미니 임플란트 직경에 따른 피로파절강도의 비교 연구

Abstract

Objective: This study was conducted to obtain difference in fracture strength according to the diameter of one?]body O-ring?]type of mini implant fixture, to determine the resistance of mini implant to masticatory pressure, and to examine whether overdenture using O-ring type mini implant is clinically usable to maxillary and mandibular edentulous patients.

Materials and methods: For this study, we prepared 13 mm long one body O-ring?]type mini implants of different diameters (2.0 mm, 2.5 mm and 3.0 mm) (Dentis, Daegu, Korea), 5 for each diameter. The sample was placed at 30?? from the horizontal surface on the universal testing machine, and off-axis loading was applied until permanent deformation occurred and the load was taken as maximum compressive strength. The mean value of the 5 samples was calculated, and the compressive strength of implant fixture was compared according to diameter. In addition, we prepared 3 samples for each diameter, and applied loading equal to 80%, 60% and 40% of the compressive strength until fracture occurred. Then, we measured the cycle number on fracture and analyzed fatigue fracture for each diameter. Additionally, we measured the cycle number on fracture that occurred when a load of 43N, which is the average masticatory force of complete denture, was applied.

Results: Compressive strength according to the diameter of mini implant was 101.5?}14.6N, 149?}6.1N and 276.0?}13.4N, respectively, for diameters 2.0 mm, 2.5 mm and 3.0 mm. In the results of fatigue fracture test at 43N, fracture did not occur until 2☓106 cycles at diameter 2.0 mm, and until 5☓106 cycles at 2.5 mm and 3.0 mm.

Conclusion: Compressive strength increased significantly with increasing diameter of mini implant. In the results of fatigue fracture test conducted under the average masticatory force of complete denture, fracture did not occur at any of the three diameters. All of the three diameters are usable for supporting overdenture in maxillary and mandibular edentulous patients, but considering that the highest masticatory force of complete denture is 157N, caution should be used in case diameter 2.0 mm or 2.5 mm is used.