Dental students ’ reports of occupational exposures to potentially infectious biological material in a Brazilian School of Dentistry

1 Departamento de Odontologia Social, Faculdade de Odontologia de Araraquara (FOAr), Universidade Estadual Paulista (UNESP) Araraquara (SP), Brazil. Study carried out at Faculdade de Odontologia de Araraquara – Araraquara (SP), Brazil. Correspondence: Camila Pinelli – Rua Humaitá, 1680 – Centro – CEP: 14801-903 – Araraquara (SP), Brazil – Email: cpinelli@foar.unesp.br Financial support: FAPESP #2011/01922-3 and 2011/01960-2. Conflict of interests: nothing to declare. Abstract Introduction: Occupational exposures to contaminated biological material in dental teaching settings can place students at higher risk of bloodborne infections. Methods: This cross sectional study was conducted using a self-administered questionnaire culturally adapted to Portuguese language, Brazil. In total, 173 undergraduate dental students agreed to participate in the study, answered the questionnaire, and filled in the details about their own occupational exposures. The association of these factors was analyzed by the chi-square test or Fisher’s exact test using Stata software. Results: High prevalence of occupational exposures (40%) was observed among the participants, and 52% of the accidents were not reported to the clinical instructor. The most frequent type of accident was related to “puncture/cut/abrasion” (56%). Significant correlation was observed between number of exposures and academic year (p=0.002), age (p=0.012), gender (p=0.010), and between number of injuries in the last 6 months and academic year (p=0.003). No significant correlation was observed between number of exposures and dominant hand, use of protective eyewear or Hepatitis B vaccination status (p>0.05). Conclusion: Additional teaching strategies need to be developed to motivate adherence to occupational post-exposure protocols regarding biological material, improving the notification of the occupational exposures that occur among dental students.


▄ INTRODUCTION
The working environment of dental professionals is a dangerous place for contamination by bloodborne pathogens 1,2 .Special concern is related to occupational exposures, which are defined as [...] any contact of non-intact skin, eye, mucous membrane, or parenteral contact (needlestick, cut, abrasion, instrument puncture) with blood or any other potentially infectious material (such as saliva) which occurs during the performance of diagnosis and treatment of patients, or when handling orally soiled impressions and prosthetic devices 3 (p.107).
Previous studies indicated that dental students may be more vulnerable to occupational exposures due to their lack of experience and lower manual dexterity 1,[3][4][5][6] .Some studies have investigated dental students' knowledge and attitudes in relation to management of occupational exposure in Brazilian dental teaching environments 6,7 , and they revealed the 'long road' to be traveled in relation to reporting accidents and improving post-exposure procedures to minimize the risks of infection.
In Brazil, there are approximately 200 dental schools 8 preparing students for professional life.However, little information is available on the frequency and nature of their occupational exposures 6 .Additionally, the high prevalence of underreporting such injuries contributes to the lack of data and inappropriate post-exposure management 9 .
There is no vaccine against HIV, and AIDS is still a major public health challenge, aggravated by the possibility of co-infection of HIV and Hepatitis B and C viruses.Such diseases share the same forms of transmission, and clinical studies conducted in Brazil show that, among HIV/AIDS-infected individuals, almost 6% are positive for HBV and from 5 to 18% are positive for HCV (10).
Another important issue is related to the fact that HIV has mutated, and diagnostic tests -especially rapid tests used in the first hours after the accident -need to be more sensitive and specific in order to track the current genetic diversity 10 .Dental schools are faced with a big challenge in seeking better strategies to raise awareness and self-efficacy, among dental students and the entire community of teachers and counselors, to avoid the threats occupational exposures to biological material may pose.
In order to raise information on how dental students faced their occupational injuries, Stewardson et al. 3 developed a questionnaire to gather important issues on occupational exposures and dental students' reports.Such an instrument could be a valuable tool to collect standardized information, and it can also be applied in different periods of time to score changes in a specific investigated group.
Epidemiologic data are required to find high-risk groups and develop strategies to focus on.To the best of our knowledge, there is still a lack of studies regarding occupational exposures among dental students in Brazil.Therefore, the aims of the present study were 1) to culturally adapt the original questionnaire proposed by Stewardson et al. 3

Cultural adaptation of the questionnaire
Translation and cultural adaptation of the original questionnaire 3 , which was authorized by the main author, were based on the protocol proposed by Guillemin et al. 11 and Guillemin 12 which consisted of the following steps: initial translation, back translation, expert committee review, and cultural adaptation.
It is important to assess the level of agreement of the results whenever a questionnaire is used as a tool.To this end, kappa statistics (κ) was applied to measure the test-retest reliability of the answers provided by a sample of the population prior to the final application of the questionnaire.
Results showed good and excellent values for intra-examiner agreement for the majority of the variables (0.66< κ <1.00), and regular values for the variables "use of protective eyewear" and "no exposure in the last 6 months" (0.47< κ <0.58).
The final translated instrument (Chart 1) comprised questions on personal details (age, gender, academic year, and dominant hand); vaccination status regarding Hepatitis B virus (HBV); occupational exposures (number and nature of occurrences, and possible associated factors) in regard to their last occurrence; reporting behavior, and follow-up procedures.

