This cross-sectional study was conducted to assess oral health status of lead acid battery workers. The study was conducted from January to December 2022. It started with protocol development and completed with final report submission. A work schedule was prepared including all the tasks in a sequence. The first four months were applied for literature review and strategy finalization. The subsequent months were passed for questionnaire development, pretesting, data collection, compilation and analysis. The study areas were selected purposively for availability of lead acid battery workers, easy communication and well cooperation from the workers. The study was conducted in four workshops of Dhaka city including Mohakhali, Saidabad, Gabtoli, Dholaikhal. The workers expressed their interest to participate voluntarily in this study.

There are about 5000 lead acid battery factory workers in Dhaka city. The sample size was calculated by using sample size calculator^[31] with 95% confidence level and 5% confidence interval. The sample size for the current study was calculated as 357, though the sample size was calculated as 357, we enrolled total 370 workers randomly for our present study. There were two types of workers in lead acid battery factories: (i) the workers who exposed to lead acid fumes (working in forming and charging department), and (ii) the workers who are not exposed to lead acid fumes (working in pasting, grid casting and packaging department). The first study group comprising 185 workers was considered as experimental group (cases) and the latter one consisting of 185 workers was regarded as control group (controls).

The study groups were fully briefed on the purpose of our current study and their consent was obtained prior to their participation to avoid any inconvenience and ensure their complete cooperation. The lead acid battery factory workers of all age groups who were present at the time of the study and willing to participate were included in our current study. The workers who were not willing to participate were excluded from this study. The examiner was well trained and calibrated to ensure consistent diagnosis and preventing any variability among the study subjects.

A detailed schedule was prepared well in advance for the survey study and the investigator visited the study area within the prescheduled timeframe during the study period until the required sample size was obtained. A sufficient number of sterile instruments were used for the examinations during the study including plain mouth mirrors, explorers, tweezers, kidney trays, containers, Betadine™, saline, gauze, cotton with a cotton holder, disposable gloves, mouth masks, and data recording proforma. Data were collected by face-to-face interview, clinical oral examination with oral health index. The interview was conducted privately as far as possible and before preceding the data collection, the detail of the study was explained to each eligible workers and informed written consents were obtained from the workers. Interview and oral checkup were taken in a quiet place; no other person was allowed to influence the replying of the workers. It took on average 30 minutes to complete the interview of a single worker. Data were collected from 10 am to 4 pm. On an average, 10 workers were interviewed daily. Information was recorded about the department within the battery factory, job duration, exposure to various working conditions, and oral symptoms. Additionally, details such as name, age, sex, location, dietary habits, deleterious habits, and oral hygiene practices were documented. All the data were recorded by maintaining the World Health Organization 2013 (WHO-2013) proforma with slight modification.

Initially ethical clearance was obtained from the Institutional Review Board (IRB) of NIPSOM. The participants were briefed properly and motivated to participate in the study. The study participants were informed about the objectives, purposes of the study and informed consent would be taken from each participant. No intervention or any invasive procedures were applied in this study. The participants were interviewed separately and confidentially would be maintained strictly.

The raw data was obtained in a tabulated form using Microsoft Excel spreadsheet software. Data analysis was performed using the Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, USA) version 20.0. The Chi-square test was used to compare categorical variables for proportions, the Mann– Whitney U-test was employed to compare quantitative ordinal variables, and the independent samples t-test was utilized to compare quantitative continuous variables. Descriptive statistical analysis included mean, median, mode, SD. Inferential statistics included chi square test to find out any significant relationship between two qualitative variables. The P values less than 0.05 were considered statistically significant.

In our current study, a total 370 Bangladeshi individuals were participated, of which 185 (50%) individuals were as experimental group where 185 (50%) were considered as control. The major portion of the both experimental group (69.7%) and control group (67.6%) were less than 30 years old. The comparison data of case and control group suggested that the experimental participants with lower weight (P value: 0.028), higher BMI (P value: 0.006), no literacy (P value: 0.001), lower income (P value: 0.003) had been significantly more suffering from oral health problems in relation to their corresponding control. Moreover, the case individuals who work with oral pipe (P value: <0.001), work more than 5 years (P value: <0.001) and work more than 8 hours per day (P value: 0.001) were significantly more affected with oral problems in comparison to their respective control group. Furthermore, the participants who brush their teeth once per day (P value: 0.003) and without toothpaste (P value: <0.001) had been significantly more suffering from oral problem rather than their respective control. But there no significant difference was found between experimental group and control group in case of body height, family type, sound sleep, exercise and use tooth brush (Figure 1 and Table S1).

