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PERCUTANEOUS INJURIES IN DENTISTRY: AN OBSERVATIONAL STUDY
ARTICLE 1
PERCUTANEOUS INJURIES IN DENTISTRY: AN
OBSEIRVATIONAL
STUDY
JENNIFER L. CLEVELAND, D.D.S., M.P.H.; STUART A. LOCKWOOD, D.M.D., M.P.H.; BARBARA F. GOOCH, D.M.D., M.P.H.; MERYL H. MENDELSON, M.D.; MARY E. CHAMBERLAND, M.D., M.P.H.; DAVID V. VALAURI, D.D.S.; SEYMOUR L. ROISTACHER, D.D.S.; JILL M. SOLOMON, M.P.H.; DONALD W. MARIANOS, D.D.S., M.P.H.
0 ercutaneous injuries pose the greatest risk of infection to health-care workers from bloodborne pathogens such as hepatitis B virus and human immunodeficiency virus.' Although blood contacts with skin and mucous membranes may be reduced through use of traditional barriers, such as gloves, these barriers are not effective in preventing injuries with sharp instruments.
Recent observational studies among non-dental surgical and operating room personnel have reported that one or more percutaneous injuries occurred during 1 to 15 percent of procedures.2-8 Risk factors for per-
injuries among surgical personnel include surgical specialty; type, duration and time of day of procedure observed; and use of certain surgical techniques (for example, holding tissue with fingers). These data have been useful in estimating the risk of occupational transmission of bloodborne pathogens and in identifying preventive measures to reduce percutaneous injuries among surgical personnel. Published accounts of injuries among dental personnel have been limited to self-reported data from U.S. dentists9'10; retrospective and prospective studies of injury reports of den-
The authors conducted an obser-
vational study of the frequency and circumstances of percuta-
neous injuries among dental residents. Their findings suggest that most percutaneous injuries
tored procedures performed by general dentistry and oral and maxillofacial surgery residents, attending faculty and fourthyear dental students. Because procedures performed by dental students and attending faculty composed less than 1 percent of the total observations, they were not included in the analy-
sustained by these dental resi-
SiS.
dents occurred extraorally and
Both hospitals required dental residents to adhere to universal precautions during patient care.16 Residents were required to wear gloves, masks and face shields during all dental procedures. In addition, both hospitals provided dental personnel with a formal mechanism for managing exposures to blood and body fluids. This policy included procedures for reporting percutaneous injuries to a needlestick coordinator, completion of an accident injury report and, when appropriate, counseling and testing of the injured HCW and/or patients. The principal investigator assured residents that information regarding an individual's technique and infection control practices would not be disclosed. Observers and observations. Two dental students and four dental assistants unaffiliated with either dental residency program conducted the ob-
were associated with denture
impression procedures. Some in-
juries may be preventable with
changes in techniques or instrument design.
cutaneous
tal students"-4; and one observational pilot study of dental personnel at a federal dental clinic.'5 To further assess the frequency and circumstances of percutaneous injuries, we conducted a prospective observational study of dental residents who perform routine dental procedures. This report summarizes the findings of this study. METHODS
Study sites and dentists. We conducted this study from March through October 1993 at three dental clinics in two teaching hospitals in New York City. Trained observers moni-
JADA, Vol. 126, June 1995 745
RESEARCH Three observers rotated daily among the three treatment areas at clinic 1; two observers rotated daily between clinics 2 and 3. Throughout the study period, a 10 percent random sample of all observed procedures was simultaneously observed by two observers.
TABLE I
servations. The first author trained the observers on site; training included oral and written instructions for completing the observation and percutaneous injury report forms. Before initiation of the study, we con-ducted a two-week pilot phase to clarify and standardize questions concerning data collection methods. From 9 a.m. to 4 p.m. daily, each observer monitored a maximum of three dentists at any one time. At clinic 1, residents in both general dentistry (n=26) and oral surgery (n=9) were observed in three treatment areas; thus, a maximum of nine chairs could be observed. At clinic 2, located at the second hospital, only general dentistry residents (n=4) were observed. This clinic contained four dental chairs separated by partitions that did not allow an observer to monitor more than two dentists at the same time. At clinic 3, also located at the second hospital, oral surgery residents 746 JADA, Vol. 126, June 1995
(n=6) were observed in a single treatment area that permitted the observer to monitor three dentists at the same time. The mean numbers of patient visits per day per dental chair for clinics 1, 2 and 3 were four, six and 10, respectively. In all three clinics, placement of dental chairs permitted the observers a sufficient view of the dentists. At clinics 1 and 2, all dental procedures (Table 1) performed on adult and pediatric patients in each assigned area were observed. Residents usually conducted procedures without the aid of chairside assistants at clinics 1 and 2. Procedures observed at clinic 3 were limited primarily to extractions, alveoloplasties, and soft-tissue biopsies; oral surgery residents not
performing surgical procedures usually provided chairside assistance. Pediatric patients did not exceed 25 percent of the total patient population observed at any clinic.
