STERILIZATION OF TEETH BY GAMMA-RADIATION

Clinical simulations and restorative materials research and developmen t conducted in vitro require the use of large numbers of extracted tee th. The simultaneous need for infection control procedures and minimal alterations of structure and properties of the tissue prompted this s tudy of gamma irradiation as a method to eliminate microbes associated with extracted teeth and their storage solutions. Evaluations of pote ntial change in structure of dentin were conducted in terms of permeab ility, Fourier transform infrared spectroscopy (FTIR), and optical pro perties. The dose required for sterilization by gamma irradiation was established by means of a tooth model inoculated with Bacillus subtili s (10(8) organisms/mL). Sterilization occurred ata dose above 173 krad with use of a Cesium (Cs-137) radiation source. Gamma irradiation did not affect permeability of crown segments of dentin. A comparative ev aluation of the effects of four sterilization methods on dentin disks was based on FTIR and ultraviolet-visible-near infrared (UV/VIS/NIR) s pectra before and after sterilization by (1) gamma irradiation; (2) et hylene oxide; (3) dry heat; and (4) autoclaving. No detectable changes were found with gamma irradiation, but all other methods introduced s ome detectable change in the spectra. This suggests that common method s of sterilization alter the structure of the dentin, but gamma irradi ation shows promise as a method which both is effective and introduces no detectable changes as measured by FTIR, UV/VIS/NIR, or permeabilit y.