Application of the research instrument
A total of two hundred and twenty-eight dental students enrolled at Araraquara School of Dentistry (FOAr-UNESP) in the third, fourth and final years (Y3, Y4, Y5) of the 5-year undergraduate dental course were asked to voluntarily complete a questionnaire in the end of their academic year, in 2011.The college under study is one of the three main Public Dental Schools in Sao Paulo state, Brazil.Approval was obtained at the local Research Ethics Committee (protocol number 05/11).All volunteers were properly informed about the survey, and the ones who agreed to participate signed an Informed Consent Form.
Data were tabulated using EPI Info  2000 software and analyzed by the chi-square test or Fisher's exact test using Stata  software (Stata Statistical Software: Release 11.0, College Station, Stata Corporation, Texas, USA) at a level of significance of 5%.

Vaccination status and reported exposures
Although 85.5% of the students reported having been completely vaccinated against HBV, only 38.2% of them had taken the seroconversion test for Hepatitis B.
Table 1 shows the distribution of dental students' academic years and the number of their occupational exposures since the beginning of the course.Almost 40% of the 173 respondents reported at least one occupational exposure.Students enrolled in Y4 and Y5 were among the most injured.
Table 2 shows the distribution of dental students' academic years and the number of occupational exposures in the last six-month period.Y4 students were the most injured (30.6%), followed by those at Y5 (25.0%).
At the time of the accident, 57.8% of them were being assisted and 22.5% were working alone when their last occupational exposure occurred.Most accidents happened in the morning (66.2%).
The nature of the exposure included puncture (needle or other sharp object)/cut/abrasion (56.3%), followed by aerosol or spatter landing on a mucous membrane (25.4%).
In relation to the procedure that was being performed at the time of the accident, the students reported that most of their accidents occurred during dental care (62.0%) to patients.
The use of complete Personal Protective Equipment (PPE) for Standard Precautions was indicated by 70.4% of the undergraduate students and comprised clinical coat, mask, cap, protective eyewear, and gloves.However, 25.3% of the students were reckless with the use of protective eyewear, and 2.8% were not wearing any PPE at the time of the exposure.
Among the injured, most students (52.1%) did not report the occurrence to the clinical instructor.In relation to the cases reported, only 32.4% of the dental students had blood collected for exams.
Table 3 shows that there was no significant correlation (p>0.05) between "number of exposures" and "dominant hand", "use of protective eyewear/lenses", "number of doses of Hepatitis B vaccine" or "test for seroconversion".No significant correlation was also observed (p>0.05) for "type of exposure" and "academic year", "gender", "work situation" and "report to the clinical instructor".There was no significant correlation (p>0.05) between "academic year" and "report to the clinical instructor", "collecting blood for exams" and "need for treatment after injury".Significant correlation was observed between "number of exposures" and "academic year" (p=0.002).The number of exposures in Y4 and Y5 students was higher than the expected.Significant correlation was also observed between "number of exposures" and "age" (p=0.012).Students above the age of 25 had more injuries than expected.There was significant correlation between "number of exposures" and "gender" (p=0.010)considering that the number of women was higher than the expected.Significant correlation was found between "number of doses of Hepatitis B vaccine" and "academic year" (p=0.012);there were more vaccinated students in Y3 and Y4 than expected.There was significant correlation between "testing seroconversion to HBV" and "academic year" (p=0.000);fewer students than expected were tested.Significant correlation occurred between "number of occupational exposures in the last 6 months" and "academic year" (p=0.003), as the number of casualties in Y4 was higher than the expected.Correlation was significant between "hour of the day that the accident occurred" and "academic year" (p=0.000);Y4 students had more accidents in the morning than expected.In addition, the number of Y5 students injured in the afternoon was higher than the expected.Significant correlation was observed between "report to the clinical instructor" and "being punctured" (p=0.000); the number of students who did not report accidents caused by spatter or aerosol contact on mucous membrane was higher than the expected.

