|Year : 2014 | Volume
| Issue : 2 | Page : 80-87
Oral health status of battery factory workers in Kanpur city: A cross-sectional study
Suchi Khurana1, C Jyothi2, CL Dileep3, K Jayaprakash4
1 Department of Public Health Dentistry, Faculty of Dental Sciences, SGT University, Gurgaon, Haryana, India
2 Department of Public Health Dentistry, Vivekanandha Dental College, Tiruchengode, Tamil Nadu, India
3 Department of Public Health Dentistry, Surendera Dental College, Hospital and Research Institute, Sriganganagar, Rajasthan, India
4 Department of Public Health Dentistry, ITS Dental College, Hospital and Research Center, Greater Noida, Uttar Pradesh, India
|Date of Web Publication||6-Sep-2014|
Department of Public Health Dentistry, Faculty of Dental Sciences, SGT University, Gurgaon, Haryana
Source of Support: None, Conflict of Interest: None
Background: The oral cavity is vulnerable to external agents and some occupational exposures are associated with oral changes in both hard and soft tissues. Objectives: To assess oral health status in battery factory workers of Kanpur city and to describe the prevalence and nature of oral health problems among workers. Materials and Methods: A total of 70 battery workers were enrolled and divided into study and control groups based on acid exposure. The data was recorded on a modified World Health Organization 1997 proforma. The data was analyzed using Statistical Package for Social Sciences version 15.0. The categorical variables were compared using Chi-square test for proportions while the quantitative ordinal variables were compared using Mann-Whitney U-test. Quantitative continuous variables were compared using Independent samples t-test. Results: The mean age of all the workers surveyed was 36.24 years. Differences in the erosion, oral hygiene and gingival index scores among the two groups were highly significant (P < 0.001). Conclusion: Oral health status was poor and significantly associated with dental erosion.
Keywords: Acid fumes, dental erosion, oral health status
|How to cite this article:|
Khurana S, Jyothi C, Dileep C L, Jayaprakash K. Oral health status of battery factory workers in Kanpur city: A cross-sectional study. J Indian Assoc Public Health Dent 2014;12:80-7
|How to cite this URL:|
Khurana S, Jyothi C, Dileep C L, Jayaprakash K. Oral health status of battery factory workers in Kanpur city: A cross-sectional study. J Indian Assoc Public Health Dent [serial online] 2014 [cited 2019 Feb 23];12:80-7. Available from: http://www.jiaphd.org/text.asp?2014/12/2/80/140254
| Introduction|| |
The oral cavity is a port for entry of many diseases and presents several unique features which make it especially prone to occupational disease. The various aspects of oral occupational disease can be analyzed on the basis of the structure affected like Instruments for prehension causes localized abrasion in cobblers, carpenters, glass blowers and due to variation in atmospheric pressure hemorrhage from gingivae can be seen in aviators.  Oral cavity is more frequently exposed to injurious agents than any other organ or region of the body. It is usually unprotected except when masks are worn. Ingestion and inhalation of foreign substances that tend to stagnate and collect within the oral cavity lead to an accumulation of irritants of a chemical, physical or bacterial nature.
It has long been known that the teeth of industrial workers exposed to inorganic acids are affected in varying degrees. On breathing an industrial acid mist, the irritant effects are localized to the nose, mouth and throat-coughing, nose running and upper respiratory tract. Irritation of the eyes and exposed skin surfaces also occurs.  Hard tissues like enamel and the underlying dentin, which, because they are both avascular, and a cellular, are affected by local factors. The ready response of enamel to acids makes it vulnerable to decalcification. The crowns of the teeth disintegrate with prolonged exposures. Soft dental structures like gingivae have been called the gateway to oral health. 
Today, because of the improvements in plant design and factory methods, many hitherto hazardous processes have been eliminated. It is mainly in the battery industry, where vast quantities of sulphuric acid are used as an essential part of the battery making process, that most tooth erosion due to acid is seen. 
