infection control

Infections Control and Sterilization

• Microbial exposures in the dental operatory involve both
• Airborne contamination (concern for personnel).
• 2. Hand to surface contamination (concern for both patients and personnel).

• Airborne Contamination

• A high-speed handpiece is capable of creating airborne contaminants from both bacterial residents in the dental unit water spray system and from microbial contaminants from saliva, tissues, blood, plaque, and fine debris cut from carious teeth.

• Hand-to-Surface Contamination

• Saliva-contaminated hands of the hygienist, dentist, and assistant could repeatedly contact or handle unprotected operatory surfaces during treatments.


• Poorly cleaned soiled surfaces provide another source of gross environmental contamination to potentially contaminate both personnel and patients.

• Overview of Aseptic Techniques

• Barrier protection of personnel using masks, protective eyewear, gloves, using high volume suction, rubber dam and gowns is a standard requirement for dental procedures.
• Remove watches, jewelry, and rings that can penetrate gloves.
• Washing hands before and after wearing and removing gloves.
• To protect against aerosols, press edges of the rectangular mask close around the bridge of the nose and face.

5. Whatever is touched is contaminated.

6. Treating all patients as infectious.
7. Using rubber cup instead of brushes, and scaling instruments instead of cavitron for patients with respiratory infections.
8. Washing skin and eye or mucosa immediately after contact with blood or potentially infectious materials.
9. Protect surfaces and equipment that are not sterilized with disposable, single-use covers (barriers). Discard them after every appointment.

Oral Manifestations of Communicable Disease:

Disease that transfer from patient to dentist or from patient to patient.
It's very important to know the oral manifestation of the communicable disease since this will affected the patient management and to prevent the potential transmission hazard (infection control).


AIDS/HIV Infection:
• Persistent oral candidiasis with easily dislodged white curdlike patches scattered over the tongue and may be extended into oral mucosa and skin neoplastic (Kaposi's sarcoma).
• Painful herpes stomatitis.
• Undetermined lymphadenopathy and aphthous like ulcer.
• Persistent, severe, recurrent gingivitis and periodontitis that brings patients for dental care.

Viral Hepatitis:

• Only 2 of 10 persons show symptoms. For this reason, it is impossible to detect most infected persons by medical history (no distinct oral changes are associated with HV. The patient still asyptomatic for several years until end stage.

Herpes Simplex I and II Virus (HSV):

• Transmitted through saliva, direct contact with lesions.
• Herpatic gingivostomatitis with red gingiva.
• Small painful vesicles on lips, facial mucosa, palate, pharynx, tonsil or gingiva may rupture to form ulcer with red irregular border.

Chickenpox and Shingles :

• Transmitted by airborne droplets and direct contact.
• The lesion on the oral mucosa as non painful, blister like ulcer that resemble aphthous.
• Routine dental care should be postponed in patient with chickenpox until all lesion have crusted.

Tuberculosis:

• It is transmitted via inhalation of respiratory droplets and aerosols ( sputum and saliva).
• Oral lesion include gingivitis, tuberculosis of lip, and ulceration of tongue.


Mumps:
• Is viral infection spread by saliva via droplet dissemination and direct contact affected child on sub lingual and submandibular gland.

Sterilization Methods

• Cleaning Instruments Before Sterilization
Ultrasonic cleaning is the safest and most efficient way to clean sharp instruments (reamers, files, and burs).

It provides fast and thorough cleaning without damaging to the instruments, reduce puncturing wounds and it is one to nine times more effective than hand cleaning.

2. Sterilization

Sterilization is defined as killing all living organisms, including the most resistant forms of bacterial spores, vegetative bacteria and viruses.
Because most instruments contact mucosa and/or penetrate oral tissues, it is essential that reused instruments be thoroughly cleaned and sterilized by accepted methods that can be routinely tested and monitored.

• Method of Sterilization:

• Physical methods.
• Chemical methods.
• Combination between both.

