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A survey of sterilization practices in selected endodontic offices
0099-2399/86/1205-0206/$02.00/0 JOURNAL OF ENDODONTICS Copyright 9 1986 by The American Associationof Endodontists
Printed in U.S.A. VOL. 12, NO. 5, MAY 1986
CLINICAL ARTICLE A Survey of Sterilization Practices in Selected Endodontic Offices Charles J. Palenik, MS, Thomas N. King, DDS,MS, Carl W. Newton, DDS,MS, Chris H. Miller, PhD, and Leonard G. Koerber, EdD
Little information exists concerning the effect(s) office asepsis procedures can have on sterilization success in dental speciality offices. Therefore, 218 randomly selected private endodontic offices in five midwestern states were sent spore strips, use instructions, and a 16-question survey. The questionnaire dealt with practitioner/auxiliary training, continuing education practices, and office sterilization procedures. Offices returning "positive" spore strips were sent additional strips and guidelines for improving sterilizer performance. Survey data were compared with sterilizer type and spore killing results. A total of 139 sterilizers in 106 offices was monitored. Testing results indicated a 15.1% overall failure rate. Of the offices with sterilization failures, only 68.2% responded for retesting. However, all of the responding offices eventually achieved negative spore tests. Dry heat ovens were most likely to have a sterilization failure (p < 0.05). None of the surveyed practices nor procedures could be related to sterilization success.
lack of equipment maintenance. Sterilizer malfunctions can result in internal temperature variations, improper steam pressures, and inadequate chemical/gas concentrations. In fact, most sterilizer failures are caused by human errors, not by mechanical malfunctions (4, 5). Because the occurrence of most sterilization problems is unpredictable, it is necessary to routinely monitor equipment performance. Physical observations and internal and external chemical monitors can provide immediate results. Unfortunately, such methods can measure only one parameter, such as temperature or the presence of a specific gas. They cannot assess all of the physical factors that must work in concert so that sterilization can be achieved. The main guarantee of sterilization is the successful killing of a bacterial endospore sample (2, 5, 6). The need to biologically verify instrument sterilization in dental offices has been graphically demonstrated in three studies. A study of 342 private Minnesota dental office autoclaves showed that about one of three was not achieving sterilization (7). Each office was sent three spore test ampules and instructed to place one in an average sterilizer load on three different days. More than 20% returned tests which failed on one of the three test days, 5% of the offices failed tests on two of the three days, and 6% failed tests on all three days. Thus, 31% of the participating offices had at least one spore test failure. Another study surveyed the sterilization procedures used by the 25 private practice oral surgeons in Norway (8). When office/clinic equipment was spore checked, sterilization failure was detected in 5 of 22 steam autoclaves, 2 of 4 dry heat ovens, and all 9 unsaturated chemical vapor sterilizers. A third study which tested sterilizers in private West German dental offices indicated that 8 of 69 steam autoclaves, 44 of 116 dry heat ovens, and 8 of 9 unsaturated chemical vapor sterilizers failed spore testings (9). Further examination of sterilization practices indicated that
Reducing the chances of cross-infections during the practice of dentistry includes the use of sterile instruments. Currently there are four types of sterilization which can be easily controlled and their effectiveness verified during use in the dental office. These include steam autoclaves, dry heat ovens, unsaturated chemical vapor sterilizers, and ethylene oxide gas sterilizers. The American Dental Association recommends that all instruments, burs, mirrors, bands, and other devices used in intraoral treatments be sterilized by one of these four methods (1-3). Regardless of the type of sterilizer used, a number of factors can interfere with the sterilization process. Many of the problems can be related to operator inattentiveness, improper wrapping and inadequate presterilization cleaning of instruments, or to a generalized 206
Vol. 12, No. 5, May 1986
Survey of Sterilization Practices
instrument overloading, opening of the sterilizer during the processing cycle, and inadequate exposure intervals were the major causes of failure. This study was undertaken because little information presently exists concerning the effects office asepsis procedures and personnel training backgrounds could have on sterilization success in private dental offices. MATERIALS AND METHODS
Study participants were randomly chosen from a current members roster of the American Association of Endodontists. The 218 selections came from five midwestern states. Packets of study materials were sent to primary office addresses only. Each packet contained an introductory letter describing the nature and significance of the research project and an invitation to participate. Also enclosed were two bacterial test strips (Spordi; AMSCO/Medical Products Division, Erie, PA) and instructions as to their use. Participants were asked to place a spore strip in the center of their sterilizer during a routine cycle. Strips were to be used on different days. Finally, the study packets contained a short office survey and a return envelope. The survey was composed of 16 questions concerning practitioner/ auxilary training, continuing education practices, and office sterilization procedures. Because the strips contained both Bacillus stearothermophilus and Bacillus subtilis (globigii) spores, they could be used to monitor steam autocalves, dry heat ovens, unsaturated chemical vapor sterilizers, and ethylene oxide gas sterilizers. Extra materials were sent upon request to offices where more than one sterilizer was present. TABLE 1. Study participation pattems
No. of Offices Sent Materials
No. of Offices Participating
% Participation
No. of Units Tested
IL MI IN OH Wl
60 45 20 60 33
29 25 12 32 20
48.33 55.56 60.00 53.33 60.61
36 30 14 39 20
Total
218
118
54.13
139"
State
* Value represents 21 offices in which two sterilizers were evaluated.
