Effects of sprue and investment on the castability of titanium

Objectives: the purpose of this study was to evaluate the castability of the titanium commercially pure (cp) in function of the number of the sprue, single (C1) or double sprue (C2), and the investment type, Rematitan Plus (RP) or Rematitan Ultra (RU), by measuring the marginal sharpness of dental castings. Methods: Sixty resin/wax patterns were fabricated on a stainless steell die with a 30º bevel finish line, with fifteen repetitions for each group; the margins of the castings were dipped in ring filled with silicone light body and after setting the impression was cut in eight segments; the deficiency of the margin on each segment were positioned in microscope and photographed; the negatives revealed the deficiency of the margin of the castings, that it can be expressed in terms of the distance between the edge of the casting and the theoretical sharp edge, calculated for the expression D=2.7•R, where R is the radius of rounding presented by the metal; the measure of the radius was done directly on the negatives in microscope; it was made eight measures for each casting and it was obtained the average of marginal deficiency. Results: the results (µm) were submitted to test ANOVA (p<.05): C2 (72±16) has significantly less marginal deficiency than C1 (97±23); RU (78±17) has significantly less marginal deficiency than RP (91±28); the effect of the use of C2 was more intense for the RP. Conclusion: it concluded that the Rematitan Ultra investment produced more castability of the titanium than Rematitan Plus; the use of double sprue produced more castability of the titanium than single sprue; the effect of the use of double sprue was more intense for the Rematitan Plus investment, producing similar results to the Rematitan Ultra investment. Financial supporte: FAPESP - project number 03/01896-6