Mechanical response to functional and therapeutic loading of a retromolar endosseous implant used for orthodontic anchorage to mesially translate mandibular molars.

Abstract

Three finite element models were created to investigate the potential of rigid osseous fixation (osseointegration) for orthodontic anchorage: a mandible without an implant; a mandible with an implant; and a mandible and implant with a superimposed orthodontic load. Force was applied to different locations and the stresses were computed. The mechanical stress distributions adjacent to the implant were not affected by different biting forces, hence only one case needed to be analyzed. The stresses adjacent to the bone-implant interface changed drastically due to implantation, with major changes occurring on the buccal and mesiobuccal sides. A strong, concordant gradient for intraosseous stress and bone remodeling rate was observed that reflects a mismatch in the moduli of elasticity between the implant and the supporting bone. These results suggest important clinical implications. Osseointegration of symmetrically threaded titanium implants appears to be maintained by a sustained elevation of the mechanical stresses that continuously stimulate the bone remodeling activity within 1 mm of the implant surface. It is unlikely that a rigidly fixed (osseointegrated) implant will lose integration due to an orthodontic load superimposed on normal function.