Objective To measure elastic modulus and hardness of supra-gingival dental calculus and to provide basis for force feedback system of dental robotics. Methods Ten specimen of supra-gingival dental calculus were obtained from 5 patients with periodontal disease. The cross-section view,4 mm × 10 mm × 10 mm in size was prepared in an epoxy mount and polished. Nanoindentation method was used to survey elastic modulus and hardness of supra-gingival calculus. Results Among the 10 specimens,a total of 100 indentat...