ε (eV)

treatment time, temperature, and pressure (for the steam case).
The devices using heat as an inactivation agent are the autoclave and the
dry heat oven. The autoclave is using a high pressure steam circulating at a
temperature of 121 ◦ C.Thetimerequiredforafulltreatmentcycleisvarying
from 20 minutes for unwrapped instruments to 30 minutes for wrapped ones. On
the other hand a more easy to sterilize sequence, when the composition of the
materials allows, is given by the dry heat. This is usually circulated by convection
through the oven chamber in order to touch all the surfaces of the instruments.
The standard temperatures are varying from 160 ◦ Cto170 ◦ C. The treatment
time is between 2 and 4 hours including the cooling time [31-34].
The major disadvantages of the heat sterilization methods come from the high
temperatures used for material processing or the high cooling periods needed after
treatment. The advantages rely on the simplicity of the method and the lack of
chemical contaminants [33, 34].
1.2.2 Sterilization by electromagnetic radiation
Photons from the ultraviolet (UV)-with wavelengths from 200 nm to 380 nm,
and vacuum ultraviolet (VUV)-with wavelengths less than 200 nm have been in-
tensively used as sterilization and disinfection agents in the past. It is believed
that the most effective wavelengths interval of the light spectrum for microorgan-
isms inactivation is between 220 nm and 285 nm [25, 35, 36]. At these wavelengths
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