Most injury prevention efforts in health care settings have focused on hollow-bore needles, because these devices have been associated with an increased risk of HIV transmission among HCP.¹⁰ Of the 57 documented cases of occupational HIV transmission to medical HCP (none were among dental personnel) reported to the Centers for Disease Control and Prevention (CDC) through December 2001, 51 (89 percent) involved a percutaneous exposure.¹¹ Of these 51 injuries, 45 (88 percent) were caused by hollow-bore needles; one-half of these needles had been used in a patient’s vein or artery. Interventions aimed at preventing sharps injuries are based on a hierarchy of controls that categorizes and prioritizes prevention strategies. Primary methods used to prevent occupational percutaneous injuries include eliminating or reducing the use of needles and implementing engineering and work practice controls.¹² Engineering controls, which can eliminate or isolate injury hazards, include the use of sharps containers, needle-recapping devices and devices with safety features (for example, self-sheathing anesthetic needles and scalpels). Passive safety devices that do not require activation by the user are preferred over active devices.¹³ Where engineering controls are not available or appropriate, work practice controls (for example, placing sharps containers close to point of use, not passing unsheathed needles between HCP, recapping needles with one hand, restricting use of fingers during administration of anesthetic) can result in safer behavior and prevent exposure.

Such interventions have successfully decreased percutaneous injuries among dentists in recent years, as evidenced by the declining frequencies of injuries.^1–8 In dentistry, needleless anesthetic delivery systems (jet-injection guns) are available but cannot deliver anesthetic solution deep enough to produce adequate anesthesia. These systems, though rarely used, target procedures such as root planing and scaling that require only numbing of superficial tissues. Most dental HCP administer anesthetic with reusable anesthetic syringes attached to single-use, small-bore (25- to 29-gauge) disposable needles. Therefore, reducing most needlesticks in dentistry will require the use of engineering controls or safer work practices rather than needleless devices.

Efforts to prevent percutaneous injuries and other occupational exposures to blood and other body fluids have resulted in a growing number of initiatives to ensure safe working conditions in health care settings. CDC’s Healthcare Safety Challenge¹⁴ and Healthy People 2010 objectives¹⁵ call for the elimination or prevention of needle-stick injuries among HCP. Initiatives such as these were promoted by the federal Needle-stick Safety and Prevention Act of 2000, which mandated changes to the Occupational Safety and Health Administration’s (OSHA’s) bloodborne pathogen standard.¹⁶ These changes clarify the requirements for employers to "document annually consideration and implementation of appropriate commercially available and effective safer medical devices designed to eliminate or minimize occupational exposure." The standard also states that employers must involve in this process employees who are responsible for "direct patient care." In 2003, CDC recommended that dental HCP "identify, evaluate, and select devices with engineered safety features at least annually and as they become available on the market."¹⁷ Medical and dental offices are exempt from maintaining an official log of reportable injuries and illnesses (OSHA Form 300).¹⁸ However, documenting the frequency and circumstances of injuries can be useful in identifying unsafe devices or work practices.

Before the passage of the Needlestick Safety and Prevention Act of 2000, few dental devices incorporated safety features. Since the act became effective, dental safety devices (for example, safer scalpels and anesthetic syringes) have been developed and marketed. OSHA requires that employers who have staff members at risk of sustaining percutaneous injuries caused by contaminated sharps consider the use of safety devices (where appropriate) or document in their exposure control plans that safety devices have been considered but are not a practical alternative to the traditional devices.¹⁶

Although several studies have estimated the frequency of percutaneous injuries among dental HCP,^1–8 few have described how and when these injuries occurred, identified which injuries may have been preventable with a safety device or safer work practice or evaluated the effectiveness of safety devices or safer work practices in reducing injuries.^19,20 To address the first two issues, we analyzed surveillance data from CDC’s National Surveillance System for Health Care Workers (NaSH) to describe percutaneous injuries among dental HCP and to explore the preventability of a subset of these injuries: needlesticks. In addition to examining percutaneous injuries among dental HCP, this article provides guidance in developing an office safety program to prevent percutaneous injuries (Box 1), selecting dental safety products for local anesthetic administration (Box 2) and identifying resources that can aid in the identification, evaluation and selection of safer dental devices as they become available (Box 3).^12,13,21

