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International Dental Education |
Key words: exposures, dental students, reporting, hepatitis B vaccination
Submitted for publication 07/17/06; accepted 02/17/07
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Abstract |
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Worldwide, the prevalence of hepatitis B virus (HBV) varies greatly. Compared with Europe and North America, where HBV currently affects less than 1 percent of the population,3–5 the virus is endemic in areas such as China, Southeast Asia, and Sub-Saharan Africa, including Nigeria, which has carrier rates exceeding 8 percent.3 Most of the infections in these areas start at childhood usually by perinatal transmission and by horizontal transmission among children.3 Specifically, chronic carrier rates among the general population in Nigeria range from about 12 percent to 48.7 percent in different states and cities.6–9 A prevalence of 18.3 percent of hepatitis B surface antigen was found in patients undergoing extractions at a Nigerian teaching hospital.10 In this respect, the Nigerian oral health care worker can be said to be at high risk of contracting HBV. A study conducted in 1997 demonstrated the high susceptibility of dentists to Hepatitis B and C infection; the findings of this study indicated that 45 percent of the Nigerian dentists examined had detectable HBsAg, indicating active infection. This level of infection among dentists was significantly higher than that reported among medical doctors in the same study.11
Safe and effective vaccines against HBV have been available since 19825 and have resulted in a dramatic decrease in the prevalence of HBV infection in many countries.12 Immunization against HBV also substantially reduced the susceptibility of health care workers to HBV infection and is thus an essential part of infection control programs for oral health care workers. Compared with the United States and Canada, where more than 90 percent of dentists have been vaccinated,13,14 and the United Kingdom, where more than 90 percent of dental students have been vaccinated,15 a significant number of dentists in Nigeria are not protected.16,17 Dental personnel who either have not completed the course of hepatitis B immunization or who are nonresponders to the vaccine are at significant risk of infection.4 However, accidental exposure to hepatitis B infection in such persons can be easily managed with prophylaxis when such exposures are reported and treatment is commenced within a short period.4
There are no data on the prevalence of HIV infection among dental staff in Nigeria, either occupationally acquired or otherwise; however, the prevalence of HIV infection among the general population of Nigerians has been reported to be 3.9 percent.18 In terms of absolute numbers, the country ranks second in Sub-Saharan Africa.19 Consequently, oral health personnel in Nigeria have substantial risk for occupational exposure to HIV due to the nature of dental treatment and the prevalence of HIV infection among the general population.
One of the groups at risk for exposure is dental students who may be at higher risk due to their inexperience with infection control procedures and the necessity to work on patients without any assistance most of the time. These risks for dental students are supported by a study by Kennedy and Hesler, which found that dental students reported significantly greater numbers of percutaneous and mucosal exposures than any other category of dental health care worker in the United States.20 Therefore, it is necessary that health professions training institutions such as dental schools implement necessary guidelines for infection control and safe work practices, as well as creating a protocol for dealing with reported occupational injuries. Adequate monitoring mandates the reporting of all occupational exposures. Accordingly, the aim of this study was to determine the frequency of occupation exposure in clinical dental students, their HBV immunization status, and the reporting practices and management of exposure incidents in the four dental schools in Nigeria.
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Method |
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The questionnaire consisted of twenty-six questions on each student’s background, HBV vaccination status, frequency of occupational exposures, including number and nature, use of protective equipments, post-exposure management, and reporting practices. Twenty-two of the questions were precoded with an open-ended option tagged "others" where necessary for respondents to specify any answer not included in the options. Questions on the number of exposures and clinic where the exposure occurred were left open ended.
For the purpose of clarity and to guide in answering the questions, a definition of occupational exposure was included in the questionnaire as "any needlestick injury, cut abrasion, or instrument puncture or any other exposure to blood and other body fluids such as splashes into the eyes, nose, mouth, or broken skin."
No institutional approval was required for the collection of this data from students at the four dental schools. However, participation of the students was voluntary, and the questionnaire was anonymous, thereby guaranteeing the confidentiality of the data obtained. The questionnaires were distributed at the end of lecture periods to all clinical dental students who attended the lectures and who were willing to participate. Results were analyzed using the EPI-INFO version 6 software. Chi-square test of association was used to compare differences, and a probability of 0.05 or less was considered statistically significant.
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Results |
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Hepatitis B Vaccination Status and Prevalence of Exposure
Eighty-seven (56.9 percent) students had started the vaccination series, but only thirty-three (37.9 percent) reported that they were fully vaccinated. None reported that they have been tested for sero-conversion. While there was no difference between schools in number of students that have started the vaccination series, there was a statistically significant difference between schools with respect to being fully vaccinated. More than one third of the students from Ibadan (40.5 percent) had completed their vaccinations compared with the other schools (p=0.0002). Table 2 shows immunization status in the various schools
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Associated Factors
The majority of the students (forty; 44.4 percent) reported that the exposure incidents occurred while performing manual scaling and polishing. This was followed by injuries sustained in the course of giving local anesthesia. This was reported by thirty-one (34.4 percent) of the students. The other procedures that resulted in the exposure incidents are shown in Figure 1. There was no difference in the risk of exposure with respect to time of conducting the procedure (whether the procedure was performed in the morning or afternoon). Also, sixty-five (76.5 percent) of the students reported that they were working unassisted when the exposure occurred.
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At the time of exposure, eighty-one (90 percent) of the students were wearing latex gloves, sixty-seven (74.4 percent) wore facemasks, and only nine wore protective eyewear (nineteen of the students use prescription lenses). One student had no protection as he was assisting someone else at the time.
