Indications for Sterilization or Disinfection of Dental Instruments
As with other medical and surgical instruments, dental instruments are classified
into three categories - critical, semi critical, or no critical - depending on their risk of transmitting infection and the need to sterilize them between uses ( 9,37-40 ). Each dental practice should classify all instruments as follows:

4 MMWR May 28, 1993

" Critical. Surgical and other instruments used to penetrate soft tissue or bone are classified as critical and should be sterilized after each use. These devices include forceps, scalpels, bone chisels, scalers, and burs.

" Semicritical. Instruments such as mirrors and amalgam condensers that do not penetrate soft tissues or bone but contact oral tissues are classified as semi critical. These devices should be sterilized after each use. If, however, sterilization is not feasible because the instrument will be damaged by heat, the instrument should receive, at a minimum, high-level disinfection.

" Noncritical. Instruments or medical devices such as external components of xray heads that come into contact only with intact skin are classified as non critical. Because these non critical surfaces have a relatively low risk of transmitting infection, they may be reprocessed between patients with intermediate-level or low-level disinfection (see Cleaning and Disinfection of Dental Unit and Environmental Surfaces) or detergent and water washing, depending on the nature of the surface and the degree and nature of the
contamination ( 9,38 ).

Methods of Sterilization or Disinfection of Dental Instruments
Before sterilization or high-level disinfection, instruments should be cleaned thoroughly to remove debris. Persons involved in cleaning and reprocessing instruments should wear heavy-duty (reusable utility) gloves to lessen the risk of hand injuries.

Placing instruments into a container of water or disinfectant/detergent as soon as possible after use will prevent drying of patient material and make cleaning easier and more efficient. Cleaning may be accomplished by thorough scrubbing with soap and water or a detergent solution, or with a mechanical device (e.g., an ultrasonic cleaner).

The use of covered ultrasonic cleaners, when possible, is recommended to increase efficiency of cleaning and to reduce handling of sharp instruments.
All critical and semi critical dental instruments that are heat stable should be sterilized routinely between uses by steam under pressure (autoclaving), dry heat, or
Chemical vapor, following the instructions of the manufacturers of the instruments
and the sterilizers. Critical and semi critical instruments that will not be used immediately should be packaged before sterilization.

Proper functioning of sterilization cycles should be verified by the periodic use (at
least weekly) of biologic indicators (I.e., spore tests) ( 3,9 ). Heat-sensitive chemical indicators (e.g., those that change color after exposure to heat) alone do not ensure adequacy of a sterilization cycle but may be used on the outside of each pack to identify packs that have been processed through the heating cycle. A simple and inexpensive method to confirm heat penetration to all instruments during each cycle is the use of a chemical indicator inside and in the center of either a load of unwrapped instruments or in each multiple instrument pack ( 41 ); this procedure is recommended for use in all dental practices. Instructions provided by the manufacturers of medical/dental instruments and sterilization devices should be followed closely.

In all dental and other health-care settings, indications for the use of liquid chemical germicides to sterilize instruments (i.e., "cold sterilization") are limited. For heat-sensitive instruments, this procedure may require up to 10 hours of exposure to a liquid.

References
1. CDC. Recommended infection-control practices for dentistry. MMWR 1986;35:237-42.

2. CDC. Recommendations for prevention of HIV in health-care settings. MMWR 1987;36:(No.2S).

3. US Department of Health and Human Services. Infection control file: practical infection control in the dental office. Atlanta, GA/Rockville, MD:CDC/FDA, 1989. (Available through the US Government Printing Office, Washington, DC, or the National Technical Information Services, Springfield, VA.)

4. Department of Labor, Occupational Safety and Health Administration. 29 CFR Part 1910.1030, occupational exposure to bloodborne pathogens; final rule. Federal Register 56(235):64004-182, 1991.

5. CDC. Update: universal precautions for prevention of transmission of human immunodeficiency virus, hepatitis B virus, and other bloodborne pathogens in health-care settings. MMWR 1988;37:377-82,387-8.

6. CDC. Guidelines for prevention of transmission of human immunodeficiency virus and hepatitis B virus to health-care and public-safety workers. MMWR 1989;38(suppl. No. S-6):1-37.

7. CDC. Protection against viral hepatitis: recommendations of the Immunization Practices Advisory Committee (ACIP). MMWR 1990;39(No. RR-2).
8. CDC. Hepatitis B virus: a comprehensive strategy for eliminating transmission in the United States through universal childhood vaccination. MMWR 1991;40(No. RR-13).

9. Garner JS, Favero MS. Guideline for handwashing and hospital environmental control, 1985. Atlanta: CDC, 1985; publication no. 99-1117.

10. Garner JS. Guideline for prevention of surgical wound infections, 1985. Atlanta: CDC, 1985; publication no. 99-2381.

11. CDC. Guidelines for preventing the transmission of tuberculosis in health-care settings, with special focus on HIV-related issues. MMWR 1990;39(No. RR-17).

12. CDC. Recommendations for preventing transmission of human immunodeficiency virus and hepatitis B virus during exposure-prone invasive procedures. MMWR 1991;40(No. RR-8).

13. CDC. Update:investigations of patients who have been treated by HIV-infected health-care workers. MMWR 1992;41:344-6.

14. Chamberland ME, Bell DM. HIV transmission from health care worker to patient: what is the risk? Ann Intern Med 1992;116:871-3.

15. Siew C, Chang B, Gruninger SE, Verrusio AC, Neidle EA. Self-reported percutaneous injuries in dentists: implications for HBV, HIV transmission risk. J Am Dent Assoc 1992;123:37-44.

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17. Hadler SC, Sorley DL, Acree KH, et al. An outbreak of hepatitis B in a dental practice. Ann Intern Med 1981;5:133-8.