	METHODS

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During the period from December 1995 through August 2004, 29 of 54 participating NaSH hospitals reported percutaneous injuries among dental HCP. We characterized these reports by the number and types of dental HCP, location where injuries occurred, type of device involved, timing of injury or needlestick in relation to use of the device, circumstances (that is, how the injury occurred), and type of dental procedure being performed at the time of the injury, as well as whether the injury occurred inside or outside the patient’s mouth (Table 1 and Table 2 [page 174]).

– category 1: manipulating a patient or needle/sharp;

– category 2: using a sharp instrument in the operative field (for example, suturing, incising);

– category 3: handling instruments (for example, passing, handling, cleaning, dismantling or disposing);

– category 4: colliding with a sharp object;

– category 5: disposing of an instrument;

– category 6: leaving a sharp in an unusual location;

– category 7: other/unknown.

For needlesticks, we estimated the proportion that might have been prevented with a safety syringe or safer work practice using criteria similar to those previously published.^24,25 Non-preventable needlesticks (those in category 1) were those that could not have been prevented solely by use of a safety syringe because they occurred while a needle was being inserted or withdrawn or because a patient moved unexpectedly (that is, during these actions, the safety feature could not be activated). Preventable needlesticks (those in categories 3–6) might have been prevented had a safety syringe been used and the safety feature activated, or if a safer work practice (for example, retracting the cheek with instruments rather than fingers) had been used. Because the NaSH database does not collect specific information on which work practices were being used at the time of the reported injury, we cannot estimate the potential impact of safer work practices on the preventability of needlesticks.

We analyzed descriptive data using Statistical Analysis System software (Version 9.0, SAS Institute, Cary, N.C.).

	RESULTS

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Of 18,584 percutaneous injuries reported by all HCP during the study period, 367 involved dental HCP. We excluded seven percutaneous injuries from our analysis: five involving clean instruments, one in which the location (labor and delivery) likely was miscoded, and one that occurred during activation of a safety device. Thus, 360 injuries were included in this analysis. The largest proportion occurred in outpatient clinic settings (68 percent) and the operating room (12 percent) (Table 1). Of percutaneous injuries reported by dental HCP, dentists reported 36 percent, oral surgeons 34 percent, dental assistants 22 percent, students 4 percent and hygienists 4 percent. Although many sharp devices were involved, four types (hollow-bore needles, suture needles, burs and scalpels) were responsible for nearly two-thirds (63 percent) of all injuries. Hollow-bore needles such as anesthetic syringe and winged-steel needles were the devices most frequently reported as being involved in injuries (31 percent) (Figure 1). Of 110 injuries with hollow-bore needles, anesthetic syringe needles accounted for the majority (80 percent).

View larger version (40K): [in this window] [in a new window]   Figure 1. Frequency of devices involved in percutaneous injuries (N = 360) among dental health care personnel, December 1995 through August 2004. Source: National Surveillance System for Health Care Workers, Centers for Disease Control and Prevention.23

View larger version (43K): [in this window] [in a new window]   Figure 2. Timing of percutaneous injuries (N = 360) by type of device among dental health care personnel, December 1995 through August 2004. Source: National Surveillance System for Health Care Workers, Centers for Disease Control and Prevention.23

View larger version (39K): [in this window] [in a new window]   Figure 3. Frequency of dental procedures during which percutaneous injuries (N = 195) occurred among dental health care personnel, December 1995 through August 2004. Source: National Surveillance System for Health Care Workers, Centers for Disease Control and Prevention.23

View larger version (38K): [in this window] [in a new window]   Figure 4. Timing of needlesticks (N = 88) by type of dental health care personnel, December 1995 through August 2004. Source: National Surveillance System for Health Care Workers, Centers for Disease Control and Prevention.23

View larger version (37K): [in this window] [in a new window]   Figure 5. Estimated proportion of needlesticks (N = 88) that might have been prevented by use of a safety syringe; based on circumstances of needlesticks among dental health care personnel, December 1995 through August 2004. Source: National Surveillance System for Health Care Workers, Centers for Disease Control and Prevention.23 (Note: No needlesticks were reported in Categories 2 or 7.)

