Background Resonance frequency analyses and quantitative ultrasound methods have been suggested to assess dental implant primary stability. Purpose The purpose of this study was to compare the results obtained using these two techniques applied to the same dental implants inserted in various bone phantoms. Materials and Methods Different values of trabecular bone density and cortical thickness were considered to assess the effect of bone quality on the respective indicators (UI and ISQ). The effect of the implant insertion depth and of the final drill diameter was also investigated. Results ISQ values increase and UI values decrease as a function of trabecular density, cortical thickness and the screwing of the implant. When the implant diameter varies, the UI values are significantly different for all final drill diameters (except for two), while the ISQ values are similar for all final drill diameters lower than 3.2 mm and higher than 3.3 mm. The error on the estimation of parameters with the QUS device is between 4 and 8 times lower compared to that made with the RFA technique. Conclusions The results show that ultrasound technique provides a better estimation of different parameters related to the implant stability compared to the RFA technique.