고정체 디자인과 골질에 따른 임플랜트의 유한요소법적 응력분석

Abstract

The propose of this study is to know how the stress is transmitted to the bone using 3-dimensional finite element analysis according to the direction and magnitude of loading applied to the implant, the cortical bone thickness, cancellous bone quality and the implant fixture design. The models of USⅡ(universal straight implant) and USⅢ(universal tapered implant) of external type AVANA implant (Ostem Co., Korea) were selected. The cortical bone thickness was divided into the normal thickness of 2.0mm and the thin thickness of 0.5mm. The material properties of the cancellous bone was divided into the typeⅡ-Ⅲ of 1,370 MPa (A), type Ⅲ-Ⅳ of 950 MPa (B), over than type Ⅳ of 550MPa (C). The magnitude of loading was used with the 200N and 400N. The direction of loading was selected to the vertical load(A) paralleled to the load axis at the central fossa, and to the oblique load (B) of 15˚ at the buccal cusp toward the central fossa. The following results were obtained : 1. The stress distribution by the implant fixture design was not different significantly, but the maximum stress equivalent to the alveolar bone was smaller to the tapered implant design than the straight implant design. 2. The thickness of the cortical bone was more influenced to the stress distribution than the quality of the cancellous bone. 3. The worse the quality of the cancellous bone was, the greater the stress to the cortical bone was concentrated and the greater the value of the maximum equivalent stress was. 4. As the magnitude wes increased from 200N to 400N, the value of the maximum equivalent stress was increased two times. 5. The maximum stress equivalent of the oblique load than that of the vertical load was shown worse. Above these results, the cortical bone thickness was most influenced among the many factors influenced to the stress distribution of the implant, and specially the unfavorable stress distribution was shown in case of the 0.5mm thickness of the cortical bone and the oblique load. The magnitude of the patient's masticatory power must be recognized in the implant prosthetic design because the magnitude of load is the directly influencing factor to the maximum stress equivalent. The implant fixture design of the straight type and the tapered type was not influenced significantly, but the maximum stress equivalent of the tapered design was smaller than that of the straight design, and also the stress distribution of the tapered design was better than that of the straight design as it was not different significantly.