title: The longitudinal accuracy of fit of titanium implant superstructures superplastically formed on investment models.
abstract: OBJECTIVE
  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 degrees C and five dies for forming at 810, 840, 873, 900 and 927 degrees 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 degrees C.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Dental Biomaterials Science, Guy's, King's and St. Thomas' Dental Institute, King's College, University of London, Floor 17, Guy's Tower, London SE1 9RT, UK. steven.soo@kcl.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Soo
authors.forename: D
authors.initials: D
authors.lastname: Garriga-Majo
authors.forename: R M
authors.initials: RM
authors.lastname: Palmer
authors.forename: R V
authors.initials: RV
authors.lastname: Curtis
mesh_terms: D000497:Alloys; D000044:Dental Abutments; D003722:Dental Alloys; D003734:Dental Casting Investment; D003735:Dental Casting Technique; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis; D006358:Hot Temperature; D008422:Materials Testing; D003765:Models, Dental; D044367:Phase Transition; D015203:Reproducibility of Results; D014025:Titanium
chemical_list: D000497:Alloys; D003722:Dental Alloys; D003734:Dental Casting Investment; C031462:titanium alloy (TiAl6V4); D014025:Titanium