Effect of sterilization by gamma radiation on nano-mechanical properties of teeth.

OBJECTIVES Extracted teeth used in dental research need to be considered infective and hence be sterilized without the materials' properties being altered. This study examined the effect of gamma radiation on the nano-mechanical properties of dentin and enamel of extracted human third molars. METHODS Whole teeth were sterilized using gamma radiation doses of 7 kGy and 35 kGy, respectively; teeth of the control group were not treated with gamma radiation. Crowns were sectioned occlusally and polished. Elastic modulus and hardness were tested using atomic force microscopy with nano-indentations under wet conditions. RESULTS The authors found no significant dose-response relationship in elastic modulus or hardness in either dentin or enamel. SIGNIFICANCE Nano-indentation is a common technique for the determination of local mechanical properties in biological hard tissues. Gamma radiation is an efficient way to sterilize extracted teeth while alteration of dentin and enamel mechanical properties are minimized.