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October 28, 2009

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Dental health- Word of mouth

Workers’ teeth are unlikely to be of much, or even any, concern to most health and safety practitioners but as Dr Chris Ide reminds us, work-related dental damage is a health risk that must be assessed like any other.

I’ve been examining patients and employees for about 40 years, and one of the most striking changes I’ve noticed during this time has been the general improvement in dental health. Many readers will remember Pam Ayres, that mischievous mistress of doggerel, who wrote “I wish I’d looked after me teeth/And spotted the perils beneath/All the toffees I chewed/And the sweet sticky food…..”  Most of us are aware of the importance of tooth-brushing, particularly after eating cakes and sweets, but who would have thought that dental health could be at risk in some working environments?

In basic terms, a tooth, irrespective of whether it is an incisor or canine (for biting and tearing), or a molar (for chewing), consists of a crown, which appears above the gum, and the root, concealed in the gum, and which embeds the tooth in the lower or upper jawbones. The crown has a capping of enamel — a very hard material, with no nerves, and so impervious to pain — which, in turn, overlies a layer of dentine — a rather less hard substance that is more responsive to pain. In the centre of the tooth is the pulp, which contains the blood vessels and nerves and hence is exquisitely sensitive.

In a review article, Finnish researchers1 described how confectionery employees had more decayed, missing and filled teeth than other workers. In particular, almost 80 per cent of those making biscuits had untreated cavities, compared to 55 per cent of bakers, and 48 per cent of sweet manufacturers. Oddly enough, of control subjects — who were not exposed to sugar — cavities were found in about 62 per cent.

Periodontal disease (causing gums to shrink, thus less effectively supporting the teeth, and exposing the more vulnerable dentine to decay) becomes more common with age. The germ populations of the mouths of the subjects of this study were similar, irrespective of the group to which they belonged, and the authors felt that some other factor(s) had to be sought to explain the raised incidence of disease, since they noted that the levels of airborne flour and sugar dust were within normal limits. Nonetheless, at the time, these materials would have been regarded as nuisance dusts, and the levels set to avoid respiratory irritation. Perhaps a lower level would have protected better against dental problems.

This compared with the experience of Indian confectionery makers, more than 60 per cent of whose employees had tooth decay — a significantly higher rate than controls, whose only exposure was to wheat flour. Not surprisingly, the prevalence of rotting teeth increased in keeping with length of employment in that job, and the number of products that were eaten each day, although it is not recorded whether the consumption was of sweetmeats at, or from work, or in the home. The highest rates were found in those manufacturing chocolate and sweets. By contrast, gum disease featured predominantly in those confectioners who produced sweets and biscuits.2

According to the introduction of the Finnish review article, the possibility of dental decay being a work-related health problem of bakers was raised by German researchers in 1886. Beginning in 1959, there was a number of studies, which, judging by their titles, seemed to suggest that a particular pattern of dental decay — initially appearing on the surface of the front teeth, which were in contact with the lips — should be regarded as an occupational disease of bakers and confectioners. Unfortunately, it was difficult, practically, to evaluate all of these papers, since few (if any) had an abstract and most of the publications appeared in German, Japanese, Romanian and Swedish journals. However, it has finally dawned on me why the Swedish chef in The Muppets spoke in that particular way!  

Oral evidence

The most spectacular occupational disease affecting the jaws and teeth was a condition called ‘Phossy Jaw’. This was originally described in the 1880s, and mainly affected matchstick makers, who used white or yellow phosphorous. The vapours given off would enter the mouth and attack the teeth, particularly if already decayed. The damage then spread to the jawbone, which disintegrated, forming abscesses that subsequently discharged foul-smelling pus through sinuses on to the skin. The facial skeleton would also glow a faint green colour at night, and the only treatment available was to remove up to half the jaw.

These terrible conditions led to the first strike about health and safety matters, and the strikers were supported by the Salvation Army, which opened a rival match factory using the much safer red phosphorous, albeit its products were about three times more expensive. The use of white phosphorous was banned internationally in 1906, although the British Government did not ratify the treaty until much later.

Even so, this cast a long shadow over events. In the late 1960s, when I was a student, I had a holiday job labouring in a match factory, which still retained the services of a dentist for its employees specifically to protect them against this hazard!

Weigand and Attin3 cited more than three dozen references to papers describing various forms of damage to the teeth of workers whose jobs involved exposure to acid mists and vapours. While one of the papers harked back to 1951,4 and several described situations in developing countries, the most recent appeared in 2005,5 and 14 were published in 2000, or after, so the problem is not one of mere historical interest.

