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Sterilizing Dental Handpieces
SPECIAL REPORT
R ESU LTS O F A W O R K S H O P O N H A N D P IE C E S A N D O TH ER IN S T R U M E N T S D E N T IS T R Y
IN
esponding to rising public concerns about dental handpiece sterilization, the ADA in A ugust convened a special workshop on handpieces and other instrum ents in dentistry. The workshop, held Aug. 27 a t ADA headquarters in Chicago, involved ADA leaders who are practicing dentists as well as representatives of key governm ent agencies, dental education, the research com m unity and the handpiece industry. Workshop participants explored a range of issues on handpiece sterilization and issued a num ber of specific recom m endations. Topics included: » th e dental handpiece im plicated as a vector in tra n sm ittin g infectious diseases; th e availability and cost of sterilizable handpieces; ■■ th e concept and definition of sterilization; ■■ the effectiveness of current sterilization methods; ■■ the effects of sterilization on handpieces; ■■ directions for future research. W hat follows is a sum m ary of the workshop’s deliberations and the group’s specific recom mendations. AVAILABILITY OF STERILIZABLE HANDPIECES
The representatives of the handpiece m anufacturers agreed th a t there is currently a shortage of sterilizable handpieces. The intense m edia attention th a t was focused on handpieces early in the sum m er caused dentists to place orders for handpieces w ith m any dealers sim ultaneously. Industry representatives indicated th a t all cu rren t back orders would be filled by the middle of Septem ber. W ith respect to price changes, all said th a t they had in stitu ted very m odest price increases to reflect inflation and th a t the price of the handpiece to the dentist is principally determ ined by the dealer or the direct sales companies. It was the consensus of the workshop th a t dental offices 44
JADA, Vol. 123, October 1992
should take an inventory of handpieces currently in their offices, which should include the num ber of handpieces, th eir age and model num bers. The m anufacturer of each handpiece should be contacted, if necessary, to determ ine if it is sterilizable. Handpieces purchased in the la st three to five years can probably be repaired/retrofitted by the m anufacturer to be compatible w ith h eat sterilization w ithout significant loss of perform ance better th a n can older models. Such an inventory should be done before ordering new handpieces. The ind u stry representatives em phasized th a t repair/retrofitting to m ake a non-sterilizable handpiece sterilizable or the rep air of a sterilizable handpiece has top priority. TRANSMISSION OF INFECTIOUS DISEASES
There was agreem ent th a t no epidemiological data exist to support the hypothesis th a t either the HIV or HBV virus has been tra n sm itte d by handpieces in dentistry.
Absence of such data, however, does not m ean th a t this has not or could not happen. F u rth er, it is probably not possible to design an ethical epidemiological study to either prove or disprove the hypothesis. A common sense approach w ith effective infection control practices is considered the best m eans to reduce any risk and protect the patient. STERILIZATION
The workshop participants agreed w ith the recom m endations of the Councils on D ental M aterials, Instrum ents and Equipm ent; D ental Practice; Dental Research; and Dental Therapeutics th a t handpieces be sterilized by a m ethod or m ethods th a t ensure sterility of in tern al and external surfaces. Although there are differences in current m ethods of sterilization, it was the consensus th a t any in strum ent th a t enters the m outh, including the handpiece, be sterilized between patients. Any disposable instru m en t— including handpieces or prophy
angles—intended for one-time use and which enters the m outh, m ust be discarded after each p atien t treatm en t is completed. METHODS OF STERILIZATION
It was agreed th a t th ere are significant differences in current m ethods of sterilization. H eat sterilization using an autoclave or chemical vapor is effective and currently recom mended by handpiece m anufacturers. Although the dry-heat oven m ethod m ay be an effective m ethod, th ere is increased risk of dam age and breakdow n of components of the handpiece. Critical factors include th e high tem perature and tim e required. Rapid dry h eat also m ay increase the risk of dam age to handpieces caused by the high tem peratures required. EFFECTS ON HANDPIECES
The life of a handpiece can be affected by sterilization, but cleaning and m aintenance according to instructions of the m anufacturer ol the handpiece JADA, Vol. 123, October 1992
45
are more critical to its lifetime th a n the sterilization method. H andpieces capable of sterilization should last indefinitely, because any component p a rt th a t fails can be replaced or repaired. The efficacy of a handpiece w ith tim e depends on the level of use and m aintenance in the dental practice. Although ethylene oxide exposure for a t least 12 hours is an effective sterilization m ethod if handpieces have been properly cleaned and dried, it is lim ited in its practicality in the practice of dentistry. Liquid chemical sterilan ts alone are not suitable for sterilization of handpieces. The use of a b arrier sleeve will reduce contam ination of external surfaces th a t do not en ter the m outh, m aking the in stru m en t easier to clean after use and before sterilization. However, use of such sleeves does not replace sterilization. U nder no conditions, a t this tim e, should chemical disinfectants be considered as an effective sterilization m ethod for handpieces. It was agreed th a t a sterilizable handpiece could be defined as one th a t can su stain a specific num ber of sterilization cycles w ithout significant reduction in perform ance or increase in noise level. A probable m ean value m ight be as high as 1,500 cycles.
