Effect of Splint Material Stiffness on Implant Impression Techniques

Objectives: The placement of angled implants in the maxilla favors the distribution of forces on implant-supported fixed prostheses, regardless the number of employed implants. Due to the importance of obtaining passive fit for the success of implant supported prostheses, to the lack agreement among the employed impression techniques and to the lack of studies evaluating impression techniques for the “All-on-4”concept, the present study evaluated in vitro the accuracy of five different impression approaches. Methods: A master cast consisting of a maxilla edentulous cast with placed implants following the all-on-four concept was used in the present study. A framework was also used to propitiate a clinically relevant simulation. Five groups, with 10 casts each, were defined according to the impression technique and the copings’ splinting method. Group 1: Impression with Metallic Closed-tray (CT); Group 2: Impression with Metallic Open-Tray and splinted copings (OP); Group 3: Impression with Metallic Open-Tray and acrylic resin splinted copings (RS); Group 4: Impression with Metallic Open-Tray and metal splinted copings (MS) and Group 5: Index (I), Implant-transfer technique without impression material. Vinyl polysiloxane impression material was used for all impressions with a metallic tray. Results: The results showed statistically significant differences between CT and the remaining groups (p<=0.001). No significant differences among RS/MS/I were detected (p>0.05) (ANOVA/Tukey α <0.05). Conclusion: Within the limitations of this study, it was concluded that CT group presented the worst mean values, representing less accuracy and fidelity to transferring implants. The groups RS/MS/I presented similar results of accuracy on angled implants obtained casts.