Impact of Implant Angulation on the Accuracy of Open and Closed Tray Impression Techniques

Implants angles relative to each other might result in inaccurate impressions, resulting in inaccurate master casts. This study aimed to evaluate the dimensional accuracy of master casts in angulated dental implants.

In this in vitro study, a unilateral partially edentulous acrylic model was prepared with two implants in the second premolar and second molar areas. Impressions were taken in nine different positions of the implant positions (0°, +15°, -15°), using two impression techniques (closed tray, open tray) (n = 3)with polyvinylsiloxane impression material. The master casts were scanned by a laser scanner, and the data were transferred to MaterialiseMagics software to measure the angulation between the implants. The dimensional accuracy of the impressions was calculated in different implant angulations (i.e., parallelism, divergence and convergenceof two implants). Data were analyzed using independent t-test and two-way ANOVA (α = 0.05).

With a 0° angle between the implants (parallelism), there was no significant difference between the two impression techniques (p value = 0.102). However, when there was a >15ºangle between the two implants, the open tray technique was significantly more accurate than the closed tray technique (p value ˂0.05).

The implant angulation and impression techniques affected the accuracy of the master casts. When implant angulation increased from 0° to30°, the distortion of the impressions increased, too.