Dental erosion is defined as a loss of dental hard tissue by a chemical process that does not involve bacteria.  The condition is multifactorial in etiology and may be caused by extrinsic factors (acidic foodstuffs and drugs), intrinsic (acid regurgitation) and occupational hazards. ,,,,,, Industrial erosion can occur in a number of occupations like zinc galvanizing plant,  battery factories  etc., The parts of the anterior teeth exposed to the atmosphere are affected and may be completely dissolved.  During an erosive attack, protons of the acidic agent attack the components of hydroxyapatite such as carbonate, phosphate and hydroxyl ions. This attack results in dissolution of the hydroxyapatite crystals with a subsequent release of calcium ions. Furthermore, frequency and duration of acidic events have an effect on the development of erosion.  There is progressive destruction of the tooth crown from direct impingement of acid droplets.  However behavioral and biological factors, such as tooth position, quality of dental hard tissues and salivary factors like composition, buffer capacity and flow rate may exert an influence on the development and progression of erosions. 
| Aim and objectives|| |
- To assess the oral health status in battery factory workers of Kanpur city
- To describe the prevalence and nature of oral health problems among workers exposed to sulphuric acid fumes
- To provide a baseline data regarding oral health status to the authorities so as to plan preventive and curative services for this population
- To suggest remedial measures for improving the oral health status of the workers.
| Materials and Methods|| |
A cross-sectional, comparative study was conducted to assess the oral health status of the battery factory workers in Kanpur city from February 26, 2010 to March 13, 2010.
All required and relevant information regarding the battery factories of Kanpur city was collected from Uttar Pradesh Battery Udyog Association, Gadarianpurwa, Kanpur. The population of battery factory workers in Kanpur city is 3000, at 90% confidence level with an error allowance of 10% the sample size for the present study comes out to be 67. The sample size was calculated using sample size calculator.  Though the sample size calculated was 67, for the purpose of the present study a total of 70 workers were enrolled from randomly selected battery factories.
The battery units have two types of workers, that is, those exposed to acid fumes or mists (working in forming/charging departments) and those who are not exposed to acid fumes (working in grid casting, pasting, pressing and packing departments). Around 67.1% workers were exposed to acid and acid fumes or mists whereas the remaining one-third (32.9%) workers in the battery factories were involved in duties that did not have exposure to acid. The former comprised the study group while the latter comprised the control group of the present study.
Approval from the authorities
Prior permission was taken from the Indian Industries Association (IIA), Kanpur and owners of battery factories to conduct the oral examination of battery factory workers.
Before starting the survey, the ethical clearance was obtained from the Institutional Ethical Committee of Rama Dental College, Hospital and Research Centre, Kanpur.
The study group was duly informed about the purpose of the study and consent was taken from them before their participation in the study in order to prevent any inconvenience and to ensure full cooperation.
- Battery factory workers of all ages, available at the time of examination were included in the study.
- Those who were not willing to participate in the study.
Training and calibration
The examiner and recording assistant (pursuing internship training) was trained and calibrated in the Department of Preventive and Community Dentistry, Rama Dental College, Hospital and Research Centre, Kanpur, under the supervision of the staff members to prevent any diagnostic variability among the study subjects during the oral examinations.
A detailed schedule of the survey was prepared well in advance. The investigator visited the study area during the prescheduled time frame in the study period, till the required sample size was obtained.
Sufficient numbers of sterile instruments were made available for the examination during the study. The following instruments and materials were used for the study: Plane mouth mirrors, explorers, tweezers, kidney trays, containers (one for used instruments and the other for sterilized instruments), Betadine™ , saline, gauze and cotton with cotton holder, disposable gloves and mouth masks and data recording proforma.
