The prevalence of occupational health-related problems in dentistry: A review of the literature

J Occup Health 2018; 60: 111-125 Review The prevalence of occupational health-related problems in dentistry: A review of the literature Rajeshree Moodley1, Saloshni Naidoo2 and Jacqueline van Wyk3 1 Discipline of Dentistry, School of Health Sciences, University of KwaZulu-Natal, Durban, KwaZulu-Natal, South Africa, Discipline of Public Health Medicine, School of Nursing and Public Health, University of KwaZulu-Natal, Durban, KwaZulu-Natal, South Africa and 3 Discipline of Clinical and Professional Practice, School of Clinical Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, KwaZulu-Natal, South Africa 2 Abstract : The study was conducted to report on the scope and prevalence of occupational health relatedproblems experienced by dentists, dental therapists, and oral hygienists in their practice of dentistry. Background: Professional practice and dental training have many risk factors, and the dental team should be able to recognize these factors to protect themselves. The prevalence of conditions related to the musculoskeletal system, stress, percutaneous injuries, ears, and eyes are of concern. The dental team should also not forget hepatitis B, hepatitis C, and HIV as risks in practice. Dental practitioners should protect themselves by selfrecognizing risk factors and by maintaining proper working conditions. Methods: The study targeted all empirical research, case studies, and systematic literature reviews written in English. All articles selected were subjected to a data analysis process. Data were captured on an Excel spreadsheet and reported in a comprehensive table. Results : The literature addressing occupational health among dental practitioners included mainly crosssectional studies and review papers (2001-2016). Fortynine studies were included in the review. Musculoskeletal disorders remain the most researched occupational health-related problems in dentistry. Eye protection compliance was low among practitioners. Percutaneous injuries especially among young dentists and students were still a concern. Conclusion: Occupational health-related problems are still prevalent in current dentistry practice, despite changes in equipment and surgery design. The reported prevalence of occupational related-health problems and other findings of investigative studies highlight Received July 19, 2017; Accepted November 13, 2017 Published online in J-STAGE December 6, 2017 Correspondence to: R. Moodley, Discipline of Dentistry, School of Health Sciences, University of KwaZulu-Natal, University Rd Reservoir Hills 4000, Durban, South Africa (e-mail: moodleyra@ukzn.ac.za) the need for continuous professional education and a need to improve clinical practice aspects of dentistry curricula. (J Occup Health 2018; 60: 111-125) doi: 10.1539/joh.17-0188-RA Key words : Musculoskeletal disorders, Occupational health, Percutaneous injury, Stress Introduction Dental practitioners in dentistry training and practice environments are challenged with a number of occupational health barriers. The dental worker is prone to physical and psychological stressors which are aggravated by the work environment 1) . Irrespective of where one works, the goal is to be in a safe environment without having fear of incurring work-based injuries. It is important to have a “philosophy of prevention” which should be followed to reach health and safety goals 2) . Occupational health is a multidisciplinary and comprehensive approach which aims to protect and promote the health of a worker. The enhancement of physical, mental, and social well-being will ensure that workers live productive lives3). Dental workers are prone to occupational health-related problems occupational health problems, with dental hazards being of a physical, biological, chemical, and psychosocial nature4). Musculoskeletal disorders (MSDs), eye injuries, vibration-induced neuropathy, and psychological conditions are some of the poor health outcomes due to occupational health issues5). Problems such as contact dermatitis, hearing loss, and toxicity from materials used during dental practice have also been noted. Other risks include incidents due to exposure to infectious diseases, radiation, and noise, and allergy to dental materials6) . The prevention of such injuries should be included in educa- 112 J Occup Health, Vol. 60, 2018 Fig. 1. Diagram of the search strategy tion and training, to reduce occupation-related health problems among dental workers. This paper reports on the scope and prevalence of occupation-related health problems experienced by dentists, dental therapists, and oral hygienists in their practice of dentistry. traction sheet. All of the extracted data were then incorporated into an Excel spreadsheet to identify common themes. Data extraction was done independently by two reviewers, and consensus was reached on the inclusion of manuscripts7,8). Methodology Results The study targeted all empirical research, case studies, and systematic literature reviews written in English. Letters to editors, conference proceedings, and policy statements were not considered. Articles were retrieved using search engines e. g. , Ebscohost, PubMed, and Google Scholar. Only articles published within a 15-year time period of 2001 and 2016 were included for review. The keywords/phrases included occupational health among dentists / dental therapists / hygienists, musculoskeletal problems among dentists/dental therapists/hygienists, risk