SRM Journal of Research in Dental Sciences

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 11  |  Issue : 3  |  Page : 128--132

A comparison of salivary thiocyanate in cigarette smokers with and without oral leukoplakia: A biochemical study


Anshul Aggarwal1, Neha Agrawal2, Md Asdullah1, Rati Goyal3,  
1 Department of Oral Medicine and Radiology/Oral Pathology, DR. Ziauddin Ahmad Dental College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pardesh, India
2 Department of Periodontics and Community Dentistry, DR. Ziauddin Ahmad Dental College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pardesh, India
3 Private Practioner, Aligarh, Uttar Pardesh, India

Correspondence Address:
Dr. Anshul Aggarwal
Department of Oral Medicine and Radiology/Oral Pathology, DR. Ziauddin Ahmad Dental College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh
India

Abstract

Objective and Background: Determining SCN (thiocyanate) levels in saliva has been the most frequently used biochemical tests for establishing an incidence of tobacco consumption among smokers and can be used as biochemical indicator in the evaluation of precancerous condition like oral leukoplakia. Materials and Methods: Group A (n = 30) consisted of a clinically diagnosed case of oral leukoplakia between the ages of 30 and 50 years (n = 30) with inclusion criteria of male gender and history of cigarette smokers with a habit of smoking 4–7 cigarettes per day for a minimum period of 4–5 years or more. Group B, cigarette smokers without leukoplakia group, consisted of individuals (n = 30) with inclusion criteria of matched age and sex and history of cigarette smoking. The salivary SCN estimation was done by the Denson analysis. The comparison of salivary SCN level for two groups was statistically compared using unpaired Student's Test. Patient's smoking history (number of cigarettes smoked, duration of smoking) was noted in pack-years. Results: Salivary thiocyanate levels (mM/L) were found to be significantly higher (P < 0.001) in smokers with leukoplakia (13.55 ± 2.58) as compared to smokers without leukoplakia (7.46 ± 1.85). Comparison of salivary thiocyanate levels (mM/L) with pack-years among smokers showed a positive correlation with P < 0.001 which was highly statistically significant. There was a progressive increase in mean salivary thiocyanate levels as the pack-years increased. Conclusion: Salivary SCN level in smokers with leukoplakia is significant high in comparison to smokers without leukoplakia.



How to cite this article:
Aggarwal A, Agrawal N, Asdullah M, Goyal R. A comparison of salivary thiocyanate in cigarette smokers with and without oral leukoplakia: A biochemical study.SRM J Res Dent Sci 2020;11:128-132


How to cite this URL:
Aggarwal A, Agrawal N, Asdullah M, Goyal R. A comparison of salivary thiocyanate in cigarette smokers with and without oral leukoplakia: A biochemical study. SRM J Res Dent Sci [serial online] 2020 [cited 2020 Nov 28 ];11:128-132
Available from: https://www.srmjrds.in/text.asp?2020/11/3/128/298265


Full Text

 Introduction



It is established that saliva is valuable in diagnosis of local diseases of salivary glands such as inflammatory conditions and autoimmune disease. A quantitative determination of specific constituent of saliva like thiocyanate (SNC) can be assessed, which acts as an indicator of tobacco consumption among smokers.[1]

The regular use of tobacco slowly deteriorates the general health of a person which is found to be a common cause of tobacco addiction, which leads to illness, disability and death of a person. Oral leukoplakia is known to be defined as “a white patch or a plaque that cannot be characterized clinically or pathologically as any other disease” by the World Health Organization.[2] The person who consumes more tobacco is at a greater risk for developing oral precancer like condition (mostly oral leukoplakia), oral cancer, various periodontal problems and other harmful oral conditions like acute necrotizing ulcerative gingivitis, oral candidiasis which usually shows a significant adverse effect on the outcome of oral care.[3]

In liver, tobacco consumption leads to the production of a toxic gas hydrogen cyanide (HCN), whose detoxification leads to production of SCN.[4] The SCN, which is produced in the liver is distributed to all of the extracellular fluids like saliva, cerebrospinal fluid, blood plasma, gastric juices and is slowly eliminated from the body through the urine excretion.[5]

A normal concentration of SCN in human saliva is 1 mM which is very less in comparison with SCNin human saliva of smokers which is around 6 mM. This high value SCN in smokers acts as a powerful catalyst of nitrosation reaction resulting in the formation of some harmful carcinogenic substances like N-nitrosopiperidine and N-nitrosopyrrolidine. These N-Nitroso compounds have been detected in all saliva samples of smokers which show increased prevalence of oral cancers.[6]

Salivary tests have the advantages of easy, noninvasive sampling and have good stability. The main significance is half-life of SCN is 14 days [7] (approximately) which make SCN an important chemical marker that best adapts to document smoking behavior among cigarette smokers.[8],[9],[10],[11]

A salivary SCN levels can be easily accessed by a simple biochemical test that can play a critical role in indicating the incidence or prevalence rate of tobacco consumption among smokers. It can be used as biochemical indicator in the evaluation of precancerous condition like oral leukoplakia. Very few studies had been carried out in this regards, hence this study is carried out with the objective to find the correlation of salivary SCN level with oralleukoplakia.