46
JADA, Vol. 123, October 1992
Accredited S tandards Committee MD156, D ental M aterials, In stru m en ts and Equipm ent, is form ulating a stan d ard th a t will include evaluation of such param eters as cutting efficiency and noise
A common sense approach w ith effective infection control practices is considered the best means to reduce any risk an d protect the patient. level. Again, it was stressed th a t any handpiece removed from a p atien t’s m outh should be considered to be contam inated. It m u st be cleaned w ithout disassem bly unless so advised by the m anufacturer and then sterilized before use on the next patient. Alcohol is not recommended for cleaning because of dehydration of residual tissue. D etergent solutions and w ater, if recommended by the m anufacturer, should be used. An ultrasonic cleaner is effective for rem oval of residual debris, again, if recommended by the m anufacturer. It was repeatedly em phasized th a t there is a potential for increased risk of handpiece
degradation when inappropriate cleaning solutions and techniques are used. L am inated wall charts containing instructions for cleaning, sterilization, care after sterilization and m aintenance are available from most m anufacturers of handpieces. The instructions should be followed scrupulously by the dental staff. TYPE OF HANDPIECE
The need for sterilization is not dependent on th e handpiece type—high or low speed—or the clinical procedure involved. If it enters the m outh, it should be capable of being sterilized. It is not practical for the office staff to decide w hether sterilization betw een patients is necessary. W hen a central sterilization facility is used, its staff will not know th e clinical use of the handpiece. The portion of a slow-speed handpiece containing a motor housing th a t does not enter the m outh can still be contam inated w ith aerosols or during handling. The use of b arrier sleeves over the m otor housing area will reduce contam ination and m ake cleaning of th e surface easier before sterilization. Most slow-speed handpieces contain a sealed motor housing and can be sterilized. W hile it is agreed
th a t chemical disinfectants can kill HIV or HBV on th e surface of a clean and dry handpiece, there is inadequate penetration into the interior of the handpiece and into tissue debris present. For this reason, the m ost reliable m ethods for sterilization are autoclaving or chemical vapor w ith heat. The m ethod of determ ining kill rate s and the effectiveness of sterilization are not repeatable or certifiable for other m ethods. D uring sterilization the procedure should be m onitored. O bservation of tem perature and pressure and the use of h eat indicators and spore strips are the best m ethods available for m onitoring the sterilization treatm ent. Proper placem ent and use of h e a t indicators in each load, and spore strips a t least once a week are im per ative to m onitor effectiveness of the sterilization technique. It was agreed th a t the Association should develop recom men dations to ensure th a t the m onitoring system s are used properly and to outline the tra in in g required of office staff to accomplish this. FUTURE RESEARCH AND EDUCATION
Recom mendations for future research and for communication to th e m em bers of the
of infection control vs. handpiece lifetime for a wide range of dental practice situations. ■ profession and public included: ■■ Provide guidance on rep air and/or replacem ent of handpieces. ■■ Provide guidance on proper use and placem ent of m onitoring devices (heat and
It was repeatedly em phasized th a t there is a p oten tial for increased risk o f handpiece degradation when inappropriate cleaning solutions an d techniques are used. spore strips) in the sterilizer or w ithin instru m en t containers. «* Recommend standardized techniques, insofar as possible, for cleaning, sterilization and subsequent storage of handpieces. Develop a standard test protocol applicable to dental needs to evaluate the effectiveness of m ethods of sterilization. ■■ Develop a protocol to determ ine performance of instrum ents, especially the handpiece, after varying cycles of sterilization. Redesign, w here necessary, to m ake handpieces and other instrum ents easier to clean before sterilization. “ Conduct cost benefit analyses