	DISCUSSION

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Injuries involving syringe needles continue to account for a large proportion of reported percutaneous injuries.^1,2,6,7 Previous studies among general dentists^1,2 and dental students and faculty^6,7 during the past two decades have found that up to one-third of reported injuries were associated with syringe needles. In one survey of oral surgeons conducted in 1992, however, wire was reported as the device most prominently associated with injuries by more than one-half (53 percent) of participating oral surgeons, followed by syringe needles and suture needles.⁴ Compared with the study among oral surgeons,⁴ the lower proportions of injuries with wires reported in our study may reflect varying methodologies, underre-porting of occupational injuries perceived to be at lower risk of infection (that is, solid surgical or orthodontic wire versus hollow-bore syringe needles), or an increase in the use of safer work practices.

Dental assistants in our study accounted for 25 percent of needlesticks among dental HCP, with 83 percent occurring after use of a syringe. Similarly, a report from a dental school in the United Kingdom analyzed the difference between needle-sticks three years before and two years after introduction of safety syringes among trainees and staff members. The authors concluded that "dental trainee nurses [that is, dental assistants] were most frequently involved in needlestick injuries" during the three years before and two years after the introduction of safety syringes.¹⁹ Although most dental assistants do not administer anesthetic, they are responsible for direct patient care and have multiple opportunities to handle or manipulate anesthetic syringes during cleanup, dismantling and disposal of used needles. Safety syringes provide guarding mechanisms for the needle that prevent needlesticks during these activities. Although the numbers in our study are small, there is no reason to believe that the circumstances of needlesticks among dental assistants in the NaSH database differ significantly from the larger pool of U.S. dental assistants, which account for 44 percent of the dental work force.²⁶ Thus, dental assistants might benefit appreciably from the protection of safer dental syringes, and they should participate in the screening and evaluation of new devices.

In a 2000 report, the Government Accounting Office²⁵ estimated that in one year, 75 percent of needlesticks occurring in hospitals were preventable: 25 percent by eliminating unnecessary use of needles, 29 percent by using needles with safety features, and 21 percent by using safer work practices. This report included data for all HCP (including dental HCP) in the NaSH database.⁹ In our study, we estimated that 53 percent of needlesticks could be prevented by use of a dental safety syringe. Safety devices—such as blunt suture needles, phlebotomy devices and butterfly needles—and their ability to reduce injuries has been documented in medical and hospital settings.^27–29

Because of low injury rates in dental settings, few studies have used statistical methods to assess the effectiveness of dental safety devices in reducing injuries. One study of medical and dental students working at an academic health center found that percutaneous injuries decreased over five years after administrative interventions, engineering controls (such as safety syringes) and educational modules were introduced.²⁰ (Injuries among medical and dental students were not presented separately.) Needlesticks also declined after introduction of safety syringes in a U.K. dental school, from an average of 11.8 injuries per 1 million hours worked per year to 0 injuries, compared with a control group in which injuries decreased from 26 to 20.¹⁹ These estimates are limited by the small sample size and because improvements were made to the safety syringe during the study period.

Clinical studies evaluating the safety syringe itself have relied predominantly on subjective, qualitative measurements related to clinical acceptability (such as ease of use related to hand size, whether the device allows for multiple injections, perception of pain by the patient).^30,31 For example, one evaluation of several dental safety syringes found that the devices did not protect workers between injections or were awkward to use.³⁰ Although CDC has developed tools to standardize qualitative characteristics used in screening and evaluating safer dental devices,²¹ these subjective measurements cannot determine if use of a safety device can reduce the number of percutaneous injuries.

