SURFACE PROTECTION PROCEDURES

• Surfaces that are likely to be contaminated by the dental surgeon handling it or by the spill or spatter of oral contaminants should be disinfected. Surfaces touched by the dental surgeon are called TOUCH SURFACES.

• E.g. unit handles, various controls, hand piece, 3 way syringe, photodynamic unit etc. These instruments need to be treated with disinfectants or covered with a protective barrier.

• The surfaces which are contaminated by contact with soiled instruments are called

TRANSFER SURFACES.

• E.g. instrument trays, tube and hand piece holders.

• SPLITTER SURFACE is any surface which is not a touch or transfer or instrument surface and is within few feet of the oral cavity e.g. the dental chair surface. These surfaces are not cross contamination surfaces.

• Prevention of contact by touching and elimination of spill and spatter is ideal for preventing infection from surfaces. Since it is not possible, two main methods of protection of surfaces are used which are disinfection and barriers

• Disinfection involves cleaning of surfaces after every patient and application of disinfectant chemical material. These chemicals include—alcohol, iodophore, synthetic phenols, gluteraldehyde, chlorine etc.

• Dental patient chair: All chair functions should be controlled from a foot switch to avoid possible contamination by use of hand operate switches. Greatest potential for cross contamination is from chair mounted controls. Covering switches with clear plastics, which is replaced between patient sessions, will allow visualization and use without contamination of switches.

• Task seat or chair: Dentist should not touch seat covering with contaminated hands. Cleaning and disinfecting of porous seat covering may be accomplished with soap and water.

• Spittoons: Spittoons should be flushed with water, scrubbed and disinfected. Assembly around spittoons can be protected by barriers and removed when contaminated.

• Cabinetry: The amount of cabinetry should be minimized and they should be made from material that will with stand repeat cleaning and disinfection.

PROCEDURE FOR CLEANING OF DENTAL UNIT
WATER LINE

• All water lines should be flushed for 3-5 minutes if the system has been idle for several hours.

• After each patient running high speed hand pieces for a minimum of 20-30 seconds to discharge water and air should be done to flush out patient material that have entered during use.

• Routine disinfection of water lines is possible by using a disinfection solution in water lines while unit is idle.

• Anti-retraction valves to prevent backflow of patient material into water line should be regularly tested for proper functioning

• Suck about 1 liter of 1% sodium hypochlorite through the suction line at the end of the day, leave it for overnight. Next day before starting the work rinse with water and use.

SURFACE DISINFECTION

• Materials like sodium hypochlorite 5.25% (1:10 dilution), iodophors like Biocide & combination synthetics (Phenolics, Multicide & Omni II Vitaphine) have the disadvantage of leaving surfaces wet for 10 minutes, which is inconvenient in a busy dental practice.

• Glutaraldehyde products that are intended to be used as surface disinfectants contain only 0.25% (w/v) glutaraldehyde. However, they should be used with care, as repeated contact may damage the skin.

• Surfasept S.A is a commercially available disinfection solution which is aldehyde free, contains Isopropyl alcohol, chlorhexidine digluconate and flavoured excipient. It must be sprayed onto the area which must be completely and uniformly moistened then wiped.

• Surface disinfection can be done by scrubbing the surface with the iodophor-soaked gauze pads and allowed to dry. Then 70% isopropyl alcohol should be used to remove the residue.

INSTRUMENT DISINFECTION

ü  Least critical instruments such as Imaging Plate System, Intraoral Sensor, OPG unit should be disinfected.

ü  Quaternary ammonium compounds are cationic surface disinfecting agents. Commonly used ones are Cetrimide and Benzylkonium chloride. Disadvantages with these compounds are that they get inactivated by soap, reduced activity in presence of metal ions common in natural water, reduced effectiveness in presence of organic matter, lack of activity against tuberculosis bacteria and are not sporicidal.

ü  8% solution of formaldehyde in alcohol and 2% solution of activated glutaraldehyde were considered to be two disinfectant of choice.

ü  To disinfect the OPG or RVG machine Switch off  the unit.

ü  Remove all visible soil, if any, with disposable cloth or paper wipe.

ü  No disassembly shall be performed on the unit Dampen (not soak) a lint-free cloth with soap and running water.

ü Thoroughly clean all accessible parts of the unit, including the temporal head clamps, with the dampened lint-free cloth.

ü Dry the unit with hygienic disposable cloth.

ü  Dampen (not soak) a lint-free cloth with a low-level disinfectant.

ü  Wipe thoroughly all accessible parts of the unit with the dampened lint free cloth.

ü  Allow to dry in the open air for a minimum of five minutes.

Cleaning and disinfecting accessories that have contact with mucous membranes

ü  Remove and discard the protective sheath from the accessory.

ü  Remove all visible soil with a disposable cloth or paper wipe. Rinse at least one minute under running water to thoroughly clean the accessory from any excess soil.

ü  Using a soft brush, apply medical enzyme detergent solutions (basically, with a multi-enzymatic formula) to all surfaces of the accessory.

ü  Rinse thoroughly under running water for at least one minute to remove detergent residue.

ü  Dry the accessory with compressed air or a hygienic disposable cloth. Visually inspect the accessory for residual soil.

ü  If soil is visible, either repeat steps two to five, or safely dispose the accessory.