Definitions. Observers defined a percutaneous injury as a visible penetration of the dentist's skin caused by a needle or other sharp instrument. They defined an anesthetic injection as any entry of a syringe needle into a patient's tissue. We identified 22 different dental procedures and divided these into nine categories (Table 1). If multiple procedures were performed on an individual patient during a single visit, all procedures were recorded. Since no more than one injury was recorded per observed procedure or patient visit, we calculated a procedure-injury rate by dividing the number of recorded injuries by the number of observed procedures; we calculated a patient-visit injury rate by dividing the number of recorded injuries by the number of observed patient visits. We recorded both procedure and patient-visit injury rates as injuries per 1,000 procedures or patient visits. We calculated the number of injuries per dentist-
-RESEARCH month by dividing the total number of injuries by the total number of dentist-months contributed by all participating dentists (one dentist-month equaled one full-time dentist observed for 34 hours per week for four weeks). Data collection and analysis. For each patient visit, observers recorded the time of day; duration, type and number of dental procedures; and the number of anesthetic injections. The number and circumstances of percutaneous injuries were recorded as they occurred. In addition, observers inspected the dentist's hands after glove removal for the presence of blood. Neither patients nor dentists were identified; therefore, we could not determine the frequency with which an individual patient or dentist was observed or injured. Injuries were identified when the observer m witnessed the injury during the procedure; - suspected an injury that was later confirmed by the dentist; - received a voluntary report of the injury by the dentist during or after the procedure; - noted the injury on the dentist's hand after glove removal. After initial identification of the injury, the observer determined if the wound was visible and if blood was present at the wound site. If a wound was visible, regardless of the presence or absence of blood, the observer completed an injury report form that recorded the circumstances of the injury, the instrument causing the injury, a description of the wound site and prior use of the instrument on a patient before the injury occurred. One of the investigators reviewed the completed forms for
inaccuracies or inconsistencies. We performed data analysis with Epi-Info software (Centers for Disease Control and Prevention) and the Statistical Analysis System (SAS Institute Inc.). Differences in proportions were compared using the X2 statistic or, when appropriate, Fisher's Exact Test. Corresponding P values were considered significant at P<0.05. RESULTS
From March to October 1993, our team observed 16,340 routine procedures during 11,210 patient visits at all three dental clinics. The median duration of patient visits was 30 minutes, with a range of 2 to 120 minutes. The total number of procedures per patient visit ranged from one to 11, with a median of two procedures. During 11,210 patient visits, dentists administered 17,831 anesthetic injections; 5,282 patients (47 percent) received at least one anesthetic injection (median of three per patient visit). Fiftyfour percent (n= 6,070) of all observed patient visits occurred in the afternoon. Observers recorded 14 percutaneous injuries for an injury rate of 0.9 per 1,000 procedures (14 per 16,340) and 1.2 per 1,000 patient visits (14 per 11,210). The rate of injuries per dentist-month was 0.33 (14 injuries per 42 dentist-months). At clinic 1, 12 injuries were recorded during 8,866 procedures (1.3 per 1,000) and 5,700 patient visits (2.1 per 1,000); at clinic 2, two injuries were recorded during 2,323 procedures (0.9 per 1,000) and 1,316 patient visits (1.5 per 1,000); at clinic 3, zero injuries were recorded during 5,151 procedures and 4,194 patient visits.
Neither procedure nor patient-visit injury rates differed significantly between clinics 1 and 2 (P 1.00). Descriptive information. Of the 14 injuries, one (7.1 percent) occurred intraorally (that is, while the dentist's fingers were inside the patient's mouth) and 12 (85.7 percent) occurred extraorally (Table 2). Observers identified one injury at the end of a patient visit following a prophylaxis when the dentist removed the latex gloves; the circumstances and instrument associated with this injury were unknown. Utility knives used for trimming denture impressions caused five injuries (35.7 percent); burs and explorers each caused two injuries (14.3 percent); and an endodontic file, syringe needle, pliers and excavator each caused one injury (7.1 percent each). Twelve injuries resulted in visible bleeding (85.7 percent). Eight injuries were caused by instruments not used on the patient previously (57.1 percent); in five of these injuries, utility knives may have been contaminated with patient fluid indirectly (for example, they may have been used on an impression that had been in the patient's mouth) and in three injuries, instruments were clean at the time of the dentist's injury. Although the study's design did not permit systematic assessment of recontacts (instances when the instrument, after injuring the HCW, was reused on the patient intraorally), an observer's report indicated that one explorer that injured the dentist outside the patient's mouth was reused on the patient. Trimming denture impressions with utility knives was JADA, Vol. 126, June 1995 747
RESEARCH TABLE 2
the most common action being performed at the time of the injury. In addition, reaching for an instrument and inadvertently contacting a second instrument resulted in three injuries. Other actions associated with the remaining six injuries are presented in Table 2. Thirteen injuries (92.8 percent) occurred on the dentist's hand or fingers and, although not to a statistically significant degree, these injuries were more common on the dominant hand (69 percent). The only non-hand injury occurred when the dentist was reaching for an instrument on the mobile dental cart and scraped an elbow on a bur in a handpiece. Injury by type of procedure and observer. Injuries were most commonly reported during removable prosthetics procedures (n=6), followed by crown and bridge, endodontic and operative procedures (Table 3). No injuries were recorded during periodontic procedures, oral surgeries or other proce748 JADA, Vol. 126, June 1995
dures. Procedure injury rates did not differ statistically among the nine categories. To assess possible inter-observer differences, patient-visit injury rates were calculated separately for each observer. The four observers who recorded one or more injuries at clinics 1 and 2 did not detect any significant differences in patientvisit injury rates; patient-visit injury rates varied from 0.8 (1 of 1,190 patient visits) to 2.5 (7 of 2,812 patient visits) per 1,000 patient visits. One observer participated for only two weeks and recorded no injuries during 461 patient visits at clinic 1. The sixth observer recorded 91 percent of the total number of procedures observed at clinic 3; this observer recorded no injuries during 3,889 patient visits. During the 10 percent random sample (procedures monitored concurrently by two observers), observers collected completely concordant injury data. Risk factors for injuries.
