L13: Sterilization method
Autoclave
EtO sterilization
Ionising radiation
Expose the implant to saturated steam @ 121 deg C
Purpose of saturated steam
Kill bacteria
Higher penetrative power than dry air
Moistens the pores --> bacteria more susceptible to moist heat
Heating to 121 deg C --> to denature the protein
Coagulate and denature protein to kill the microorganisms at high temperature and pressure
Includes lethal chemical changes within the microorganisms
EtO gas used
Gamma ray
Electron Beam
Radiation interacts with water, leading to the formation of free radicals that can diffuse far enough to reach and damage the DNA of the microorganism - Death of microorganism
Disadvantages
High capital cost
Decay of isotopes -
periodic need for additional isotope
Disadvantages
High capital cost
Limited penetration
- unsuitable for thick packaged product
Advantages
Wide range of materials are compatible with radiation
Disadvantages
Cause chain scission or crosslinking in polymers
- Change in mechanical properties : weaken the material
Cause discolouration (turn yellow) in polymers
Alkylation of amine groups on nuclei acid which prevents normal cellular metabolism
Require pre-conditioning step
Disadvantages
Can kill all types of microorganisms
Toxic, flammable and carcinogen
Chosen method
- Wear proper PPE
- Aeration to remove the EtO in material
- Proper release of EtO is needed
aeration uses water and air to remove the residue