18. CDC. Hepatitis B among dental patients-Indiana. MMWR 1985;34:73-5.

19. Levin ML, Maddrey WC, Wands JR, et al. Hepatitis B transmission by dentists. JAMA 1974;228:1139-40.

20. Rimland D, Parkin WE, Miller GB, et al. Hepatitis B outbreak traced to an oral surgeon. N Engl J Med 1977;296:953-8.

21. Goodwin D, Fannin SL, McCracken BB. An oral surgeon-related hepatitis B outbreak. Calif Morbid 1976;14.
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23. Goodman RA, Ahtone JL, Finton RJ. Hepatitis B transmission from dental personnel to patients: unfinished business. Ann Intern Med 1982;96:119.

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24. Shaw FE, Barrett CL, Hamm R, et al. Lethal outbreak of hepatitis B in a dental practice. JAMA 1986;255:3261-4.

25. CDC. Outbreak of hepatitis B associated with an oral surgeon, New Hampshire. MMWR 1987;36:132-3.

26. Ciesielski C, Marianos D, Chin-Yih OU, et al. Transmission of human immunodeficiency virus in a dental practice. Ann Intern Med 1992;116:798-805.
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28. Gooch B, Marianos D, Ciesielski C, et al. Lack of evidence for patient-to-patient transmission of HIV in a dental practice. J Am Dent Assoc 1993;124:38-44.

29. Canter J, Mackey K, Good LS, et al. An outbreak of hepatitis B associated with jet injections in a weight reduction clinic. Arch Intern Med 1990;150:1923-7.

30. Kent GP, Brondum J, Keenlyside RA, LaFazia LM, Scott HD. A large outbreak of acupuncture- associated hepatitis B. Am J Epidemiol 1988;127:591-8.

31. Polish LB, Shapiro CN, Bauer F, et al. Nosocomial transmission of hepatitis B virus associated with the use of a spring-loaded finger-stick device. N Engl J Med 1992;326:721-5.

32. Siew C, Gruninger SE, Mitchell EW, Burrell KH. Survey of hepatitis B exposure and vaccination in volunteer dentists. J Am Dent Assoc 1987;114:457-9.

33. CDC. Immunization recommendations for health-care-workers. Atlanta, GA: CDC, Division of Immunization, Center for Prevention Services, 1989.

34. Petersen NJ, Bond WW, Favero MS. Air sampling for hepatitis B surface antigen in a dental operatory. J Am Dent Assoc 1979;99:465-7.

35. Bond WW, Petersen NJ, Favero MS, Ebert JW, Maynard JE. Transmission of type B viral
hepatitis B via eye inoculation of a chimpanzee. J Clin Microbiol 1982;15:533-4.

36. CDC. Public Health Service statement on management of occupational exposure to human immunodeficiency virus, including considerations regarding zidovudine postexposure use.MMWR 1990;39(No. RR-1).

37. Miller CH, Palenik CJ. Sterilization, disinfection, and asepsis in dentistry. In: Block SS, ed.Disinfection, sterilization, and preservation, 4th ed. Philadelphia: Lea & Febiger, 1991:676-95.

38. Favero MS, Bond WW. Chemical disinfection of medical and surgical materials. In: Block SS,
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39. FDA, Office of Device Evaluation, Division of General and Restorative Devices, Infection Control
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40. Rutala WA. APIC guideline for selection and use of disinfectants. Am J Infect Control 1990;18:99-117.

41. Proposed American National Standard/American Dental Association Specification No. 59 for portable steam sterilizers for use in dentistry. Chicago: ADA, April 1991.

42. CDC. Recommendations for preventing transmission of infection with human T-lymphotropic virus type III/lymphadenopathy-associated virus in the workplace. MMWR 1985;34:682-6,691-5.

43. Council on Dental Materials, Instruments, and Equipment; Dental Practice; and Dental Therapeutics. American Dental Association. Infection control recommendations for the dental office and the dental laboratory. J Am Dent Assoc 1988;1126:241-8.

44. Lewis DL, Boe RK. Cross infection risks associated with current procedures for using highspeed dental handpieces. J Clin Microbiol 1992;30:401-6.

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49. Garner JS, Simmons BP. CDC guideline for isolation precautions in hospitals. Atlanta, GA: CDC, 1983; HHS publication no. (CDC)83-8314.

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50. Tate WH, White RR. Disinfection of human teeth for educational purposes. J Dent Educ 1991;55:583-5.

51. Favero MS, Bond WW. Sterilization, disinfection, and antisepsis in the hospital. In: Balows A, Hausler WJ, Herrmann KL, Isenberg HD, Shadomy HJ, eds. Manual of clinical microbiology, 5th ed. Washington, DC: American Society for Microbiology, 1991:183-200.

52. The Michigan Medical Waste Regulatory Act of 1990, Act No. 368 of the Public Health Acts of 1978, Part 138, Medical Waste, Section 13807-Definitions.

53. Oregon Health Division. Infectious waste disposal; questions and answers pertaining to the Administrative Rules 333-18-040 through 333-18-070. Portland, OR: Oregon Health Division, 1989.

54. Bell DM. Human immunodeficiency virus transmission in health care settings: risk and risk reduction. Am J Med 1991;91(suppl. 3B):294-300.

55. Bell DM, Shapiro CN, Gooch BF. Preventing HIV transmission to patients during invasive procedures: the CDC perspective. J Public Health Dent (in press).

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MMWR

U.S. Government Printing Office: 1993-733-131/83011 Region IV
The Morbidity and Mortality Weekly Report (MMWR) Series is prepared by the Centers for Disease Control and Prevention (CDC) and is available on a paid subscription basis from the Superintendent of Documents,
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