Thread design optimization of a dental implant using explicit dynamics finite element analysis.

To optimize the thread design of a commercial dental implant for ideal stress distribution in the peri-implant bone. The models of the BLT((R)) Phi4.1 x 10 implant (Institut Straumann AG) and the alveolar bone were created. Dynamic von Mises stress (sigma(vM)) in the peri-implant cortical bone during and immediately after implantation was calculated using explicit dynamics finite element analysis (EDFEA). The combination of thread pitch, depth, tip width (TW), and coronal/apical surface angle (CSA/ASA), which produced minimal sigma(vM) was determined as the optimal thread design by orthogonal experimental design. The implants with optimal and original thread designs were fabricated and implanted into rabbits' tibias. Implant stability quotient (ISQ), bone-to-implant contact (BIC), and bone volume fraction in 500 mum (BV/TV-500) and 1000 mum range (BV/TV-1000) were measured to evaluate the osseointegration performance of the implants. The implant thread design of 0.8-mm pitch, 0.2-mm depth, 0.15-mm TW, 10-degree CSA, and 10-degree ASA produced minimal sigma(vM) for the maxillary posterior region (OPT-max). The thread design of 1.0-mm pitch, 0.3-mm depth, 0.2-mm TW, 0-degree CSA, and 20-degree ASA produced minimal sigma(vM) for the mandibular posterior region (OPT-man). Optimized implants showed significantly improved ISQ value (p < 0.05) 4 weeks after implantation. The BV/TV-500 and BV/TV-1000 around the OPT-max, and the BIC and BV/TV-500 around the OPT-man implant were significantly higher than those around the originally designed implant, respectively (p < 0.05). The thread design significantly affects the stress in the peri-implant bone during and immediately after the implantation. The optimal thread design based on EDFEA promoted the osteogenesis around the implant.