Impact of Impression Tray on the Accuracy of Implant Impressions

Objectives: Nowadays, special stock trays are offered that target implant impressions. The aim of this study was to investigate the accuracy of implant impressions performed with these trays in comparison to a conventional laboratory made custom tray.
Methods: A master model of a dentate upper jaw with 6 implants (BEGO Semados RI, Standard Plus RN) was fabricated. To increase the accuracy, all implants were mounted on a steal base plate. The model was completed with an acrylic mask. A total of 80 impressions (10 per series) were carried out with four different impression trays (custom tray, Border-Lock, Miratray, Wintray) and two different impression materials (Impregum Penta 3M, Aquasil Ultra DECA 380, Dentsply). The impressions were poured with type-IV-plaster (Fujirock, GC) and stored for a minimum of 7 days. Thereafter the 3-dimensione implant position was assessed with the help of a coordinate-measuring-machine (Thome, Germany) and - with regard to implant rotation, inclination of the axis and the shift of the implant position along the X/Y- and Z-axis compared to the master model. Data were analyzed using for normal distribution and thereafter subjected to an ANOVA procedure.
Results: Data ranged from 0.59°±5.54° [custom tray, Impregum, BEGO] to 0.89°±0.69° [Miratray, Aquasil, Straumann] (sign., p<0.05) for rotation and from 0.12°±0.13° [Border Lock, Impregum, BEGO Semados] to 0.27°±0.21° [Miratray, Aquasil, Straumann] (n.s.) for inclination. The deviation along the X-axis showed results from 0.063mm±0.060mm [Border Lock, Aquasil, BEGO] to 0.132mm±0.164mm [Miratray, Impregum, Straumann] (sign., p<0.05).
Conclusions: Within the limits of this study it can be concluded that the use of special stock trays for implant impressions (Border Lock) may be a true alternative to a custom tray.