Abstract :This study evaluated the effectiveness of different ultrasound machines for removing metal cast post-and-cores. 24 models of maxillary central incisors roots were made using acrylic resin. Each root had his canal patterned with resin Duralay (Reliance Dental) for making prosthetic metal cast post-and-cores, which were fused in Nickel-Chromium alloy (VeraBond II). Cores were cemented to the roots using zinc phosphate cement (SS White) and then stored in a humid environment for 30 days. The samples were divided randomly into two groups (n = 12), according to the ultrasound equipment used to remove the cores. For group I, a Sonic Jet-Total (Gnatus) unit was used and for Group II the Jet Ultrasound (D700) appliance was used.