Spore strips were aerobically incubated at 37~ (steam autoclave and unsaturated chemical vapor) or 56~ (dry heat or ethylene oxide) immediately upon their return (10-12). The culture medium was trypticase soy broth (BBL Microbiology Systems, Cockeysville, MD) supplemented with 0.25% (wt/vol) glucose. Tubes were examined after 5, 7, and 10 days of incubation. Aliquots from tubes demonstrating microbial growth were subcultured and Gram stained. Offices returning positive spore strips were sent additional monitoring materials and a set of guidelines for improving sterilizer performance. Offices with negative spore tests were notified by mail. The office survey contained 16 questions which dealt with practitioner and auxiliary training backgrounds, professional memberships, continuing education practices, and office sterilization procedures. Information obtained from the survey responses were statistically compared using a x 2 analysis to the type(s) of sterilizing equipment present in the office and spore strip results. RESULTS
Table 1 contains participation patterns according to state. In the five-state sampling area, 54.13% or 118 offices returned processed spore strips and completed surveys. Twenty-one offices requested extra monitoring supplies so that a second office sterilizer could be evaluated. Test sterilizers included 66 steam autoclaves, 56 dry heat ovens, 16 unsaturated chemical vapor sterilizers, and 1 ethylene oxide gas sterilizer (Table 2). A single type of sterilizer predominated (p < 0.05) in four states. For example, steam autoclaves were used by a significant number of endodontists in Indiana, while the dry heat oven was the major type of sterilizer in Ohio offices. Slightly more than 33% of participating offices indicated in their surveys that they used some type of alkaline glutaraldehyde solution. Spore strip results are presented in Table 3. Of the 139 sterilizers tested, 21 (15.1%) returned at least one positive spore strip. Ten (7.19%) sterilizers failed both spore strip tests. The dry heat oven produced significantly higher (p < 0.05) rates of spore strip killing failures (26.79%) than any of the other types of steriliz-
TABLE 2. Distribution of sterilization methods
State
Steam Autoclave*
Dry Heat*
Unsaturated Chemical Vapor*
Ethylene Oxide*
Alkaline Glutaraldehydest
IL MI IN OH Wl
21/58.33 14/46.67 10/71.43 14/35.90 7/35.00
11/30.56 14/46.67 4/28.57 23/58.97 4/20.00
4/11.11 2/6.66 0/0.00 2/5.13 8/40.00
0/0.00 0/0.00 0/0.00 0/0.00 1/5.00
13/36.11 7/23.33 7/50.00 13/33.33 6/30.00
Total
66/47.48
56/40.29
16/11.50
1/0.72
46/33.09
* Number of units testedJpercentage of unite tested per state. t Number of offices using the agent/percentage of offices participating per state.
207
208
Journal of Endodontics
Palenik et al.