factors for occupational health in dentistry, eye / sight / ear problems in dentistry, dental occupational health, and occupational health among oral hygienists and dental therapists. The titles, keywords, and abstracts of articles were considered for potential relevance, and the full articles were obtained for those articles deemed to be relevant (Fig. 1). The articles were then subjected to data extraction and critical analysis through the use of a data extraction sheet. The extraction sheet was piloted on five articles, and adjustments were made. The authors, study designs, participants, locations, interventions, prevalences, outcomes, and conclusions were recorded in the electronic data ex- The results are presented in a table format so as to summarize the methods, prevalence data, outcomes, and recommendations. The literature addressing occupational health among dental practitioners includes mainly crosssectional studies and review papers. Most of the literature (90%) addresses MSDs among dentists, with limited literature covering occupational health or MSDs among oral hygienists and dental therapists. The selected studies focused on the prevalence of occupational health-related problems and not on the intervention to potentially address the particular issue. Forty-nine studies were included in the review and were selected after an initial electronic search through keywords (Table 1). The results are presented as the prevalence of stress, burnout, musculoskeletal disease (back, neck, hands, and shoulders, etc.), vision-related occupational health-related problems, percutaneous injury (PCI), noise, mercury-related occupational health issues, allergy, and infections. The outcomes and recommendations of the studies were included (Table 1). Title/Reference Work-related musculoskeletal disorders in Australian dentists and orthodontists: Risk assessment and prevention 9) Relationship between Comorbid Health Problems and Musculoskeletal Disorders Resulting in Musculoskeletal Complaints and Musculoskeletal Sickness Absence among Employees in Korea 10) Evaluation of musculoskeletal disorders in dentists and application of DMAIC technique to improve the ergonomics at dental clinics and meta-analysis of literature 11) Prevalence of musculoskeletal disorder and alternative medicine therapies among dentists of North India: A descriptive study 12) The relationship between physical load and musculoskeletal complaints among Brazilian dentists 13) Sample Design Prevalence 450 dentists Cross sectional 88.9%-dentists 83.6%-orthodontists 447 ortho- study dontists 29,711 workers Cross sectional 32.26%-muscular pain study 60 dentists Cross sectional 68.3%-MSD study intervention 3598 dentists Cross sectional 80%-MSD study Intervention by complementary and alternative medicine 340 dentists Cross sectional 58.4%-lower back study Outcome Recommendations Less than1/3 received ergonomics training. Musculoskeletal problems which were associated with increased levels of stress at work. More research into interventions. For management of musculoskeletal complaints in the workplace, differences in health problems between employees with musculoskeletal complaints as well as the physical and psychological risk factors should be considered. After three months only 23 respondents applied ergonomics at their work place, prevalence of pain was reduced in neck from 47.8% to 21.7% out of total 23 respondents, shoulder pain 39.1% to 17.3%, pain in elbows from 26% to 21.7%, as well as in other locomotor organs. The p-value was significant with p<0.05. Complementary and alternative medicine was remarkably good for MSD management. Pain complaints were associated with the following characteristics: awkward posture at work; prolonged standing or sitting; strenuous position of the upper limbs; excessive tightening of the hands during clinical treatment; and the use of vibrating tools. The outcome highlights the need of workshops to create awareness of ergonomics as effective measures for reducing MSD among dentists. Rajeshree Moodley, et al.: Occupational health problems in dentistry Table 1. Results Complementary and alternative medicine should be scientifically tested to establish those that work. Randomised control trial should be conducted to establish efficacy. The results of the present study suggest a high prevalence of musculoskeletal complaints in dentists that are significantly associated with variables related to their physical workload. 113 Title/Reference Sample Design Prevalence Outcome Stress among dentists in Yemen 14) Stress was reflected in dentists with the 368 dentists Cross sectional The most prevalent factors study that contribute to stress were signs being musculoskeletal fatigue in 63% and nervousness in 57.1%. uncooperative patients (72.3%), amount of work (too much, too little) (60.5%) and constant drive for technical perfection (54.6%). Occupational mercury exposure in association with prevalence of multiple sclerosis and tremor among US dentists 15) Prevalence of Upper Extremity Musculoskeletal Disorders in Dentists: Symptoms and Risk Factors 16) Neck and upper extremity symptoms among male dentists and pharmacists 17) Occupational Hazards among Dentists: A Descriptive Study 18) 13902 dentists Investigative 0.18% reported MS and 1.24% reported tremor. 