ATTITUDE AND PRACTICE ON HANDLING OF EXTRACTED TEETH FOR EDUCATIONAL USE AMONG THE STUDENTS OF A DENTAL COLLEGE IN SOUTHERN INDIA

Abstract

The objective of this study is to assess the attitude and practice on handling of extracted teeth among the students of a dental college in Southern India. A self-designed questionnaire was distributed among the 162 third and fourth year BDS students of a dental college in Southern India. Independent t test was used to compare the mean attitude and practice scores across genders and years of study. More than half of the respondents felt that extracted teeth could cause infection if used without adequate precautions. About 93.2% of the students stated that extracted teeth need to be sterilized before use, while about 90.7% considered that mouth masks were necessary while disinfecting/sterilizing extracted teeth, as about 80.2% of them used the extracted teeth for preclinical exercises in the Department of Conservative Dentistry and Endodontics. Most of the participants collected the extracted teeth from private practitioners. Hydrogen peroxide was the most commonly preferred storage medium of extracted teeth.

Headnote

Abstract

Objective. To assess the attitude and practice on handling of extracted teeth among the students of a dental college in Southern India.

Materials and method. A self-designed questionnaire was distributed among the 162 third and fourth year BDS students of a dental college in Southern India. Independent t test was used to compare the mean attitude and practice scores across genders and years of study.

Results. More than half of the respondents felt that extracted teeth could cause infection if used without adequate precautions. About 93.2% of the students stated that extracted teeth need to be sterilized before use, while about 90.7% considered that mouth masks were necessary while disinfecting/sterilizing extracted teeth, as about 80.2% of them used the extracted teeth for preclinical exercises in the Department of Conservative Dentistry and Endodontics. Most of the participants collected the extracted teeth from private practitioners. Hydrogen peroxide was the most commonly preferred storage medium of extracted teeth. Only 48.7% of the students answered correctly that extracted teeth should be disposed off in yellow garbage bins after use.

Conclusion. Although the dental students had a good attitude and practice on handling of extracted teeth for educational use, they did not indicate the most appropaite method of extracted teeth disposal after usage.

Keywords: extracted teeth, dental education, infection control

1. INTRODUCTION

Since a long time, extracted human teeth have been commonly used in dental institutions to train students acquire the skills to perform on live patients. Dental students practice their preclinical skills on artificial tooth models, typodont teeth, extracted teeth, etc., to learn numerous dental procedures. As artificial models and teeth pose no hazard, many of the dental procedures are best learnt on extracted human teeth, as they best simulate the clinical situations. Since the students procure extracted teeth from various sources - private dental clinics, oral surgery clinics, hospitals, etc., the teeth need to he stored and preserved for a considerable amount of time, before they are actually put into use. If the teeth are not stored in a liquid medium, they become brittle and unsuitable for use. Various solutions have been used to store and transport extracted teeth, the most common ones being formalin, saline, hydrogen peroxide and sodium hypochlorite. Since these liquids are easily available in dental clinics, they have become the obvious choice to store extracted teeth.

The Occupational Safety and Health Administration (OSHA) Blood-borne Pathogens Standard considers the human teeth used for research and teaching purposes as a potential source of hlood-horne pathogens [1]. As, prior to their extraction, they form a part of the human body, they may he a serious source of infection, so that CDC also recommends that they should he treated as potential hlood-horne pathogens. The Center for Disease Control and Prevention has adopted guidelines for infection control of the extracted teeth used for research and teaching, imposing their sterilization before use, to minimize the risk of transmission of blood-borne pathogens [2, 3].

Hence, apart from teeth storage and transport in a liquid, it is also important that the medium used is capable of disinfecting and sterilizing them. Studies have been conducted in the past to assess the disinfection efficiency of these agents [4]. Chemical heat, microwave radiation and autoclave sterilization methods are recommended for preventing crosscontamination during in intro dentin bonding investigations [4,5]. The obtained results suggest that 10% formahn, 5.25% sodium hypochlorite and autoclaving for 15-20 minutes at 121 psi assurre disinfection/ sterilization of the extracted teeth [6, 7, 5, 8-10]. As formalin poses risks as a potential carcinogen, some studies evidenced that sodium hypochlorite failed to disinfect all samples [10-12]. Autoclaving of extracted teeth may not be a suitable method for dental students; teeth with amalgam restorations should not be autoclaved because of the mercury vapours released in the air [6].CDC recommends storage of extracted teeth in 1:10 bleach [13].