TABLE 3. Sterilization results of initial evaluation by method No. of Positive Spore Strips Returned*
Sterilization Method Steam autoclave Dry Heat Unsaturated chemical vapor Ethylene oxide Total
0
1
2
62/93.94 41/73.21 14/87.50 1/100.00
1/1.52 9/16.08 1/6.25 0/0.00
3/4.54 6/10.71 1/6.25 0/0.00
118/84.89
11/7.91 10/7.19 21/15.1
* Numberof unitstested/percentageof sterilizertypetested. TABLE 4. Results of sterilizer retesting Sterilization Trial First Second Third
No. of Positive Spore Strips Returned*
0
1
2
118 12 1
11 4 0
10 0 0
* Resultsindicatea 15.1%failureratefromthe entirestudy;76.2%of the "positivespore strip" officestook advantageof a secondtestingwhileonly25.0%performeda thirdtesting. TABLE 5. Survey questions not correlatable to sterilizer performance 1. Years as a practicing endodontist 2. Site and type of speciality training 3. Board certification status 4. Culturing procedures used 5. Dental journals routinely reviewed 6. Attendance at the annual American Association of Endodontists meeting 7. Continuing education attendance and preferences 8. Office instrument packaging procedures 9. Experience levels of office auxiliaries 10. Training backgrounds of office auxiliaries 11. Physical and chemical methods used to monitor sterilizer performance 12. Frequency of biological monitoring
ers. The overall failure rate for steam autoclaves was 6.06% and for unsaturated chemical vapor it was 12.5%. The single ethylene oxide gas sterilizer produced a negative spore test result. All offices that returned positive spore strips were sent additional strips and guidelines for improving sterilizer performance. All offices taking advantage of the additional testing eventually achieved a negative spore strip test. Sixteen of 21 sterilizers with spore strip failure were retested (Table 4). All participating offices returned completed surveys. None of surveyed office/practitioner practices or procedures could be correlated to sterilization success. Survey data that could not be correlated to sterilizer performance are presented in Table 5.
quite limited, this rate is lower than those determined in private general practice or oral surgery offices (7-9). However, any sterilization failure demands immediate remediation. Certain types of sterilizers predominated in four of the five states studied. This could be related to a familiarity with a certain type of sterilizer during undergraduate, graduate, or military training or experiences. It is also important to note that more than onethird of the test offices used some type of alkaline glutaraldehyde solution. The use of such materials is on the rise (13, 14), and it appears that endodontists are participating in this trend. The dry heat oven had a significantly higher (p < 0.05) rate of sterilizer failure than the other types of sterilizers. Although its operation is simple and inexpensive, problems with dry heat oven sterilization have been previously noted (8, 9, 15, 16). Because most sterilization failures can be related to human error, the greater failure rate could be due to inadequate instrument exposure intervals, of special concern are sufficient warm-up times, equipment overloading, poor internal air circulation, and improper wrapping. Failures noted in the steam autoclave and unsaturated chemical vapor sterilizers could also be related to these factors and also to inadequate internal gas pressures or improper chemicals. A total of 21 positive spore strip tests was recorded. All offices that participated in a second or third testing eventually achieved a negative result. Usually a change in sterilization procedure was all that was needed. In a limited number of cases equipment repair was warranted. Information collected from all study participants concerning personnel training and continuing education practices as well as office aseptic procedures were compared with sterilizer failure or success. None of these items could be correlated to sterilizer effectiveness. It appears difficult to correlate sterilization success or failure to a single personal or practice trait. Although the major causes of sterilization problems are well documented, the application of one such parameter to individual situations may be suspect. The sterilization process is a combination of a variety of procedures which include both human and material factors. It would have been interesting if this study had determined the critical importance of one or two practice or personal elements. However, the inability to establish such identifications only reinforces the known complexity of the sterilization process. To achieve sterilization it is necessary to adhere strictly to procedures for instrument cleaning and wrapping and to follow carefully the sterilizer manufacturer's operating and maintenance instructions.
