title: The use of gamma irradiation for the sterilization of enamel for intra-oral cariogenicity tests.
abstract: The dose of gamma irradiation sufficient to sterilize enamel samples to be used for intra-oral cariogenicity tests (ICT) without alteration to the structure or solubility of the enamel was determined. Each bovine incisor used was cut vertically into eight portions and each portion assigned to one of eight groups. Group 1 was used as control while other groups were subjected to respective doses of gamma irradiation from a cobalt-60 source. Following sterilization, both control and experimental groups were incubated in nutrient broth for 7 days at 37 degrees C under aerobic and anaerobic conditions. Caries-like lesions were subsequently produced in each specimen using acidic buffer solution, and mineral loss quantified using transverse microradiography. Data were analysed statistically. There was no significant difference in mineral loss between the control and experimental groups, but the numerical value of mineral loss was lower in groups irradiated with> 4080 Gy, in addition to full sterilization and enamel discoloration to cream colour observed in these groups. Microbial growth was observed in the control group and in groups irradiated with <4080 Gy but no discoloration. With 4080 Gy full sterilization without discoloration was observed. It was concluded that 4080 Gy of gamma irradiation is optimal for sterilization of enamel samples for use in ICT.
authors.affiliation: Cariology Research Group, Department of Clinical Dental Sciences, The University of Liverpool, UK. b.t.amaechi@liverpool.ac.uk
authors.forename: B T
authors.initials: BT
authors.lastname: Amaechi
authors.forename: S M
authors.initials: SM
authors.lastname: Higham
authors.forename: W M
authors.initials: WM
authors.lastname: Edgar
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003037:Cobalt Radioisotopes; D003732:Dental Caries Activity Tests / Q000295:instrumentation / Q000379:methods*; D003733:Dental Caries Susceptibility; D003743:Dental Enamel / Q000382:microbiology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays / Q000009:adverse effects; D006801:Humans; D066298:In Vitro Techniques; D013242:Sterilization / Q000379:methods* / Q000706:statistics & numerical data; D013499:Surface Properties / Q000528:radiation effects; D017001:Tooth Demineralization / Q000209:etiology
chemical_list: D003037:Cobalt Radioisotopes