No risk factors for injuries were identified. Univariate analysis indicated that injury rates were not related to the duration or time of day of patient visits or to the clinic site (P >0.3). Because several procedures could have been recorded for each patient visit, it was not possible to evaluate the association of patient-visit injury rates to types or duration of procedures. DISCUSSION
This report presents findings of a prospective, observational study describing the frequency and circumstances of injuries among dental residents. These data, along with the prevalence of bloodborne pathogen infection among patients and the likelihood of transmission of infection per exposure, are important in defining the risk for occupational transmission of bloodborne pathogens to
HCWs.1'17 In this study conducted at two New York City hospitals, the finding of 0.33 injuries per
DESEADCHm TABLE 3
dentist-month of observation is similar to self-reported occupational injury rates of dentists participating in the health screening program (HSP) of the American Dental Association.9 In 1990 (n=1,497) and 1991 (n=1,620), HSP dentists reported a mean of 0.45 and 0.29 injuries in the preceding month, respectively. Injury rates per 1,000 procedures among dental personnel at dental teaching institutions in San Francisco also were similar to those found in this observational study." Injury rates recorded per hour of observation in our study were lower than those observed among surgical personnel in one CDC study, which was restricted to injuries from instruments contaminated with patient blood (J.I. Tokars, M.D., M.P.H., unpublished data, 1990). Among surgical personnel, 99 injuries occurred during 2,970 hours of observation (33.3 per 1,000 hours). By comparison, we found that 11 of 14 injuries occurred with instru-
ments possibly contaminated with patient fluid during 5,903 hours of observation (1.9 per 1,000 hours). Consistent with findings among oral surgery residents in our study, data from two prospective hospital-based studies of operating personnel reported no percutaneous injuries during 53 oral surgery operations.4" Retrospective, self-reported data among 321 U.S. oral surgeons at the 1992 American Association of Oral and Maxillofacial Surgeons' meeting, however, recorded a mean percutaneous injury rate of 0.31 per month.'0 In the history of their practices, these surgeons indicated, injuries most frequently were associated with wires, suture needles and syringe needles. In our study, the absence of injuries observed during oral surgery procedures may be associated with the types of outpatient procedures, which tended to be less complex and did not involve wires.
With the exception of syringe needles, which in our study caused only 7.1 percent of injuries, the frequency of lacerations with sharp instruments and bur injuries was similar to that of self-reported occupational injuries at three U.S. dental schools.'1-4 The lower frequency of injuries by syringe needles in our study may have been due to training these residents in safer techniques. These techniques included using instruments instead of fingers to retract tissue during anesthetic injections, as well as using a onehanded technique or mechanical device for needle recapping. Safety devices such as self-sheathing needles also may reduce injuries sustained during needle recapping. Examination of the circumstances of percutaneous injuries among dentists in our study provides additional prevention strategies. For example, we found that injuries caused by sharp instruments, such as utilJADA, Vol. 126, June 1995 749
0ESEARCH ity knives, often involved an uncontrolled, forceful movement of a sharp instrument toward the thumb or palm of the hand holding the instrument. In contrast, injuries that occur during suturing commonly involve the non-dominant hand when palpating the needle tip2 or grabbing the suture needle.18 Preventive interventions for the types of lacerations observed in our study may include using plastic finger guards or using alternate methods (such as dental lathes) to contour denture impression materials. In addition, injuries caused by burs may be prevented through changes in handpiece delivery system design or modifications in work practices. Most of the injuries in this study occurred extraorally (93 percent). In 1991, dentists participating in the ADA's HSP also reported a history of more frequent extraoral injuries (55 percent extraoral vs. 39 percent intraoral).9 Although extraoral injuries may place the worker at risk for infection, injuries that occur extraorally should provide adequate opportunity to prevent contact of the patient with the contaminated instrument. For example, these injuries allow the dentist time to replace a contaminated instrument with a sterile instrument. Certain biases inherent in the observational methodology may have influenced the occurrence or reporting of injuries. First, an awareness of the presence of the observer may have altered the dentist's technique. Second, because observers were required to monitor more than one dentist at the same time, it is possible that not all injuries were observed or recorded. However, as we stated previous750 JADA, Vol. 126, June 1995
