構成材料の違いがインプラント体の強度に及ぼす影響：非線形有限要素解析による検討

抄録

Objective: The influences of abutments made from zirconia (Y-TZP) and cement materials on the strength of titanium implants were investigated by using the finite element method.
Methods: Non-linear analysis was performed using a finite element method program (ANSYS Ver. 11, ANSYS, Canonsburg, U. S. A.) and a personal computer. For the analysis model, the bisection, trisection, and modified trisection types, for which the reliability of analytical accuracy has been established by experiments, were used. Regarding the combination of constituent materials, fixtures made of JIS class-4 pure titanium were used for all samples, and the materials of the abutment and abutment-screw were changed. Temporary cement and resin cement were used for adhesion materials. The materials of the superstructure and abutment were the same, and compact bone was used under all conditions. A force of up to 1,000 N was loaded in the 45° oblique direction to the superstructure. The fixture, abutment, and abutment-screw were placed in contact, the bone bottom was entirely fixed, and the lateral sides were fixed excluding the longitudinal direction.
Results: When JIS class-4 pure titanium abutment-screws were used in the trisection type implant, the strength reached the maximum. In the case of the bisection and modified trisection types implants, the strength decreased greatly when using abutments made from zirconia, although their fracture strengths were equivalent to the fatigue strength of JIS class-4 pure titanium implants. The influence of the two types of cement on strength of implant depended on the structure and materials of the implant. However, no major difference due to the cement type was noted in the strength of any implant.
Conclusion: When the abutment and superstructure are prepared with zirconia, the maximum strength can be obtained by using JIS class-4 pure titanium abutment-screws in the trisection type. The design appropriate for all titanium implants is not necessarily appropriate for zirconia abutments; an appropriate design for zirconia abutments needs to be investigated. For the two kinds of cement examined, the strength of implant was hardly affected by the kind of cement.