J Dent Educ. 71(9): 1223-1227 2007
© 2007 American Dental Education Association
International Dental Education |
Infection Control Procedures in Commercial Dental Laboratories in Jordan
Ziad Nawaf Al-Dwairi, B.D.S., Ph.D.
Key words: infection, dental, technician, laboratory, Jordan
Submitted for publication 01/24/06;
accepted 06/07/07
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Abstract
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The risk of cross-infection in dental clinics and laboratories has attracted the attention of practitioners for the past few years, yet several medical centers have discarded compliance with infection control guidelines, resulting in a non-safe environment for research and medical care. In Jordan, there is lack of known standard infection control programs that are conducted by the Jordanian Dental Technology Association and routinely practiced in commercial dental laboratories. The aim of this study was to examine the knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan. Data were collected from the dental technicians by a mailed questionnaire developed by the author. The questionnaire asked respondents to provide demographic data about age and gender and to answer questions about their knowledge and practice of infection control measures: use of gloves, use of protective eyeglasses and face shields, hepatitis B virus (HBV) vaccination, laboratory work disinfection when sent to or received from dental offices. and regularly changing pot water or pumice slurry. Of the total respondents, 135 were males (67.5 percent) and sixty-five were females (32.5 percent) with a mean age of twenty-seven years. The results showed that 24 percent of laboratory technicians wore gloves when receiving dental impressions, while 16 percent continued to wear them while working. Eyeglasses and protective face shields were regularly worn by 35 percent (70/200) and 40 percent (80/200) of technicians, respectively. Fourteen (14 percent) had received an HBV vaccination, and 17 percent inquired if any disinfection measures were taken in the clinic. Eighty-six percent of the technicians reported that pumice slurry and curing bath water were rarely changed. Only five dental technicians (two males and three females) were considered to be fully compliant with the inventory of infection control measures, a compliance rate of 2.5 percent with no significant difference between males and females (p>0.05). In conclusion, there is lack of compliance with infection control procedures of dental technicians working in commercial laboratories in Jordan.
There is growing concern about the issue of cross-infection in dental clinics and laboratories, especially after several studies found that transmission of infection to dental laboratory technicians is mainly by contaminated impressions or by improper handling of clinical items after arrival at the dental laboratory. Three studies published in 1990, 1996, and 2002 reported that more than 60 percent of prostheses delivered to dental clinics from laboratories were contaminated with pathogenic microorganisms originating in the oral cavity of patients.1–3 In prosthetic laboratories, lathes and pumice used for polishing and finishing of prostheses have been described as the greatest sources of contamination.4
Potential pathogenic microbiologic cross-contamination from various sources by way of the dental laboratory has been documented, and guidelines to reduce it have been published.5 A previous study reported that nine out of ten sterile complete dentures that were fractured and sent to different dental laboratories for repair were contaminated with potentially pathogenic microorganisms.6 Several studies have found pumice in commercial laboratories that was contaminated by potentially pathogenic microorganisms, such as gram-negative bacilli of the genus Acinetobacter, as well as Micrococcus, Pseudomonas, Moraxella, and Alcaligenes.6–8 These bacteria, which are not part of normal oral flora, can cause serious diseases if passed to patients whose dentures are polished with contaminated material and to the technician by exposure to contaminated aerosol. Williams et al.9 reported an increase in cases of pneumonia in individuals exposed to lathe aerosol. Another study reported ten cases of infection by Mycoplasma pneumoniae involving persons working in dental prosthetic laboratories; the investigators suspected that these infections were derived from manipulation of prostheses contaminated by these microorganisms.10
Dental prostheses should be disinfected before they are sent to the laboratory and upon return to the dental clinic. However, despite rigorous control of sterilization and disinfection of instruments in dental clinics, prosthetic appliances do not always receive adequate infection control.11
Other studies demonstrated the presence of bacteria on impressions, although at a low level. One study showed that 12 percent of impressions taken from known tuberculosis patients harbored mycobacterium tuberculosis, and seventy-seven out of 107 alginate impressions yielded growth of bacteria after they were transported in sealed plastic bags to prevent any contamination, while no growth was recorded in the remaining thirty samples.3 Another study showed that 67 percent of the impressions sent to a dental laboratory had been contaminated with bacteria such as Enterobacter cloacae, Escherichia Coli, and Klebsiella oxytoca.8 These findings indicate that infection control programs should be developed and completed by dental technicians before handling any clinical items that arrive from dental clinics.
In Jordan, there are no strict national guidelines imposed by the Dental Technology Association regarding handling of impressions and prostheses between dental laboratories and clinics, and there are no previous articles on this topic in journals published in Jordan. Of two reports published recently, the first was in the American Journal of Infection Control and the second was in the Journal of Dental Education. The first report addressed infection control knowledge and practices among dentists and dental nurses at a Jordanian university teaching center,12 and the second investigated compliance with infection control programs in private dental clinics in Jordan.13
Therefore, the present investigation aimed to examine the knowledge and practices in infection control among dental technicians working in commercial dental laboratories in Jordan.
