnicam, 3M True Definition Scanner, 3Shape TRIOS3 and Carestream CS 3600). STL files of the different methods were superimposed and analyzed with control software (Geomagic Control X, 3D systems) to determine the mean deviation between scans. RESULTS: Compared to elastomeric impressions, optical impressions showed a significantly improved mean precision. TRIOS3 and CS3600 showed a significantly improved mean trueness compared to that of closed tray, CEREC Omnicam and TrueDefinition. All methods showed a certain degree of implant rotation over their axes, which was significantly higher in the closed tray and the open tray nonsplinted techniques. CONCLUSIONS: Optical impressions, taken under these in vitro conditions, showed improved accuracy compared with that of elastomeric impressions.

Impact of design and length on the accuracy of closed tray transfer copings.

BACKGROUND: The aim of this study was to evaluate the accuracy of two closed-tray transfer copings for implant impressions (a new design vs. an old design) in two different lengths (short and long). MATERIAL AND METHODS: Four groups of transfer copings (NS - new short, NL - new long, OS - old short and OL - old long) were tested. An epoxy resin model was prepared of missing teeth 1.4, 1.5 and 1.6. Two Alpha-Bio analogues were placed in position of teeth 1.4 and 1.6, at a 10o angulation. Two calibrated operators took 10 closed-tray impressions for each group with polyether in a Rim-Lock impression tray. RESULTS: After measuring and comparing impressions, a significant difference was found between the two new transfer copings and the old short transfer coping. CONCLUSIONS: The new transfer coping design significantly improved impression accuracy. An adequate transfer coping design for the closed-tray impression technique can help to achieve clinically acceptable impressions for two-unit implant supported bridges. Key words:Closed tray, impression coping, transfer coping, implant impression.