The purpose of thisstudy was to assess the physical and mechanical properties of dental excasvating burs Three different kinds of #558 friction grip type dental excavating burs (S.S.White, Jet and Komet burs manufactured by S.S.White, Sybron and
Brasseler) were selected. Specimens were classified by non-sterilized control group and 4 testing groups with autoclaving, autoclaving, autoclaving using sodium nitrite, chemiclaving, and cold sterilization using Glutarex performed 10, 20, 30, 40
and 50
times. Components were analyzed by EPMA, surface hardness measured by Vickers hardness tester, degrees of corrosion, cutting efficiency,and neck strengthtested before and after sterilization. The results of tests were compared with normal control
group.
The results were as follows ;
1. Main components of heads of the burs were tungsten and cobalt. Iron was the main component of shanks of the burs. The shank of Komet contained 13% of chromium.
2. Surface hardness of heads were higher than shanks(p<0.01). Komet showed the lowest head hardness(p<0.05). S.S.White showed the highest shank hardness(p<0.01).
3. Chemiclaving showed the lowest corrosion. Komet showed the highest corrosion resistance and Jet the lowest.
4. Jet and Komet showed decrease in cutting efficiency after autoclaving irrespective of autoclaving times(p<0.05). All kinds of burs showed decrease in cutting efficiency after cold sterilization using Glutarex irrespective of cold steriization
times(<0.05).
5. Neck strength of S.S.White strilized autoclaving using sodium nitrite were decreased(p<0.05), but neck strength of other testing groups showed no changes irrespective of sterilization methods and times
In summary, chemiclaving appeared to be the comparatively desirable clinical sterilization method considering resisistance of corrosion, cutting efficiency and neck strength,
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