130 dentists Descriptive, 55.9%-neck Cross sectional 43.8%-shoulder study 39.2%-waist 34.5%-wrist 32.5%-back 252 dentists Cross sectional 76.2%-neck or hands study 66 dentists Hg0 exposure was not associated with MS 15% of the subjects had to leave their clinic or reduce their work hours, and overall 68.9% of the subjects reported that they had experienced pain and discomfort at least once over the last year Praying and reading the Quran was reported by over two thirds (70.6%) of the participants to manage stress. Dentists with less than 30 years of experience displayed more stress. Lack of experience, low income, uncooperative patients, and dental procedurerelated factors were the main significant factors that caused stress Occupational Hg0 exposure in US dentists decreased over time and now is approaching that of the general population. Our results suggest a positive association between Hg0 exposure and tremor High pain frequency and high risk levels suggest inappropriate and incorrect ergonomic postural habits existing among dental professionals Male dentists are at risk of developing musculoskeletal disorders in the neck and upper extremities more than male pharmacists Cross sectional 83.3%-neck pain study 9%-Allergy 59%-PCI 42.2%-stress Regular physical exercise was associated with decreased neck pain As for psychosocial factors, high job demand was associated with symptoms in the shoulder Working hours per day were associated with neck paina MSD most common problem and ergonomics not featured in dental curricular in India. Continuing dental education programmes should include education regarding ergonomics, new materials, operating methods, new laws, vaccination 4) Primary prevention Early intervention Continuous education J Occup Health, Vol. 60, 2018 Prevalence of work-relat- 272 dentists Cross sectional 88%-MSD ed musculoskeletal study 83.8%-Neck symptoms of the neck and upper extremity among dentists in China 19) Recommendations 114 Table 1. Results (continued) Title/Reference Design and evaluation of ergonomic interventions for the prevention of musculoskeletal disorders in India 20) Use of complementary and alternative medicine for work related musculoskeletal disorders associated with job contentment in dental professionals: Indian outlook 21) Work Characteristics and musculoskeletal disorders among Postgraduate Dental Students: A Pilot Study 22) Self-reported musculoskeletal pain among dentists in South Africa: A 12-month prevalence study 23) Sample Design Prevalence Case study Outcome Recommendations Proper implementation of ergonomic interventions can improve the economy of the nation The cause for concern is that most of the interventions are not properly designed 601 dentists Cross sectional 82%-MSD study Dentists who do not suffer from MSD experience higher job satisfaction. Dentists who use CAM therapies for the prevention and management of WRMSD may experience higher job satisfaction and longevity than those who use conventional therapies 264-dentists Cross sectional who are study/observapost gradu- tional ate students Correlation between body mass and pain Females displayed more pain than males Special attention should be paid to the design of the working environment in faculties conforming to ergonomic principles 49%-MSD 34% lower back 26%-neck 20%-upper back Musculoskeletal disorders, may substantially affect the over-all well-being of the dentist. Dentistry is a profession that is prone to burnout with low energy and motivation It suggested that ergonomics should be covered in the educational system to reduce risks to dental practitioners. Musculoskeletal complaints may have connection with general health. One must pay attention with one’s nutrition and exercise The dental staff must be informed in order to recognize, control and prevent the potential occupational hazards in the workplace 115 338 dentists Cross sectional 79.9%-Neck study 72.4%-Shoulders 69.8%-Lower back 54.5%-Upper back 24%-Hips/thighs 27.4%-Knees 19.6%-Ankles/feet 49.7%-Wrists/hands 59.3%-were aware of ergonomics Ergonomics and muscu- 170 dentists Cross sectional 73.9%-MSD study 31.7%-Neck loskeletal disorder: As an 18.9%-Shoulder occupational hazard in 7.2%-Arms dentistry 24) 29.2%-Back 13%-Hands 152 dentists Cross sectional 91%-exposed to an occupaOccupational health study tional risk. problems among dentists 41.8%-percutaneous injury in Moldavian Region of caused by sharp instruments Romania 25) in the last year. 49.3%-eye injuries caused by solid particles 13.2%-blood splashes. 14.7% and/or chemicals Rajeshree Moodley, et al.: Occupational health problems in dentistry Table 1. Results (continued) Title/Reference Dental ergonomics to combat musculoskeletal disorders: A review 2) Musculoskeletal disorders and symptom severity among Australian dental hygienists 26) A study on job postures and musculoskeletal illnesses in dentists 27) Sample Design Prevalence Review paper 624 hygien- Cross sectional 84.9%-neck ists study 69.7%-shoulder 68%-lower back 61.8%-upper back 60.1%-hand 65 dentists Cross sectional 75.9%-neck and observa58.6%-shoulder tional 56.9%-upper back 48.3%-lower back 44.8%-wrist 733 dentists Cross sectional 68%-MSD Occupational health study 42%-PCI problems of dentists in the 18%-contact dermatitis United Arab Emirates 28) 53%-eye 5%-hearing review Reports of musculoskeletal Musculoskeletal disorders symptoms among dental and ergonomic risk factors professionals are conspicuin dental practice 29) ously high and manifested mainly as neck, shoulder, hand, arm wrist and low back pain. Recommendations An interdisciplinary approach is necessary to address the concern, and progressive efforts should be taken to prevent MSDs in dental professionals. The problems