The Frequency of Posterior Teeth Decay in Smokeless Tobacco Users in the South of Iran

Background : Tobacco has been reported to have multiple negative effects on oral health. This study aimed to investigate the frequency of posterior teeth decay due to smokeless tobacco (ST). Materials and Methods: This cross-sectional study included consistent nas and tanbak users for more than 2 years in Bandar Abbas, Iran in 2018-2019. General characteristics, including age, gender, education, occupation, income, residence, the number of family members, and smoking status, as well as the duration of ST use, the use of mouth wash, and the frequency of using dental floss and toothbrush, were recorded based on the study aim. All patients underwent complete oral examination and posterior teeth decay was noted based on the results. The surface of teeth with decay (lingual, buccal, mesial, distal, and occlusal) was recorded as well. Results: From 150 patients evaluated in this study with a mean age of 37.95 ± 12.02 years, 136 (90.7%) cases were males. Posterior teeth decay was found in 135 patients (90%). The mean number of decayed posterior teeth was 3.37 ± 2.58. The highest decayed tooth surface was the mesial surface (78.7%), followed by the occlusal (77.3%) and the distal (76.7%) surfaces. The binary logistic regression model revealed that the odds of posterior teeth decay were approximately 4-folds higher in employed participants compared to the unemployed ones (OR = 4.29, 95% CI: 1.19-15.49, P = 0.026). Overall, occupation, income, duration of ST use, number of family members, and dental floss use were able to predict posterior teeth decay with an area under the ROC curve of 0.787 (95% CI: 0.671-0.902, P < 0.001), the sensitivity of 85.9%, and specificity of 60%. Conclusion: A very high frequency of posterior teeth decay was observed in patients with ≥ 2 years of ST use. Posterior teeth decay appears to be affected by a combination of factors such as occupation, income, duration of ST use, number of family members, and the use of dental floss.

Tob Health. Vol 1, No 2, 2021 64 http://thj.hums.ac.ir http contribute to tooth decay by suppressing the immune system's response to oral infections (2). In addition, the wide range of additives and sweeteners used for the preparation of different tobacco products, as well as the abrasive constituents of ST can increase the risk of dental caries (6). The current study aimed to determine the frequency of posterior teeth decay due to ST use while investigating the potential predisposing factors.

Materials and Methods
Participants Individuals with consistent ST use, including nas and tanbak for more than 2 years were evaluated in this cross-sectional study. Participants were recruited from Bandar Abbas, Hormozgan, Iran from March 21, 2018, to March 20, 2019, through multi-stage cluster sampling. Individuals with less than 2 years of ST use were excluded from the study.

Study Design
The general characteristics of the participants were recorded, including age, gender, education, occupation, income, residence, the number of family members, and smoking status in addition to the duration of ST use, the use of mouth wash, and the frequency of using dental floss and toothbrush. All patients underwent complete oral examination by an expert dentist using a mouth mirror, a tongue depressor, and a sterile gauze in the dental health care center. Posterior teeth decay, defined as the loss of enamel or dentin, or the destruction of roots visible by the naked eye, was noted based on the evaluation. Therefore, interproximal decay, caries not visible by the naked eye, and arrested enamel decay were not taken into account. The surface of teeth with decay (lingual, buccal, mesial, distal, and occlusal) was recorded as well.

Data Analysis
The Statistical Package for the Social Sciences (SPSS) software (version 25.0, Armonk, NY: IBM Corp.) was used for data analysis. The mean, standard deviation, frequency, and percentages were applied to describe the results. Based on the results of the Kolmogorov-Smirnov normality test, the Mann-Whitney test was used to compare quantitative variables between patients with and without posterior teeth decay. Further, chi-square and Fisher's exact tests were employed to compare qualitative variables between groups. All variables, including age, gender, residence, occupation, education, income, smoking status, duration of ST use, and the number of family members, as well as a mouth wash, dental floss, and toothbrush use, were entered into the binary logistic regression model separately with posterior teeth decay as the dependent variable. Variables with P values < 0.2 were included in the final regression model. A receiver operating characteristic (ROC) curve was drawn to show the predictive power of variables included into the final regression model. The area under the curve (AUC) was calculated, and the sensitivity and specificity of this model were also determined for the prediction of posterior teeth decay. P values ≤0.05 were regarded as statistically significant.