ly, injury data collected simultaneously by the primary and secondary observer during 10 percent of all observed procedures were in complete agreement. Findings from this study of a small defined group of dental residents should not be generalized to all U.S. dentists. Compared to the population of U.S. dentists, study dentists were younger and had fewer years of clinical practice. Study dentists also practiced in an area of high AIDS incidence and in a dental setting in which academic training was provided. Although the types of observed procedures were similar to those likely to be performed in general dental practice, the frequency of performing certain categories of procedures (such as dentures fabrication) may have differed in these teaching programs. The reliability of the data recorded in this study may be strengthened by the fact that both self-reported and directly observed injuries were recorded. The low number of recorded injuries, however, may have limited the statistical power to identify factors associated with injuries among these dentists. Future studies among dental personnel of broader age ranges, occupations and practice settings may describe more accurately factors associated with percutaneous injuries and prevention strategies. CONCLUSION
In this observational study of dental residents, we found that most percutaneous injuries oc-
curred extraorally and during removable prosthetics procedures. The frequency of injuries among these residents is similar to those reported from sur-
veys of U.S. dentists and injury reports of dental students but is less than that reported by general surgeons. With the exception of lacerations caused by syringe needles, the frequency of lacerations and bur injuries among these residents also was similar to that in previous reports of dentists and dental students. Safer work practices (such as using the instrument instead of a finger to retract tissue), safer instrument design (including self-sheathing needles or changes in dental unit design) and continued worker education may reduce percutaneous injuries among dental workers. Dr. Lockwood is an epidemiologist, Division of Oral Health, National Center for Prevention Services, Centers for Disease Control and Prevention, Atlanta. Dr. Gooch is a dental officer, Division of Oral Health, National Center for Prevention Services, Centers for Disease Control and Prevention, Atlanta. Dr. Mendelson is the director, Infection Control, Division of Infectious Diseases, Department of Medicine, The Mount Sinai Medical Center, New York. Dr. Chamberland is a medical officer, Hospital Infections Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta. Dr. Valauri is an assistant clinical professor, Department of Dentistry, The Mount Sinai Medical Center, New York.
Dr. Roistacher is a professor, Dental Health, Department of Dental Medicine, Queens Hospital Center, Queens, N.Y. Ms. Solomon is a research coordinator, Division of Infectious Diseases, Department of Medicine, The Mount Sinai Medical Center, New York. Dr. Marianos is division director, Division of Oral Health, National Center for Prevention Services, Centers for Disease Control and Prevention, Atlanta.
The opinions expressed or implied are strictly those of the authors and do not necessarily reflect the opinions or official policies of the American Dental Association or its subsidiaries. This article is based on research presented at the Annual Meeting of the International Association of Dental Research, Seattle, March 1994. Abstract No. 1433.
RESEARCH 1. Bell DM. Human immunodeficiency virus transmission in health care settings: risk and risk reduction. Am J Med 1991;91(3B):294S300S. 2. Tokars JI, Bell DM, Culver DH, et al. Percutaneous injuries during surgical procedures. JAMA 1992;267:2,899-904. 3. Panlilio AL, Foy DR, Edwards JR, et al. Blood contacts during surgical procedures. JAMA 1991;265:1,533-7. 4. Gerberding JL, Littell C, Tarkington A, Brown A, Schecter WP. Risk of exposure of surgical personnel to patients' blood during surgery at San Francisco General Hospital. N Engl J Med 1990;322:1,788-93. 5. Popejoy SL, Fry DE. Blood contact and exposure in the operating room. Surg Gynecol Obstet 1991;172:480-3. 6. Quebbeman EJ, Telford GL, Hubbard S, et al. Risk of blood contamination and injury to operating room personnel. Ann Surg 1991;214:614-20. 7. Rudnick J, Chamberland M, Panlilio A, et al. Blood contacts during obstetrical procedures (Abstract). Am J Obstet Gynecol 1992;168:425. 8. White MC, Lynch P. Blood contact and exposures among operating room personnel: a multicenter study. Am J Infect Control 1993;21:243-8. 9. Siew C, Chang S, Gruninger S, Verrusio C, Neidle E. Self-reported percutaneous in-
juries in dentists: implications for HBV, HIV transmission risk. JADA 1992;123(7):37-44. 10. Gooch B, Siew C, Cleveland J, Gruninger S, Lockwood S. Occupational blood contact reported by oral surgeons: United States 1992 (Abstract no. 85). J Dent Res 1995;74:22. 11. Ramos-Gomez F, Greenspan D, Greene IC, Bird W, Lowe SE, Gerberding JL. Accidental injuries among dental health-care workers (Abstract). 121st Annual Meeting of the American Public Health Association, San Francisco, 1993. 12. Gonzalez CD, Pruhs RJ, Sampson E. Clinical occupational bloodborne exposure in a dental school. J Dent Educ 1994;58:217-20. 13. Cottone JA, Dillard RL, Dove SB. Frequency of percutaneous injuries in dental care providers (Abstract no. 14). J Dent Educ 1992;56:96. 14. Wisnom C, DePaola L, Overhoster CD, Lee R. A five-year study of parenteral exposures in dental health care workers (Abstract no. P163). 5th national forum on AIDS, hepatitis, and other bloodborne diseases, Atlanta, 1993. 15. Hudson CA, Summers CJ, Gravelle RJ, Davis RJ. The nature, frequency, and circumstances of percutaneous injuries in a dental setting of the Indian Health Services (IHS) (Abstract no. 457). 1993 American Industrial
