Evaluation of compressive strength for refractory casts made from different investment materials


Aims: To compare the compressive strength of refractory casts made from investments for cobalt–chromium and investment for titanium and to study the effect of mixing fluid on compressive strength.Materials and Methods: Three types of investments were used, one for titanium and two for cobalt–chromium, each one is mixed with three types of mixing fluids; tap water, distilled water and special liquid,to produce refractory casts. Compressive strength test was carried out using compression testing machine.Results: Showed significant differences in compressive strength between the types of investments, withtitanium investment mixed with special liquid showed the highest value. There were significant differencesbetween subgroups of the same type by changing mixing fluid type. Conclusions: Refractory casts madefrom titanium investment showed significantly higher compressive strength than refractory casts madefrom Co–Cr investments, and there was a difference between the two special liquids used, and tap water inwhich it produced casts with higher compressive strength than distilled water in two out of the threeinvestment materials tested.