Information regarding department in the battery factory, duration of the job, exposure to various working conditions and oral symptoms recorded along with the name, age, sex, location, dietary habits, deleterious habits, oral hygiene practices. The oral health status was assessed using the dentition status and treatment needs index as recommended by the World Health Organization (WHO), oral health survey, basic methods (1997). Indices were used to assess dental erosion, , Simplified oral hygiene  and gingival index (GI).  The data was recorded on a modified WHO 1997 proforma. 
Clinical examination was done solely by the investigator with the study subjects seated on an ordinary chair using natural daylight. All the data was recorded by a recording assistant specially trained for the purpose. During the examination, the recording assistant was made to sit closely so that instructions and codes could be easily heard and repeated for confirmation. The interview and examination of a single subject took on average about 15 to 20 min. Those workers who needed immediate care for pain or infection were referred for immediate attention and further treatment.
The raw data obtained was tabulated using the Microsoft Excel spreadsheet software (Microsoft). The data was analyzed using Statistical Package for Social Sciences (SPSS Inc., Chicago,IL, USA) version 15.0. Chi-square test is used to compare the categorical variables for proportions. Mann-Whitney U-test is used to compare the quantitative ordinal variables. Independent samples t-test is used to compare quantitative continuous variables.
| Results|| |
The study was conducted in battery factories of Kanpur city. As the battery units have two types of workers, the data was divided into two groups. Around one third (control group) workers in the battery factories were involved in duties that did not have direct exposure to acid whereas the remaining (study group) workers were working in the conditions that involved direct exposure to acid and acid fumes.
Age wise distribution
Majority of workers in the control group were aged from 21 to 40 years (91.3%) while only 2 (8.7%) of control group subjects were aged above 40 years, whereas among study group there were 22/47 (46.9%) workers who were aged above 40 years. The difference was statistically significant (P = 0.014) [Figure 1]. All the workers surveyed were males with a mean age of 36.24 years.
Period of exposure (duration of the job)
As compared to study group, in the control group the period of exposure was significantly lower (P < 0.001). It was seen that in the control group more than two third (69.5%) respondents had up to 5 years of experience whereas in study group the period of exposure was more than 5 years in 89.3% subjects [Table 1].
Exposure to various working conditions
The type of exposure amongst study group subjects was draft and unpleasant smell in all except around one-tenth (10.6%) subjects; however, in the control group it was chiefly the dust (91.3%). The difference was statistically significant about the type of exposure (P < 0.001) [Table 2].
|Table 2: Distribution of subjects according to exposure to various working conditions |
Click here to view
As far as the oral symptoms were concerned, all the subjects in study group had some oral symptom present. In study group sensitive teeth, sharp and thin teeth, disturbed sense of taste, dry mouth and foul breath were significantly higher as compared to the control group. No significant difference between two groups was seen regarding presence of bleeding gums and toothache [Table 3].
Oral hygiene practices
Majority of subjects in both the groups used toothpowder and finger that is 70.2% of study group and 69.6% of control group subjects. Toothbrush and toothpaste were being used by 10.6% of study and 17.4% of control group subjects only while toothpaste with finger was being used by 19.1% of study and 13.0% of control group subjects. Statistically, there was no significant difference in the method of oral hygiene between the two groups (P = 0.643) [Figure 2].
Tobacco consuming habit was proportionately higher in study group, and addiction to alcohol was higher among control group subjects, but the difference between two groups was not statistically significant (P = 0.332). Tobacco and alcohol in combination was distributed almost equally (12.8% and 13.0% respectively) in the two groups showing no statistically significant difference (P = 0.974). No adverse habit was seen in 1 (4.3%) subject of the control group only [Figure 3].
The study group shows decayed, missing and filled teeth with a mean of 2.43, 0.68, and 0.04 whereas control group subjects with a mean of 2.26, 0.57 and 0.13 respectively. No statistically significant difference between the two groups was seen in decayed-missing-filled (DMF) status [Table 4].
