A 3-DIMENSIONAL, FINITE-ELEMENT ANALYSIS OF BONE AROUND DENTAL IMPLANTS IN AN EDENTULOUS HUMAN MANDIBLE

The design of dental superstructures influences the loading on dental implants and the deformation of the anterior interforaminal bone in an edentulous mandible. This deformation causes stress in the bone around the implants and may lead to bone resorption and loss of the implant. The stress distribution around dental implants in an edentulous mandible was calculated by means of a three-dimensional, finite-element model of an entire lower jaw. This model was built from data obtained from slices of a single human mandible and was provided with two endosseous implants in the interforaminal region. The implants were either connected with a bar or remained solitary, and were loaded with a horizontal bite force of 10 N, a vertical bite force of 35 N, or an oblique bite force of 70 N. The most extreme principal stresses in the bone were always located around the neck of the implant. Stress around the implant was, therefore, not only caused by the local deformation of the bone due to movement of the implant and interface relative to the surrounding bone but also by the bending of the mandible. The most extreme principal stress was found with oblique bite forces. The highest maximum and lowest minimum principal stresses were 7.4 and - 16.2 MPa in the model without the bar and 6.5 and - 16.5 MPa in the model with the bar. When differences in the amount of bite force were eliminated, the vertical bite force resulted in the lowest stress. Differences in the stress concentration between the model with and without a bar were small and the direction of the bite force had much more influence than the connection of the implant abutments.