 Materials and Methods



The sample size was determined based on the pilot study performed. A sample of 30 was determined as the minimum in each group to estimate and to calculate for the statistical analysis. Therefore, the study sample included a total of 60 subjects who were divided into the following groupings.

Group A was group of cigarette smokers with leukoplakia. This group consisted of clinically diagnosed cases of oral leukoplakia between the ages of 30 and 50 years (n = 30) with inclusion criteria of the male gender and history of cigarette smokers with the habit of smoking at least 4–7 cigarettes per day with a time period of about 4–5 years or more.

Group B, cigarette smokers without leukoplakia group, consisted of individuals (n = 30) with inclusion criteria of matched age and sex and history of cigarette smoking.

Exclusion criteria for both groups were a subject giving history of tobacco consumption in the form of chewing and a history of both cigarette and bidi smoking and tobacco chewing. The person who had taken the high intake of food rich in thiocyanate in significant amount like a raw cabbage, cauliflower, Brussels sprouts, cooked broccoli, patients with a history of chemotherapeutic medication especially chlorambucil, melphalan, and ifosamide were excluded from this study.

The oral examination of the patients was performed by asking patients to comfortably sit in a dental chair equipped with white artificial light and by using mouth mirrors. The Lesions of the oral cavity were recorded on the basis of WHO standard recording form for oral mucosal diseases.[12] The criteria as provided by the WHO, modified by Axell were adopted in making the clinical diagnosis of oral leukoplakia.[13] A detailed case history was recorded. Informed patient consent was obtained for this study.

Collection of samples

All the subjects were asked not to eat, drink or smoke an hour before to collection of saliva. Then they were asked to accumulate and hold saliva in the mouth for about 2 min, and spit the accumulated saliva in a sterile plastic container. The collected unstimulated saliva was refrigerated at −20°C, and processed for further analysis within 24 h.

Method for evaluation of SCN in saliva

For standardization of technique, MODULAB 4010 spectrophotometer was used. The salivary SCN estimation was done by the Denson method.[7]

Principle

Tobacco smoke contains toxic HCN gas. After ingestion of this gas it dissociates into its components which are shown according to the following equilibrium equation:

HCN (aq) H + (aq) + CN -(aq)

In the liver, the CN − ion which is obtained after dissociation of HCN is then converted into the ionic form of SCN. This SCN ion is now reacting with the Fe 3+ ion to form FeSCN2+ complex that can be easily detected by spectrophotometric method.

In this study, a standard curve was constructed with the help of the absorbance of several solutions consisting of varying concentration of FeSCN 2+ complexes measured at 405 nm. This standard curve was constructed using a linear relationship between absorption and concentration of solution which helps in determining the unknown concentration of FeSCN 2+ ion in the saliva samples.

The data so collected was stored and analyzed.

Statistical analysis

The data obtained were tabulated and subjected to statistical analysis. For statistical analysis, SPPS Version 16 was used (SPSS Inc released 2007. SPSS for Windows, Version 16.0, Chicago, USA). For comparison of salivary SCN level for two groups, mean and standard deviation was statistically compared using unpaired Student's test.

The patient's habit of smoking history was evaluated in terms of pack-years. Pack-years is basically a method which helps in quantification of the amount a person smoking history. Pack-years depends on the duration of smoking and the number of cigarettes smoked. It usually evaluates the amount of person has smoked in a particular period of time. Assuming that 1 pack has 20 cigarettes, the number of pack years is calculated by the formula given below.[14]

[INLINE:1]

In clinical care, quantification of pack-years smoked plays a very important role, because it helps in correlation of degree of tobacco exposure with the risk of developing a disease such as lung cancer.[15] The comparison of salivary thiocyanate levels (mM/L) with pack-years among smokers correlation was done by Spearman's correlation coefficient. Analysis variance test was used for intragroup comparison of smokers were divided into various groups based on pack-years.

 Results



Salivary thiocyanate levels (mM/L) were found to be significantly higher (P < 0.001) in smokers with leukoplakia (13.55 ± 2.58) as compared to smokers without leukoplakia (7.46 ± 1.85) [Figure 1].{Figure 1}

Comparison of salivary thiocyanate levels (mM/L) with pack-years among smokers showed a positive correlation with P < 0.001 which was highly statistically significant.

For intragroup comparison, smokers were divided into four groups based on pack-years:

Group I: 1 to <2 pack-years (7 cases)Group II 2 to <3 pack-years (10 cases)Group III: 3 to <4 pack-years (16 cases)Group IV: 4 to <5 pack-years (27 cases).