DISCUSSION A spore strip monitoring of 139 sterilizers in 118 private endodontists' offices indicated an overall 15.1% failure rate. Although the number of similar studies is
CONCLUSIONS The findings of this study indicate that sterilization failures occur in private endodontic offices. The overall
Vol. 12, No. 5, May 1986
Survey of Sterilization Practices
rate was somewhat lower than those determined in other types of dental offices. In four of the five states used in the study, endodontists preferred one type of sterilizer. The dry heat oven produced a significantly higher rate of sterilization failure than the other types of sterilizers. None of the procedural methods or educational traits obtained from the study's survey could be correlated to sterilization success. This research project was supported by a grant from the American Association of Endodontists Endowment and Memorial Foundation. Mr. Palenik is associate professor and coordinator of clinical asepsis, Department of Oral Microbiology, Indiana University, School of Dentistry, Indianapolis, IN. Dr. King is chief, Endoclontics Section, Dental Division (160), VAMC West LA, Los Angeles, CA. Dr. Newton is professor and chairman, Department of Endodontics, Indiana University, School of Dentistry, Indianapolis, IN. Dr. Miller is professor and chairman, Department of Oral Microbiology, Indiana University, School of Dentistry. Dr. Koerber is director and professor of instructional development, Indiana University, School of Dentistry.
References 1. Council on Dental Materials and Devices, Council on Dental Therapeutics. Infection control in the dental office. J Am Dent Assoc 1978;97:671-3.
209
2. Council on Dental Materials, Instruments and Equipment. Current status of sterilization of instruments, devices and methods for the dental office. J Am Dent Assoc 1981 ;102:683-9. 3. Amedcan Dental Association. Dentists' desk reference: materials, instruments and equipment. 2nd ed. Chicago: Amedcan Dental Association, 1983:390-401. 4. Perkins JJ. Principles and methods of sterilization in health sciences. 2nd ed. Springfield, IL: Charles C Thomas 1969:156-7,483-5. 5. AHA Committee on Infection within Hospitals. Infection control in the hospital. 3rd ed. Chicago: Amedcan Hospital Association, 1974:97-8. 6. Palenik CJ, Miller CH, Spandau DF. Monitodng the dental office sterilizer. J Indiana Dent Assoc 1981 ;60:25-7. 7. Simonsen KF, Schachtele CF, Jocs RW. An evaluation of stedlization by autoclave in dental offices [Abstract 1236]. J Dent Res 1979;58:400. 8. Skaug N. Proper monitoring of sterilization procedures used in oral surgery, tnt J Oral Surg 1983;12:153-8. 9. Engelhardt FP, Fiskvatin H. Hygiene in der Zahnarztpraxis--Wunsch und Wirklichkeit. Dtsch Zahnarztl Z 1976;31:277-81. 10. Runnells RR. Infection control in the wet finger environment. Salt Lake City, UT: Publishers Press, 1984:84-6. 11. Cdgger LP, Matis, BA, Young, JM. Infection control in Air Force dental clinics. 2nd ed. USAFSAM Aeromed Rev 1983;2-83:1-16. 12. Kolstad R, Bourell K, Crawford J. Biotests for sterilizers: licensure and clinical applications [Abstract 989]. J Dent Res 1980;59:516. 13. American Dental Association. Council clarifies disinfectant use. Questions on glutaraldehyde dilution answered. Am Dent Assoc News 1984;15:9. 14. Council on Dental Therapeutics, Council on Prosthetic Services and Dental Laboratory Relations. Guidelines for infection control in the dental office and the commercial dental laboratory. J Am Dent Assoc 1985;110:969-72. 15. Block SS. Disinfection, sterilization, and preservation. 3rd ed. Philadelphia: Lea & Febiger, 1983:27-30. 16. Quercus Corporation. Sanitization, disinfection and sterilization of dental instruments and equipment. Castro Valley, CA: US Department of Health, Education, and Welfare, 1979:80-102.
Printed in U.S.A. VOL. 12, NO. 5, MAY 1986
CLINICAL ARTICLE A Survey of Sterilization Practices in Selected Endodontic Offices Charles J. Palenik, MS, Thomas N. King, DDS,MS, Carl W. Newton, DDS,MS, Chris H. Miller, PhD, and Leonard G. Koerber, EdD
Little information exists concerning the effect(s) office asepsis procedures can have on sterilization success in dental speciality offices. Therefore, 218 randomly selected private endodontic offices in five midwestern states were sent spore strips, use instructions, and a 16-question survey. The questionnaire dealt with practitioner/auxiliary training, continuing education practices, and office sterilization procedures. Offices returning "positive" spore strips were sent additional strips and guidelines for improving sterilizer performance. Survey data were compared with sterilizer type and spore killing results. A total of 139 sterilizers in 106 offices was monitored. Testing results indicated a 15.1% overall failure rate. Of the offices with sterilization failures, only 68.2% responded for retesting. However, all of the responding offices eventually achieved negative spore tests. Dry heat ovens were most likely to have a sterilization failure (p < 0.05). None of the surveyed practices nor procedures could be related to sterilization success.