start at undergraduate level therefore interventions should begin there. Promoting training on both ergonomics (biomechanics) and stress reduction (psychosocial and physical) in dental schools as a prevention strategy MSD is a common problem that requires medical attention. Further research into the epidemiology, risk factors, and impact on employment Job analysis by the use of Rapid Entire Body Assessment (REBA) showed that 89.6% of limbs in group A and 79.3% of limbs in group B had a score >4. Only neck and lower back pain have significant relationship with the risk levels obtained using the REBA method. Work postures of dentists need to improve Education, work station design, rest period during work and regular physical activities should be taken into account Awareness of occupational health problems should be highlighted in all research and clinical congresses. Further studies into the interventions to reduce prevalence Principles of ergonomics and design can be applied to workstations so that there are more neutral workstations. Job rotations and work planning can be introduced to prevent cumulative MSD. Dental training to improve ergonomics. Introduce micro breaks Introduce flexibility and strengthening exercises Further research into causes of MSD Knowledge of scope of ergonomics should be disseminated. Health and safety measures should be researched and shared J Occup Health, Vol. 60, 2018 Prevalence of musculo- 118 dentists Cross sectional 46.4%-neck study 33.8%-Wrist skeletal disorders among 28.8%-back dentists in Kerman, Iran 30) 27.5%-shoulder Outcome 116 Table 1. Results (continued) Title/Reference Sample Design 90 dentists, Cross sectional study dental therapists, assistants and technologists Work-related musculo- 220 dentists Cross sectional skeletal disorders among study dentists-a questionnaire survey 32) Occupational health issues of oral health care workers in Edo State, Nigeria 31) Prevalence and associated factors of back pain among dental personnel in the north eastern state of Malaysia 6) Musculoskeletal disorders among Brazilian dentists 33) Outcome 92%-MSD 47%-neck 35%-lower back 29%-fingers 23%-hip 20%-mid back 20%-shoulders 18.3%-knees 298 dentists Cross sectional 22.2%-back pain study 86%-MSD 56%-back 47%-neck 26%-wrist 254 dentists Cross sectional 79.8%-MSD study 58%-neck 52.7%-lumbar area 40.5%-back 27.1%-wrist 24.3%-shoulders Recommendations MSD was the predominant occupational health problem and the potential impact requires urgent educational and ergonomic intervention 66.7%-wrist pain 76.7%-waist pain 84.4%-body pain 6.6%-Infection 17.8%-latex allergy 350 denCross sectional 44.9% back pain tists, nurses study and technicians Risk factors and preva- 200 dentists Interviews lence of musculoskeletal disorders among Jordanian dentists 34) Ergonomics and musculoskeletal pain among postgraduate students and faculty members of the School of Dentistry of the University of Barcelona (Spain). A cross-sectional study 35) Prevalence 63.3%-no assistant 33% worked with no break 36.4% had one break. More females experienced pain in the fingers/males had more lower back symptoms Significant relationships were found between MSDs and both standing work position and non-use of rest breaks. Risk factors were poor posture. 3.8%-work activities interrupted health problems The symptoms of MSDs increased with the number of years of practice Innovations for an ergonomically friendly dental equipment would probably improve the work practice and therefore the health of dental personnel Rajeshree Moodley, et al.: Occupational health problems in dentistry Table 1. Results (continued) Dentists are at higher risk to develop musculoskeletal disorders, especially back pain, arthritis, and tendonitis, than the general population Need for further training and continuing education Females reported more back pain and less shoulder pain than males. Neck, shoulder and back pain were significantly increased among older dentists and dentists with more years of professional experience The participants who did stretching or other MSD is common among dentists with preventive actions between patients suffered higher incidence among women. lesser low back pain. The neck is the most affected. Oral surgeons showed a higher incidence of neck pain 117 Title/Reference Sample Glutathione enzyme and 515 dental selenoprotein polymor- professionphisms associate with als mercury biomarker levels in Michigan dental professionals 36) Occupational noiseinduced hearing loss 37) Self-reported occupational health of general dental practitioners 38) Design Cross sectional Dentists had significantly Survey/investi- higher hair mercury levels gative compared to non-dentists. review 750 dentists Cross sectional 47%-dermatitis 59%-neck study 57%-lower back 45%-shoulders 1670 Cross sectional 91%-Back pain dentists study 57.1%-back pain 83.1%-hanks 42%-emotional exhaustion 8%-burnout on all 3 scales 52%-treating children as a stressor 48%-time pressure 43% high levels of concentration 247 dentists Cross sectional 57%-eye protection in laborastudy tory Female higher prevalence than male 19%-workplace bullying 94.7%-burnout Higher levels of work engagement were found amongst dentists who had additional professional qualifications, worked longer hours and worked in large group practices. Recommendations While dentists’ occupational exposures are higher than the average population, a shift toward use of composite resin fillings and safer handling of mercury may result in dentists having urine