There was a progressive increase in mean salivary thiocyanate levels as the pack-years increased in both groups, but it was statistically higher in patients with leukoplakia [Figure 2].{Figure 2}

 Discussion



Saliva plays a critical role in monitoring and regulating the health of oral cavity, and helps in keeping the integrity of the oral mucosa.[16] As the saliva collection is noninvasive method to obtain so its popularity is increasingly day by day in field in dentistry as a diagnostic fluid. Human saliva is composed of various numbers of solids (organic and inorganic) constituents like sodium, potassium, SCN, proteins, and immunoglobulins. A salivary SCN levels can be easily accessed by a simple biochemical test that can play a critical role in indicating the incidence or prevalence rate of tobacco consumption among smokers. As SCN is a metabolic product obtained from the combustion of HCN, it acts as a useful tool for the detection of smokeless tobacco, but it also plays a critical role in evaluating and understanding the patterns of smoking behavior, especially in adult and can be used as biochemical indicator in the evaluation of precancerous condition like oral leukoplakia.[17]

Leukoplakia is considered in the category of a premalignant lesion with the risk for development of oral cancer.[18] The most important known etiological factor, considered in development of oral leukoplakia is tobacco smoking.[19] Various Cross-sectional studies show a much higher prevalence rate of occurring leukoplakia among smokers, with a positive dose-response relationship between tobacco use and oral leukoplakia, and intervention studies show a deterioration of the lesion after the cessation of smoking with time.[19] Leukoplakias of the floor of mouth was more common among smokers than nonsmokers. Further, the use of tobacco has been significantly linked to the development of leukoplakia and oral submucous fibrosis which is potent to cause malignant transformation.[20]

The present study consists of 60 subjects, where 30 subjects are cigarette smokers with leukoplakia and age- and sex-matched 30 subjects are cigarette smokers without leukoplakia. The age group of 30–50 years was taken in our study, which is supported by various previous studies which shows that oral leukoplakia occurs more frequently is this age group.[13],[21] There were only male subjects in our study habit of as tobacco consumption is more prevalent among males in the population. This could be attributed to the varying tobacco habits in various populations.[13]

In our study, salivary SCN level was significantly higher in cigarette smokers with leukoplakia in comparison with cigarette smokers without leukoplakia. This may be because of the fact that tobacco smoking is considered as a significant risk factor for the occurrence of precancerous lesions in the mouth. A previous study shows that smokers usually have a significantly higher prevalence rate of leukoplakia in comparison with nonsmokers [21],[22] and the frequency and duration of the habit of smoking show a positive dose-response relationship.[23],[24] It has also been demonstrated that there is a positive dose-response relationship between tobacco consumption and the risk of malignant transformation of oral leukoplakia [24],[25]. Bokor-Bratiae in their study observed that the more the duration of the habit of smoking, the higher will be the prevalence rate of oral leukoplakia. They also observed that peak time for the development of leukoplakia was usually associated with duration of cigarette smoking of 4 years. Furthermore, smokers with leukoplakia statistically show a longer mean of duration of cigarette smoking in comparison to smokers without leukoplakia. Moreover, the duration of the habit of smoking is usually associated with a significant increased risk of just beginning of oral leukoplakia.[26]

A significant increase of the SCN level in saliva with more duration and frequency of smoking represented in this study in terms of pack-years may be due to the fact that with intake of each cigarette increases the HCN level approximately by 30–200 μg in the mouth of a smoker.[27] In the liver this HCN is metabolized to SCN. It indicates clearly that longer duration and frequency of smoking increases the level of HCN, which in turn results in increased levels of salivary SCN. Our finding is also supported by another study, which says Salivary thiocyanate levels were significantly higher in smokers than controls and showed significant correlation with the number of pack-years.[28]

Armenio et al. observed that chronic smokers clearly had significantly higher values of salivary SCN in comparison with moderate smokers.[27] Tenovuo and Makinen observed a positive correlation of significant increase in salivary SCN level with duration and frequency of smoking.[29] According to another study, smokers with a longer duration of smoking showed significantly higher SCN levels in comparison to smokers with short duration.[30]

This study has added to available knowledge by showing that in smokers, the total number of pack-years is related with a significant increase salivary thiocyanatelevel. The study also once again proved the usefulness of salivary thiocyanate tests as an acceptable biomarker for smoking. Salivary thiocyanate level can be used as a motivating tool for smokers by asking them to reduce the salivary thiocyanate level because lower thiocyanate level in saliva less will be a possibility of malignant transformation. Thus, this can act as a good alternate tool which will help smokers in quitting smoking. Furthermore, in any population group, the increase in the incidence or prevalence of oral leukoplakia should raises the question of possibilityof malignant transformation and successive increase in the incidence of oral cancer with that group.[31],[32]

 Conclusion



The present study shows significant correlation of increase in salivary level of SCN in saliva of smokers with leukoplakia in compare to smokers without leukoplakia. The main source of SCN in smokers is tobacco smoke. This tobacco smoke contains toxic HCN gas, which is absorbed in the lungs and later metabolized to SCN. The present study revealed that there is a significant relationship between cigarette smoking habit and oral leukoplakia. Pack-years which are calculated on the basis of duration of smoking and the number of cigarettes were significantly associated with the presence of oral leukoplakia. Moreover, in this study, smokers with leukoplakia had a higher concentration of thiocyanate, which may predispose to oral carcinoma.

Thus, this study observed that salivary SCN can act as a reliable biochemical indicator for assessing smoking behavior among smokers and can be used as a noninvasive tool to identify a biomarker for oral leukoplakia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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