In our current investigation, the food habit of the study participants was analyzed and a significant proportion of experimental participants (who were suffering from oral health problem) were found to intake less than 8 glass of water per day (P value: 0.004), to eat fast food regularly (P value: 0.012), to take soft drinks in regular basis (P value: 0.017) rather than their respective controls. Moreover, a significant number experimental participants with oral health problem were detected to consume betel leaf (P value: 0.009) and betel nut (P value: 0.009), to take jorda (P value: 0.001), having smoking habit (P value: <0.001), and to take oral tobacco (P value: 0.002) in comparison to their corresponding controls. But no significant number of experimental participants with oral health problem were found in case of taking carbohydrate, protein, fat, vegetables, fruits, supplemental vitamins and minerals, and drinking tea or coffee in relation to their respective controls (Figure 2 and Table S2).

The analysis of overall distribution of study participants based on ore-dental problems revealed that a significant number cases were suffering from dental caries (P value: <0.001), dental erosion (P value: <0.001), sensitive teeth (P value: <0.001), gingivitis (P value: <0.001), oral ulcer (P value: <0.001), stained teeth (P value: 0.022), and mouth odor (P value: 0.048), compared to their corresponding controls. However, no significant differences were observed between experimental group and control group regarding of dry mouth, toothache, root infections, enamel erosion, periodontics, broken teeth, tooth cavity, Hyperdontia and cracked tooth when compared to their respective controls (Figure 3 and Table S3).

The subgroup analysis by dental caries suggested that a significant proportion of experimental participants experiencing with dental caries whose family income is comparatively lower (53%, P value: <0.001), working with oral pipe (41%, P value: 0.027), working in the workshop more than 5 years (45%, P value: <0.001), not brushing twice per day (48%, P value: <0.001), brushing without toothpaste (57%, P value: 0.001), drinking water less than 8 glass per day (34%, P value: 0.003), intaking betel leaf and betel nut (42%, P value: <0.001), taking Jorda (34%, P value: <0.001), taking tobacco orally (35%, P value: 0.042) and having smoking habit (54%, P value: 0.015). But no significant difference was found among experimental participants with or without dental caries in case of obesity, educational status, working hour, intake sugar rich food, and intake fast food or soft drinks Table 1.

The results of subgroup analysis by dental erosion revealed that obesity (P value: 0.003) and educational status (P value: 0.043) is not significantly associated with dental erosion where low income (P value: 0.028), working with oral pipe (P value: <0.001), and working more than 5 years (P value: 0.002) were significantly related with dental erosion. Additionally, a significant number of experimental participants have been suffering from dental erosion who did not brushing twice daily (50%, P value: <0.001), brushing without toothpaste (56%, P value: 0.008), consuming sugar rich foods (30%, P value: <0.001), fast foods or soft drinks (52%, P value: <0.001), and having habit of chewing betel leaf or betel nut (44%, P value:<0.001), Jorda (42%, P value: <0.001), oral tobacco (40%, P value: <0.001). But no significant portion of the study participants were experiencing with dental erosion regarding by daily working time, intaking water glass per day and having habit of smoking (Table 1).

The subgroup analysis by sensitive teeth demonstrated that a significant number of experimental participants have sensitive teeth who is not obese (P value: 0.005), having educational status (P value: 0.011), belonging to lower income family (P value: <0.001), working with oral pipe (P value: 0.005), working at factories in more than 5 years (P value: <0.001), working more than 8 hours daily (P value: 0.011), not brushing twice daily (P value: <0.001), brushing without toothpaste (P value: 0.002), consume sugar rich foods (P value: 0.001), drinking less than 8 glass of water daily (P value: <0.001), taking fast foods or soft drinks (P value: 0.009), having habit of using betel leaf or betel nut (P value: <0.001), taking Jorda (P value: <0.001) and oral tobacco (P value: <0.001) and smoking (P value: 0.002) (Table 1).

The results of the subgroup analysis based on gingivitis indicated that participants with higher educational status were significantly more likely to experience gingivitis (49%, P value: 0.037). Furthermore, a significant proportion of experimental participants have been facing with gingivitis who are working from more than 5 years (36%, P value: 0.026), brushing without toothpaste (55%, P value: 0.002), not drinking more than 8 glass of water (48%, P value: <0.001), taking betel nut or betel leaf (49%, P value: <0.001), taking oral tobacco (37%, P value: <0.001), and having habit of smoking (54%, P value: <0.001). However, a significant number of participants have not suffered from gingivitis who are working with oral pipe (36%, P value: <0.001), not brushing twice per day (41%, P value: <0.001), not taking Jorda (37%, <0.001). But no significant number of participants were experiencing with gingivitis regarding of obesity, status of family income, daily working time, taking sugar rich foods and intaking fast foods or soft drinks (Table 1).