biomarker levels comparable to that of the general population Hearing conservation program (decrease source and level of noise) Providing free protective devices and training to be given on proper use Should be a permissible exposure level In a high noise environment-a 12 hour shift should be followed by a day off. Performing periodic hearing appraisals Pregnant women-exposure to noise-affects the hearing of the unborn child The prevalence of musculoskeletal problems and dermatoses was high and impacted significantly on the daily lives of dentists Early treatment and diagnosis Increased knowledge of dental workers Assessing impact of patient care is critical Work stress relieving factors were exercise, Cope using active coping strategies forgetting about work and interaction with people Eye protection compliance was low The need for eye protection in all clinics and labs. Bi annual eye tests J Occup Health, Vol. 60, 2018 Self-reported occupational health issues among Lithuanian dentists 39) Occupational burnout 354 dentists Cross sectional study and work engagement: a national survey of dentists in the United Kingdom 40) 700 dentists Cross sectional Job stressors of New study Zealand dentists and their coping strategies 41) Eye care habits of dentists registered in the United Kingdom 42) Outcome Prevalence 118 Table 1. Results (continued) Title/Reference Sample Design Prevalence The effect of tool handle Experimental shape on hand muscle load and pinch force in a simulated dental scaling task 43) Outcome of career 110 dentists Cross sectional 55.2%-stress at work study 45.1%-staff management expectancies and early professional burnout among newly qualified dentists 44) Recommendations The instrument handle with a tapered, round shape and a 10mm diameter required the least muscle load and pinch force when performing simulated periodontal work. Modify work practice by rescheduling patients with heavy calculus, taking breaks and using sharp instruments. This will reduce MSD of the upper extremities Practice management is the professional aspect about which young professionals worry most. It is recommended that dental schools pay attention to practice management skills and the stressfulness of work in the curriculum Pilot audiometric data showed a hearing loss Further studies are required to provide more at 4,000 Hz for the left ear, indicative of details on the risks for occupational hearing occupational noise trauma. impairment and vibration hand neuropathy The two-point discrimination ability of the and to determine whether the problems dominant hand tended to diminish in line described were related to the practice of with the number of years of practice. dentistry Mercury levels in whole blood were not high in exposed dentists, although it was reported that dentists have almost twice the concentration of mercury in their blood as non-dentists Eye protection is sub optimal and it should in this environment Implementation of ergonomics decreases MSD. Creating guidelines for the implementation of ergonomics 119 380 dentists Cross sectional 54%-low back pain, (stressstudy correlated); 52.3%-vision problems, (age-correlated) 9%-infections 22.5%-allergies, (mainly latex) 7-stress level was scored on a scale from 0 to 10; 6%-diminished sensitivity of the fingertips 19.6%-auditory disorders 10 dentists Cross sectional Statistical correlation was Mercury Exposure in Dental Practice 46) study and inves- found between blood mercury tigative levels and the duration of time working in dental offices (r=0.01); this ranged from 5 to 9 years. 138 dentists Cross sectional 80%-wore eye protection Eye safety in operative and hygien- study 48%-experienced ocular trauma dentistry—A study in 96% of hygienists wore eye general dental practice 47) ists protection The dentists saw a clear Evaluation of ergonomic 57 dentists Intervention Cross sectional relation between their impleinterventions to reduce study mentation of recommendamusculoskeletal disortions and a reduction in MSD; ders of dentists in the 72% of the dentists reported a Netherlands 48) reduction or disappearance of the main complaint. Potential occupational health problems for dentists in Flanders, Belgium 45) Outcome Rajeshree Moodley, et al.: Occupational health problems in dentistry Table 1. Results (continued) Title/Reference Visual impairment on dentists related to occupational mercury exposure 49) Sample 15 dentists Prevalence of musculo- 430 dentists skeletal disorders in dentists 50) Mercury vapour levels in 180 dental dental practices and body surgeries mercury levels of dentists and controls 51) Design Cross sectional/ comparative/ investigative Cross sectional 62%-MSD study Cross sectional Urinary mercury levels of Investigative dentists were 4 times higher than control Prevalence of Carpal 305 hygien- Cross sectional ists Tunnel Syndrome and Investigative upper extremity tendinitis among dental hygienists 52) 264 dentists Interview and Back & neck problems observation among dentists and dental auxiliaries 53) Mercury vapour release from a dental aspirator 54) Outcome Recommendations Contrast sensitivity functions were also significantly affected in the group of dentists compared to the age-matched control group. They were uniformly reduced at all spatial frequencies examined for both luminance and chromatic (red-green and blue-yellow) contrasts. The physical load among dentists seems to put them at risk for the occurrence of musculoskeletal disorders. 