The geological fluoroapatite single crystal was significantly harder than the teeth (which additionally contained an organic matrix). In our nanoindentation tests, no significant anisotropy was found between basal and side faces.
The geologicalfluoroapatite single crystal was significantly harder than theteeth (which additionally contained an organic matrix). In our nanoindentationtests, no significant anisotropy was found betweenbasal and side faces.