Introduction
Infection control program aims at providing a framework in which dental treatment can be rendered safely and effectively. In the dental office infection may be transmitted via direct contact with blood, saliva, secretions via indirect contact with contaminated instruments, environmental surfaces and via air through aerosols of infectious body fluids.
A comprehensive infection control plan involves creation of protocols to safeguard health and safety of both patient and dental team; continuous review of infection control hazards and exposure, and routinely performing it in a strict manner.

Standard precautions
The Centre for Disease Control defines standard precautions as "any standard of care designed to protect health care personnel and patients from pathogens that can be spread by blood or any other body fluids, excretion or secretion". Many infectious diseases including HIV, Hepatitis B, C and D are commonly asymptomatic making it impossible to identify all those who may be carrying such infectious disease. Therefore, all body fluids from all patients should be treated as potential carriers of infective agents and the same infection control procedures must be used for every patient.

Information and training
All clinical staff including laboratory technicians must receive mandatory training covering Occupational Safety and Health Administration (OSHA) standards, blood borne diseases and their immunization, use of personal protective equipment (PPE), post exposure protocol and disposal of biohazard waste. It should be conducted annually and its formal record should be kept. All procedures in which actual/potential exposure to blood or infectious material may be anticipated and all individuals performing these procedures which are at great risk for exposure to pathogens should be identified. The risk of infection following exposure is determined by inoculum’s size, method of exposure and susceptibility of the host.

Immunization:-
All of the staff who are at potential risk of exposure should be offered vaccination for Hepatitis B virus. Immunization against rubella, mumps, influenza, rubeola, varicella zoster, tetanus is also recommended.

Infection Control procedures:-
Personal protective equipment (PPE):-
Appropriate PPE should be provided for all clinical staff.
Protective clothing: It is the outer layer/covering of garments that would first be contacted by the contaminating droplets. Protection against sprays, splashes, spatter, spills of body fluids or chemicals can be provided by high neck, long- sleeved, knee length garments.
Hand washing: Hand washing is an important means of protection and disease prevention. Hands should be washed with an antimicrobial soap (e.g. 4% chlorhexidine) or an alcohol based hand rub.
Gloves: Gloves should be worn for all patient contact activity. These needs to be changed between patients and a pair of gloves should not be used repeatedly. Hands should be washed before donning gloves and after their removal. Surgeon’s gloves should be worn during surgical procedures. Heavy utility gloves provide better protection during surface cleaning and disinfection and when handling contaminated instruments during clean-up.

Face masks: Face masks prevent patient’s spatter, splashes of contaminated solutions from contacting mucous membrane of mouth or nose of dental staff along with reduction in the inhalation of air borne particles.
Eyewear: Eyewear with face shield should be whenever aerosolization, spray or spatter is encountered.

Limiting contact with aerosol and spatter:-
While performing procedures on the patient steps should be taken to minimize splashing splattering and generation of aerosol. This is accomplished with the use of rubber dam, high-volume evacuation (HVE) and low-volume saliva ejector. Patient should not close his lips around the ejector tip or during use of HVE as it leads to back flow as a result of decrease in line pressure. Patient rinsing with an antimicrobial mouthrinse before starting the procedure helps in minimizing aerosol contamination.

Sterilization:-
Use of disposable items best prevents patient to patient contamination. These include gloves, masks, gowns, patient bibs, saliva ejector tips, trays etc. Only sterilized instruments should be used on patients. Presterilization cleaning should be done. Ultrasonic cleaning has shown effective results in removing dried blood and saliva. Usually, 2 to 20 minutes is needed to clean instruments ultrasonically. The cleaning solution used should be changed at least daily. After cleaning the instruments should be packed in a self-sealing, paper/plastic peel pouches.
To sterilize dental instruments various procedures are given. These can basically be categorized into:-
High-temperature sterilization/heat sterilization:- dry heat, steam, flash sterilization etc.
Low-temperature sterilization:- ethylene oxide gas, radiation, gas plasma hydrogen peroxide sterilization etc.
Liquid sterilants at room temperature:- 2.0% to 3.2% solutions of glutraldehyde for a contact time of at least 10 hours.

Sterilization monitoring:
 Three types of monitoring process are there to ensure that the instruments are safe for patient care.
· Physical – these include use of gauges, dials, indicators to show proper levels of time, temperature or pressure.
· Chemical/Process indicators – it uses heat sensitive inks that show change in color at a certain temperature.
· Biologic – it measures whether highly resistant bacterial spores have been killed. For steam and unsaturated chemical vapor Bacillus stearothermophilus spore and Bacillus subtilis for dry heat, ethylene oxide and gas plasma hydrogen peroxide is used.
This monitoring should be done weekly or monthly.

