骨適合性を有する多相系生医学材料に関する研究

第1報ハイドロキシアパタイト-合成高分子-金属多相系材料の機械的性質

抄録

This study intended to develop a substitute material for the hard tissue used for replacement and reconstruction of a defective tooth and bone, namely, artificial materials with mechanical and biological compatibility with the bone as well as excellent processability and manipulatability.The author developed a hydroxyapatite [HAP]-polymer composite material consisting of HAP particles, poly (2, 2, 2-trifluoroethyl methacrylate)[PTFEMA] or poly (methyl methacrylate)[PMMA], and ternary multiphase material in which metal was incorporated, as an inner core, into the composite material, and then compared these physical and mechanical properties with those of human mandibular cortical bone [MCB], HAP ceramics block and synthetic polymer.
1) The physical and mechanical properties of MCB were compressive strength 1130.0±203.0 kg/cm ², Brinell hardness number 27.0±5.2, transverse strength 1690.0±287.0 kg/cm ² and modulus of elasticity (10.5±2.3)×10⁴kg/cm ².2) Each homopolymer of PTFEMA and PMMA was generally inferior to the bone in regards to physical and mechanical properties, and its modulus of elasticity showed that the material was soft.On the other hand, while having remarkably higher values of compressive strength, modulus of elasticity and Brinell hardness number than those of the bone, the HAP ceramics block proved to be hard and brittle, with poor transverse strength.3) The HAP-polymer composite material showed physical and mechanical properties close to those of the bone at HAP 70 wt%, except for transverse strength.4) While the transverse strength and diametral tensile strength of PMMA-HAP composite material decreased as HAP content increased, those of PTFEMA-HAP composite material showed a gradual increase.5) The water absorption of PTFEMA-HAP composite material is extremely small compared with that of PMMA-HAP composite material, and changes with time was hardly seen in the physical and mechanical properties by immersion in water at 37°C.6) The transverse strength of HAP-PTFEMA-metal multiphase material in which HAP-PTFEMA composite material and core metal were used has improved rapidly, showing a strength equal to that of MCB, with the modulus of elasticity also close to that of the bone.7) The molding method for HAP-polymer composite and HAP-polymer-metal multiphase material is by heatcuring polymerization using powder and liquid, such having superior processability and manipulatability.
Thus, the usefulness for clinical application of the multiphase material in which PTFEMA and HAP 70 wt% composite materials are used with a core metal has been proved as a substitute material for hard tissue, characterize by toughness, mechanical bone compatibility, excellent stability in wet conditions and easy processability and manipulatability.