OBJECTIVES: The stress-strain and thermal expansion characteristics of a @entity1391 -bonded investment material were measured to determine its suitability as a die material for superplastic forming of dental appliances. @entity702 alloy denture bases and implant superstructures have been fabricated successfully using this investment material, but a greater understanding of its properties was sought to optimize the forming technique before exploitation could proceed. The effect of a @entity8240 powder on the properties of @entity1391 -bonded investment was also investigated. METHODS: Three-point bend test specimens were cast in the @entity1391 -bonded investment material. Four groups of test samples were produced at specified water-to-powder ratios (w/p ratios). For one group 5 wt.% @entity8240 powder was added to the investment powder before mixing with water. For stress-strain measurements specimens were heated to 920 degrees C and held for 30 min prior to the application of load. For thermal expansion measurements specimen length was measured for the entire heating and cooling cycle. RESULTS: Curves of stress versus strain and thermal expansion were recorded for all four test groups. For increasing initial w/p ratio failure stress decreased with lowest failure stresses for specimens containing @entity8240 . @entity177 also decreased with increasing initial w/p ratio, except for the group containing @entity8240 which showed relatively large elongations to @entity174 . Specimen surfaces with higher initial w/p ratios were observed to have larger surface porosity. Thermal expansion curves for three groups were very similar, but differed considerably from the group containing @entity8240 . CONCLUSIONS: The lowest initial w/p ratio should be used for highest hot strength. Hot deformation of @entity1391 -bonded investment dies for superplastic forming is an issue that requires further investigation because of potential die deformation and the resulting loss of fit between the superplastic superstructure and implant components. @entity8240 could be used in @entity1391 -bonded investment to decrease thermal expansion, but the consequences of reduced hot strength and increased strain to failure may make the modified material unsuitable as a die for superplastic forming.

Stress-strain and thermal expansion characteristics of a XXXX -bonded investment mould material for dental super plastic forming.

@entity174 :: ('MESH:D050723', 'Disease') :: ['fracture'] @entity177 :: ('MESH:D051437', 'Disease') :: ['Strain to failure'] @entity1391 :: ('CHEBI:26020', 'Chemical') :: ['phosphate'] @entity702 :: ('MESH:D014025', 'Chemical') :: ['Titanium'] @entity8240 :: ('MESH:C017282', 'Chemical') :: ['Boron nitride', 'boron nitride']
@entity1391 :: (CHEBI:26020,Chemical) :: ['phosphate']