None of the subjects in study group had GI score of 0 or 1, 28 (59.6%) subjects had a GI score of 2 while the remaining 19 (40.4%) of the subjects had GI score of 3. In contrast in the control group, 3 (13%) subjects had GI score of 1 and the remaining 20 (87%) had GI score of 2. None of the subjects in the control group had a GI score of 0 or 3. On statistical comparison, a significant difference between two groups was seen (P < 0.001) [Figure 4].
Dental erosion index
None of the subjects in study group had erosion score of 0 as compared to control group where 14 (60.9%) subjects had erosion score of 0. Of the remaining 9 control subjects, 2 (8.7%) had erosion score of 1 while 7 (30.4%) had erosion score of 2. In contrast, almost half (48.9%) of the study subjects had erosion score of 3 and around one-fifth (19.1%) had erosion score of 4. Statistically, a significant difference was seen between the two groups (P < 0.001) [Figure 5].
Simplified oral hygiene index (OHI-S)
None of the respondents in either group had OHI-S score of 0.0 or 0.1-1.2. Thirty-nine (83.0%) subjects in study group and 2 (8.7%) of the control group subjects had OHI-S score of 3.1-6.0. As compared to control group the OHI-S score of study group subjects was significantly higher (P < 0.001) [Figure 6].
|Figure 6: Distribution of subjects according to simplified oral hygiene index|
Click here to view
| Discussion|| |
The present study was undertaken to assess the oral health status in battery factory workers and to describe the prevalence and nature of oral health problems among workers exposed to sulphuric acid fumes in battery factories of Kanpur city. The survey comprised workers in battery factories, and a response rate of 100% was obtained. All the workers surveyed on the day of examination were males. As per employers' psychology, occupation has risk as it requires good handling of sulphuric acid for which males are generally preferred. Sulphuric acid contains 20% or more of sulphur trioxide dissolved in the acid, which fumes strongly at room temperature and has a sharp, penetrating odor. 
Acid mist is frequently detected in the workplace as it continuously discharges from open containers. Exposure is detectable to human beings at the level of 0.5-0.7 mg/m 3 , is irritating at 1.0-2.0 mg/m 3 and causes coughing at 5.0-6.0 mg/m 3 . A previous report,  published in 1961, showed that workers in a battery factory were exposed to acid fumes levels as high as 0.8-16.6 mg/m 3 . In a study from Finland,  battery workers were exposed to 0.06-2.0 mg/m 3 . The acid fumes concentration in work air of the Tanzanian Fertilizer Company varied from <1 to >5 mg/m 3 .  Comparison of the findings of these studies suggest that the higher concentrations of acid fumes in the working environment are related to the higher proportions of subjects with loss of tooth substance. Unfortunately, data on acid fume levels in the sites we visited were not available. However, the high proportion of affected workers and our observation of unprotected acid handling and reduced safety measures indicate that workers were exposed to excessive acid fumes. 
Majority of workers in the control group were aged from 21 to 40 years (91.3%) while only 2 (8.7%) of control group subjects were aged above 40 years, whereas among study group there were 22/47 (46.9%) workers who were aged above 40 years. Reason of the higher age of study group subjects may be that in the battery industry, in the forming and charging departments where there is direct exposure to acid (study group), owing to job-related risks more skilled workers are required while those who are not that much skilled are placed in less risk-prone jobs such as pasting, drying and packing departments (control group) in which there is no direct exposure to acid. Our study is in agreement with the study done by Ten Bruggen Cate in 1968 in which control workers (acid-free departments) were from the younger, unskilled apprentice section of the labor force. 
Industrial erosion first affected the surfaces of the teeth most exposed to the atmosphere. These were the incisal one-third to one-half of the labial surfaces of the front teeth. No erosion of the posterior teeth was seen.  Similar finding was seen by Malcolm and Paul in 1961.  Study by Amin et al. in 2001 also showed that tooth surface loss caused by acid fumes confined to the labial surfaces of the upper anterior teeth, posterior teeth are protected by cheeks and lips which is in agreement with our study. Only the surface of the teeth uncovered by lips and cheeks is affected. The lips provides direct shield from the acid spray and also bathe the teeth with protective saliva.
