title: Effect of different investments and mold temperatures on titanium mechanical properties.
abstract: OBJECTIVE
  The aim of the present study was to evaluate commercially pure titanium (CP Ti) casting quality when a specific to titanium and a conventional phosphate bonded investments were used under different mold temperatures. For this, the evaluated parameters were surface roughness, bending strength, Vickers microhardness, casting quality by radiographies and microstructure of CP Ti.
  
  
  METHODS
  Wax patterns (28 mm × 3 mm × 1 mm) were invested using two phosphate bonded investments: Rematitan Plus (REM), specific to titanium, and Castorit Super C (CAS), a conventional investment, fired and cooled until reaching two mold temperatures: 430 °C (430) and room temperature (RT). Specimens were cast from CP Ti by plasma. After casting, specimens were radiographically examined and submitted to Vickers microhardness, roughness and bending strength evaluation. Microstructure was analyzed in the center and at the surface of specimen.
  
  
  RESULTS
  Qualitative analysis of radiographs showed that specimens which were cast using CAS-RT presented more casting porosities while the specimens which were cast with REM-430 did not present any casting porosity. No significant difference was noted among the groups in the surface roughness and Vickers microhardness data, but the bending strength of the specimens cast using CAS was greater than REM groups. The microstructure of the specimens of the different groups was similar, presenting a feather-like aspect.
  
  
  CONCLUSIONS
  Casting porosities found in the specimens cast using conventional investments (CAS) and lower mold temperatures would limit their use, even mechanical properties were similar than in specimens cast using specific to titanium investment (REM) at temperatures recommended by the manufacturer.
authors.affiliation: Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo, Av. do Café, s/n, Monte Alegre, 14040-904 Ribeirão Preto, SP, Brazil. renata@forp.usp.br
authors.forename: Renata Cristina Silveira
authors.initials: RC
authors.lastname: Rodrigues
authors.forename: Elanio Pereira de
authors.initials: EP
authors.lastname: Almeida
authors.forename: Adriana Cláudia Lapria
authors.initials: AC
authors.lastname: Faria
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Macedo
authors.forename: Maria da Gloria Chiarello
authors.initials: Mda G
authors.lastname: de Mattos
authors.forename: Ricardo Faria
authors.initials: RF
authors.lastname: Ribeiro
mesh_terms: D055598:Chemical Phenomena; D003734:Dental Casting Investment; D003735:Dental Casting Technique; D010710:Phosphates; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry
chemical_list: D003734:Dental Casting Investment; D010710:Phosphates; D014025:Titanium