lack of equipment maintenance. Sterilizer malfunctions can result in internal temperature variations, improper steam pressures, and inadequate chemical/gas concentrations. In fact, most sterilizer failures are caused by human errors, not by mechanical malfunctions (4, 5). Because the occurrence of most sterilization problems is unpredictable, it is necessary to routinely monitor equipment performance. Physical observations and internal and external chemical monitors can provide immediate results. Unfortunately, such methods can measure only one parameter, such as temperature or the presence of a specific gas. They cannot assess all of the physical factors that must work in concert so that sterilization can be achieved. The main guarantee of sterilization is the successful killing of a bacterial endospore sample (2, 5, 6). The need to biologically verify instrument sterilization in dental offices has been graphically demonstrated in three studies. A study of 342 private Minnesota dental office autoclaves showed that about one of three was not achieving sterilization (7). Each office was sent three spore test ampules and instructed to place one in an average sterilizer load on three different days. More than 20% returned tests which failed on one of the three test days, 5% of the offices failed tests on two of the three days, and 6% failed tests on all three days. Thus, 31% of the participating offices had at least one spore test failure. Another study surveyed the sterilization procedures used by the 25 private practice oral surgeons in Norway (8). When office/clinic equipment was spore checked, sterilization failure was detected in 5 of 22 steam autoclaves, 2 of 4 dry heat ovens, and all 9 unsaturated chemical vapor sterilizers. A third study which tested sterilizers in private West German dental offices indicated that 8 of 69 steam autoclaves, 44 of 116 dry heat ovens, and 8 of 9 unsaturated chemical vapor sterilizers failed spore testings (9). Further examination of sterilization practices indicated that
Reducing the chances of cross-infections during the practice of dentistry includes the use of sterile instruments. Currently there are four types of sterilization which can be easily controlled and their effectiveness verified during use in the dental office. These include steam autoclaves, dry heat ovens, unsaturated chemical vapor sterilizers, and ethylene oxide gas sterilizers. The American Dental Association recommends that all instruments, burs, mirrors, bands, and other devices used in intraoral treatments be sterilized by one of these four methods (1-3). Regardless of the type of sterilizer used, a number of factors can interfere with the sterilization process. Many of the problems can be related to operator inattentiveness, improper wrapping and inadequate presterilization cleaning of instruments, or to a generalized 206
Vol. 12, No. 5, May 1986
Survey of Sterilization Practices
instrument overloading, opening of the sterilizer during the processing cycle, and inadequate exposure intervals were the major causes of failure. This study was undertaken because little information presently exists concerning the effects office asepsis procedures and personnel training backgrounds could have on sterilization success in private dental offices. MATERIALS AND METHODS
Study participants were randomly chosen from a current members roster of the American Association of Endodontists. The 218 selections came from five midwestern states. Packets of study materials were sent to primary office addresses only. Each packet contained an introductory letter describing the nature and significance of the research project and an invitation to participate. Also enclosed were two bacterial test strips (Spordi; AMSCO/Medical Products Division, Erie, PA) and instructions as to their use. Participants were asked to place a spore strip in the center of their sterilizer during a routine cycle. Strips were to be used on different days. Finally, the study packets contained a short office survey and a return envelope. The survey was composed of 16 questions concerning practitioner/ auxilary training, continuing education practices, and office sterilization procedures. Because the strips contained both Bacillus stearothermophilus and Bacillus subtilis (globigii) spores, they could be used to monitor steam autocalves, dry heat ovens, unsaturated chemical vapor sterilizers, and ethylene oxide gas sterilizers. Extra materials were sent upon request to offices where more than one sterilizer was present. TABLE 1. Study participation pattems
No. of Offices Sent Materials
No. of Offices Participating
% Participation
No. of Units Tested
IL MI IN OH Wl
60 45 20 60 33
29 25 12 32 20
48.33 55.56 60.00 53.33 60.61
36 30 14 39 20
Total
218
118
54.13
139"
State
* Value represents 21 offices in which two sterilizers were evaluated.