The site of the erosive lesions suggests a direct action of acid fumes on the teeth exposed during talking or during breathing through the mouth. ,,, Mouth breathing was very common among workers of the battery industry  which is in agreement with our study in which dry mouth is present in 74.5% in study group and 26.1% in the control group [Table 3]. It was likely that acid workers breathed through their mouths, when the acid level in the atmosphere became so high that nose breathing became unpleasant. Evidence indicated that the lack of salivary lubrication in a dry mouth resulted in great tooth wear. 
As compared to study group, in the control group the period of exposure was significantly lower (P < 0.001). It was seen that in the control group more than two-third (69.5%) respondents had up to 5 years of experience whereas in study group the period of exposure was more than 5 years in 89.3% subjects. Reason might be that the workers employed in direct exposure departments might have adequate experience. Previous studies ,,,, have suggested a relationship between the occurrence of dental erosion in acid workers and length of exposure which is in agreement with our study in which the proportion of subjects with erosion and severity of erosion increased with prolonged duration of exposure.
The type of exposure amongst study group subjects was draft and unpleasant smell in all except around one-tenth (10.6%) subjects, however, in the control group it was chiefly dust (91.3%). In a study conducted by Petersen and Gormsen  in 1991, percentages of workers who reported exposure to an unpleasant smell was 84%, and vibration was 13% whereas in our study it was 55.3% and 8.7%.
As far as the oral symptoms were concerned, all the subjects in study group had some oral symptom present. No significant difference between two groups was seen regarding presence of bleeding gums and toothache. Loss of the sense of taste or development of bad taste sensation was a common feature among acid workers in the study done by Amin et al.  done in 2001 and the German survey  in 1991which is also a common feature with our study in which it is 72.3% among acid workers [Table 3]. This could be related to possible atrophic changes in the taste buds as a result of exposure to acid fumes in the workplace environment.
Majority of respondents in both the groups used toothpowder and finger. Toothpaste with finger was being used by 19.1% of study and 13% of control subjects. Statistically, there was no significant difference in oral hygiene practices between the study and control groups (P = 0.643). The oral hygiene practice was poor (14% of acid workers and 25% of controls brushed their teeth) in the study conducted by Amin et al.  which was in agreement with our study in which 10.6% of study group and 17.4% of control group workers used to brush their teeth.
In our study majority of workers (85.71%) are pan/tobacco chewers whereas in the study conducted by Amin et al.  in 2001 in Jordan were smokers (58%). Among the various oral habits, tobacco was the most common adverse oral habit in both the groups [Figure 3]. This is because shifts in global tobacco consumption indicate that an estimated 930 million of the world's 1.1 billion tobacco consumers live in developing countries with 182 million in India alone (2004). 
In our study, no statistically significant difference between the two groups was seen in DMF status and no evidence of any relation between DMF status and degree of erosion was seen which is in agreement to the study done by Malcolm and Paul  in 1961, Ten Bruggen Cate  in 1968 and Tuominen et al.  in 1989.
None of the respondents in study group had GI score of 0 or 1, 28 (59.6%) respondents had a GI score of 2 while the remaining 19 (40.4%) of the respondents had GI score of 3. In contrast in control group 3 (13%) respondents had GI score of 1, and the remaining 20 (87%) had GI score of 2. None of the respondents in the control group had a GI score of 0 or 3 [Figure 4].
Differences in the GI scores and oral hygiene scores between study group and control group was highly significant (P < 0.001) in our study which was also in agreement with the study done by Amin et al. 