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Materials and Methods
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Data were collected from dental technicians by a mailed questionnaire developed by the author. The questionnaire was pilot-tested by distributing it to twenty dental technicians who work in a university-based hospital. Responses from the pilot test were analyzed to assess the clarity and relevance of the questions, and modifications were made. After receiving feedback from pilot test participants, I sent each of 200 dental technicians a personalized letter that explained the goal of the study and a self-addressed, stamped return envelope along with the questionnaire. Follow-up consisted of reminder postcards and two additional mailings of the questionnaire to nonrespondents. The study was conducted between August and November 2005.
The questionnaire asked respondents to provide demographic data about their age and gender and to answer questions about their knowledge and practice of infection control measures. Respondents were asked if they used each of the following infection control practices: gloves, protective eyeglasses and face shields, hepatitis B virus (HBV) vaccination, laboratory work disinfection when sent to or received from dental offices, and regularly changing pot water or pumice slurry. Finally, technicians were asked if infection control procedures imposed a financial burden on them. Dental technicians were considered compliant if they adhered to the complete list of infection control procedures included in the questionnaire. This list is shown in Table 1
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The returned questionnaires were reviewed for completeness. An SPSS statistical package was used to analyze the data. A binary outcome variable was generated to indicate compliance with infection control procedures, and compliance was presented as percentages. P value was used to assess the association of gender with compliance, and significance was set at the 0.05 level.
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Results
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All the 200 dental technicians included in this study completed the questionnaires, which represents a 100 percent response rate. Of the total respondents, 135 were males (67.5 percent) and sixty-five were females (32.5 percent), with an overall mean age of twenty-seven years (Table 2).
Twelve percent (24/200) of these dental technicians reported that they wear gloves regularly when receiving clinical items from various dental clinics, but only six of the twenty-four (3 percent overall; 6/200) continued to wear gloves during technical work. Eyeglasses and protective face shields were regularly worn by 35 percent (70/200) and 40 percent (80/200) of technicians, respectively (Table 3). Ten percent (20/200) of dental technicians had been vaccinated against HBV. Only 17 percent (34/200) asked clinical staff if the materials they delivered from the clinic had received any form of disinfection. Six technicians (3 percent) reported that they regularly disinfected clinical items after arrival if they had not been disinfected in the clinic. The majority of dental technicians (86 percent) reported that they did not change the pumice slurry or water of the curing bath regularly, and only 20 percent disinfected laboratory work before sending it back to the clinic. The majority of technicians (80 percent; 160/200) agreed that implementing infection control procedures in their laboratories required extra budget and imposed financial burdens on them.
Only five dental technicians (two males and three females) were considered to be fully compliant with the inventory of infection control measures listed in Table 1
, a compliance rate of 2.5 percent with no significant difference between males and females (p>0.05).
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Discussion
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The dental profession in Jordan has been expected to meet traditional standards of cross-infection control, but recent expression of concern by both the public and the profession over the transmissibility of infectious diseases in the dental office has demanded a formalized and extended teaching of cross-infection control in the dental curriculum. This is the first study conducted to assess the compliance of dental technicians working in commercial laboratories in Jordan with infection control procedures. Infection control in commercial laboratories in Jordan was investigated because these facilities often lack hazard risk instructions or occupational health policies that are more commonly available in universities and hospitals.
The response rate to the questionnaire in this study (100 percent) was higher than previous studies.14 This high rate is presumably due to the importance of the issue of infection in dental laboratories and because technicians recognize that dental laboratories are as important as dental clinics in following infection control programs to create a safe work environment. Many of the technicians who participated in this study wrote comments on the questionnaire that reflected their interest in this issue. Follow-up—which included reminder postcards and two additional mailings of the questionnaire to nonrespondents—might be another reason for the high response rate
Dental laboratory technicians are at risk of cross-contamination from the clinical items they receive and handle from dental offices.15 The use of protective measures is important. In this study, only 12 percent of the technicians wore gloves when receiving the impressions or any work delivered from the clinic. This is in contrast to a previous report in which 90 percent of the technicians in the United Kingdom wore gloves when handling dental work received and opened in the laboratory.16 A recent study reported that 39.5 percent of dental technicians in Nigeria never wear gloves while working in the laboratory.14 Dermatological reactions related to glove use and difficulties in adjusting to the use of gloves were the main reasons reported by dental technicians for not using gloves regularly.