W orkshop participants were: Dr. K enneth Anusavice, workshop chairm an, director, SMSRC an d chairm an, D epartm ent of D ental Biom aterials, U niversity of Florida; Dr. David L. Lewis, Faculty of Ecology, U niversity of Georgia; Lt. Cmdr. Jo h n K uehne, USAF D ental Investigation Service, A rm strong Laboratory/AOCD, Brooks AFB, Texas; Dr. W illiam S. TenPas, ADA 11th D istrict Trustee; Dr. Jam es H. Pearce J r., ADA 14th D istrict Trustee; Dr. P atrick J. F errillo J r., Southern Illinois U niversity, School of D ental Medicine; Dr. Richard A. M urphy, D epartm ent of O ral Medicine, U niversity of Illinois, Chicago; Dr. C hris H. Miller, D epartm ent of O ral Microbiology, Indiana U niversity School of D entistry; Dr. J. Thomas Arrowsmith-Lowe, FDA/CDRH, Office H ealth Affairs, Rockville, Md.; Dr. K eith Cox, Cox Sterile Products, Inc.; Mr. Rick M aynard, KaVo Am erican Corp.; Mr. Cecil Bean, DENTAL-EZ, Inc.; Dr. Donald W. M arianos, D ental D isease Prevention Activity, C enters for Prevention Services, C enters for Disease Control; Mr. A. B rennan, M idwest D ental Products Inc.; Mr. C raig L ares, L ares Research; Dr. Robert A. Kolstad, Baylor College of D entistry; Dr. E nid Neidle, division director, Scientific Affairs, ADA; Dr. Jo h n W. Stanford, director, CDMIE, ADA. Observers were: Dr. John A. Bogert, Am erican Academy of P ediatric D entistry; Dr. Jerom e Pisano, Am erican Association of Endodontists; Dr. Ludwig Leibsohn, Academy of G eneral D entistry; Dr. Jo n a th an W iens, F ederation of Prosthodontic O rganizations; Mr. Nikolaj M. Petrovic, Am erican D ental Trade Association. Association sta ff included: Dr. W illiam A. Allen, executive director; Dr. M ichael Perich, associate executive director; Dr. K enneth Burrell, CDT; Dr. P. L. F an, CDMIE; Dr. C. M. Schoenfeld, CDMIE; Dr. W. T. Wozniak, CDMIE; Dr. C. W hall, CDT; Ms. S. Stanford, CDMIE; Ms. S. McGill, CDMIE; Ms. E. H om uth, CDMIE.
JADA, Vol. 123, October 1992
47
R ESU LTS O F A W O R K S H O P O N H A N D P IE C E S A N D O TH ER IN S T R U M E N T S D E N T IS T R Y
IN
esponding to rising public concerns about dental handpiece sterilization, the ADA in A ugust convened a special workshop on handpieces and other instrum ents in dentistry. The workshop, held Aug. 27 a t ADA headquarters in Chicago, involved ADA leaders who are practicing dentists as well as representatives of key governm ent agencies, dental education, the research com m unity and the handpiece industry. Workshop participants explored a range of issues on handpiece sterilization and issued a num ber of specific recom m endations. Topics included: » th e dental handpiece im plicated as a vector in tra n sm ittin g infectious diseases; th e availability and cost of sterilizable handpieces; ■■ th e concept and definition of sterilization; ■■ the effectiveness of current sterilization methods; ■■ the effects of sterilization on handpieces; ■■ directions for future research. W hat follows is a sum m ary of the workshop’s deliberations and the group’s specific recom mendations. AVAILABILITY OF STERILIZABLE HANDPIECES
The representatives of the handpiece m anufacturers agreed th a t there is currently a shortage of sterilizable handpieces. The intense m edia attention th a t was focused on handpieces early in the sum m er caused dentists to place orders for handpieces w ith m any dealers sim ultaneously. Industry representatives indicated th a t all cu rren t back orders would be filled by the middle of Septem ber. W ith respect to price changes, all said th a t they had in stitu ted very m odest price increases to reflect inflation and th a t the price of the handpiece to the dentist is principally determ ined by the dealer or the direct sales companies. It was the consensus of the workshop th a t dental offices 44
JADA, Vol. 123, October 1992
should take an inventory of handpieces currently in their offices, which should include the num ber of handpieces, th eir age and model num bers. The m anufacturer of each handpiece should be contacted, if necessary, to determ ine if it is sterilizable. Handpieces purchased in the la st three to five years can probably be repaired/retrofitted by the m anufacturer to be compatible w ith h eat sterilization w ithout significant loss of perform ance better th a n can older models. Such an inventory should be done before ordering new handpieces. The ind u stry representatives em phasized th a t repair/retrofitting to m ake a non-sterilizable handpiece sterilizable or the rep air of a sterilizable handpiece has top priority. TRANSMISSION OF INFECTIOUS DISEASES
There was agreem ent th a t no epidemiological data exist to support the hypothesis th a t either the HIV or HBV virus has been tra n sm itte d by handpieces in dentistry.
