Long-term mechanobiological adaptation around immediately loaded dental implants

Abstract

Surgical insertion of dental implants causes damage to the surrounding bone tissue. Tissue healing and bone adaptation in the surrounding region are partly regulated by mechanical factors, and determine the long-term stability of the implant. While immediate loading of the implants is shown to be a successful treatment protocol, excessive micromotion of the implant may lead to implant encapsulation by soft tissue and subsequent failure of the treatment. The exact threshold and type of mechanical loading below which bone healing is not sacrificed needs to be determined.Biot's theory of Poroelasticity was used to model the mechanics of bone deformation during loading. Using Finite Element Method, the mechanical stimuli around an implant was calculated during loading and short- and long-term adaptations were modeled using previously developed mechano-regulatory models. Development of the mechanical stimuli during healing was found to be load-rate dependent, with complex spatial-temporal variations. Computational predictions of bone healing were consequently found to be very sensitive to subtle changes in mechanical loading. Loading by cyclical functions provided explainable mechanical behavior with less numerical instabilities. Progression of healing around implants under various modes of loading was investigated. The implant micromotion and its rate of motion were found to be the determinants of the healing outcome. Different modes of healing were also observed under different modes of loading. Gradually increasing the pressure on the implant showed a successful healing with proper functional recovery in terms of load carrying capacity. Long-term adaptation around dental implants was investigated by continuous adaptation of the healed bone. Different levels of initial implant micromotion-that led to different healed states-affected the patterns of long-term adaptation around implants as well. An optimal range of micromotion can be helpful at the patient-specific level for the most desired outcome.