No disinfectant mentioned in the literature as 100% effective is completely safe, however disinfectant media are used, in spite of such limitations. Even if several studies on the effectiveness of disinfectants are available, assessment of the attitude and practice on handling of extracted teeth is rare among dental students. Hence, the present study aims at assessing the attitude and practice regarding handling of extracted teeth among the students of a dental college in Southern India.

2. MATERIALS AND METHOD

Ethical approval to conduct the study was obtained from the Institutional Ethical Committee of the college. Participation in the study was voluntary. The participants were informed on the aim of the study and informed consent from the part of those interested was obtained. No incentives were given to the participants.

Survey instrument: A self-designed questionnaire containing 10 questions was distributed among 162 third and fourth year BDS students of a dental college in Southern India. The questionnaire included sociodemographic details, 5 questions (1 - 5) on attitude and 5 questions (6 - 10) on the practice of handling of extracted human teeth. This was a close-ended questionnaire and the subjects were asked to tick the most appropriate answer for each question. The questionnaire, elaborated in English, was validated by the test-retest method, involving its administering to 10 students. Reliability was assessed by the split half reliability coefficient test (p = 0.83, good reliability).

The responses were given in Microsoft excel and descriptive analysis of the data was done using frequencies and percentages. The independent t test was used to compare the mean attitude and practice scores across genders and years of study.

3. RESULTS

A total of 162 dental students from the third and fourth year BDS participated in the experiment. Table 1 shows the socio-demographic distribution of the study sample. Out of the 162 students, 80 attended the third BDS and 82 - the fourth BDS. 65 were males and 97 females. Their responses to the questions are presented in Table 2.

Most of the students (88.3%) thought that extracted teeth could he a source of infection. More than half of the respondents (61.1%) felt that extracted teeth could cause infection if used in educational settings without adequate precaution, while a vast majority (93.2%) answered that extracted teeth need to he sterilized before use. About 90.7% of them also felt that mouth masks were necessary while disinfecting/ sterilizing extracted teeth and 93.8% of the subjects considered that wearing mouth mask was necessary while working on extracted teeth.

Most of the students (80.2% ) used the extracted teeth for preclinical exercises in the Department of Conservative and Endodontics. 87% of them collected the extracted teeth from private practitioners, the others - from institutions/ quacks. Hydrogen peroxide was the most commonly used storage medium preferred by students (93.8%). Few of them used sodium hypochlorite (4.3%) and normal saline (1.9%). Students responses related to working on typhodont (46.3%) or extracted teeth (53.7%) were almost equal. The solutions proposed for the disposal of extracted teeth after use suggested yellow garbage bins (48.7%), common dust bins (45.1%) and others (6.2%).

Table 3 presents compatively the mean attitude score according to gender and year of study. The overall mean attitude score was 3.3+1.3. The mean attitude score among males and females was 3.2+0.84 and 3.5+1.32, respectively. The mean attitude score among Illrd year students was 3.8+0.78, while that registered for the IVth year ones was 3.6+0.81. However, the differences as to gender and year of study were not statistically significant.

Table 4 presents comparatively the mean practice score according to gender and year of study. The overall mean practice score was 3.6+1.34. The mean practice score among males and females was 3.7+0.58 and 3. 3+1.2, respectively, which means a statistically significant difference. The mean practice score among Illrd year students was 3.2+0.83, and 3.5+1.14, respectively, in the IVth year ones, namely a not statistically significant difference.

4. DISCUSSION

Dental educators and students have to handle the extracted human teeth very carefully. Since these teeth can harbour pathogens viable in the root canals for extended periods of time, the persons handling them are at risk during their drilling [6]. It is evident that many blood-borne pathogens, including HIV, HBV, HCV and bacterial pathogens, may exist in the pulp, radicular and periradicular tissue of extracted human teeth [14]. As tooth preparation in laboratories is usually done without a cooling liquid, there is a greater chance of contact the pathogenic organism and the danger of infection spreading, both through aerosoles and unintentional injuries that might occur with dental instruments during handling [10].