The U.S. Food and Drug Administration (FDA) regulates medical and dental devices and requires that manufacturers submit a premarket notification application (known as a "510[k]") to establish that a proposed device can perform the same function as a device already being marketed. Devices with safety features require a simulated clinical study to assess the effectiveness of the safety feature and to gather user input to guide labeling. Some sharps injury prevention features are incorporated as integrated components of finished devices. Others are marketed separately as accessories that are attached to a device by the user at the point of use, such as a needle shield. The FDA guidelines apply to both integrated sharps injury prevention features and accessories marketed separately.

One challenge in developing safer alternatives for reusable anesthetic dental syringes is that the design must incorporate a method to protect dental HCP between multiple injections (that is, the needle must be able to be locked temporarily in the safety position). This unique requirement has hindered the development of dental safety syringes with passive designs. Most early devices have been either redesigned or taken off the market entirely as newer designs have emerged. Thus, published studies evaluating earlier products do not always reflect current products and should not be used as the sole source of information when one is making a decision about which devices to consider. However, such studies can be useful for identifying evaluation criteria for ongoing review of dental safety devices.

Underreporting, lack of a suitable denominator and lack of data preclude the calculation of rates of injuries among dental HCP in NaSH. Nonetheless, descriptive information on the circumstances of injuries among this population can be used to develop injury prevention priorities and strategies. The CDC is creating a new surveillance system, The National Safety Healthcare Network (NSHN), which will integrate NaSH, the Dialysis Surveillance Network and the National Nosocomial Infections Surveillance System. The NSHN will allow a broader array of dental HCP, such as those in schools and other institutions, to submit and track their occupational exposures to blood and other body fluids. This database will be available online for use by private practitioners to use in selecting and evaluating dental safety devices or developing safer work practices.

Our study has several limitations. First, it is a retrospective review of self-reported data from a small number of large, urban hospitals voluntarily enrolled in NaSH. Larger teaching hospitals and those in the northeastern United States are over-represented in NaSH. Although NaSH data may be representative of some hospital-based and private practice dental HCP, they may not represent all types of dental HCP. In addition, underre-porting and reporting bias may have affected the accuracy and completeness of reports. Our estimate of the preventability of needlesticks is based on the assumption that if dental safety syringes are used, they can prevent 100 percent of needle-sticks, providing that safety features are activated and work properly, and that no failures occur. We could not calculate rates of injuries among dental HCP in NaSH because the total number of dental HCP from which the reports were collected is not available. In 2000, the NaSH questionnaire was revised to collect additional dental data such as the type of dental procedure being performed at the time of an injury and whether an injury occurred inside or outside the patient’s mouth. Thus, information on these factors is available only for injuries that were reported since 2000. Finally, these data may represent only a fraction of injuries among dental HCP in these facilities, because some studies among dental students and faculty indicate that many injuries go unreported.^6,7,32 Nonetheless, most of the circumstances of injuries described in this study are similar to findings in previous reports.

	CONCLUSIONS

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This study found that percutaneous injuries—particularly needlesticks—among dental HCP continue to occur, and that a majority occur at a point in the workflow at which acceptable safety syringes and safer work practices could contribute to their prevention. This finding underscores the importance of including all dental HCP (including dental assistants) who may sustain a needlestick during cleanup, dismantling or disposal of dental syringes in the selection and evaluation of safer alternatives. All dental practices should include a comprehensive written program for preventing sharps injuries in their exposure control plan. This plan should describe mechanisms for implementing procedures for identifying, screening and adopting acceptable safety devices; reporting injuries promptly and providing medical follow-up for percutaneous injuries; and educating and training dental HCP in safe work practices and the proper use of dental safety devices. Consideration and documentation of this process likely will meet OSHA requirements, keep dental HCP aware of available safety devices and provide feedback for manufacturers of dental devices that may drive development of improved safety devices.