Reporting and Management of Exposure
None of the students formally reported the exposure. Thirty-five (38.9 percent) of the students indicated that they did not know that they had to report, while twenty-five (27.8 percent) said there was nobody indicated to receive the report and twenty (22.2 percent) thought it was not necessary. The remaining ten students (11.1 percent) did not respond to the question. Over 90 percent of the students claimed that they are not aware of any guideline or protocol for post-exposure management in their institution.
Rinsing of exposure site with water was the most frequently used first aid measure in 46 percent of cases. Other measures used by the students included rinsing with hypochlorite solution (fourteen students) and methylated spirit or denatured alcohol (twenty-four students). However, twelve students (13.3 percent) did nothing concerning the wound, and notably, eight of these students had puncture wounds.
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Discussion |
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The findings indicated a very low rate of HBV vaccination with only thirty-three (37.9 percent) students completing the three-dose vaccination series. The vaccination rate is much lower than that noted amongst dental students in the UK.15 A similar low rate of uptake of HBV vaccination has been reported among cadres of dental personnel including dental students at the University College Hospital, Ibadan, despite the free access to the vaccine for all workers23 and amongst Nigerian dentists in another study.16 However, this study found that students from Ibadan still had a higher rate of vaccination than the other three universities; this can be attributed to the reported free access to the vaccine. Therefore, the rate of vaccination can be improved if the other universities take a cue from this example.
The low vaccination rate reported is a serious shortcoming, especially in an area regarded as endemic for the hepatitis B virus.3 This stresses the need for closer monitoring and enforcement of vaccination amongst dental personnel including dental students. It is the responsibility of training institutions to ensure that students are protected against hepatitis B virus before they are placed in clinical situations where they are at risk for exposure to HBV. A number of reasons may be responsible for the failure to complete the vaccination series although this study did not investigate for the possible reasons. There appears to be a high rate of noncompliance with multiple dose vaccines.24,25
For the population under consideration, more in-depth study is necessary to develop protocols that can be put into place to help improve students’ compliance with the vaccination regime in view of its critical importance for both their health and the patients’ health.
The finding from this study that 58.8 percent of the students have experienced occupational exposures demonstrates that dental students are at a high risk of developing serious infections with bloodborne pathogens including HIV infection. For example, it has been shown that the estimated risk of acquiring infection of hepatitis B from a percutaneous exposure ranges from 5 to 45 percent.21
In contrast to findings in Canada,26 where bur injuries were the most frequently recorded exposures among dental students, the use of manual instruments for tooth cleaning appears to be associated with the highest rate of occupational injury in our study. This is somewhat similar to findings in the UK, which noted that the greatest percentage of exposures amongst year five students occurred during tooth cleaning.15,21 Manual cleaning of teeth and root surfaces requires dexterity and good techniques. Our study suggests that there may an indication for more training of the students especially in work practice controls. Such controls might include restricting the use of the fingers for tissue retraction and minimizing the potential uncontrolled movements of scalers and similar instruments.
Another factor that might increase the risk of occupational exposures may be the absence of chairside assistants. More exposures were noted to have occurred when students were working alone than when assisted in the UK.21 Nigerian students frequently work unassisted due to shortage of chair-side assistants, who are referred to as dental nurses in Nigeria. Shortage of middle level oral health manpower is a problem in Nigeria and may be due to an inadequate number of training schools leading to inadequate supply rather than financial reasons. An effort to address this shortage involves a new dental nursing training program at the Lagos University Teaching Hospital. It is anticipated that the training program will increase the number of assistants to parallel the increase in dental student enrollment, which has occurred in recent years.
Students’ use of personal protective equipment in this study, which is a critical component of standard precautions, was found to be similar to a previous Nigerian study,16 which noted that the use of protective eyewear was inadequate. Only 10 percent of the students in this study were wearing protective eye shields. Although some students wore prescription glasses, prescription glasses alone are not acceptable to adequately protect the eyes. Protective eyewear should have solid side shields or alternatively a face shield.1 This finding, however, is not peculiar to Nigeria, as the study in the UK also noted that 60 percent of the students were not wearing protective eyewear when they experienced an exposure incident.21 While the risk of infection is less with mucosal splash than via percutaneous injuries, this may be an important route of exposure in this population, considering the fact that saliva and blood splashes were the next most commonly cited exposures after puncture wounds. Dental students should receive instructions to help them understand the risks associated with treating patients without protective eyewear; hopefully, comprehension of the risks will improve compliance with the use of protective eyewear.
An aspect of post-exposure management that was completely inadequate was the reporting of occupational exposures. None of the students reported the exposure incidents. Although studies have observed that reporting of occupational exposures in most centers is generally low,20,21,27 reasons given by the students in this study centered around the lack of post-exposure protocol in each of the centers. This is similar to reasons given by a group of Nigerian dentists in a previous study.17 We confirmed that post-exposure management protocols exist in all four Nigerian schools, but the implementation of these protocol appears to be suboptimal given the students’ lack of awareness of these procedures. There is a need for the development of a formal reporting protocol, which would include the exact protocol to be followed as well as the consequences of not reporting. It is important that such protocol and post-exposure incident services be introduced to students at the time of their orientation before they begin their clinic experiences. Access to such programs should be readily available and rapid so that the time between exposure and post-exposure prophylaxis is as short as possible.
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Conclusions |
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Footnotes |
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REFERENCES |
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