Abstract
This study was conducted to investigate the stress distribution of the surrounding bone by two-dimensional finite element methods, and histologically examine the flattening effect of alveolar ridge.
The alveollar bone conditions were classified into three patterns:model-① without alveoplasty of the ridge, model-② with slight alveoplasty of cortical bone, and model-③ with exposed cancellous bone.
The results were as follows
1. Based on the model of no alveoplasty, high stresses were distributed in cortical bone around the neck of the implant.
2. On the model of the alveoplasty within cortical bone, higher stresses concentrated on the remaining cortical bone, and the stresses in cancellous bone around the implant were much lower than those in cortical bone of its neck. These tendencies were similar to the result of the control.
3. The stress distribution of flattening to cancellous bone showed different tendencies in comparison with the two previous models. The stresses in the apical portion of the implant with vertical load greatly increased because of the loss of cortical bone, and compressive stresses occurred in extensive cancellous bone due to opposite horizontal load application.
4. In the animal experiment three months after implant placement with alveoplasty to cancellous bone, the well-matured cortical bone wall was around the implant.
These results suggested that the complete placement in the cancellous bone would be preferable in the case of implantation with flattening.