Absence of such data, however, does not m ean th a t this has not or could not happen. F u rth er, it is probably not possible to design an ethical epidemiological study to either prove or disprove the hypothesis. A common sense approach w ith effective infection control practices is considered the best m eans to reduce any risk and protect the patient. STERILIZATION
The workshop participants agreed w ith the recom m endations of the Councils on D ental M aterials, Instrum ents and Equipm ent; D ental Practice; Dental Research; and Dental Therapeutics th a t handpieces be sterilized by a m ethod or m ethods th a t ensure sterility of in tern al and external surfaces. Although there are differences in current m ethods of sterilization, it was the consensus th a t any in strum ent th a t enters the m outh, including the handpiece, be sterilized between patients. Any disposable instru m en t— including handpieces or prophy
angles—intended for one-time use and which enters the m outh, m ust be discarded after each p atien t treatm en t is completed. METHODS OF STERILIZATION
It was agreed th a t th ere are significant differences in current m ethods of sterilization. H eat sterilization using an autoclave or chemical vapor is effective and currently recom mended by handpiece m anufacturers. Although the dry-heat oven m ethod m ay be an effective m ethod, th ere is increased risk of dam age and breakdow n of components of the handpiece. Critical factors include th e high tem perature and tim e required. Rapid dry h eat also m ay increase the risk of dam age to handpieces caused by the high tem peratures required. EFFECTS ON HANDPIECES
The life of a handpiece can be affected by sterilization, but cleaning and m aintenance according to instructions of the m anufacturer ol the handpiece JADA, Vol. 123, October 1992
45
are more critical to its lifetime th a n the sterilization method. H andpieces capable of sterilization should last indefinitely, because any component p a rt th a t fails can be replaced or repaired. The efficacy of a handpiece w ith tim e depends on the level of use and m aintenance in the dental practice. Although ethylene oxide exposure for a t least 12 hours is an effective sterilization m ethod if handpieces have been properly cleaned and dried, it is lim ited in its practicality in the practice of dentistry. Liquid chemical sterilan ts alone are not suitable for sterilization of handpieces. The use of a b arrier sleeve will reduce contam ination of external surfaces th a t do not en ter the m outh, m aking the in stru m en t easier to clean after use and before sterilization. However, use of such sleeves does not replace sterilization. U nder no conditions, a t this tim e, should chemical disinfectants be considered as an effective sterilization m ethod for handpieces. It was agreed th a t a sterilizable handpiece could be defined as one th a t can su stain a specific num ber of sterilization cycles w ithout significant reduction in perform ance or increase in noise level. A probable m ean value m ight be as high as 1,500 cycles.
46
JADA, Vol. 123, October 1992
Accredited S tandards Committee MD156, D ental M aterials, In stru m en ts and Equipm ent, is form ulating a stan d ard th a t will include evaluation of such param eters as cutting efficiency and noise
A common sense approach w ith effective infection control practices is considered the best means to reduce any risk an d protect the patient. level. Again, it was stressed th a t any handpiece removed from a p atien t’s m outh should be considered to be contam inated. It m u st be cleaned w ithout disassem bly unless so advised by the m anufacturer and then sterilized before use on the next patient. Alcohol is not recommended for cleaning because of dehydration of residual tissue. D etergent solutions and w ater, if recommended by the m anufacturer, should be used. An ultrasonic cleaner is effective for rem oval of residual debris, again, if recommended by the m anufacturer. It was repeatedly em phasized th a t there is a potential for increased risk of handpiece
degradation when inappropriate cleaning solutions and techniques are used. L am inated wall charts containing instructions for cleaning, sterilization, care after sterilization and m aintenance are available from most m anufacturers of handpieces. The instructions should be followed scrupulously by the dental staff. TYPE OF HANDPIECE