None of the respondents in study group had erosion score of 0 as compared to control the group where 14 (60.9%) subjects had erosion score of 0. Of the remaining 9 of control subjects, 2 (8.7%) had erosion score of 1 while 7 (30.4%) had erosion score of 2. In contrast, almost half (48.9%) of the study subjects had erosion score of 3, and around one-fifth (19.1%) had erosion score of 4 [Figure 5]. Differences in the erosion scores between study group and control group was highly significant (P < 0.001) which was in agreement with the study done by Amin et al. 
In a survey on battery workers conducted by Amin et al.,  total of 79.2% of acid workers and 46.7% of controls showed erosion which was in agreement with our study in which all workers in study group and 39.1% in the control group had erosion.
In their study, 62.5% of acid workers had grades 2 and 3 erosion, 16.7% had grade 4 erosion which was in agreement with our study in which 70.2% of study group had grades 2 and 3 erosion, and 19.1% had grade 4 erosion.
In battery factories, exposure to sulphuric acid fumes in the work place was significantly associated with dental erosion and poor oral health status [Figure 6] among workers. Similar finding was suggested by Malcolm and Paul,  Ten Bruggen Cate,  Tuominen et al.,  and Petersen and Gormsen  which is in agreement with our study.
Oral manifestations of occupational origin are readily predisposed and aggravated by neglect of oral health, and the problem of prevention of oral occupational hazards must be attacked both by improving the working conditions and by establishing and maintaining oral health. The oral occupational diseases observed in this study present a challenge to the authorities in industrial and public health to provide adequate measures for the prevention, early recognition and treatment of oral occupational disease. 
| Conclusion and Recommendations|| |
Oral health status in battery factory workers was poor. The markedly better general and oral health conditions in the control groups composed to their acid exposed counterparts confirmed the association between deterioration of the oral health status and a hazardous workplace environment. Exposure to sulphuric acid fumes is significantly associated with deteriorated oral health status and dental erosion.
The Evidence-Based Practice Group of WorkSafeBC recommends that the "arising out of and in the course of employment" rule to be an appropriate basis of any assessment when concluding on "occupational hazards (s)" as the main contributing factor (s) of dental erosion. 
Oral hygiene is an essential part of industrial hygiene. Adequate provisions for industrial health should include the prevention, the early recognition and the treatment of oral occupational diseases. Thus, oral health is more than additive or reducing factor in the production of oral occupational disease; it is a controlling factor.
In the light of the present alarming findings associated with excessive exposure to sulphuric acid fumes in the workplace, occupational health authorities are invited to implement effective safety measures, including:
- Efficient surveillance and routine monitoring of acid fumes in workplace air
- Installation of efficient ventilation and exhaust systems of the work sites
- Automation of manufacturing processes 
- Implementation and mandatory use of protective masks,  mouthguards,  goggles and face guards
- Use of alkaline mouthwashes and regular routine check-up
- Providing medical and dental care services.