Dr. Cleveland Is a
dental officer and epidemiologist, Divisian of Oral Health,
Hygiene Conference and Exposition, New Orleans, 1993. 16. Centers for Disease Control and Prevention. Update: universal precautions for prevention of transmission ofhuman immunodeficiency virus, hepatitis B virus, and other bloodborne pathogens in health-
National Center for
care settings. MMWR
Prevention Services,
1983:7-28-. 17. .Short LJ, Bell DM. Risk of occupa-
Centers for Disease Control and ProvenAdtion, Atlanta. Ad-
t'on
dress reprint re-
tional infection with
bloodborne pathogens in operating and de-
quests to Dr. Clove-
livery room settings.
land, Division of Oral Health, Centers for Disease Control
Am J Infect Control 1993;21:343-50. 18. Schwimmer A,
Massoumi M, Barr C. Efficacy of double gloving to prevent inner glove perforation during outpatient oral surgical procedures. JADA 1994;125:196-8.
and Prevention, Mallstop F-10, Atlanta 30333.
JADA, Vol. 126, June 1995 751
PERCUTANEOUS INJURIES IN DENTISTRY: AN
OBSEIRVATIONAL
STUDY
JENNIFER L. CLEVELAND, D.D.S., M.P.H.; STUART A. LOCKWOOD, D.M.D., M.P.H.; BARBARA F. GOOCH, D.M.D., M.P.H.; MERYL H. MENDELSON, M.D.; MARY E. CHAMBERLAND, M.D., M.P.H.; DAVID V. VALAURI, D.D.S.; SEYMOUR L. ROISTACHER, D.D.S.; JILL M. SOLOMON, M.P.H.; DONALD W. MARIANOS, D.D.S., M.P.H.
0 ercutaneous injuries pose the greatest risk of infection to health-care workers from bloodborne pathogens such as hepatitis B virus and human immunodeficiency virus.' Although blood contacts with skin and mucous membranes may be reduced through use of traditional barriers, such as gloves, these barriers are not effective in preventing injuries with sharp instruments.
Recent observational studies among non-dental surgical and operating room personnel have reported that one or more percutaneous injuries occurred during 1 to 15 percent of procedures.2-8 Risk factors for per-
injuries among surgical personnel include surgical specialty; type, duration and time of day of procedure observed; and use of certain surgical techniques (for example, holding tissue with fingers). These data have been useful in estimating the risk of occupational transmission of bloodborne pathogens and in identifying preventive measures to reduce percutaneous injuries among surgical personnel. Published accounts of injuries among dental personnel have been limited to self-reported data from U.S. dentists9'10; retrospective and prospective studies of injury reports of den-
The authors conducted an obser-
vational study of the frequency and circumstances of percuta-
neous injuries among dental residents. Their findings suggest that most percutaneous injuries
tored procedures performed by general dentistry and oral and maxillofacial surgery residents, attending faculty and fourthyear dental students. Because procedures performed by dental students and attending faculty composed less than 1 percent of the total observations, they were not included in the analy-
sustained by these dental resi-
SiS.
dents occurred extraorally and
Both hospitals required dental residents to adhere to universal precautions during patient care.16 Residents were required to wear gloves, masks and face shields during all dental procedures. In addition, both hospitals provided dental personnel with a formal mechanism for managing exposures to blood and body fluids. This policy included procedures for reporting percutaneous injuries to a needlestick coordinator, completion of an accident injury report and, when appropriate, counseling and testing of the injured HCW and/or patients. The principal investigator assured residents that information regarding an individual's technique and infection control practices would not be disclosed. Observers and observations. Two dental students and four dental assistants unaffiliated with either dental residency program conducted the ob-
were associated with denture
impression procedures. Some in-
juries may be preventable with
changes in techniques or instrument design.
cutaneous
tal students"-4; and one observational pilot study of dental personnel at a federal dental clinic.'5 To further assess the frequency and circumstances of percutaneous injuries, we conducted a prospective observational study of dental residents who perform routine dental procedures. This report summarizes the findings of this study. METHODS
Study sites and dentists. We conducted this study from March through October 1993 at three dental clinics in two teaching hospitals in New York City. Trained observers moni-
JADA, Vol. 126, June 1995 745
RESEARCH Three observers rotated daily among the three treatment areas at clinic 1; two observers rotated daily between clinics 2 and 3. Throughout the study period, a 10 percent random sample of all observed procedures was simultaneously observed by two observers.