Disinfection refers to an action that reduces the microbial load present on the surface of an object, whereas the term sterile refers to an object without a detectable microbial load. According to this definition, it is possible to disinfect an object up to the point at which it becomes sterile [11]. CDC recommends storing of extracted teeth in 1:10 household bleach, which was not successful. [6, 15, 16] Ethylene oxide can he also used as a sterilizing agent, its efficiency on the Bacillus subtilis spores in extracted teeth ranging betweeen 20-36% [17]. Various new methods of sterilization have been introduced, with negligible effect on the tooth structure, such as gamma radiation sterilizations at low temperature, high pressure, chemicals or gases, no effect being observed upon the nanomechanical properties of teeth [18].

In spite of the numerous studies carried out to assess the disinfection/ sterilization of extracted teeth, the attitudes and practices of the students who use them most commonly have not been assessed. The present study attempts at collecting information from the part of the students on handling of extracted teeth, so that adequate precautions should be taken in this respect. Most of the students used the extracted teeth in the Department of Conservative and Endodontics, learning preclinical manoeuvres, such as root canal treatment. Extracted teeth are highly suitable for such exercises, and they are also cheaper than typhodont teeth. Private dental practitioners were the most common choice for procuring extracted teeth.

Since the third and fourth year BDS students have already passed the microbiology and pathology exams, they had fair knowledge about blood-borne pathogens, most of them considering extracted teeth a possible source of infection, capable of provoking cross-infections in educational settings. Most of them agreed that these samples need to be sterilized/ disinfected before use, and that adequate precautions - like wearing mouth masks, etc. - should be taken.

Surprisingly, even if formalin is a common disinfectant of extracted teeth, it was not used by students [6-8], most of them preferring hydrogen peroxide. Apart from formalin autoclaving for 30-40 min at 240°F and 15-20 psi, 5.25% sodium hypochlorite has also assured effective disinfection [8, 10, 19]. Chemicals like 5% Microten, 5% Deconex, 2% glutaraldehyde have been tried to disinfect extracted teeth, with negative results [12]. A study employing 5% Virkon and Gigasept PA showed their efficiency against the laboratory model of disinfection, being further applied to freshly extracted human teeth. Gigasept PA was the only disinfectant that sterilized 100% of the tooth samples. The authors considered Gigasept PA to be a safer and effective alternative to formalin for the sterilization of extracted teeth destined for teaching purposes [11]. Gigasept PA is a high-level hospital disinfectant used for medical instruments, not easily available. In spite of the evidence demonstrated by numerous studies, students still use hydrogen peroxide, sodium hypochlorite, normal saline etc., because of their availability in the dental college.

Most of the students agreed that it was necessary to use mouth masks while handling/ working on extracted teeth. The students were equally divided when asked about their preference for typhodont or extracted teeth. While most of the preclinical procedures, such as cavity cutting, crown cutting, veneers, jacket crowns, etc., can be easily practiced on the typhodont teeth, procedures like RCT do require extracted teeth for teaching purposes. Procuring extracted human teeth from various sources may be tedious, whereas the typhodont teeth are much more expensive. They do not induce the risk of cross-infection and the natural tooth is better felt. While there is no need to use cooling agents when using typhodont teeth, this is absolutely necessary when working on extracted teeth. Since both samples have their own pros and cons, the students were almost equally divided as to their preferences.

Many of the students were not aware of the correct method of disposal of extracted teeth after usage as, even after use, these tissues can be a source of infection and adequate precautions need to he followed not only while handling them, hut also for their disposal. In this respect, the following guidelines were issued by CDC for handling extracted teeth [13]:

* Extracted teeth used for teaching dental health care workers should be considered infective and classified as clinical specimens as they contain blood.

* All persons who collect, transport or manage extracted teeth should handle them with similar precautions as for a biopsy sample.

* Prior to employing the extracted teeth in dental educational training, they should he first cleaned of any adhering material, by scrubbing with detergent and water or by using an ultrasonic cleaner.

* Teeth should be then stored, immersed in a fresh solution of sodium hypochlorite (household bleach 1:10 with tap water), or in any other chemical germicide liquid for clinical specimen fixation.

* Persons handling extracted teeth should wear gloves. Gloves will he disposed off properly and hands washed after work. Additional personal protective equipment, e.g. face shield or surgical mask and protective eyewear should be worn if the mucous membrane contacts the debris, or spatter is expected during specimen handling, cleaning or manipulation.