| References|| |
|1.||Schour I, Sarnat BG. Oral manifestations of occupational origin. JAMA 1942;12:1197-207. |
|2.||Anfield BD, Warner CG. A study of industrial mists containing sulphuric acid. Ann Occup Hyg 1968;11:185-94. |
|3.||Ellis P. Acid erosion in the teeth of industrial workers. J R Soc Promot Health 1963;3:163. |
|4.||Pindborg JJ. Pathology of the Dental Hard Tissues. Copenhagen: Munksgaard Publishers; 1970. p. 1-445. |
|5.||Järvinen VK, Rytömaa II, Heinonen OP. Risk factors in dental erosion. J Dent Res 1991;70:942-7. |
|6.||Smith BG, Bartlett DW, Robb ND. The prevalence, etiology and management of tooth wear in the United Kingdom. J Prosthet Dent 1997;78:367-72. |
|7.||Hattab FN, Yassin OM. Etiology and diagnosis of tooth wear: A literature review and presentation of selected cases. Int J Prosthodont 2000;13:101-7. |
|8.||Tuominen ML, Tuominen RJ, Fubusa F, Mgalula N. Tooth surface loss and exposure to organic and inorganic acid fumes in workplace air. Community Dent Oral Epidemiol 1991;19:217-20. |
|9.||Schroeder PL, Filler SJ, Ramirez B, Lazarchik DA, Vaezi MF, Richter JE. Dental erosion and acid reflux disease. Ann Intern Med 1995;122:809-15. |
|10.||Ten Bruggen Cate HJ. Dental erosion in industry. Br J Ind Med 1968;25:249-66. |
|11.||Tuominen M, Tuominen R, Ranta K, Ranta H. Association between acid fumes in the work environment and dental erosion. Scand J Work Environ Health 1989;15:335-8. |
|12.||Remijn B, Koster P, Houthuijs D, Boleij J, Willems H, Brunekreef B, et al. Zinc chloride, zinc oxide, hydrochloric acid exposure and dental erosion in a zinc galvanizing plant in the Netherlands. Ann Occup Hyg 1982;25:299-307. |
|13.||Petersen PE, Gormsen C. Oral conditions among German battery factory workers. Community Dent Oral Epidemiol 1991;19:104-6. |
|14.||Erosion of the teeth by acid. Lancet 1980;2:353. |
|15.||Wiegand A, Attin T. Occupational dental erosion from exposure to acids: A review. Occup Med (Lond) 2007;57:169-76. |
|16.||Malcolm D, Paul E. Erosion of the teeth due to sulphuric acid in the battery industry. Br J Ind Med 1961;18:63-9. |
|17.||Available from:http://www.macorr.com/ss_calculator.htm [Last Accessed on 2014 Mar 29]. |
|18.||Smith BG, Knight JK. An index for measuring the wear of teeth. Br Dent J 1984 23;156:435-8. |
|19.||Johansson AK, Johansson A, Birkhed D, Omar R, Baghdadi S, Carlsson GE. Dental erosion, soft-drink intake, and oral health in young Saudi men, and the development of a system for assessing erosive anterior tooth wear. Acta Odontol Scand 1996;54:369-78. |
|20.||Greene JC, Vermillion JR. The Simplified oral hygiene index. J Am Dent Assoc 1964;68:7-13. |
|21.||Loe H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Scand 1963;21:533-51. |
|22.||Oral health surveys. Basic methods. Geneva: World Health Organization; 1997. |
|23.||Amin WM, Al-Omoush SA, Hattab FN. Oral health status of workers exposed to acid fumes in phosphate and battery industries in Jordan. Int Dent J 2001;51:169-74. |
|24.||Milosevic A, Agrawal N, Redfearn P, Mair L. The occurrence of toothwear in users of Ecstasy (3,4-methylenedioxymethamphetamine). Community Dent Oral Epidemiol 1999;27:283-7. |
|25.||Skogedal O, Silness J, Tangerud T, Laegreid O, Gilhuus-Moe O. Pilot study on dental erosion in a Norwegian electrolytic zinc factory. Community Dent Oral Epidemiol 1977;5:248-51. |
|26.||Subramanian SV, Nandy S, Kelly M, Gordon D, Davey Smith G. Patterns and distribution of tobacco consumption in India: Cross sectional multilevel evidence from the 1998-9 national family health survey. BMJ 2004;328:801-6. |
|27.||Edeer D, Martin CW. Occupational Dental Erosion. Richmond, BC: Work Safe BC Evidence Based Practice Group; 2010. p. 1-31. |
|28.||Suyama Y, Takaku S, Okawa Y, Matsukubo T. Dental erosion in workers exposed to sulfuric acid in lead storage battery manufacturing facility. Bull Tokyo Dent Coll 2010;51:77-83. |
|29.||Kim HD, Douglass CW. Associations between occupational health behaviors and occupational dental erosion. J Public Health Dent 2003;63:244-9. |
|30.||Eccles JD. The treatment of dental erosion. J Dent 1978;6:217-21. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]