The attention is often paid toknowledge processing procedure including knowledge acquisition,knowledge expression and knowledge utilization when expert system is studied and designed.The knowledge expression is the most basic topic among them.Knowledge expression system and its application tomedical diagnosis computer-aided system are discussed in this paper.

OBJECTIVETo study the precise stress distribution of the apical foramen area of endodontic endosseous implant, in order to improve the prosthetics of endodontic endosseous implant.

METHODSAfter analysis of the two-dimensional endodontic endosseous implants model with finite element method, left and right areas beside the apical foramen were selected as infinite domains to calculate. D-N interactive method was used to connect the finite and infinite domains.

RESULTSUnder 45 degrees axial right oblique loading, the stress concentration occurred in both infinite domains of the apical foramen. The infinite domain nearing the load side was tension stress concentration, but the other side was compressive stress concentration. Two stress concentration points were just at the central points, which were intersections between implant and dentin. The stress reduced in all directions from these two stress concentration points, but in the ligament, the result was contrary.

CONCLUSIONSThe change of the tooth rotational center is helpful to the tooth stability and carrying capacity after restoration. In the implant area, the diameter of implant at the apical foramen of root shall not be reduced to protect root in clinical work. It is very important to preserve the tissue of periodontal ligament for endodontic endosseous implants.

Dental Implantation, Endosseous ; Dental Models ; Dental Stress Analysis ; methods ; Humans