Spore strips were aerobically incubated at 37~ (steam autoclave and unsaturated chemical vapor) or 56~ (dry heat or ethylene oxide) immediately upon their return (10-12). The culture medium was trypticase soy broth (BBL Microbiology Systems, Cockeysville, MD) supplemented with 0.25% (wt/vol) glucose. Tubes were examined after 5, 7, and 10 days of incubation. Aliquots from tubes demonstrating microbial growth were subcultured and Gram stained. Offices returning positive spore strips were sent additional monitoring materials and a set of guidelines for improving sterilizer performance. Offices with negative spore tests were notified by mail. The office survey contained 16 questions which dealt with practitioner and auxiliary training backgrounds, professional memberships, continuing education practices, and office sterilization procedures. Information obtained from the survey responses were statistically compared using a x 2 analysis to the type(s) of sterilizing equipment present in the office and spore strip results. RESULTS
Table 1 contains participation patterns according to state. In the five-state sampling area, 54.13% or 118 offices returned processed spore strips and completed surveys. Twenty-one offices requested extra monitoring supplies so that a second office sterilizer could be evaluated. Test sterilizers included 66 steam autoclaves, 56 dry heat ovens, 16 unsaturated chemical vapor sterilizers, and 1 ethylene oxide gas sterilizer (Table 2). A single type of sterilizer predominated (p < 0.05) in four states. For example, steam autoclaves were used by a significant number of endodontists in Indiana, while the dry heat oven was the major type of sterilizer in Ohio offices. Slightly more than 33% of participating offices indicated in their surveys that they used some type of alkaline glutaraldehyde solution. Spore strip results are presented in Table 3. Of the 139 sterilizers tested, 21 (15.1%) returned at least one positive spore strip. Ten (7.19%) sterilizers failed both spore strip tests. The dry heat oven produced significantly higher (p < 0.05) rates of spore strip killing failures (26.79%) than any of the other types of steriliz-
TABLE 2. Distribution of sterilization methods
State
Steam Autoclave*
Dry Heat*
Unsaturated Chemical Vapor*
Ethylene Oxide*
Alkaline Glutaraldehydest
IL MI IN OH Wl
21/58.33 14/46.67 10/71.43 14/35.90 7/35.00
11/30.56 14/46.67 4/28.57 23/58.97 4/20.00
4/11.11 2/6.66 0/0.00 2/5.13 8/40.00
0/0.00 0/0.00 0/0.00 0/0.00 1/5.00
13/36.11 7/23.33 7/50.00 13/33.33 6/30.00
Total
66/47.48
56/40.29
16/11.50
1/0.72
46/33.09
* Number of units testedJpercentage of unite tested per state. t Number of offices using the agent/percentage of offices participating per state.
207
208
Journal of Endodontics
Palenik et al.
TABLE 3. Sterilization results of initial evaluation by method No. of Positive Spore Strips Returned*
Sterilization Method Steam autoclave Dry Heat Unsaturated chemical vapor Ethylene oxide Total
0
1
2
62/93.94 41/73.21 14/87.50 1/100.00
1/1.52 9/16.08 1/6.25 0/0.00
3/4.54 6/10.71 1/6.25 0/0.00
118/84.89
11/7.91 10/7.19 21/15.1
* Numberof unitstested/percentageof sterilizertypetested. TABLE 4. Results of sterilizer retesting Sterilization Trial First Second Third
No. of Positive Spore Strips Returned*
0
1
2
118 12 1
11 4 0
10 0 0
* Resultsindicatea 15.1%failureratefromthe entirestudy;76.2%of the "positivespore strip" officestook advantageof a secondtestingwhileonly25.0%performeda thirdtesting. TABLE 5. Survey questions not correlatable to sterilizer performance 1. Years as a practicing endodontist 2. Site and type of speciality training 3. Board certification status 4. Culturing procedures used 5. Dental journals routinely reviewed 6. Attendance at the annual American Association of Endodontists meeting 7. Continuing education attendance and preferences 8. Office instrument packaging procedures 9. Experience levels of office auxiliaries 10. Training backgrounds of office auxiliaries 11. Physical and chemical methods used to monitor sterilizer performance 12. Frequency of biological monitoring
ers. The overall failure rate for steam autoclaves was 6.06% and for unsaturated chemical vapor it was 12.5%. The single ethylene oxide gas sterilizer produced a negative spore test result. All offices that returned positive spore strips were sent additional strips and guidelines for improving sterilizer performance. All offices taking advantage of the additional testing eventually achieved a negative spore strip test. Sixteen of 21 sterilizers with spore strip failure were retested (Table 4). All participating offices returned completed surveys. None of surveyed office/practitioner practices or procedures could be correlated to sterilization success. Survey data that could not be correlated to sterilizer performance are presented in Table 5.