The workplaces where the risks were greatest were found to be galvanising and electroplating shops, battery-making and fertiliser factories, and other places like smelting plants, where acidic mists or aerosols of mineral acids, such as sulphuric, nitric and phosphoric acid, etc. had the potential to develop. The amount of tooth decay and erosion varied but, as a rule of thumb, greater levels were associated with longer duration of exposure and greater proximity to the vapour, or mist source.

Where control populations of workers were included in the analyses, there was considerable variation in the amount of dental damage. I found this rather puzzling, until I checked the dates of publication. Then I realised that, as the papers became more recent, the amount of decay generally declined, reflecting the comment I made at the beginning of this article about the general improvements in dental health.

The industries mentioned above could be said to belong to the ‘smokestack’ or ‘metal-bashing’ era. Other traditional occupations in which these sorts of hazards have been identified include flour milling, where a Polish report6 described almost 94 per cent of employees as having characteristic patterns of dental erosion or decay. No control group was incorporated, but the authors observed that about 50 per cent of the population of Katowice were similarly affected.

Extractive industries can also pose this problem, with accounts of increased dental wear and tear in Danish granite workers7 and Norwegian olivine (a material used in making sand moulds for aluminium castings) miners.8

More modern processes may give rise to similar hazards. The employees described by Johannson and others in their 2005 paper5 worked in a factory that produced silicone sealants. During the curing process, fumes of acetic acid were generated, and the 13 who worked at this process had more evidence of decay and gum disease than unexposed workers in the same factory.

A patient referred to a Danish dental hospital with an unusual pattern of loss of dental enamel triggered a wider investigation of fellow employees, who worked in a factory that manufactured proteolytic enzymes for detergents. Almost 25 per cent of workers in that particular department had a similar pattern of tooth damage. While this did not support their original contention (that work with proteolytic enzymes caused a particular pattern of dental erosion) it did find a positive association with a particular pattern of restorative dental work.9

In vino detrimentum

I was intrigued to find that dental erosion has been recognised as an occupational problem among wine-tasters. When I started to work my way through the relevant literature, I was surprised that several of the papers reported research using rats, hamsters, monkeys and dogs, or described in vitro (literally ‘in glass’) studies, in which teeth were placed in wine and other beverages.

Not surprisingly, the English-language papers that have reported this phenomenon in actual wine-tasters have tended to originate in countries with a sizable viticulture industry, such as South Africa, New Zealand and Australia. The findings seem to be similar to those reported in Swedish wine-tasters, in which 14 out of 19 displayed dental erosion, the degree of erosion becoming greater with increasing duration of employment,10 while a South African study of 21 vintners, with 15 spouses acting as (unexposed) controls, also showed more marked erosion in the wine-tasters.11

Professional wine-tasters will often sample 15 to 50 wines a day, holding them in their mouths for up to a minute at a time to assess the flavours and quality of the wine before spitting it out. The pH of wine is generally between 3.0 and 3.6, so it is quite heavily acidic. Furthermore, the acids in wine — tartaric, succinic, malic and citric acids, in particular — are comparatively undissociated (unlike mineral acids, such as sulphuric, hydrochloric and nitric acids, which readily break down into positively-charged hydrogen ions and negative sulphate, chloride and nitrate ones). This makes these organic acids more efficient at leaching out calcium from the enamel.

The increasing trend towards professionalism in sport has highlighted another group at risk of work-related dental problems: swimmers. In 1983, following the discovery of two patients with marked dental erosion who were both keen swimmers at the same club, a survey of more than 700 other members demonstrated a prevalence of symptoms of erosion in 3 per cent of the non-swimming affiliates, 12 per cent of those who swam, but increasing to 39 per cent of the club’s swimming team who spent the most time in the water. Testing the water showed it had a pH of 2.7 — about 100,000 times more acidic than it should have been!12

Since then, there have been several other case reports, most recently in 2008, describing a lady who suffered significant erosion after just two weeks exposure, so the lesson has clearly not yet been fully appreciated.13 While this may sound rather esoteric, do remember that section 3 of the Health and Safety at Work, etc. Act 1974 places on employers a duty of care to members of the public who might be affected by work activities, so while very few readers will have any responsibility for teams of professional athletes, many more will advise managers of local-authority leisure centres with swimming pools, or hotel proprietors who run spas and pools within their premises.

