Abstract
This paper proposes an easy-to-use torsion test method for bioceramics in artificial bone application, because the artificial bones were sometimes broken in torsion in clinical courses and an international standard of torsion test has been needed to guarantee durability of the bioceramics. The dimensions of specimens were 8 mm in diameter, 20 mm in gage and 10 mm square in grip. The samples were chalk, 3 types of porous hydroxyapatites (porosity = 75% or 50%), and porous and dense hydroxyapatite / tri-calcium phosphate composites (porosity = 35% or 0%). The specimen was set in an opening torque measuring device for PET bottles, attached with cylindrical jigs to grip it. Torque was given by hands, with a special attention paid not to cause bending moment and axial load to the specimen. Except for dense hydroxyapatite / tri-calcium phosphate composite, most of samples were fractured in torsion at the gage, leaving spiral fracture surfaces. The torsion strength of the bioceramics ranged from several MPa to several tens MPa.