The subgroup analysis of oral ulcers showed that participants with higher educational status were significantly less likely to suffer from oral ulcers (77%, P value: 0.002). Besides, a significant percentage of experimental participants were experiencing with oral ulcer who are working with oral pipe (41%, P value: <0.001), working at workshop form more than 5 years (48%, P value: <0.001), brushing without toothpaste (54%, P value: 0.016), not drinking more than 8 glass of water (49%, P value: <0.001), taking fast foods and soft drinks (47%, P value: 0.046), taking betel leaf or betel nut (50%, P value: <0.001), having habit of using oral tobacco (44%, P value: <0.001) and smoking (54%, P value: <0.001). But participants who brushed twice per day have been not suffering from oral ulcer significantly (35%, P value: 0.022) where comparatively larger proportion of participants were facing with oral ulcer who did not take Jorda (39%, P value: <0.001). However, no significant number of participants were experiencing with oral ulcer in case of obesity, family income, working time per day, and intake sugar rich foods (Table 1).

The overall regression analysis of the study variables suggested that anthropometric characteristics including weight (< 50 Kg) [OR: 1.93, 95% CI (1.06-3.48), P value: 0.030]; Body mass index (≥ 30 Kg/m2) [OR: 2.08, 95% CI (1.23-3.54), P value: 0.007]; illiteracy [OR: 3.52, 95% CI (1.67-7.42), P value: 0.001] and low income [OR: 1.90, 95% CI (1.23-2.92), P value: 0.004] showed significant correlations with overall oral health problems (Table 2). Moreover, the results of this analysis revealed that the participants working with oral pipe [OR: 3.86, 95% CI (2.50-5.94), P value: <0.001]; working more than 5 years [OR: 2.10, 95% CI (1.39-3.19), P value: <0.001]; working more than 8 hours daily [OR: 2.65, 95% CI (1.50-4.70), P value: 0.001]; brushing once per day [OR: 1.92, 95% CI (1.25-2.94), P value: 0.003]; and brushing without toothpaste [OR: 14.3, 95% CI (7.58-26.9), P value: <0.001] have significant correlation with overall Oro-dental complications (Table 2).

Furthermore, the analysis of eating habit demonstrated that the participants who are drinking 8 glass of water per day [OR: 1.84, 95% CI (1.21-2.81), P value: 0.004]; eating fast foods regularly [OR: 1.83, 95% CI (1.14-2.94), P value: 0.013]; and taking soft drinks [OR: 1.74, 95% CI (1.10-2.73), P value: 0.017]; were significantly more affected by oral health problems in comparison to their respective controls (Table 2). Additionally, the habit of taking betel leaf [OR: 1.73, 95% CI (1.14-2.61), P value: 0.009]; and betel nut [OR: 1.73, 95% CI (1.14-2.61), P value: 0.009]; using Jorda [OR: 2.02, 95% CI (1.31-3.14), P value: 0.002]; having oral tobacco [OR: 1.94, 95% CI (1.27-2.97), P value: 0.002]; and smoking [OR: 3.22, 95% CI (2.08-4.98), P value: <0.001]; have significant relationship with overall oral health problems (Table 2).

Besides, the regression analysis on Oro-dental problems showed that a significant proportion of experimental participants were affected by dental caries [OR: 8.98, 95% CI (5.37-14.9), P value: <0.001]; dental erosion [OR: 7.09, 95% CI (4.35-11.5), P value: <0.001]; sensitive teeth [OR: 2.87, 95% CI (1.88-4.40), P value: <0.001]; gingivitis [OR: 6.01, 95% CI (3.72-9.69), P value: <0.001]; oral ulcer [OR: 10.7, 95% CI (6.16-18.7), P value: <0.001]; stained teeth [OR: 1.61, 95% CI (1.07-2.43), P value: 0.022]; and mouth odor [OR: 1.51, 95% CI (1.00-2.88), P value: 0.048] in relation to their corresponding control (Table 2).

The main objective of this study was to assess oral health status of lead acid battery workers. This study revealed that lead acid battery workers do have some sort of Oro-dental health problems such as dental caries, dental erosion, oral ulcer, sensitive teeth, stained teeth, gingivitis, periodontitis and so on. On the basis of this study findings, to recommend following measures for the lead acid battery workers: firstly, to improve oral health status of the workers, special attention should be given by adopting effective measures like health education, awareness program, work health facility. Secondly, to prevent dental caries comprehensive measures including fluoride containing tooth paste, mouth wash and brushing of teeth twice daily and need proper treatment and dental flossing. Thirdly, to control Oro-dental health problems of the workers, special preventive measure like regular mouth gargling, scaling, filling etc. should be given. Fourthly, to prevent dental erosion of the workers, regular oral checkup should be arranged and according measures should be taken. Fifthly, to prevent oral ulcer specific initiation like consumption of oral tobacco, hard food like betel nut should be reduced. Sixthly, to improve Oro-dental health of the workers, usage of oral pipe should be reduced in their working place. These will help the workers to reduce exposure to lead. Finally, to combat the existing Oro-dental problems of the workers by regular and periodic dental checkup and giving necessary treatment, proper health education regarding dental hygiene.