Characteristics of commercial quick-heating phosphate-bonded investments for the accelerated casting technique

Objective: Commercial quick-heating phosphate-bonded investments are frequently used to reduce the operating time during the dental casting process. The aim of this study was to evaluate the characteristics of commercial quick-heating phosphate-bonded investments. Method and Materials: Characterization of the 2 investments (Maruvest-Speed [Megadental] and Z4 C&B [Neirynck and Vogt]) focused on the setting expansion, compressive strength, thermal expansion, and surface roughness. Two different heating methods-the quick-heating method (QHM) and conventional heating method (CHM)-were used with the investments. The dimensional accuracy and surface roughness of the nickel-chromium alloy castings obtained from the investments were also examined. Results: The Maruvest-Speed investment had a significantly greater setting expansion (2.2%) than the Z4 investment (1.1%) after a 30-minute setting time. The fired strength of both investments was greater with QHM (21.2 to 27.7 MPa) than with CHM (13.8 to 17.9 MPa). The thermal expansion of the Maruvest-Speed investment and Z4 with QHM was 1.7% and 1.4%, respectively. There was no significant difference in surface roughness of the castings between samples treated with QHM and CHM. The dimensional accuracy of the castings was larger in length and slightly deformed in bend. Conclusion: The characteristics of the 2 commercial quick-heating phosphate-bonded investments for the accelerated casting technique may be acceptable. Keywords: accelerated casting technique, compressive strength, phosphate-bonded investment, setting expansion, thermal expansion