▄ DISCUSSION
The survey achieved a response rate of 75.9%, which was similar to that reported by Myers et al. 1 , with 72.1% of the responses.The fact that more students responded to the questionnaire makes data reflect the reality with a higher degree of certainty.Although response rate was high, it should be considered that the information collected was dependent on the individual memory and honesty of students when reporting their exposure to biological material.Therefore, a reliability study was performed to ensure higher accuracy.This study showed good to excellent values of agreement for the majority of studied variables, except for the results related to "use of protective eyewear" and "number of exposures in the last six months".Conclusions drawn from the analysis of these last two variables should be considered with certain limitations.
The analysis of the factors associated with occurrence and level of report on occupational exposures can provide educational guidance to develop protocols and procedures to reduce their prevalence 3 .
An instrument that could provide such information among students would be valuable in the dental teaching setting.Bear in mind that the present study culturally adapted the questionnaire to Portuguese language (Brazil).The literature shows the advantages related to the cross-cultural adaptation of a questionnaire, as it demands less time than developing a new instrument 13 .In the present study, the culturally adapted questionnaire can be considered a reliable instrument and, therefore, it can be applied in future surveys.
An increased number of occupational exposures have been verified among the present students since the beginning of the undergraduate course.A large number of participants reported at least one injury (41.1%).Y5 students were the most affected ones.This result was expected considering that Y5 students have spent more time treating patients 3 .Clinical experience does not imply better prevention of injuries among students or professionals, and decreasing fear on injuries was observed as students gained experience 14 .
Higher frequency was found with respect to "number of exposures in the last 6-month period" among Y4 students.Such finding agrees with a previous research 3 , and may have occurred due to reckless use of PPE; students were not using them in 21 cases of reported exposure.Protective eyewear was the least commonly used equipment, which was absent in all of the 21 cases.Students should be monitored by tutors to ensure proper wearing 3,15 .
The most frequently reported type of injury was puncture/ cut/abrasion (56.3%), followed by spatter landing on a mucous membrane (25.4%).These results corroborate previous literature findings 1,16 .
The exposures occurred mainly during clinical care (61.9%), followed by the time spent when processing instruments (26.8%).These findings support the study by Myers et al. 1 , in which 51.3% of the exposures occurred during clinical care and 23.1% during the cleaning of instruments.
In the present study, 52.1% of the 71 cases of occupational exposure were not reported to the clinical instructor, and the majority of unreported cases (23.9%) occurred due to aerosol/spatter landing on a mucous membrane.Underreporting cases is very common and it was even higher in other recent studies.A study conducted in Shiraz, Iran reported that 73.6% of the 80% injured students surveyed did not report their exposure to the instructor 17 .In a study conducted in China, only one of 34% of students injured reported the occurrence 18 .
Reasons for not reporting such incidents were probably related to the fact that the students did not take the occurrence as a significant health risk 4,7 .The literature also shows that other reasons for the underreporting of accidents are related to individual personality traits, lack of time, or excessive paperwork related to the reporting, and also to dissatisfaction with follow-up procedures 9,19 .Students should pay attention to the importance of reporting cases of occupational exposures so that they can receive proper medical treatment and follow-up 3 .
Studies show that the estimated risk of contracting human immunodeficiency virus (HIV) after a percutaneous contact with infected blood is of approximately 0.3%, and also if exposure occurs through mucous membrane, chances are reduced to approximately 0.09% 12 .Based on these figures, the group investigated should be well aware of the implicit risks they are exposed to, because they can acquire a potentially lethal infection.
Despite of presenting a high rate of vaccination against HBV (85.5% were vaccinated), a low percentage of Anti-HBsAg tests performed, and a high underreporting of occupational exposures, this local study probably represents the reality of many other dental schools in Brazil.The literature shows a low coverage of complete Hepatitis B vaccination among healthcare workers 20 and dental students 21 .Some of the students (50.3%) who reported not having been tested for seroconversion against HBV may also be at risk of acquiring HB, because vaccination failures may occur.Also, there is a considerable risk of contracting more than one disease at the same time.Some coinfections commonly seen in people infected with HIV include HBV and/or HCV 22 .
More effective educational efforts can improve compliance with the prevention and management of occupational exposures.A shift in paradigm is important to ensure dental students' understanding of better practices related to post-exposure protocols.

▄ CONCLUSION
1) The present study culturally adapted a questionnaire developed in English (UK) to Portuguese (Brazil), and the results show it can be considered a reliable tool to investigate the occurrence of occupational exposures among Brazilian dental students; 2) The occurrence of exposures, as well as the underreporting of cases, presented high percentages among participants in the institution investigated.Most participants had received the complete vaccination against Hepatitis B, but half of them did not undergo the seroconversion test.Regarding the accidents, it was observed that the most frequent type of exposure was puncture/cut/abrasion, followed by aerosol/spatter landing on a mucous membrane.
Education strategies to draft a prevention policy -including closer supervision to remind dental students about the importance of using PPE and notifying the occurrences -need to be developed.A better targeting of the teaching strategies can allow for reduction in the number of accidents and increase in the reporting of cases, providing safety for undergraduate students and patients.

Chart 1 .
Occupational exposure questionnaire culturally adapted to Brazilian Portuguese.FOAr-UNESP, 2011 so that it becomes available for use as an instrument in such diagnosis, and 2) to investigate the occurrence and nature of occupational exposures in a Public School of Dentistry in Sao Paulo state, Brazil.

Table 1 .
Distribution of dental students according to academic year and number of occupational exposures occurred since the beginning of the course.FOAr-UNESP, 2011

Table 2 .
Distribution of dental students according to academic year and number of occupational exposures occurred in the last 6-month period.FOAr-UNESP, 2011

Table 3 .
Number of students (n), association tests (p-value), and level of significance according to the variables analyzed.FOAr-UNESP, 2011 *significant; ns non-significant