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This paper describes evaluation process of bending strengths of plasma-sprayed hydroxyapatite (HAp) coatings. Plasma-sprayed HAp coatings are widely used in the fields of medical implant in order to improve the biocompatibility of substrate alloys in vivo. Their strength is normally evaluated by indentation-fracture method (IF method) or shearing tests. However, these results are considerably varied because of the pores on the surfaces of coatings and to accurately discuss the quality of coatings, the effects of pore size distributions on their strengths must be considered. The maximum pore size was then predicted using extreme statistics and modified Saltycov's method. In order to calculate fracture toughness of the specimen, indentation fracture method (IF) was applied. Fracture probability model were then used to determine the strength of the coating layers. [ABSTRACT FROM AUTHOR]