Abstract

Structural properties have been shown to be critical in the osteoconductive capacity and strength of bioactive ceramic bone scaffolds. Given the cellular foam-like structure of bone scaffolds, nanoindentation has been used as a technique to assess the mechanical properties of individual components of the scaffolds. Nevertheless, nanoindents placed on scaffolds may violate the rigid support assumption of the standard Oliver-Pharr method currently used in evaluating the Meyer hardness, H, and elastic modulus, E-s, of such structures. Thus, the objective of this research was to use the structural compliance method to assess whether or not specimen-scale flexing may occur during nanoindentation of bioceramic bone scaffolds and to remove the associated artifact on the H and E-s if it did occur. Scaffolds were fabricated using tricalcium phosphate and sintered at 950 degrees C and 1150 degrees C, and nanoindents were placed in three different (center, edge, and corner) scaffold locations. Using only the standard Oliver-Pharr analysis it was found that H and E-s were significantly affected by both sintering temperature and nanoindents location (p < 0.05). However, specimen-scale flexing occurred during nanoindentation in the 1150 degrees C corner location. After removing the effects of the flexing from the measurement using the structural compliance method, it was concluded that H and E-s were affected only by the sintering temperature (p < 0.05) irrespective of the nanoindent locations. These results show that specimen-scale flexing may occur during nanoindentation of components in porous bioceramic scaffolds or in similar structure biomaterials, and that the structural compliance method must be utilized to accurately assess H and E-s of these components. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.