TABLE I
servations. The first author trained the observers on site; training included oral and written instructions for completing the observation and percutaneous injury report forms. Before initiation of the study, we con-ducted a two-week pilot phase to clarify and standardize questions concerning data collection methods. From 9 a.m. to 4 p.m. daily, each observer monitored a maximum of three dentists at any one time. At clinic 1, residents in both general dentistry (n=26) and oral surgery (n=9) were observed in three treatment areas; thus, a maximum of nine chairs could be observed. At clinic 2, located at the second hospital, only general dentistry residents (n=4) were observed. This clinic contained four dental chairs separated by partitions that did not allow an observer to monitor more than two dentists at the same time. At clinic 3, also located at the second hospital, oral surgery residents 746 JADA, Vol. 126, June 1995
(n=6) were observed in a single treatment area that permitted the observer to monitor three dentists at the same time. The mean numbers of patient visits per day per dental chair for clinics 1, 2 and 3 were four, six and 10, respectively. In all three clinics, placement of dental chairs permitted the observers a sufficient view of the dentists. At clinics 1 and 2, all dental procedures (Table 1) performed on adult and pediatric patients in each assigned area were observed. Residents usually conducted procedures without the aid of chairside assistants at clinics 1 and 2. Procedures observed at clinic 3 were limited primarily to extractions, alveoloplasties, and soft-tissue biopsies; oral surgery residents not
performing surgical procedures usually provided chairside assistance. Pediatric patients did not exceed 25 percent of the total patient population observed at any clinic.
Definitions. Observers defined a percutaneous injury as a visible penetration of the dentist's skin caused by a needle or other sharp instrument. They defined an anesthetic injection as any entry of a syringe needle into a patient's tissue. We identified 22 different dental procedures and divided these into nine categories (Table 1). If multiple procedures were performed on an individual patient during a single visit, all procedures were recorded. Since no more than one injury was recorded per observed procedure or patient visit, we calculated a procedure-injury rate by dividing the number of recorded injuries by the number of observed procedures; we calculated a patient-visit injury rate by dividing the number of recorded injuries by the number of observed patient visits. We recorded both procedure and patient-visit injury rates as injuries per 1,000 procedures or patient visits. We calculated the number of injuries per dentist-
-RESEARCH month by dividing the total number of injuries by the total number of dentist-months contributed by all participating dentists (one dentist-month equaled one full-time dentist observed for 34 hours per week for four weeks). Data collection and analysis. For each patient visit, observers recorded the time of day; duration, type and number of dental procedures; and the number of anesthetic injections. The number and circumstances of percutaneous injuries were recorded as they occurred. In addition, observers inspected the dentist's hands after glove removal for the presence of blood. Neither patients nor dentists were identified; therefore, we could not determine the frequency with which an individual patient or dentist was observed or injured. Injuries were identified when the observer m witnessed the injury during the procedure; - suspected an injury that was later confirmed by the dentist; - received a voluntary report of the injury by the dentist during or after the procedure; - noted the injury on the dentist's hand after glove removal. After initial identification of the injury, the observer determined if the wound was visible and if blood was present at the wound site. If a wound was visible, regardless of the presence or absence of blood, the observer completed an injury report form that recorded the circumstances of the injury, the instrument causing the injury, a description of the wound site and prior use of the instrument on a patient before the injury occurred. One of the investigators reviewed the completed forms for
inaccuracies or inconsistencies. We performed data analysis with Epi-Info software (Centers for Disease Control and Prevention) and the Statistical Analysis System (SAS Institute Inc.). Differences in proportions were compared using the X2 statistic or, when appropriate, Fisher's Exact Test. Corresponding P values were considered significant at P<0.05. RESULTS
From March to October 1993, our team observed 16,340 routine procedures during 11,210 patient visits at all three dental clinics. The median duration of patient visits was 30 minutes, with a range of 2 to 120 minutes. The total number of procedures per patient visit ranged from one to 11, with a median of two procedures. During 11,210 patient visits, dentists administered 17,831 anesthetic injections; 5,282 patients (47 percent) received at least one anesthetic injection (median of three per patient visit). Fiftyfour percent (n= 6,070) of all observed patient visits occurred in the afternoon. Observers recorded 14 percutaneous injuries for an injury rate of 0.9 per 1,000 procedures (14 per 16,340) and 1.2 per 1,000 patient visits (14 per 11,210). The rate of injuries per dentist-month was 0.33 (14 injuries per 42 dentist-months). At clinic 1, 12 injuries were recorded during 8,866 procedures (1.3 per 1,000) and 5,700 patient visits (2.1 per 1,000); at clinic 2, two injuries were recorded during 2,323 procedures (0.9 per 1,000) and 1,316 patient visits (1.5 per 1,000); at clinic 3, zero injuries were recorded during 5,151 procedures and 4,194 patient visits.
