PERSPECTIVE DENTISTRY: Methods of Sterilization

Sterilization

• removal of forms of microorganisms from the surface of an infection.

• Completely destroys all forms of microbial life including highly resistant bacterial force.

Disinfection

• process of eliminating or reducing pathogenic microorganisms such as fungi, bacteria, viruses on surfaces.

Physical and Chemical Methods of Sterilization

Methods of Sterilization

Heat Sterilization, Filtration, Irradiation, Sound waves vibration Sterilization, Fractional Sterilization

types of Physical Method of Sterilization

Moist heat sterilization and dry heat sterilization

types of heat sterilization

Moist heat sterilization

•  is done with the help of an instrument called an autoclave. An autoclave works on the principle of producing steam under pressure.

  • __________ is also known as your steam sterilization or autoclaving sterilization

  • What happens using an autoclave? Water is boiled in an autoclave at 121-134c at pressure of 15ksi

  • Optimum way of sterilization especially in healthcare field

Dry heat sterilization

• used on objects that are sensitive to moisture.

• relies on oxidation

Filtration

• mechanical method of sterilization in microbiology. This method uses membranous filters with small pores to filter out the liquid so that all the bigger particles and microbes cannot pass through.

• 3 steps of filtration: sieving, adsorption, trapping

• Usually not used in dental clinic, more on laboratory settings/microbiology settings

non-ionising radiation

• ultraviolet radiation is exposed to the object, which is absorbed by nucleic acids of the microorganisms.

• Leads to the formation of the pyrimidine dimers in the DNA strand of the bacteria which causes the replicative error and eventually the microbes dies

Ionising Radiation

• upon exposure to ionising radiations such as gamma rays and X-rays, reactive oxygen species such as hydrogen peroxide and superoxide ions are formed that oxidise the cellular components of the microbe, and they die.

Sound Waves Vibration

• Sonix sound waves ranging from 20-40 kHz in frequency are applied across the fluid to be sterilized.

• Sound waves produce an alternation of compressive and tensile forces forming cavities in the solution

• This cavities suddenly collapse which makes a microscopic voids and removes microorganisms from the container

Fractional Sterilization

• Method used for media containing gelatin or sugar.

• Typically, exposure to 100C for 20 minutes on 3 successive days is required.

• Usually use for petria dishes before use for lab works

• Principle: first exposure kills all the spores, they will be killed in subsequent forces

• This method may fail to kill spores of a certain smth

Gaseous Sterilization and liquid sterilization

types of chemical sterilizations

Gaseous Sterilization

• Is the method where the object is exposed to gas in a closed, heated and pressurised chamber.

• Gaseous chemical agents used include ethylene oxide, formaldehyde, nitrogen dioxide, ozone

• Gaseous sterilization is not commonly use for dental setting, we usually use liquid sterilization esp for outreaches

Liquid Sterilization

• process of immersing the object in a liquid such that it kills all the viable microorganisms and their spores.

• This method is less effective than gaseous sterilization and is used to remove low levels of contamination

• Common liquid agents that are used: hydrogen peroxide, glutaraldehyde,  hypochlorite solution

Tyndallization

also known as fractional sterilization