IV형 골질로 재생된 골에 식립된 내측연결시스템을 가진 임플란트에 대한 유한요소법적 분석

Abstract

The purpose of this study was to investigate the distribution of stress on the implant with internal connection type placed in the regenerated IV bone using three dimensional finite element stress analysis. Using EMRC NISA DISPLAY Ver. 12 program (IronCAD LLC, USA), a program was written to generate a model simulating a cylindrical block section of the mandible 20 ㎜ in height and 10 ㎜ in diameter. The 4.1 X 11.5-㎜ screw implant system with 8° morse taper, internal connection, and double tapered body (OSSTEM SS Ⅲ, Busan, KOREA) was modeled for this study, and was assumed to be 100% osseointegrated. The implant with external connection type (OSSTEM US III, Busan, KOREA) placed in native bone was used as a control group. And it was restored with gold crown with resin filling at the central fossa area. The implant was surrounded by the regenerated type IV bone, with 3.0 ㎜ in width and 7 ㎜ in length from the platform edge of implant. And the regenerated bone was surrounded by type I, type III of native bone, respectively. The present study used a fine grid model incorporating elements of 278,336 and nodal points of 53,942. A load of 200N was applied at the 2 points on occlusal surfaces of the restoration, the central fossa (A point), and the functional cusp (B point), at a parallel direction to the vertical axis of the implant, respectively. The stress values were calculated in implant and type Ⅳ regenerated bone interface, and 3-㎜ away point from implant fixture for implant with internal connection type. The results were as follows: 1. Stress on the implant with internal connection type/native bone interface was lower compared to that with external connection type/native bone interface irrespective of bone quality surrounding implant and loading points on implant prosthesis. 2. When the implant fixture was surrounded by native bone and loading was applied on central fossa, stress on implant/bone interface for the implant with internal connection type was lower compared to that with external connection type/native bone interface and distributed along the implant axis evenly. 3. When the implant fixture was surrounded by native bone and the load was applied on functional cusp, stress on implant/bone interface was concentrated with coronal part of implant, irrespective of connection system of implant. 4. Stress on implant/regenerated bone interface for the implant with internal connection type was distributed along the implant axis evenly, when the load was applied on the central fossa. 5. Stress on implant/regenerated bone interface for the implant with internal connection type was concentrated with coronal part of implant when the load was applied on the functional cusp. In summary, these data indicated that clinicians should select implant fixture according to the bone quality deliberately as stress distribution on implant with internal connection type is different from that on implant with external connection type.