ü  Wrap the cleaned accessory using a standard packaging material for autoclaving.

ü  Steam autoclave at 132°C (270°F) for four minutes or depending on your local regulation you can steam autoclave at 134°C (273°F) for 18 minute

Intra Oral Sensor

ü  Remove the protective hygienic sleeves.

ü  Remove the debris or organic matter from the sensor surface with a disposable wipe or surface brush.

ü  Inspect the sensor for debris.

ü  Repeat cleaning if there is any debris left Disinfect the sensor head with disinfecting wipes or soak it in a disinfecting solution with intermediate-level hospital disinfectant with label claims of tuberculocidal activity eg. A chlorine-containing product, a quaternary ammonium compound with alcohol, a phenolics, an iodophors.

STERILIZATION

Sterilization can be accomplished in one of several ways. Some of the most common ways that are followed in dental practice include steam autoclave sterilization, dry heat sterilization, chemical vapour sterilization and ethylene oxide sterilization

Instrument Processing

The overall process consists of

• Holding ( presoaking )

• Pre cleaning

• Corrosion control, drying, lubrication

• Packaging

• Sterilization

• Sterilization monitoring

• Handling processed instruments

·       Presoaking:

Placing instruments in presoak solution until time is available for full cleaning prevents drying, begins to dissolve organic debris and in some instances begin microbial kill. Presoak solution consists of detergents, enzymes, or detergents containing disinfectants. Used solution should be discarded at least once a day.

·       Cleaning:

Blood, saliva and materials on instrument can insulate underlying microorganisms from sterilizing agents. Cleaning reduces this bio burden. Cleaning solutions with antimicrobial activity can eliminate build up of contaminants as the cleaning solution is being repeatedly used.

Hand cleaning:  It is an effective method if performed properly. Heavy utility gloves and protective eyewear should be worn during hand cleansing of instruments. Instruments should be immersed in the detergent solution and then scrubbed with soft brush.

·       Mechanical/Ultrasonic cleaning:

ü  Coupling of powerful ultrasonic vibrations with cold disinfection increases the effectiveness of the process.

ü  In a densely packed pile of instruments, there is only a thin layer of disinfectant around each instrument; vibration assures penetration of a properly concentrated solution into every area of every instrument.

ü  Cleaning solution specifically recommended for use in ultrasonic cleanser should be used in proper dilution. The instruments are kept in the ultrasonic cleanser basket and submerged in the cleaning solution.

·       Ultrasonic Cleaner:

ü  The cleaner should be covered and operated for 6-10 minutes or until no visible debris remains. If instrument cassettes are used cleaning time is increased to 15 minutes.

ü  After cleaning instruments are thoroughly rinsed. Cleaned instruments must be considered contaminated and handled with gloved hands.

Corrosion

CORROSION CONTROL AND LUBRICATION

It is an electrolytic process in which the contact of two dissimilar metals or dissimilar areas within a single metal sets up a potential difference resulting in an electron flow. The electron flow leaves behind reactive ions that readily combine with atmospheric oxygen to form oxides (rust). Conditions such as extreme temperatures, physical abrasion, galvanism, or reactive extraneous ions that disrupt the chromium oxide layer will render the steel vulnerable to corrosion. Instruments made of carbon or 400 series steel are more susceptible than those of 300 series steel. Recent studies showed no significant difference in mean wear whether sterilized with steam autoclave or dry heat.

To reduce corrosion

• Clean and remove debris from the instruments and rinse with distilled water.

• Avoid tap water which contains dissolved alkali and metallic ions.

• Water must be deionized and of good quality.

• Keep the pH of steam above 6.4; otherwise pitting will occur.

• Chrome plated instruments and stainless steel instruments should be sterilized separately because the electrolyte action can carry carbon particles from the exposed metal of a chromium plated instrument and get deposited on stainless steel.

• It is better to keep the instruments in wrapping. Detergents with chloride bases should be avoided because chloride residue unites with steam to form HCl.

• Detergents with pH of more than 8.5 may disrupt chromium oxide layer.

Packaging: Cleaned instruments should be packed prior to sterilization to protect them from recontamination after sterilization. The instruments should be packed in an appropriate wrapping material before sterilization. A wrapping material designed for a particular type of sterilizer should be used with the sterilizer. E.g. A single layer cloth wrap for steam sterilization, self sealing polyfilm paper pouches for chemical vapour sterilization, paper wrap for dry heat sterilization. Wrapping material should be self sealing or heat sealed or double folded and sealed with appropriate tape.

TYPES OF STERILIZATION

AUTOCLAVE:

ü Moist heat denatures and coagulates protein of microorganisms. The sterilization is due to latent heat of vaporization present in moist heat.

ü  When steam condenses on contact with cooler surfaces, it becomes water and gives latent heat to that surface.

ü  This principle is used in autoclave.

ü  Temperature required is 121°C for 20 minutes at 15 pounds pressure. For practical considerations high pressure vacuum models are operated at a temperature of136°C for 5 minutes at 30 pounds pressure.

ETHYLENE OXIDE STERILIZATION:

ü  Ethylene oxide at normal temperature is a gas with very high penetrating ability. It acts by alkylating the amino, carboxyl, sulphydril groups in protein molecules.

ü  It reacts with RNA and DNA.

ü  It sterilizes heat sensitive