A comparative evaluation of primary stability of two dental implant systems in synthetic and natural bone

Given the increasing use and availability of dental implants, this study aimed to compare the primary stability of two commonly used implants with similar designs: 'type A (Cowellmedi), an imported design, and type B (DRI), a domestically manufactured implant,' in both synthetic (polyurethane foam) and natural bone (bovine rib). Both implants had a diameter of 4 mm and a length of 10 mm, with a buttress thread profile. Type B was single-threaded, while type A was double-threaded with a more conical design. In natural bone, type A demonstrated significantly higher maximum insertion torque (p = 0.033), bone-implant construct stiffness (p < 0.001), and maximum push-in force (p < 0.001) compared with type B. In contrast, in synthetic bone, type B showed significantly higher bone-implant construct stiffness (p = 0.02) and greater maximum push-in force (p < 0.001). Implant stability quotient (ISQ) values did not differ between the two designs in either bone type. The findings suggest that type A achieved greater primary stability due to its double-threaded configuration and longer conical region. Subtle design differences, such as single- versus double-threading and a longer conical region, can therefore have a considerable impact on primary stability and should not be overlooked when developing new implant designs. Finally, the discrepancies observed between stability outcomes in natural and synthetic bone are likely due to differences in their mechanical behavior. This highlights the need for caution when interpreting data derived from synthetic bone, particularly when attempting to extrapolate findings to natural bone-implant systems.