quite limited, this rate is lower than those determined in private general practice or oral surgery offices (7-9). However, any sterilization failure demands immediate remediation. Certain types of sterilizers predominated in four of the five states studied. This could be related to a familiarity with a certain type of sterilizer during undergraduate, graduate, or military training or experiences. It is also important to note that more than onethird of the test offices used some type of alkaline glutaraldehyde solution. The use of such materials is on the rise (13, 14), and it appears that endodontists are participating in this trend. The dry heat oven had a significantly higher (p < 0.05) rate of sterilizer failure than the other types of sterilizers. Although its operation is simple and inexpensive, problems with dry heat oven sterilization have been previously noted (8, 9, 15, 16). Because most sterilization failures can be related to human error, the greater failure rate could be due to inadequate instrument exposure intervals, of special concern are sufficient warm-up times, equipment overloading, poor internal air circulation, and improper wrapping. Failures noted in the steam autoclave and unsaturated chemical vapor sterilizers could also be related to these factors and also to inadequate internal gas pressures or improper chemicals. A total of 21 positive spore strip tests was recorded. All offices that participated in a second or third testing eventually achieved a negative result. Usually a change in sterilization procedure was all that was needed. In a limited number of cases equipment repair was warranted. Information collected from all study participants concerning personnel training and continuing education practices as well as office aseptic procedures were compared with sterilizer failure or success. None of these items could be correlated to sterilizer effectiveness. It appears difficult to correlate sterilization success or failure to a single personal or practice trait. Although the major causes of sterilization problems are well documented, the application of one such parameter to individual situations may be suspect. The sterilization process is a combination of a variety of procedures which include both human and material factors. It would have been interesting if this study had determined the critical importance of one or two practice or personal elements. However, the inability to establish such identifications only reinforces the known complexity of the sterilization process. To achieve sterilization it is necessary to adhere strictly to procedures for instrument cleaning and wrapping and to follow carefully the sterilizer manufacturer's operating and maintenance instructions.
DISCUSSION A spore strip monitoring of 139 sterilizers in 118 private endodontists' offices indicated an overall 15.1% failure rate. Although the number of similar studies is
CONCLUSIONS The findings of this study indicate that sterilization failures occur in private endodontic offices. The overall
Vol. 12, No. 5, May 1986
Survey of Sterilization Practices
rate was somewhat lower than those determined in other types of dental offices. In four of the five states used in the study, endodontists preferred one type of sterilizer. The dry heat oven produced a significantly higher rate of sterilization failure than the other types of sterilizers. None of the procedural methods or educational traits obtained from the study's survey could be correlated to sterilization success. This research project was supported by a grant from the American Association of Endodontists Endowment and Memorial Foundation. Mr. Palenik is associate professor and coordinator of clinical asepsis, Department of Oral Microbiology, Indiana University, School of Dentistry, Indianapolis, IN. Dr. King is chief, Endoclontics Section, Dental Division (160), VAMC West LA, Los Angeles, CA. Dr. Newton is professor and chairman, Department of Endodontics, Indiana University, School of Dentistry, Indianapolis, IN. Dr. Miller is professor and chairman, Department of Oral Microbiology, Indiana University, School of Dentistry. Dr. Koerber is director and professor of instructional development, Indiana University, School of Dentistry.
References 1. Council on Dental Materials and Devices, Council on Dental Therapeutics. Infection control in the dental office. J Am Dent Assoc 1978;97:671-3.
209
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