When I first agreed to write this article, I struggled for inspiration. So I posted on an electronic forum and, within half an hour, had received reminders from other occupational physicians, hygienists and nurses that the gum disease gingivitis is associated with poisoning by lead, mercury and bismuth; that vanadium produces a green pigmentation of the tongue and gums; and of a condition called ‘Seamstress’s gap’ — a characteristic deformity of the incisors arising from the chipping away of the teeth as a result of using them to bite thread. Others told me of work-related heartburn, which produced water brash so severe the acid contained therein was sufficient to erode teeth.

Conclusion

Safety officers already charged with preventing the organisation for which they work from breaking down because of dermatitis, diarrhoea, diabetes, disaffection and death now find themselves burdened with bringing dental disorders under control. So what is the way forward? The important thing is to organise a proper risk assessment. Do any of the processes mentioned above — or others that might create aerosols, mists or vapours — exist within the workplace? Do any of the materials used have safety data sheets containing the risk phrases R37/R38, i.e. potential irritants to respiratory tract/skin, and do workers have these complaints? If so, might not dental damage be occurring (as well as respiratory and skin harm) if the hazard is not properly controlled? (Provision of appropriate respiratory protection can also, if worn correctly, greatly reduce the amount of tooth damage.)14 Can line managers, or the personnel department provide information about the number of employees who request time away from work to attend dental appointments, especially if more than once or twice a year?

Of course, dental erosion and decay have many other causes that have nothing to do with the workplace. Therefore, appropriate use of health education and promotion resources to highlight the importance of regular dental care and a good, balanced diet to promote dental health will also be beneficial, reducing the chances of employees falling victim to what the famous Scottish bard Robert Burns described as “Thou hell o’ a’ diseases”.  

References
1    Masalin K, Murtomaa H, Meurmann JH (1990): ‘Oral health of workers in the modern Finnish confectionery industry’, Comm Dent Oral Epidemiol 1990,18;3:126-130
2    Rekha R, Hiremath SS (2002): ‘Oral health status and treatment requirements of confectionery workers in Bangalore City’, Indian J Dent Res 2002;13:161-165
3    Weigand A, Attin T (2007): Occupational dental erosion from exposure to acids — a review’, Occupational Medicine 2007, 57;3:169-176
4    Elsbury WB, Browne RC, Boyes J (1951): ‘Erosion of teeth due to tartaric acid dust’, Br J Ind Med 1951;8:179-180.
5    Johannsen AK, Johannsen A, Stan V, Ohlson CG (2005): ‘Silicone sealers, acetic-acid vapours and dental erosion: a work related risk?’ Swed Dent J 2005;29:61-69
6    Bachaneck T, Chalas R, Pawlowicz A, Tarczyalo B (1999): ‘Abrasion of hard-tooth tissue among workers in flour mills’, Ann Agric Environ Med 1999,6;147-149
7    Petersen PE, Henman P (1988): ‘Oral conditions among workers in the Danish granite industry’, Scand J Work Environ Health 1988,14;5:328-331
8    Jocksfad A, Von der Fehr FR, Lovlie GR, Myron T (2005): ‘Wear of teeth due to occupational exposure to airborne olivine dust’, Acta Odont Scand 2005,63;5:294-249
9    Westergaard J, Larsen IB, Holmen L et al (2001): ‘Occupational exposure to airborne proteolytic enzymes and lifestyle risk factors for dental erosion — a cross-sectional study’, Occup Med 2001,51;3:189-197
10    Wiktorsson AM, Zimmerman M, Angmar-Mansson B (1997): ‘Erosive tooth wear: prevalence and severity in Swedish wine-tasters’, Eur J Oral Sci 1997;105:544-550
11    Chitke UM, Naidoo S, Kolze TJ, Grobler SR (2005): ‘Patterns of tooth surface loss among wine-makers’, SADJ 2005;60:370-374
12    Centerwall BS, Armstron CW, Funkhouser LS, Elzay RP (1983): ‘Erosion of dental enamel among competitive swimmers at a gas-chlorinated swimming pool’, Am J Epidemiol 1983,123;4:641-647
13    Dawes C, Boroditsky CC (2008): ‘Rapid and severe tooth erosion from swimming in an improperly chlorinated swimming pool’, J Can Dental Assoc 2008,74;4:359-361
14    Kim HD, Douglass CW (2003): ‘Association between occupational health behaviour and dental erosion’, J Public Health Dent 2003,63;4:244-249

Chris Ide is an occupational physician and regular contributor to SHP.

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