D R. S U LTA N Z A H I R

STERILIZATION IN DENTISTRY

STERILIZATION & DISINFECTION

• Sterilization is defined as the process where all the living microorganisms, including bacterial spores are killed.

• Sterilization can be achieved by physical, chemical and physiochemical means. Chemicals used as sterilizing agents are called chemisterilants.

• Disinfection is the process of elimination of most pathogenic microorganisms (excluding bacterial spores) on inanimate objects. Disinfection can be achieved by physical or chemical methods. Chemicals used in disinfection are called disinfectants. Different disinfectants have different target ranges, not all disinfectants can kill all microorganisms.

IMPORTANCE OF STERILIZATION

• Sterilization procedures are very important to any good dental practice. These are a part of basic care and handling of patients. Patients mouth are teeming with microbes, and any dental office that sees a large number of patients a day has an inherent potential for spreading infectious germs between patients and dental staff, through contaminated instruments and surfaces. These can be greatly minimized by following proper infection control procedures.

• Good dental infection control starts with the dentist’s room itself. A well-ventilated room with air-circulating devices prevents building up of aerosols produced from the dental drills. The sterile dentist and assistant are immunized against hepatitis, wear clean personal protective equipment—a scrub apron, eyewear, disposable gloves and facemasks. The patient is draped, and may be given a protective “face shield” to prevent skin contamination from the dental drill’s water spray. An anti-microbial mouth rinse just before a dental procedure is important to reduce contamination.

• The dental chair’s knobs and handles need to be chemically disinfected between patients.

• Surgical procedures require more stringent measures to eradicate all chances of infection and need special preparation of the dentist’s room. The dentist, assistant and patient all need sterilized gowns, and all instruments, drills, suction apparatus has to be completely sterilized.

STERILIZATION AND DISINFECTION OF DENTAL INSTRUMENTS

• According to the Centers for Disease Control, dental instruments are classified into three categories depending on the risk of transmitting infection.

• Critical• Semi critical • Non critical

• Critical instruments are those used to penetrate soft tissue or bone, or enter into or contact the bloodstream or other normally sterile tissue. They should be sterilized after each use. Sterilization is achieved by steam under pressure (autoclaving), dry heat, or heat/chemical vapor. Critical instruments include forceps, scalpels, bone chisels, scalers and surgical burs.

• Semi-critical instruments are those that do not penetrate soft tissues or bone but contact mucous membranes or non-intact skin, such as mirrors, reusable impression trays and amalgam condensers. These devices also should be sterilized after each use. In some cases, however, sterilization is not feasible and, therefore, high-level disinfection is appropriate.

• Non-critical instruments are those that come into contact only with intact skin such as external components of x-ray heads, blood pressure cuffs and pulse oximeters. Such devices have a relatively low risk of transmitting infection; and, therefore, may be reprocessed between patients by intermediate-level or low-level disinfection.

• An intermediate-level disinfectant (e.g., phenolics, iodophors, and chlorine-containing compounds).

• A low-level disinfectant (e.g., quaternary ammonium compounds).

METHODS OF STERILIZATION

Microbial Control Methods

Physical Agents Chemical AgentsMechanical Removal

Methods

Chemical Agent

Gas

Sterilization

Liquids

Mechanical Removal Methods

Filtration

Air

Disinfection

PHYSICAL METHODS OF STERILIZATION

• Dry Heat Sterilization • Kills by oxidation effects•The oven utilizes dry heat to sterilize articles • Operated between 50oC to 250/300oC.•A holding period of 160oC for 1 hr is desirable.• There is a thermostat controlling the temperature. •Double walled insulation keeps the heat in and conserves energy,

DRY HEAT STERILIZATION USE

• To sterilize Forceps, Scissors, Scalpels, Swabs.

• Pharmaceuticals products like Liquid paraffin, dusting powder, fats and grease.

MOIST HEAT STERILIZATION

• Kills microorganisms by coagulating their proteins.

MOIST HEAT STERILISATION IS CARRIED OUT WITH FOLLOWING METHODS: • Temp below 100oC: “Pasteurization”, Inspissator.

• Temperature at 100oC: Boiling.

• Steam at atmospheric pressure: Koch/Arnold’s steamer.

• Steam under pressure: Autoclave.

STEAM UNDER PRESSURE - AUTOCLAVE

AUTOCLAVE

• Autoclave consists of a vertical or a horizontal cylinder.

• One end has an opening which is meant for keeping materials to be sterilized.

• The lid is provided with a Pressure gauge, to measure the pressure

• A safety valve is present to permit the escape of steam from the chamber

• Articles to be sterilized are placed in the basket provided

• Sterilization is carried out under pressure at 121º for 15 minutes.

CHEMICAL AGENTS

Alcohol –Ethanol, isopropyl alcohol

Aldehyde – Formaldehyde, Glutaraldehyde

Ethylene oxide

Dyes

Halogens- iodine, Iodophores, Sodium hypochlorite

Phenolics- Carbolic acid 2.5%

Surface active agents

Metallic salts

Diguanides

Amides

ETHYLENE OXIDE

• Highly inflammable, mixed with inert gases – CO2, N

• Especially for sutures, syringes & all dental equipment's

RADIATION

Two types of radiations are used

NON –IONISINGIONISING• Non ionizing –

• Infra Red radiation ( rapid mass sterilization of syringes, etc.)

• Ultra Violet radiation (enclosed areas)

• Ionizing – Gamma, X ray, cathode ray(plastics, syringes, oil, metal foils)

• Infection control measures not only reduce the chances of getting a dental infection, they also reduce the risk of catching serious diseases like HIV and hepatitis.