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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 34  |  Issue : 2  |  Page : 203-207

Comparative assessment of salivary flow rates among reverse smokers and smokers using modified schirmer test: A randomized prospective trial


1 Department of Oral Medicine and Radiology, Panineeya Mahavidyalaya Institute of Dental Sciences and Research Centre, Hyderabad, Telangana, India
2 Department of Oral Medicine and Radiology, GITAM Dental College and Hospital, Vishakhapatnam, Andhra Pradesh, India

Date of Submission06-Jan-2022
Date of Decision08-Apr-2022
Date of Acceptance05-Jun-2022
Date of Web Publication22-Jun-2022

Correspondence Address:
Diksha Chikte
Post graduate in Oral Medicine and Radiology, Panineeya Mahavidyalaya Institute of Dental sciences and Research centre, Hyderabad, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_13_22

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   Abstract 


Background: Saliva, a complex fluid secreted by the salivary glands within the oral cavity, is the first to interact with smoke while smoking. Nicotine in smoke causes structural and functional changes in the saliva, leading to a significant reduction in salivary flow. Aim: The present study was done to compare the salivary flow between reverse smokers, regular smokers, and non-smokers with the help of the Modified Schirmer Test (MST) to assess unstimulated saliva. Materials and Methodology: Ninety subjects were randomly divided into three groups; Group A (30) subjects who had the habit of reverse smoking daily for >6 months, Group B (30) subjects who had the habit of smoking daily for >6 months, and Group C (30) healthy, non-tobacco users. MST was done in the morning hours; they were not asked to eat/drink for 2 h before the procedure. Later, they were asked to raise their tongue, and the rounded end of Schirmer's strip was placed on the floor of the mouth. Wetting of the strip was recorded every 1, 2, and 3-minute intervals. Results: Data was recorded, and statistical analysis was done by the paired t-test. The mean value of salivary flow rate in reverse smokers per 3 minutes (19.73 ± 4.16) was less when compared to conventional smokers (22.53 ± 2.75) and healthy individuals (31.53 ± 2.90), with a significant P value of P < 0.0001. Conclusion: There was a significantly reduced unstimulated salivary flow rate in reverse smokers compared to conventional smokers and healthy individuals.

Keywords: Hyposalivation, saliva, Schirmer test, smokers, smoking


How to cite this article:
Ameer S, Mamatha B, Chikte D, Damera A, Kumar YP, Reddy CS. Comparative assessment of salivary flow rates among reverse smokers and smokers using modified schirmer test: A randomized prospective trial. J Indian Acad Oral Med Radiol 2022;34:203-7

How to cite this URL:
Ameer S, Mamatha B, Chikte D, Damera A, Kumar YP, Reddy CS. Comparative assessment of salivary flow rates among reverse smokers and smokers using modified schirmer test: A randomized prospective trial. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2022 Dec 7];34:203-7. Available from: http://www.jiaomr.in/text.asp?2022/34/2/203/347908




   Introduction Top


Saliva, a complex body fluid, plays an essential role in oral health.[1] It maintains homeostasis and is an antimicrobial and anti-fungal agent.[2],[3] Thus, alteration in the quantity and quality of saliva leads to harmful effects.[2]

Saliva is categorized into stimulated and unstimulated saliva. Stimulated saliva is useful in chewing and digestion, whereas unstimulated saliva protects oral mucosa. The normal unstimulated salivary flow rate is 0.29–0.41 ml/min,[4] and a flow rate <0.2 ml/min is considered 'hyposalivation'.[5]

Tobacco, a harmful substance, is burned and inhaled during smoking and is practiced by one billion people.[6] Tobacco smoke spreads to all parts of the oral cavity, and saliva is the first to interact with the smoke, causing structural and functional changes.[2] Long-term tobacco smoking presumably causes a decrease in sensitivity to taste receptors and depressed salivary reflex.[7]

Reverse smoking, a peculiar form of smoking, is seen in groups with low economic resources. The smoker puts the lit end of the chutta in their mouth, and smoke is inhaled from the lit end.[6]

Many studies were done, and they showed results that the salivary flow rate was low in conventional smokers. Still, limited studies compared the salivary flow rate between conventional and reverse smokers. Modified Schirmer test (MST) showed promising results in screening the resting whole saliva wetting.[8] Hence, it is used to assess the unstimulated salivary flow rate in conventional, reverse smokers, and non-smokers for comparison in the present study.