The need for sterilization is not dependent on th e handpiece type—high or low speed—or the clinical procedure involved. If it enters the m outh, it should be capable of being sterilized. It is not practical for the office staff to decide w hether sterilization betw een patients is necessary. W hen a central sterilization facility is used, its staff will not know th e clinical use of the handpiece. The portion of a slow-speed handpiece containing a motor housing th a t does not enter the m outh can still be contam inated w ith aerosols or during handling. The use of b arrier sleeves over the m otor housing area will reduce contam ination and m ake cleaning of th e surface easier before sterilization. Most slow-speed handpieces contain a sealed motor housing and can be sterilized. W hile it is agreed
th a t chemical disinfectants can kill HIV or HBV on th e surface of a clean and dry handpiece, there is inadequate penetration into the interior of the handpiece and into tissue debris present. For this reason, the m ost reliable m ethods for sterilization are autoclaving or chemical vapor w ith heat. The m ethod of determ ining kill rate s and the effectiveness of sterilization are not repeatable or certifiable for other m ethods. D uring sterilization the procedure should be m onitored. O bservation of tem perature and pressure and the use of h eat indicators and spore strips are the best m ethods available for m onitoring the sterilization treatm ent. Proper placem ent and use of h e a t indicators in each load, and spore strips a t least once a week are im per ative to m onitor effectiveness of the sterilization technique. It was agreed th a t the Association should develop recom men dations to ensure th a t the m onitoring system s are used properly and to outline the tra in in g required of office staff to accomplish this. FUTURE RESEARCH AND EDUCATION
Recom mendations for future research and for communication to th e m em bers of the
of infection control vs. handpiece lifetime for a wide range of dental practice situations. ■ profession and public included: ■■ Provide guidance on rep air and/or replacem ent of handpieces. ■■ Provide guidance on proper use and placem ent of m onitoring devices (heat and
It was repeatedly em phasized th a t there is a p oten tial for increased risk o f handpiece degradation when inappropriate cleaning solutions an d techniques are used. spore strips) in the sterilizer or w ithin instru m en t containers. «* Recommend standardized techniques, insofar as possible, for cleaning, sterilization and subsequent storage of handpieces. Develop a standard test protocol applicable to dental needs to evaluate the effectiveness of m ethods of sterilization. ■■ Develop a protocol to determ ine performance of instrum ents, especially the handpiece, after varying cycles of sterilization. Redesign, w here necessary, to m ake handpieces and other instrum ents easier to clean before sterilization. “ Conduct cost benefit analyses
W orkshop participants were: Dr. K enneth Anusavice, workshop chairm an, director, SMSRC an d chairm an, D epartm ent of D ental Biom aterials, U niversity of Florida; Dr. David L. Lewis, Faculty of Ecology, U niversity of Georgia; Lt. Cmdr. Jo h n K uehne, USAF D ental Investigation Service, A rm strong Laboratory/AOCD, Brooks AFB, Texas; Dr. W illiam S. TenPas, ADA 11th D istrict Trustee; Dr. Jam es H. Pearce J r., ADA 14th D istrict Trustee; Dr. P atrick J. F errillo J r., Southern Illinois U niversity, School of D ental Medicine; Dr. Richard A. M urphy, D epartm ent of O ral Medicine, U niversity of Illinois, Chicago; Dr. C hris H. Miller, D epartm ent of O ral Microbiology, Indiana U niversity School of D entistry; Dr. J. Thomas Arrowsmith-Lowe, FDA/CDRH, Office H ealth Affairs, Rockville, Md.; Dr. K eith Cox, Cox Sterile Products, Inc.; Mr. Rick M aynard, KaVo Am erican Corp.; Mr. Cecil Bean, DENTAL-EZ, Inc.; Dr. Donald W. M arianos, D ental D isease Prevention Activity, C enters for Prevention Services, C enters for Disease Control; Mr. A. B rennan, M idwest D ental Products Inc.; Mr. C raig L ares, L ares Research; Dr. Robert A. Kolstad, Baylor College of D entistry; Dr. E nid Neidle, division director, Scientific Affairs, ADA; Dr. Jo h n W. Stanford, director, CDMIE, ADA. Observers were: Dr. John A. Bogert, Am erican Academy of P ediatric D entistry; Dr. Jerom e Pisano, Am erican Association of Endodontists; Dr. Ludwig Leibsohn, Academy of G eneral D entistry; Dr. Jo n a th an W iens, F ederation of Prosthodontic O rganizations; Mr. Nikolaj M. Petrovic, Am erican D ental Trade Association. Association sta ff included: Dr. W illiam A. Allen, executive director; Dr. M ichael Perich, associate executive director; Dr. K enneth Burrell, CDT; Dr. P. L. F an, CDMIE; Dr. C. M. Schoenfeld, CDMIE; Dr. W. T. Wozniak, CDMIE; Dr. C. W hall, CDT; Ms. S. Stanford, CDMIE; Ms. S. McGill, CDMIE; Ms. E. H om uth, CDMIE.
JADA, Vol. 123, October 1992
47