Results
Of 150 patients included in this study, 136 (90.7%) were males and 14 (9.3%) were females. Their mean age and the mean duration of ST use were 37.95 ± 21.02 and 10.49 ± 8.82 years, respectively. Table 1 presents the general characteristics of the study participants. Most of the participants were urban dwellers, unemployed, and illiterate. Furthermore, the majority of patients had low incomes. In general, 48 patients (32%) were cigarette smokers.
Only 10 participants (6.7%) used mouth wash. Regular use of toothbrush and dental floss was reported by 31.3% and 4% of patients, respectively. Posterior teeth decay was found in 135 patients (90%). The mean number of decayed posterior teeth was 3.37 ± 2.58. The highest decayed tooth surface in the whole study population  Table 2.
The comparison of various study variables between patients with and without posterior teeth decay showed a significant difference in occupation (P = 0.048). A significantly higher number of patients with posterior teeth decay were self-employed compared to patients without decay (Table 3).
The binary logistic regression model revealed that the odds of posterior teeth decay were approximately 4-folds higher in employed participants compared to the unemployed (OR = 4.29, 95% CI: 1.19-15.49, P = 0.026, Table 4). In general, occupation, income, duration of ST use, number of family members, and dental floss use could predict posterior teeth decay with an area under the ROC curve of 0.787 (95% CI: 0.671-0.902, P < 0.001), sensitivity of 85.9%, and specificity of 60% ( Figure 1).

Discussion
Overall, posterior teeth decay was found in 90% of patients with ≥ 2 years of consistent ST use. The prevalence of  dental caries was 71.53% among the tobacco chewers in the study by Nishat et al (2). The increased prevalence of dental caries in individuals using ST was also reported by Campus et al (7). However, tooth decay was only observed in 11.11% of individuals using ST in one study (8) lower rate of dental caries observed in some of these studies, compared to our findings, can be justified by the difference in sociodemographic features, the type of STs and their methods of use, and the overall oral health of the study populations. Interestingly, Chaitanya et al assessed the prevalence of dental caries in ST users and smokers and concluded that tooth decay was significantly more prevalent in the control group, followed by the ST group and the smokers. They attributed the lower prevalence of dental caries in smokers to the potential anticarcinogenic activity of thiocyanate in the saliva. Additionally, they associated the higher prevalence of tooth decay in ST users, compared to smokers, with the presence of sweeteners in ST products, especially chewing tobacco (12).
The majority of ST users in our study, in the groups with and without posterior dental caries, were males.
According to previous studies, men appear to be the predominant users of ST (9,10,(12)(13)(14). The reason behind this predilection might be the cultural boundaries for women; even if they use ST, they have a tendency to hide it, which accounts for the demographic findings of our study with very few females engaged in ST use.
Importantly, dental caries is a multifactorial disease with socioeconomic, lifestyle, and sociodemographic elements as influential factors. Meanwhile, tobacco use has been suggested as a confounding factor rather than having a direct causal effect on tooth decay (15,16). To assess the plausible effects of the aforementioned factors, a logistic regression analysis was performed, and the results revealed that a set of features, including occupation, income, duration of ST use, number of family members, and dental floss use were able to predict posterior teeth decay with 85.9% sensitivity and 60% specificity. This confirms the findings of previous studies; nevertheless, considering that all participants in the current study were ST users, it was impossible to ascertain whether ST use has a causal relationship with dental caries or acts as a confounder.
It was also found that the highest decayed tooth surfaces were the mesial, occlusal, and distal surfaces, respectively. This can largely depend on the placement site of ST as has been reported by Muthukrishnan and Warnakulasuriya, demonstrating an increased risk of mucosal changes and periodontal diseases at the ST placement sites in ST users (6).
This study had some limitations. One limitation was that we had no control group, (i.e., individuals with no smokeless or smoked tobacco use). Therefore, we could not compare the frequency of posterior teeth decay between ST users and non-ST users, which would have shown the true effect of ST on tooth decay.

Conclusion
The result of the current study represented a very high frequency of posterior teeth decay in individuals with ≥ 2 years of consistent ST use. Being employed (compared to having no job) significantly influenced the occurrence of posterior teeth decay. Future studies with different designs and larger sample sizes are required to confirm the findings of this study.

Funding
There was no funding.

Informed Consent
The present study was carried out after obtaining informed consent.