Neither procedure nor patient-visit injury rates differed significantly between clinics 1 and 2 (P 1.00). Descriptive information. Of the 14 injuries, one (7.1 percent) occurred intraorally (that is, while the dentist's fingers were inside the patient's mouth) and 12 (85.7 percent) occurred extraorally (Table 2). Observers identified one injury at the end of a patient visit following a prophylaxis when the dentist removed the latex gloves; the circumstances and instrument associated with this injury were unknown. Utility knives used for trimming denture impressions caused five injuries (35.7 percent); burs and explorers each caused two injuries (14.3 percent); and an endodontic file, syringe needle, pliers and excavator each caused one injury (7.1 percent each). Twelve injuries resulted in visible bleeding (85.7 percent). Eight injuries were caused by instruments not used on the patient previously (57.1 percent); in five of these injuries, utility knives may have been contaminated with patient fluid indirectly (for example, they may have been used on an impression that had been in the patient's mouth) and in three injuries, instruments were clean at the time of the dentist's injury. Although the study's design did not permit systematic assessment of recontacts (instances when the instrument, after injuring the HCW, was reused on the patient intraorally), an observer's report indicated that one explorer that injured the dentist outside the patient's mouth was reused on the patient. Trimming denture impressions with utility knives was JADA, Vol. 126, June 1995 747
RESEARCH TABLE 2
the most common action being performed at the time of the injury. In addition, reaching for an instrument and inadvertently contacting a second instrument resulted in three injuries. Other actions associated with the remaining six injuries are presented in Table 2. Thirteen injuries (92.8 percent) occurred on the dentist's hand or fingers and, although not to a statistically significant degree, these injuries were more common on the dominant hand (69 percent). The only non-hand injury occurred when the dentist was reaching for an instrument on the mobile dental cart and scraped an elbow on a bur in a handpiece. Injury by type of procedure and observer. Injuries were most commonly reported during removable prosthetics procedures (n=6), followed by crown and bridge, endodontic and operative procedures (Table 3). No injuries were recorded during periodontic procedures, oral surgeries or other proce748 JADA, Vol. 126, June 1995
dures. Procedure injury rates did not differ statistically among the nine categories. To assess possible inter-observer differences, patient-visit injury rates were calculated separately for each observer. The four observers who recorded one or more injuries at clinics 1 and 2 did not detect any significant differences in patientvisit injury rates; patient-visit injury rates varied from 0.8 (1 of 1,190 patient visits) to 2.5 (7 of 2,812 patient visits) per 1,000 patient visits. One observer participated for only two weeks and recorded no injuries during 461 patient visits at clinic 1. The sixth observer recorded 91 percent of the total number of procedures observed at clinic 3; this observer recorded no injuries during 3,889 patient visits. During the 10 percent random sample (procedures monitored concurrently by two observers), observers collected completely concordant injury data. Risk factors for injuries.
No risk factors for injuries were identified. Univariate analysis indicated that injury rates were not related to the duration or time of day of patient visits or to the clinic site (P >0.3). Because several procedures could have been recorded for each patient visit, it was not possible to evaluate the association of patient-visit injury rates to types or duration of procedures. DISCUSSION
This report presents findings of a prospective, observational study describing the frequency and circumstances of injuries among dental residents. These data, along with the prevalence of bloodborne pathogen infection among patients and the likelihood of transmission of infection per exposure, are important in defining the risk for occupational transmission of bloodborne pathogens to
HCWs.1'17 In this study conducted at two New York City hospitals, the finding of 0.33 injuries per
DESEADCHm TABLE 3
dentist-month of observation is similar to self-reported occupational injury rates of dentists participating in the health screening program (HSP) of the American Dental Association.9 In 1990 (n=1,497) and 1991 (n=1,620), HSP dentists reported a mean of 0.45 and 0.29 injuries in the preceding month, respectively. Injury rates per 1,000 procedures among dental personnel at dental teaching institutions in San Francisco also were similar to those found in this observational study." Injury rates recorded per hour of observation in our study were lower than those observed among surgical personnel in one CDC study, which was restricted to injuries from instruments contaminated with patient blood (J.I. Tokars, M.D., M.P.H., unpublished data, 1990). Among surgical personnel, 99 injuries occurred during 2,970 hours of observation (33.3 per 1,000 hours). By comparison, we found that 11 of 14 injuries occurred with instru-
ments possibly contaminated with patient fluid during 5,903 hours of observation (1.9 per 1,000 hours). Consistent with findings among oral surgery residents in our study, data from two prospective hospital-based studies of operating personnel reported no percutaneous injuries during 53 oral surgery operations.4" Retrospective, self-reported data among 321 U.S. oral surgeons at the 1992 American Association of Oral and Maxillofacial Surgeons' meeting, however, recorded a mean percutaneous injury rate of 0.31 per month.'0 In the history of their practices, these surgeons indicated, injuries most frequently were associated with wires, suture needles and syringe needles. In our study, the absence of injuries observed during oral surgery procedures may be associated with the types of outpatient procedures, which tended to be less complex and did not involve wires.
