RESUMEN
A 6-year prospective study was conducted to assess the clinical success rates and crestal bone response of a dental implant system with a stress-diversion design. Mathematical modeling, digital radiography with applied isodensity, and finite element analysis were used to highlight the effect of the stress distribution design. A total of 386 hydroxyapatite-coated prototypes and 234 commercial grit-blasted external hex implants were placed in virgin bone as well as various grafted maxillary regions, with 36% of the posterior implants being immediately loaded. Prototypes achieved 96.6% survival over a 3-year period. The grit-blasted implant, placed from 2000 to 2003, showed a 95% survival rate. There were no significant changes in crestal bone levels after the first 12 months of prosthetic loading. Engineering evaluations suggested that undesirable stresses were distributed from the crest of the ridge down through the center of the implant body.