Accuracy of Definitive Casts Using 4 Implant-level Impression Techniques in a Scenario of Multi-implant System with Different Implant Angulations and Subgingival Alignment Levels

Purpose: To evaluate the effect of various implant-level impression techniques on the accuracy of definitive casts for a multiple internal connection implant system with different implant angulations and subgingival depths.

Material And Methods: Six tapered Screw-Vent implants were placed in a reference model with different angles (0, 15, and 30 degrees) and subgingival positions (0, 1, and 3 mm). Twenty medium-consistency polyether impressions of this model were made with 4 techniques (n = 5 per group): (1) indirect technique, (2) unsplinted direct technique, (3) acrylic resin-splinted direct technique, and (4) metal-splinted direct technique. Impressions were poured with type IV dental stone. The interimplant distances were measured for casts using a coordinate measuring machine and the deviations compared with the reference model were calculated. Data were analyzed using intraclass correlation coefficient, ANOVA and Bonferroni test (α = 0.05).

Results: Four impression procedures showed significant differences (P = 0.0001). Only group 4 casts showed no significant differences in comparison with the reference model (P = 0.666) (ANOVA repeated measures).

Conclusions: The impression procedure affected the accuracy of definitive casts. The metal-splinted direct technique produced the most accurate casts, followed by acrylic resin-splinted direct, indirect, and unsplinted direct techniques.