With the exception of syringe needles, which in our study caused only 7.1 percent of injuries, the frequency of lacerations with sharp instruments and bur injuries was similar to that of self-reported occupational injuries at three U.S. dental schools.'1-4 The lower frequency of injuries by syringe needles in our study may have been due to training these residents in safer techniques. These techniques included using instruments instead of fingers to retract tissue during anesthetic injections, as well as using a onehanded technique or mechanical device for needle recapping. Safety devices such as self-sheathing needles also may reduce injuries sustained during needle recapping. Examination of the circumstances of percutaneous injuries among dentists in our study provides additional prevention strategies. For example, we found that injuries caused by sharp instruments, such as utilJADA, Vol. 126, June 1995 749
0ESEARCH ity knives, often involved an uncontrolled, forceful movement of a sharp instrument toward the thumb or palm of the hand holding the instrument. In contrast, injuries that occur during suturing commonly involve the non-dominant hand when palpating the needle tip2 or grabbing the suture needle.18 Preventive interventions for the types of lacerations observed in our study may include using plastic finger guards or using alternate methods (such as dental lathes) to contour denture impression materials. In addition, injuries caused by burs may be prevented through changes in handpiece delivery system design or modifications in work practices. Most of the injuries in this study occurred extraorally (93 percent). In 1991, dentists participating in the ADA's HSP also reported a history of more frequent extraoral injuries (55 percent extraoral vs. 39 percent intraoral).9 Although extraoral injuries may place the worker at risk for infection, injuries that occur extraorally should provide adequate opportunity to prevent contact of the patient with the contaminated instrument. For example, these injuries allow the dentist time to replace a contaminated instrument with a sterile instrument. Certain biases inherent in the observational methodology may have influenced the occurrence or reporting of injuries. First, an awareness of the presence of the observer may have altered the dentist's technique. Second, because observers were required to monitor more than one dentist at the same time, it is possible that not all injuries were observed or recorded. However, as we stated previous750 JADA, Vol. 126, June 1995
ly, injury data collected simultaneously by the primary and secondary observer during 10 percent of all observed procedures were in complete agreement. Findings from this study of a small defined group of dental residents should not be generalized to all U.S. dentists. Compared to the population of U.S. dentists, study dentists were younger and had fewer years of clinical practice. Study dentists also practiced in an area of high AIDS incidence and in a dental setting in which academic training was provided. Although the types of observed procedures were similar to those likely to be performed in general dental practice, the frequency of performing certain categories of procedures (such as dentures fabrication) may have differed in these teaching programs. The reliability of the data recorded in this study may be strengthened by the fact that both self-reported and directly observed injuries were recorded. The low number of recorded injuries, however, may have limited the statistical power to identify factors associated with injuries among these dentists. Future studies among dental personnel of broader age ranges, occupations and practice settings may describe more accurately factors associated with percutaneous injuries and prevention strategies. CONCLUSION
In this observational study of dental residents, we found that most percutaneous injuries oc-
curred extraorally and during removable prosthetics procedures. The frequency of injuries among these residents is similar to those reported from sur-
veys of U.S. dentists and injury reports of dental students but is less than that reported by general surgeons. With the exception of lacerations caused by syringe needles, the frequency of lacerations and bur injuries among these residents also was similar to that in previous reports of dentists and dental students. Safer work practices (such as using the instrument instead of a finger to retract tissue), safer instrument design (including self-sheathing needles or changes in dental unit design) and continued worker education may reduce percutaneous injuries among dental workers. Dr. Lockwood is an epidemiologist, Division of Oral Health, National Center for Prevention Services, Centers for Disease Control and Prevention, Atlanta. Dr. Gooch is a dental officer, Division of Oral Health, National Center for Prevention Services, Centers for Disease Control and Prevention, Atlanta. Dr. Mendelson is the director, Infection Control, Division of Infectious Diseases, Department of Medicine, The Mount Sinai Medical Center, New York. Dr. Chamberland is a medical officer, Hospital Infections Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta. Dr. Valauri is an assistant clinical professor, Department of Dentistry, The Mount Sinai Medical Center, New York.
Dr. Roistacher is a professor, Dental Health, Department of Dental Medicine, Queens Hospital Center, Queens, N.Y. Ms. Solomon is a research coordinator, Division of Infectious Diseases, Department of Medicine, The Mount Sinai Medical Center, New York. Dr. Marianos is division director, Division of Oral Health, National Center for Prevention Services, Centers for Disease Control and Prevention, Atlanta.
The opinions expressed or implied are strictly those of the authors and do not necessarily reflect the opinions or official policies of the American Dental Association or its subsidiaries. This article is based on research presented at the Annual Meeting of the International Association of Dental Research, Seattle, March 1994. Abstract No. 1433.
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