임플란트 고정체의 나사산 형태에 따른 지지골 응력분석

Abstract

The purpose of this study was to compare the stress pattern on the crestal cortical bone, cortical-cancellous bone interface and fixture-bone interface of the two fixtures using 3-dimensional finite element stress analysis. The finite element model was designed with the splinted crowns on the parallel placement of two standard fixtures(4.0 mm diameter×11.5 mm length) on the region of mandibular 1st and 2nd molars. Three dimensional finite element model was created with the components of the implant and surrounding bone. This study simulated loads of 200 N at the central fossa in a axial direction (load 1), 200 N at the buccal offset load that is 2 mm apart from central fossa in a axial direction (load 2), 200 N at the buccal offset load that was 2.7 mm apart from central fossa in a axial direction (load 3), and 200 N at the buccal offset load that was 3.5 mm apart from central fossa in a axial direction (load 4). Von Mises stress values were recorded and compared in the supporting bone. The results were as follows; 1. In the crestal cortical bone of the three thread models, the von Mises stress value of off-site region was higher than that of central fossa region. 2. With the loading of central fossa region, the von Mises stress pattern of the analyzing path on the fixture thread-bone interface were fluctuated following the positive and negative forms of the thread. 3. With the loading of central fossa region, the von Mises stress value of the base of thread was higher than the value of relative stress, and the stress value on the lingual base of equi-triangular thread type was higher than that of the crestal cortical bone. 4. With the buccal offset-loading of 2 mm apart from the central fossa region, the stress level on the base of the three fixtures was lower than the average value on the three thread types. The lingual base of the fixtures on the 1st and 2nd molars was higher than the level of the thread in the equi-triangular thread type model. 5. With the buccal offset-loading of 2.7 and 3.5 mm apart from the central fossa region which was positioned without the diameter of the fixture, the von Mises of the crestal cortical bone on the square thread type model was the highest among the three models. These results concluded that the thread type of the fixture was a mechanical factor which was affecting the stress pattern on the crestal cortical bone, the cortical-cancellous bone interface and the fixture-bone interface around the two fixtures under the same loading conditions and the geometry of the implant full body. With the buccal offset-loading apart from the diameter of the fixture, the stress was concentrated on the crestal cortical bone and the cortical bone. In conclusion, it should be considered that the design of occlusal scheme and the adjustment of the occlusal contacts follow the diameter of the fixture.