Does implant design affect primary stability in extraction sites?

Objective: Immediate implant placement and restoration following tooth extraction is desirable for shortening treatment times and maintaining oral structures. With a variety of bone-level implants available on the market, the goal of this in-vitro study was to compare different implant designs. Method and Materials: Using a polyurethane foam sandwich model with an intermediate cortical layer, a standardized extraction socket model was created. The following implant systems were assessed: OsseoSpeed EV (Astra), Straumann Bone Level Tapered (BLT), and Nobel Active (NA). Implant stability assessment included implant insertion torque (IT) and implant stability quotient (ISQ). The three implant systems were compared in a statistical analysis based on the two sample tests with the level of significance set at ? = .05 and Bonferroni correction for multiple comparisons. The relationship between IT and ISQ was assessed using the Pearson correlation coefficient. Results: IT values were highest for NA implants, with a mean of 36.52 Ncm, which was significantly greater than in BLT (P .001) and Astra (P .001). ISQ values were highest for NA, with a mean 53.9, which was significantly higher than for BLT (P .001) but not for Astra (P = .07). BLT showed significantly lower ISQ as compared to NA (P .001) and Astra (P .001). Overall, the IT and ISQ measurements did not correlate. Conclusion: The developed extraction model allowed for consistent measurements of implant stability parameters at a clinically relevant level. Implant design seems to play a relevant role for achieving primary stability in challenging situations. Next evaluation steps should involve testing under dynamic loading conditions. Keywords: extraction socket, immediate implant placement, implant design, implant stability, insertion torque