80%-environmental mercury above occupational exposure standard Reduction in the use of mercury Monitoring Adoption of safety protection Regular monitoring of dentists’ visual functions in order to evaluate the presence of very low-level mercury exposure 28%-Carpal Tunnel Syndrome 7%-tendonitis 54.4%-neck pain 73.5%-back pain 37%-of those complaining of back pain sought medical help. Investigative 10 times more air concentra- Venting of aspirated waste air to the outside tion of mercury vapour-25 μg/ is clearly desirable in view of the findings of m3 is the current limit of this report. occupational exposure 178 dentists Cross sectional 78%-musculoskeletal pain study 50%-percutaneous injury 22%-contact dermatitis mostly caused by allergy to latex gloves 15%-eye problems 3%-hearing problems. Psychosocial aspects should be taken into account when investigating MSD Greater emphasis is needed in the safe handling of mercury greater emphasis should be made relating to safe handling of amalgam in the training and continuing professional development of dentists The prevalence of hand and finger symptoms in the dominant hand among dental hygienists in this study was high. Prevalence for CTS was nearly the same as the general population Aerobic and relaxation exercise to prevent limitations and to increase productive years Posture correction and weight monitoring The safety of dental aspirators with respect to mercury emissions warrants further research Further continuing education as a recommendation in the avoidance of PI/allergens To identify appropriate intervention to reduce its prevalence Further studies are needed to identify causes of musculoskeletal pain and to identify appropriate interventions to reduce its prevalence, as would similar measures to reduce exposure to agents which may be producing contact dermatitis J Occup Health, Vol. 60, 2018 Occupational health problems of dentists in southern Thailand 55) Prevalence 120 Table 1. Results (continued) Rajeshree Moodley, et al.: Occupational health problems in dentistry Discussion The prevalence of occupational health-related problems is a concern among dental practitioners, with MSDs, stress, and PCIs being the most prevalent problems. A number of studies have found that occupational healthrelated problems are on the increase, despite new and innovative equipment being developed and used in dental practice. Several studies showed that dental workers presented with at least one occupational hazard 25,31) . To illustrate this, in the Moldavian region of Romania, the majority of dentists (91%) considered that they were exposed to at least one occupational risk25). Biswas et al., in a review paper, concurred that musculoskeletal symptoms among dental professionals were conspicuously high and manifested mainly as neck, shoulder, hand, arm, wrist, and lower back pain. The capabilities of the dental worker, job demands, and improper work process and hand tool use impose strain on the musculoskeletal system29). MSDs were the most common occupational health-related problems reported among dentists in the Edo State of Nigeria. These findings led the researchers to conclude that urgent education and ergonomic intervention are needed 31) . This review showed that female dentists had a higher prevalence of occupational health-related problems compared with that of male dentists 22,32,34,38) . Ayers et al. reported higher incidences of percutaneous injuries ( PCIs ) and MSDs among female practitioners, which places women at a higher risk of health problems38). Stress and burnout Stress among dentists is prevalent, and this expresses a need for a stress management system. Practice and financial management are stressors among young dentists 56) . The majority of dentists in the Puriene et al. study complained of burnout ( 94.7% ) , and 40.5% of those with burnout presented with chronic symptoms39). A report of a study conducted in the UK stated that 42% of surveyed dentists displayed high scores of emotional exhaustion 40) . Factors that caused stress among newly qualified dentists were those concerning legal and insurance matters (61.2%), practice organization (56.6%), and staff management (55.2%)44). The most common stressors reported for a New Zealand study were treating difficult children (52%), time pressures (48%), and maintaining high levels of concentration (43%)41). Stress (50%) and lapses in concentration and fatigue (32.9%) were the most common causes for needle-stick injury (NSI) 57) . To improve this situation, there is a need to look at dentistry curricula and to investigate whether each dentistry curriculum prepares students to manage a practice. Patients with fear present to dental practitioners and students. There is concern that undergraduate training does not prepare dentistry students to deal with fear in their patients. This leads to stress and 121 anxiety. Alzahem et al. suggest that students should have access to psychologists to teach them how to deal with fear56) . Psychologists in a dental training context can also assist students with strategies to deal with their own fears, i.e., the fear of failing and dealing with their fears, and this in turn will assist the students to cope with fears in private practice. Strategies to cope with stress and burnout were identified as active coping, planning, religion, sports, forgetting about work, interaction with people, and acceptance41,58). Musculoskeletal disorders (MSDs) The most common sites for MSDs were neck, lower back, and shoulders38). Women showed a higher frequency of intense pain involving