Physical Methods

• Boiling Water:
• Its economic methods but does not kill spores, viruses and cannot sterilize instruments, also rusting the instruments and dulling the sharp edges ( rust can be minimize by using rust inhibitor such as sodium bicarbonate). Well- cleaned items must be completely submerged and allowed to boil at 100˚C for 10-30 min..


2. Dry Heat Sterilization:
• Conventional Dry Heat Ovens:
• Efficient and economic, sterilization achieved at temperatures above 320° F(160° C) for 30 minutes to achieve sterilization.
b. Short-Cycle, High-Temperature Dry Heat Ovens:
• A rapid high-temperature process that uses a mechanical convection oven that circulates air with a fan or blower. It reduces total sterilization time to 6 minutes for unwrapped and 12 minutes for wrapped instruments, sterilization achieved at temperatures approximately (370-375)˚F (185˚C).

• Advantages of Dry Heat Sterilization:

• Carbon steel instruments and burs do not rust, corrode, or lose their temper or cutting edges if they are well dried before processing.
• Disadvantages of Dry Heat Sterilization:
• High temperatures may damage more heat-sensitive items, such as rubber or plastic; without careful calibration more sterilization failures are obtained, the high temperature will affected the sharpness of instruments, and good sterilization cycles are prolonged at the lower temperatures.

3. Steam pressure sterilization (autoclaving):

• Moist heat in form of super-heated under pressure is one of the most effective in destroying microorganisms including viruses, fungi and spores in relatively short time.
• To insure sterilization, instruction related to time, temperature, and pressure must be followed carefully ( for light load of instrument the use of 20 pound/inch for 20 min. at 170˚C is enough to kill all M.O.) All metal items must be dry, moisture evaporating from instruments can slow the heating process.

Disadvantages: Rust carbon steel instruments and burs, this can be reduced by keeping them submerged in a small amount of 1% sodium nitrite solution for 2 min..

4. Radical Sterilization:

• Its efficient method but expensive, we use ultra-violet light, gamma, beta rays, we use this method to sterilize disposable needles and drugs.

5. Gas Method:

• Ethylene oxide sterilization is the best method for sterilizing complex instruments and delicate materials. Automatic devices sterilize items in several hours and operate at temperatures below 100° C. Less expensive devices operate overnight. Hand-pieces are sterilized by this method.


• Chemical Methods (Disinfection)
• It is always of two-step procedure: the initial step involves vigorous scrubbing of the surfaces to be disinfected (organic debris on the instruments reduce the activity of the disinfectant); the second step involves wetting the surface with a disinfectant and leaving it wet for the time prescribed by the manufacturer disinfectants.

• Disadvantages:

• (1) Disinfection cannot occur until fresh disinfectant is re-applied to a thoroughly cleaned surface and (2) disinfection does not sterilize (3) bacterial spores and many vegetative organism and viruses may not be killed (4) placing wet items into disinfectant trays dilutes the solution and lead to lost their activity.

• High-level liquid disinfectants

Used mainly for plastic items that enter the mouth and that cannot withstand heat sterilization like glutaraldehydes at 2% to 3% concentration.

Disadvantage: irritating, sensitizing to skin and respiratory passages, and can be toxic so need well-vented area.

2. Other Chemical Disinfectant:

• Alcohol: Methylated spirit, effective at 70%.
• Chlorhexidine: It has bactericidal effect against G+ and G- bacteria but not kill the virus.
• Hydrogen peroxide (H2 O2): Its mild antibacterial, librated O2 rapidly.
• Sodium hypochlorite: It has powerful germicidal effect.

Combination Between Chemical and Physical Methods

Chemical vapor pressure sterilization (chemiclaving):
Sterilization by chemical vapor under pressure is performed in a Chemiclave at 270° F (131° C) and 20 pounds of pressure. They are similar to steam sterilizers and have a cycle time of approximately half an hour.


Advantages:
Carbon steel and other corrosion-sensitive burs, instruments, and pliers are said to be sterilized without rust or corrosion.
Disadvantages:
Items sensitive to the elevated temperature will be damaged. Towels and heavy cloth wrappings of surgical instruments may not be penetrated to provide sterilization.