* The working surfaces and instruments should be cleaned and decontaminated with a suitable liquid sterilizer after work.

5. CONCLUSIONS

Although dental students had a corresponding attitude and practice regarding handling of extracted teeth for educational use, they were not aware of the most suitable method for extracted teeth disposal after their usage.

References

References

1. Dominici J. T., Eleazer P. D., Clark S. J., Staat R. H., Scheetz J. P., (2001), Dismfection/Sterilization of Extracted Teeth for Dental Student Use. J. Dent. Educ. 65:1278-80.

2. Handling Extracted Teeth. Available from http:// www.ada.org/sections/professionalResources/ pdfs/cdc_handlmg_extracted.pdf accessed on 24-07-2013

3. Lee J. J., Nettey-Marbell A., Cook A. Jr., Pimenta L. A., Leonard R., Ritter A. V., (2007), Using extracted teeth for research: the effect of storage medium and sterilization on dentin bond strengths. /. Am. Dent. Assoc. 138(12):1599-603.

4. De Wald J. P., (1997), The use of extracted teeth for in vitro bonding studies: a review of infection control considerations. Dent Muter. 13(2):74-81.

5. Viana P. S., Machado A. L., Giampaolo E. T., Pavarina A. C., Vergani C. E., (2010), Disinfection of Bovine Enamel by Microwave Irradiation: Effect on the Surface Microhardness and Demineralization/ Remineralization Processes. Caries Res. 44:349-357.

6. Kumar M., Sequeira P. S., Peter S., Bhat G. K., (2005), Sterilisation of Extracted Human Teeth for Educational Use. Indian Journal of Medical Microbiology. 23(4):256-258.

7. Nikita V. L., Vidya B. S., Sham S. B., (2007), Disinfection Methods of Extracted Human Teeth. J. Oral Health Comm. Dent. l(2):27-29.

8. Chandki R., Maru R., Gunwal M., Garg A., Mishra A., (2013), A Comparison of Different Methods for Disinfection or Sterilization of Extracted Human Teeth to be Used for Dental Education Purposes. World J. Dent. 4(1):29-31.

9. Cuny E., Carpenter W. M., (1997), Extracted teeth: decontamination, disposal and use. Calif. Dent. Assoc. J. 25:801-4.

10. Sandhua S. V., Tiwari R., Bhullar R. K., Bansal H., Bhandari R., Kakkar T., Bhusri R., (2012), Sterilization of extracted human teeth: A comparative analysis. Journal of Oral Biology and Craniofacial Research. 2(3):170-75.

11. Hope C. K" Griffiths D. A., Prior D. M., (2013), Finding an Alternative to Formalin for Sterilization of Extracted Teeth for Teaching Purposes. /. Dent. Educ. 77(1): 68-71.

12. Tabrizizadeh M., Abrisham M., Dehghan Marvasti F., (2009), Comparison of different techniques for disinfection of teeth internal space in preclinical teaching. J. of Dent. Med. 22(3):120-124.

13. CDC. Guidelines for infection control in dental health-care settings e 2003. MMWR. 2003;52(RR17):'1-61: Available at: http://www.cdc. gov / mmwr / preview / mmwrhtml/rr5217al.htm. Accessed on 24-07-2013

14. Schulein T. M., (1994), Infection control for extracted teeth in teaching laboratory./. Dent. Educ. 58:41 le413: 15.

15. Pantera E. A., Schuster G.S., (1990), Sterilization of extracted human teeth. J Dent Educ. 54:283-285.

16. Tate W. H., White R. R., (1991), Disinfection of human teeth for education purposes. J. Dent. Educ. 55:583-585.

17. White R. R., Hays G. I., (1995), Failure of ethylene oxide to sterilize extracted human teeth. Dent Mil ter. 11:321-323.

18. Brauer D. S., Saeki K., Hilton J. F., Marshall G. W., Marshall S. J., (2008), Effect of sterilization by gamma radiation on nano-mechanical properties of teeth. Dent. Mater. 24(8):1137-1140.

19. Ghosh A., Chowdhury S., (2013), Sterilization and Disinfection of Extracted Human Teeth for Institutional Use. hit. Journal of Clinical Dental Science. 4(1):9-12.