title: Porosity of cpTi casting with four different casting machines.
abstract: BACKGROUND
  Porosity is a well-known problem in dental titanium casting, resulting in inferior mechanical properties of dental restorations.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the porosity of cpTi castings produced with different casting machines.
  
  
  METHODS
  Four groups of 20 rectangular (30 x 3 x 0.5 mm) wax patterns were fabricated. Group CyII was cast in a CyclarcII casting machine, Group DAM in a Dor-A-Matic, Group TiF in a Titec 201F, and Group ETi in an EasyTi with cpTi, according to manufacturers' instructions. Groups CyII, DAM and TiF were invested with magnesia based Titavest CB and Group ETi with Ticoat S+L silica based investment. The percentage porosity of each specimen was determined using standardized digital radiographs and calculated by quantitative image analysis procedure. The results were statistically analyzed by nonparametric Kruskal-Wallis test (alpha=.05).
  
  
  RESULTS
  No statistical differences were found among the groups tested; nevertheless, pore distribution among the specimens of the same group was inhomogeneous. The results show that the casting machines tested produced nonuniform porosity.
  
  
  CONCLUSIONS
  Under the conditions of the present study, the type of casting machine does not significantly influence the internal porosity in cpTi castings.
authors.affiliation: Department of Biomaterials, Dental School, Univeresity of Athens, Athens, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Eliopoulos
authors.forename: Spiros
authors.initials: S
authors.lastname: Zinelis
authors.forename: Triantafillos
authors.initials: T
authors.lastname: Papadopoulos
mesh_terms: D001128:Argon; D003734:Dental Casting Investment; D003735:Dental Casting Technique / Q000295:instrumentation*; D003748:Dental Equipment / Q000592:standards*; D007283:Inlay Casting Wax; D016062:Porosity; D011856:Radiographic Image Enhancement / Q000592:standards; D018709:Statistics, Nonparametric; D014025:Titanium
chemical_list: D003734:Dental Casting Investment; D001128:Argon; D007283:Inlay Casting Wax; D014025:Titanium