title: Effect of sterilization by gamma radiation on nano-mechanical properties of teeth.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Preventive and Restorative Dental Sciences, UCSF School of Dentistry, Box 0758, San Francisco, CA 94143, USA. d.brauer@imperial.ac.uk
authors.forename: Delia S
authors.initials: DS
authors.lastname: Brauer
authors.forename: Kuniko
authors.initials: K
authors.lastname: Saeki
authors.forename: Joan F
authors.initials: JF
authors.lastname: Hilton
authors.forename: Grayson W
authors.initials: GW
authors.lastname: Marshall
authors.forename: Sally J
authors.initials: SJ
authors.lastname: Marshall
mesh_terms: D001696:Biomechanical Phenomena; D003743:Dental Enamel / Q000528:radiation effects; D003804:Dentin / Q000528:radiation effects; D004548:Elasticity; D005720:Gamma Rays / Q000627:therapeutic use*; D006244:Hardness; D006801:Humans; D018625:Microscopy, Atomic Force; D008964:Molar, Third; D036103:Nanotechnology; D011829:Radiation Dosage; D013242:Sterilization / Q000379:methods*; D014070:Tooth / Q000528:radiation effects*; D019228:Tooth Crown / Q000528:radiation effects; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water