Background: Implant primary stability is determined by screw characteristics and surgical procedure. The aim of the present study was to evaluate, on a polyurethane model, the insertion torque (IT), removal torque (RT), and resonance frequency analysis (RFA) of multi-scale roughness dental implants of different diameters. Methods: Two implant sizes were tested on two polyurethane blocks (20 pounds per cubic foot (PCF) and 30 PCF): 3.0 diameter and 13 mm length and 5.0 diameter and 13 mm length. The IT, RT, and RFA were assessed. Results: A significant difference of IT and RT was present in favor of wider implants at both polyurethane densities. No statistical difference was present between the 5.0 diameter and 3.0 diameter implants at both polyurethane densities. A statistically increased RFA was reported for 5.0 implant 30 PCF polyurethane blocks. Conclusions: Multi-scale roughness dental implants of both diameters showed high insertion torque and primary stability on polyurethane blocks, which is valuable for implant loading protocols.