Effect of Progressive Versus Standard Implant Thread Designs on Primary Stability and Insertion Torque: An In Vitro Study

PURPOSE: To compare primary stability and insertion torque between implants with standard (SI) and progressive (PI) thread designs in vitro, and to evaluate manufacturer-specific differences and the relationship between these two parameters. MATERIALS AND METHODS: A total of 240 screw-type implants with either standard or progressive thread designs were inserted into standardized polyurethane blocks simulating three different bone densities. Insertion torque [Ncm] was recorded during implant placement, and primary stability was measured immediately after insertion using RFA, expressed as implant stability quotient [ISQ]. Statistical comparisons were made between SI and PI groups, within manufacturer-matched subgroups, and across simulated bone densities. RESULTS: Overall, implants with progressive thread designs showed significantly higher insertion torque values than standard thread designs (p = 0.008), and ISQ values were also higher in the PI group (p = 0.033). However, manufacturer-matched analyses revealed that this effect was not consistently reproducible across all implant systems. Significant differences between standard and progressive designs were seen for some manufacturers, while others showed no statistically significant differences. A positive correlation between insertion torque and ISQ values was found across all implant groups. CONCLUSIONS: Within the limits of this in vitro study, progressive thread designs were associated with increased primary stability in the overall analysis. However, this effect was not consistent across all manufacturer-matched implant systems, suggesting that macrodesign-related performance is system-specific rather than universally dependent on design.