(A) Photoelastic stress analysis model of the basic implant design. Note the higher levels of stress at the coronal (crestal bone) portion of the implant. The stresses are generally evenly distributed along the entire length of the implant to both the crestal and trabecular bone. (B) Grit-blasted, progressive threads characteristic of this implant design. Each thread has a different size and pitch. (C) Photoelastic stress analysis model of an Ankylos implant design. Note the lower stress accumulation at the coronal portion of the implant adjacent to the crestal bone and the gradual increase is stresses toward the apical end. (D) Stability (Periotest values [PTVs]) of both another screw implant design (shown in yellow) and the Ankylos implant (shown in red). Since the implant is designed to engage flexible trabecular bone, there is about 1 PTV difference in each bone density for Quality-1 and Quality-2 bone. This difference becomes less as the bone density decreases