The most significant step in fabricating an accurate implant prosthesis is to transfer the precise 3D intraoral location of the implants to the definitive cast. Various impression techniques have been described to achieve the necessary accuracy. The open tray impression has been widely used; however, translation and rotation of these transfer impression copings may occur when the copings are detached from the implant fixture and during placement of the implant analog. Lee et al concluded in their systematic review that splinting transfer impression copings produced an accurate definitive cast and prevented micromovement of the impression copings. Various methods, including dental floss and pattern resin, have been used to splint the open tray impression coping. However, dental floss may slip over the open tray impression coping and is tedious to handle when making a complete-arch impression. The purpose of this article was to present an alternative technique for splinting open tray impression copings by using orthodontic elastomeric chain and light-polymerizing composite resin for complete-arch implant impression making.
Remove the healing abutments (TS Fixture, Healing abutment; Osstem Implant Co, Ltd). Place the open tray impression copings (TS Fixture, Pick up impression coping; Osstem Implant Co, Ltd) and tighten to 10 Ncm. Make periapical radiographs to verify proper seating of the impression copings.
Take a short continuous orthodontic elastomeric chain (Dental Power E Chain; Pyrax Polymars) and pass it over the head of the impression copings ( Fig. 1 ). Do not stretch the elastomeric chain to prevent elastic tension.
Apply bulk fill flowable light-polymerizing composite resin (Tetric N-Flow Bulk fill; Ivoclar Vivadent AG) over the elastomeric chain to stabilize the open tray impression copings ( Fig. 2 ). Bulk fill flowable composite resin is preferred over a lower filler content composite resin to minimize polymerization shrinkage.