The longitudinal accuracy of fit of titanium implant superstructures superplastically formed on investment models

Objectives. To measure the effect of three special liquid proportions and five forming temperatures on the length of superplastically formed titanium dental implant superstructures made using Rematitan dental casting investment. Methods. Rematitan dental casting investment was used to make models that contained two implant abutment analogues 8 mm apart. The investment was hand-mixed with 30, 50 or 70% special liquid proportions and ten models of each were made. Dies for superplastic forming (SPF) were made that contained three models (one for each special liquid proportion). Five dies were made for forming at 810 °C and five dies for forming at 810, 840, 873, 900 and 927 °C using 2 mm thick Ti-6Al-4V discs. The distance between the abutment impressions in the formed discs was measured with a traveling microscope and compared with the distance between the abutments of the master model to determine the most accurately fitting superstructure beam. Results. The proportion of special liquid used to make the SPF models had an unpredictable effect on the length of the superstructure at each forming temperature. Superstructure beams formed at lower temperatures had a better fit compared to the master model for all special liquid proportions. The most accurately sized beams were formed at 810 °C. Significance. SPF can provide an alternative method for the production of dental implant superstructures. The fit was affected predominantly by the forming temperature, but also by the special liquid proportion used for making the SPF investment model.