the cervical, lumbar, dorsal, and wrist areas (p < 0.05), placing them at a higher risk of injury 35) . Although the study of Alexandre et al. reported a higher prevalence of complaints from male dentists about back pain, the authors reported that female dentists were at higher risk of tendonitis33). The introduction of the principles of ergonomics in practice is suggested by many researchers2,4,11,24,29,30,48) . This is not consistent with the study conducted by Rafeemanesh et al., where 60% of the participants were aware of correct ergonomic posture, yet nearly 74% of these dentists reported MSDs of the back and neck being the most painful 27) . For that study, the researchers also reported that pain increased with age and time spent in clinical practice and that the specialty whose practitioners were at greatest risk was prosthodontics27). The Rafie et al. study using both a cross-sectional survey and observation using rapid upper-limb assessment showed that 82.8% of the subjects were at risk of MSDs. Nearly 69% of the subjects in that study had experienced pain and discomfort over the preceeding 12-month period, while 15% had to leave clinical work or reduce the hours worked due to MSD symptoms 16) . The prevalence of hand and finger symptoms was high among dental hygienists, with a high rate of upper extremity tendonitis 59) . The job-related activities of dental hygienists, including the use of vibratory tools and the repetitive nature of their work, places these practitioners at risk for MSDs of the hands. MSDs of the neck (85%), shoulder (70%), and lower back (68%) regions were frequently reported by dental hygienists26). The information gathered from a study of Swedish dentists tended to put dentists at the higher end of the spectrum of healthcare professionals in terms of severity of musculoskeletal injury and lost work time. This emphasizes the need to educate newly qualified practitioners and students on musculoskeletal health60). However, job posture analysis revealed that the extraction of the left and right lower jaw teeth, and also extraction of the right upper jaw teeth and restoration of the upper teeth, exacerbated the worst job postures 27) . A higher incidence of wrist pain was recorded for professionals exclusively dedicated to oral sur- 122 gery (p < 0.05 ) . No statistically significant correlation was found between the workload (hours) and pain in the different anatomical locations (p > 0.05) 35) . Despite the evidence of the occurrence of MSD pain caused by the work done by dental health workers, job posture analysis and workplace analysis are not carried out very often in dentistry. These forms of analysis should be carried out by new and old practitioners to remove risks in dental practice, thereby reducing the prevalence of MSDs. Vision-related occupational health issues Ocular hazards are common in dentistry 61) . Extreme caution should be taken when performing clinical work. The most striking evidence reported from the Lönnroth & Shahnavaz study is that few dentists use eye protection. The hazards reported in that study include injury from rotary instruments and chemical handling61). Chadwick concluded that a limited use of eye protection exposed dentists to unnecessary occupational risks 42) . The CantoPereira et al. study investigated visual impairment and occupational exposure to mercury among dentists and found that visual color discrimination and contrast sensitivity were indicators of a subtle neurotoxic effect of elemental mercury 49) . The use of mercury in Nordic countries is banned, with other countries proposing the phasing down of amalgam use until an amalgam replacement can be found. Visits to ophthalmologists should be regular, as dental work impacts vision, yet Chadwick et al. found that dentists with known eyesight problems were the only ones who presented for regular eye examinations. The study also found that the use of magnification was not universally adopted and that eye protection compliance was low 42) . Magnification enhances vision, preventing dental practitioners from bending their necks, thereby decreasing the chances of developing MSDs. Percutaneous injury (PCI) In Southern Thailand, PCI was experienced by 50% of dentists, while 41.8% of dentists in the United Arab Emirates (UAE) experienced at least one PCI in the previous year 25,55) . In a German study, 61.7% of dentists sustained at least one NSI. The injuries were caused by surgical devices (46.2%), needles (25.4%), and scalpels (14.2%). Only a few injuries were due to bite wounds (3.6%), skin contact (0.6%), and muco-cutaneous contact ( 6.5% ) 57) . Wicker & Rabenau and Leggat et al. concurred that students and younger dentists were at risk of PCIs 57,62) . This demonstrates the importance of education programs for younger dentists and vigilant supervision of dental students. Noise More studies need to be conducted into the effects of noise on the dental worker. Noise in dental training is significant, and this is highlighted by Sampaio Fernandes et J Occup Health, Vol. 60, 2018 al., who stated that the noisiest area is the gypsum and prosthetic laboratory, followed by the preclinical area. They further described clinical areas as having continuous high noise levels, especially for clinical supervisors and students. According to their research, the minimal acoustic comfort level is required in a dental setting and, to achieve this, sound levels have to be reduced by at least 10 dBa 63) . Szymanska and Chopra & Pandey concurred that the