Implant prosthesis impressions: measurement of contraction in polymeric resins used for pickup transfer of the intraoral implant position.

Objective The purpose of the present work was to analyze the contraction of resins used to transfer the position of splinted abutments. Materials and methods Measurements were made with a dedicated device equipped with two extensometers: one measured tension resulting from resincontraction during polymerization and the other measured thermal deformation. We evaluated several self-polymerized and light-cured resins, and a system, which, by means of a building process, remarkably reduced the contraction of all resins during polymerization. Results The systems based on light-cured resins displayed significantly higher tensions than those based on self-polymerized resins, but they also had shorter stabilization times. Using a system with an appropriate design, we were able to reduce tension to a minimum, regardless of the type of resin used. Conclusion Passive fit between the metal bridge and the implants is critical for lasting osseointegration. Accurate transfer of oral data to the laboratory is paramount because internal tensions may develop in the fixing material connecting the transfers. These tensions can generate deformations when the structure is removed and is no longer subject to binding by the in situ implants.