What is Sterilisation and Disinfection?
Sterilisation is a process of killing or eliminating all forms of microorganisms such as bacteria, viruses, fungi, algae and protozoa from clothes, equipment, and surfaces. Sterilisation can be achieved using chemicals, dry or moist heat, filtration or exposure to UV light.
Disinfection is the use of chemicals to eliminate most of the microorganisms from the surface of equipment, surgical devices, clothes or the floor of a room. Sterilisation and disinfection are standard practice in clinics, hospitals and laboratories to prevent the transmission of disease.
What Happens if Dental Instruments are Not Sterilised?
The instruments used in dental practice include forceps, periodontal knives, surgical burs, scalers, tweezers, plastic instruments, impression trays, mirrors and pulse oximeters.
They can be classified into 3 types depending on the risk of transmitting disease from microorganisms:
- Critical Instruments: These instruments penetrate deep into the soft tissue and bone of the jaw and need to be sterilised after every use. An example is a surgical bur.
- Semi-critical Instruments: These instruments come in contact with mucous membranes or unbroken skin and need cleaning followed by disinfection. An example is a reusable impression tray.
- Non-critical Instruments: These are instruments that come in contact only with intact skin and therefore require only disinfection. An example would be a pulse oximeter.
The oral cavity is a reservoir of microorganisms including bacteria, viruses, fungi and protozoa. Cross-contamination (from one person to another) may occur due to improper sterilisation of dental instruments. In recent years, certain bacteria have gained resistance to antibiotics and may cause serious infections. For example, mycobacterium can cause multi-drug-resistant tuberculosis. Moreover, certain open and invasive dental procedures may transfer the hepatitis virus or HIV from an infected to a healthy person.
Standard protocol of sterilisation includes the following steps:
- Pre-soaking and Cleaning: The instruments are immersed in a pre-soaking solution (containing phenols) to remove any debris and kill microorganisms. Scrubs may be used for cleaning.
- Corrosion Control and Lubrication: The instruments are dried. A rust inhibitor may be applied to prevent corrosion.
- Sterilisation of Instruments: The common sterilisation techniques used in dentistry include:
- Steam sterilisation using an autoclave is a widely practised technique to sterilise most reusable surgical instruments.
- Dry-heat sterilisation using a hot air oven is used to sterilise certain instruments like surgical burs which may be corroded by moist heat.
- Chemicals such as aldehydes, alcohols, ethylene oxide, phenols and halogens are used to disinfect semi-critical instruments.
- Filtration is used to sterilise liquids.
- Radiation such as UV is used to surface sterilise certain instruments and packaging materials.
- Storage and Distribution: The instruments are carefully packed and properly stored to avoid contamination and can be used whenever required.
Precautionary Measures for Dental Practitioners
Measures to be followed while performing a dental procedure and handling dental instruments include:
- Wearing an apron, gloves, mask and protective glasses to avoid contact with blood or saliva.
- Avoiding accidental pricking by needles or sharp instruments.
- Disposing of biomedical waste such as syringes and bandages separately.
- Having first-aid medicines, sterile bandages and equipment on hand in case of any emergencies.
Precautionary Measures for Patients
Precautionary measures for patients undergoing a dental procedure include:
- Look for an advanced dental clinic with proper facilities and hygienic practices.
- Talk to your doctor if you are pregnant or have an infection such as AIDS, and discuss medicines needed prior to the dental procedure. Inform your doctor if you are allergic to anaesthesia.
- Follow specific instructions provided by your dentist and take prescribed medications after the procedure.