Radiographic asepsis:-
Surface of X-Ray unit should be covered. Plastic disposable covers should be placed on packs before they are placed into patient’s mouth. If these covers are not used, gloves must be worn for handling films. The contaminated wrappers are discarded, gloves removed and films are processed.

Laboratory asepsis:-
All contaminated items e.g. impressions, prostheses should be cleaned to remove blood, saliva, debris then disinfected with glutraldehyde, hypochlorite or iodophor before they are sent to the dental laboratory. Similarly, the items should be disinfected before they are sent back to the dental office from the laboratory. Laboratory equipment should also be sterilized or disinfected.

Surface asepsis:-
The surfaces in the dental treatment area can be separated into housekeeping surfaces e.g. floor, walls, and clinical contact surfaces that are often touched during treatment (e.g. handles, switches, instrument arms) requiring more thoroughly disinfection than housekeeping surfaces. PPE should be worn when performing surface cleaning/disinfection.
There are two general approaches for surface asepsis – to clean and disinfect contaminated surfaces and secondly use of surface covers to prevent the surfaces from contamination.
Surface disinfection – housekeeping surfaces must be cleaned with a detergent or disinfect on a regular basis.
Clinical contact surfaces should be disinfected with a tuberculocidal surface disinfectant. Other intermediate disinfectants which are bactericidal or virucidal can also be used. Hypochlorite, iodophor, water-based/alcohol-based synthetic phenolics, alcohol-based quaternary ammonium compounds are active ingredients in surface disinfectants.
Surface covers- materials that are impervious to moisture (e.g. thin plastics) are used as surface covers to prevent contamination of surfaces. These are particularly useful in areas that are difficult to clean and disinfect (dental light handles, knurled handles, air-water syringe buttons). In case the covered surfaces become contaminated, it should be removed and replaced.

Dental Unit Waterline (DUW):-
For surgery and endodontic irrigation dental unit water should not be used as microbes are present in it. For this purpose sterile irrigating solutions must be used. In dental unit water tubing the bacteria exists in the form of biofilm that coats inside of the lines. DUW effluent must contain less than 500 CFU of bacteria per mL. The control unit should be activated for 30 seconds before starting patient’s treatment. Flushing of water units with a disinfectant (hypochlorite solution), use of a bacterial filter into waterline of handpiece and air-water syringe and installing an anti-retraction valve to reduce retraction of contaminated water and saliva through dental handpiece into the water lines are the steps recommended to decrease the microbial potential for disease transmission.

Post Exposure Protocol:-
In case of an exposure, the route(s) of exposure and the circumstances under which the exposure occurred, the employee’s vaccination status should be documented. The sources individual’s blood should be treated to check for HBV, HIV diseases etc. after exposure, the employee’s blood should be tested immediately and follow-up should be done for 90 days.

Summary:-
Infection control consists of a series of procedures directed at reducing the number of microbes shared among people. Success of infection control depends upon establishing the proper procedure for it and then incorporating it in to daily practice in a disciplined manner. Due to emergence of new threats, it becomes extremely important to remain aware of these changes so as to provide effective infection control in order to safeguard the health of patient as well as clinical staff while providing dental health care.

References
1. American Academy of Oral and Maxillofacial Radiology: Infection control guidelines for dental radiographic procedures. Oral Surg Oral Med Oral Pathol 73:248-249, 1992.
2. American Dental Association Council on Scientific Affairs and ADA Council on Dental Practice. Infection control recommendation for the dental office and the dental laboratory. J Am Dent Assoc 127:672-680, 1996.
3. Cochran MA, Miller CH, Sheldrake MA: The efficacy of the dental dam as a barrier to the spread of microorganisms during dental treatment. J Am Dent Assoc 119: 141-144, 1989.
4. Craig DC, Quale AA: The efficacy of face-masks. Br Dent J 158: 87-90, 1985.
5. Miller CH: Disciplined microbial control. Dent Clin North Am 35:339-355, 1991.
6. Miller CH: Infection control. Dent Clin North Am 40: 437-456, 1996.
7. Miller CH, Sheldrake MA: The ability of biological indicators to detect sterilization failures. Am J Dent 7: 95-97, 1994.
8. Mc Dowell JW, Paulson DS, Mitchell JA: A simulated- use evaluation of a strategy for preventing biofilm formation in dental unit waterlines. J Am Dent Assoc 135: 799-805, 2004.
9. Sanchez E, Macdonald G: Decontaminating dental instruments. Testing the effectiveness of selected methods. J Am Dent Assoc 126: 359-368, 1995.
10. Terezhalmy GT, Gitto CA : Today’s minimal requirements for a practical dental office infection control and exposure control program. Dent Clin North Am 42: 629-642, 1998.
11. Thomas MV, Jarboe G, Frazer RQ: Infection control in the dental office. Dent Clin North Am 52: 609-628, 2008.