noise of the suction devices, salivary ejectors, turbines, amalgamators, model trimmers, mixing devices, ultrasonic scalers, and compressors causes impaired hearing 64,65) . Occupational noise is the most common cause of hearing loss in adults. Noise-induced hearing loss is irreversible, as there is damage to the cochlear hair cells of the inner ear and if staff and students are in a skills lab where there is constant noise then they are exposed to irreparable damage to their ears. Given that mercury exposure affects the auditory senses, dentists and dental therapists who are exposed to dental amalgam from the time of undergraduate training and throughout practice are at greater risk due to long-term use 37) . Additional risks are the quality of hand pieces used in dental training and practice, which differs for different manufacturers, and so does the associated noise level. Newly qualified dental practitioners order equipment on the basis of funding and affordablility rather than looking at the noise levels. Surgery design is an important factor in the reduction of noise64). Furthermore, noise reduction in a dental setting is needed for both patient and operator comfort. Mercury-related occupational health-related problems Mercury exposure as measured in the dental operatory zone was found to be 10 times greater than the acceptable exposure levels after 20 minutes of aspiration; this is due to the corrugated tubing that traps amalgam 54) . A significant difference was reported between the level of urinary mercury of Scottish dentists and that of a control group, with the levels of dentists being 4.17 times higher in a Scottish study 51) . In a study conducted by Atesagaoglu et al., mercury levels in whole blood were not high among the dentists, although this was not the case in other studies. The methyl mercury level was higher than mercury in blood, and the authors concluded that mercury from other sources was a greater risk than the mercury found in amalgam 46) . There was a positive association between mercury exposure and tremors among American dentists66). Dental operators were found to have a significantly higher hair mercury level than non-dentists in a Michigan study 36) . Dental students in a restorative clinic work with dental amalgam and are exposed to mercury from 1st to 5th year. This exposure is a source of blood mercury, as mercury crosses the pulmonary membrane and reaches the blood stream. Improvement of mercury hygiene and technical equipment can reduce exposure to mercury. The curriculum of restorative dentistry includes mercury han- 123 Rajeshree Moodley, et al.: Occupational health problems in dentistry dling and care, but there is a need to include this topic in clinical and preclinical training and in continuous professional development activities67). Mercury vapor inhaled by dental operators is retained in the brain, endocrine organs, and other tissues. Cutright et al., as cited by Guzzi et al., stated that there was a positive correlation between inhaled mercury dust and deposition of the inhaled mercury in blood and tissues 68) . This reveals the need for a phase-down approach to amalgam use and the corresponding increased use of amalgam alternatives. Allergy Allergy, mainly latex related ( 22.5% ) , was reported among dentists from Belgium where potential occupational health problems were investigated45). A latex allergy presents as pruritus, urticaria, eczema, and asthma. Almost half the sample of dentists (47%) had experienced a dermatitis-type condition in the previous 12 months in New Zealand38). Allergies associated with professional activity were reported by 76.1% of the dentists in the UAE 25) . Dentistry is regarded as “wet work” which may damage the skin barrier and lead to exposure to skin irritants and sensitivity to components in gloves. Airway irritants may also be present in the work environment of dental workers 69) . Dental students are intensive users of gloves, which places them at risk of latex allergies. The type of gloves used in training is central to sensitization rates and latex-allergy symptoms. Low-protein nonpowdered gloves reduce exposure to the latex allergen45). Infection Belgian dentists ( 9% ) reported infections related to dentistry 45) . In the UAE, 74.6% of dentists are protected by vaccination against Hepatitis B and 76.1% against influenza 25) . PCIs due to the small operating field, patient movement, and the variety of sharp instruments used on a daily basis are greater in a dental setting and teaching environment when compared with those in other healthcare settings. This exposes dental staff to HIV and Hepatitis B and Hepatitis C viruses. A hands-on approach in the students’ learning process and the introduction of safer products and clinical procedures should form part of the curriculum to protect the student70). A limitation to this review includes the number of articles selected and the fact that articles written only in English were selected. Conclusion This review shows that occupational health-related problems still affect dental workers, with MSDs being the most frequent problem. More research is being conducted among dentists than among dental therapists and oral hygienists, with great gaps about factors affecting the health of dental therapists and oral hygienists. The prevalence and the investigative studies highlight the need for continuous professional education and a need to review dentistry curricula at a tertiary level. 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