Abstract: Objective: To observe effects of investments methods with and without ring on marginal seating of the Pd-Ag castings. Methods: Forty unify standard models of Pd-Ag castings were made. Wax patterns were prepared on the models and were divided into two groups (n=20 in each group). Two different investing methods with the same investing material were performed. The marginal seating of the castings was measured by metallurgical microscope. Data were analyzed by SPSS statistical software. Results: The marginal seating of the Pd-Ag castings without ring investment had significant difference compared with that with ring investment (P<0.05). Conclusion: The marginal seating of the Pd-Ag castings without ring investment is more accurate than that with ring investment. Investment without ring can improve the marginal seating of the castings.

Key words: Marginal seating, Investing methods, Pd-Ag