Other protective measures, such as aprons, protective glasses, and lathes with efficient shields, should be used while working; these methods of protection will reduce the risk of cross-contamination.17 In the present investigation, 35 percent and 40 percent of dental technicians reported that they used protective eyeglasses and face shields, respectively. This contrasts with a previous report in which 74 percent were found to wear protective eye spectacles when trimming or polishing prostheses.16
Occupational infection of the dental laboratory technician with HBV has been reported.18 Only 10 percent of the technicians who participated in this study had received an HBV vaccination; this is lower than another study in which 24.4 percent had received an HBV vaccination.14 Furthermore, in this study a low percentage (17 percent) inquired about the disinfection status of materials they received from the clinics. This is a disappointing result because it is well established that contaminated impressions transfer microorganisms to the casts and harbor them; this transfer process will spread infection throughout the laboratory when the casts or dies are trimmed.7 As a result, dentists should always ensure that impressions are adequately disinfected before sending them to the laboratory. A recent study reported that 44 percent of the 400 U.S. dental laboratories knew if incoming impressions had been disinfected or not.4
Impressions have been considered the main source of infections in dental laboratories.3 It is easy for impressions to be contaminated with microorganisms that are present in a patient’s saliva and blood. Disinfection protocols have been recommended to prevent technicians from exposure to infectious diseases such as hepatitis B, hepatitis C, tuberculosis, herpes, and AIDS.19 Furthermore, it has been demonstrated that the impression material can act as a vehicle for the transfer of both bacteria and viruses. McNeill et al. reported that the virus was present in the body of the impression and, under certain conditions, may evade decontamination.20
Contaminated invisible aerosol particles remain in the air for long periods of time when lathes have been used for the polishing of prostheses.2,4 In spite of the fact that it is not possible to eliminate all sources of contamination in the laboratory, a series of preventive measures to decrease these levels should be adopted. The use of sterile pumice and rag wheels or the association of disinfectants with pumice for polishing are viable alternatives to significantly reduce cross-contamination in the laboratory.7,8,21,22
Pumice slurry is a major source of cross-infection in the dental laboratory: microorganisms can be harbored there easily unless the slurry is changed regularly or mixed with a disinfectant. A study by Kugel et al. published in 2000 concluded that non-clinical laboratories are not immune from the presence of potentially pathogenic microorganisms in pumice slurry.4 An earlier study by Witt and Hart2 published in 1990 showed that all pumice samples mixed with tap water were heavily contaminated and aerobic Gram-positive bacilli including B.Cereus, B. brevis, and B. licheniformis with members of the coli-aerogenes group predominated. On the other hand, samples that were prepared with the disinfectant Virkon had growth of less than 1.0 and were stable for four days. A study by Verran et al. published in 1996 showed the growth of a range of bacteria and yeasts from pumice and water bath.1 The most common were Staphylococcus, Candida and other yeasts, Pseudomonas, and Micrococcus. In the present study, only 14 percent of laboratory technicians changed pumice and water bath regularly. Unfortunately, none of the technicians used a disinfectant while working with pumice.
In conclusion, the results of this study confirm the lack of adequate infection control compliance by dental technicians in commercial dental laboratories in Jordan. Only five of 200 (2.5 percent) technicians complied with all infection control procedures, a percentage that is very disappointing and represents the lowest compliance among published data from several different nations.14
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Recommendations
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The most important strategy to improve compliance is to provide formal and obligatory infection control courses and guidelines for dental technicians by the Jordanian Dental Technology Association. In addition, standard infection control manuals that incorporate current recommendations should be disseminated. As for dental technology students, they should be educated about this important issue as a component of their curriculum. These instructions should be updated as required; there should be individual counseling, post-exposure evaluation, and follow-up to prevent any misunderstanding about the procedures and to cover any exposure incidents that could happen in the dental clinics and laboratory.
Considering the limitations of this study, more research is needed to provide comprehensive data on compliance with all recommended infection control programs by dental technicians. Inclusion of a greater observational element within the study design may help to reduce the socially desirable responses resulting from the questionnaire currently available.23
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Footnotes
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Dr. Al-Dwairi is Assistant Professor, Department of Restorative Dentistry, Jordan University of Science and Technology. Direct correspondence and requests for reprints to Dr. Ziad Nawaf Al-Dwairi, Department of Restorative Dentistry, Jordan University of Science and Technology, P.O. Box 3030, Irbid-Jordan; ziadd{at}just.edu.jo.
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- Verran J, Kossar S, McCord JF. Microbiological study of selected risk areas in dental technology laboratories. J Dent 1996; 24:77–80.[Medline]
- Witt S, Hart P. Cross-infection hazards associated with the use of pumice in dental laboratories. J Dent 1990; 18: 281–3.[Medline]
- Sofou A, Larser T, Fiehn NE, Owell B. Contamination level of alginate impressions arriving at a dental laboratory. Clin Oral Investig 2002; 6:161–5.[Medline]
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- Wakefield CW. Laboratory contamination of dental prostheses. J Prosthet Dent 1980; 44:143–6.[Medline]
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Abstract
Materials and Methods