   Methodology Top


The present study was conducted on subjects who visited the Oral Medicine and Radiology department of the Vishakhapatnam region, Andhra Pradesh, for routine dental check-ups over the past three months. According to Van Der EB et al.,[9] the prevalence of reverse smoking habits practiced was 33% in north rural coastal areas of Andhra Pradesh population. A sample was calculated by –



Thus, a minimum of 30 subjects were included in our study. The subjects were informed about the study and the procedure and were divided into three groups-reverse smokers, conventional smokers, and healthy individuals based on their smoking habits. The study was done in accordance with the code of ethics. Ethical clearance was approved and obtained from the Institutional Ethical Committee [GDCH/EC/2015/OMR-12] under the guidelines provided by the World Medical Association (Declaration of Helsinki) on ethical principles for medical research involving human studies. Duly signed written informed consents were taken.

Ninety subjects were included and were divided into three groups (A, B and C) with 30 in each group, based on their smoking habits. This was a randomized, prospective trial. Subjects with any systemic diseases, drug therapy, radiotherapy, a denture wearer, and habitually consuming alcohol were excluded from the study.

Group A included 30 subjects who had the habit of reverse smoking daily for >6 months. Group B included 30 subjects who had the habit of conventional smoking daily for >6 months with no other associated habits. Group C included 30 subjects who were healthy and non-tobacco users. The subjects were asked to refrain from eating and drinking two hours before the procedure. The test was done in the morning hours. During the procedure, the subjects were asked to swallow once to clear the salivary secretion in the mouth and then told not to swallow during the entire procedure. Modified Schirmer Test (MST) consists of a strip of filter paper with readings from 5 to 35 mm and has a rounded end at the end of the strip [Figure 1]. The strip was positioned on the floor of the mouth vertically as shown in [Figure 2]. To avoid accidental wetting of the strip, subjects were asked to raise their tongue. Based on the wetting length, reading was recorded immediately at 1, 2, and 3-minute intervals [Figure 3]. They reading <25 mm obtained after a 3-minute interval was considered indicative of hyposalivation.
Figure 1: Modified Schirmer Test (MST) kit consists of a strip of filter paper with a rounded end and 5 to 35 mm readings

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Figure 2: The rounded end of the strip is positioned vertically on the floor of the mouth adjacent to the right or left lingual frenum

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Figure 3: Wetting of the filter strip till 13 mm is noticed

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The collected data were subjected to statistical analysis using the Stata 13.1 version program by Stata Corp, California, and the paired t-test was used with variance at P value < 0.005.


   Results Top


Ninety subjects were included in the present study and were divided into three groups based on their smoking habits—Group A, B and C, with 30 subjects in each group. The unstimulated salivary flow rate was measured in the subjects at every 1, 2, and 3-minute intervals. Data were recorded, and comparisons were drawn. Statistical analysis was carried out.

(A) Gender characteristics:

The total subjects in the study were 90, which included 53 males and 37 females, with a larger male population. Group A (reverse smokers) included two males and 28 females, with a larger female population when compared to group B (conventional smokers), which had 30 males and no females, and group C (healthy individuals) had 21 males and nine females. The mean age in Group A, B and C is 49.86 ± 11.35, 44 ± 14.06, and 44.36 ± 14.34, respectively. [Table 1]
Table 1: Gender characteristics

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(B) Mode of smoking:

In the present study, subjects with three different smoking methods, such as cigarette smokers, chutta smokers, and beedi smokers, were noted. In group A (reverse smokers), the mode of smoking used was only chutta smoking in 30 individuals. In contrast, in group B (conventional smokers), the mode of smoking seen was cigarette smoking in 28 subjects, chutta smoking in one individual, and beedi smoking in one individual. [Table 2]
Table 2: Mode of smoking

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(C) Salivary flow rate characteristics:

The mean salivary flow rates measured at the 1-minute interval for the groups A, B, and C are 6 ± 1.85, 6.66 ± 1.95, and 9.93 ± 1.12, respectively; at the 2-minute interval they are 13.86 ± 3.92, 14.3 ± 2.94, and 20.83 ± 2.36 respectively; at the 3-minute interval they are 19.73 ± 4.16, 22.53 ± 2.75, and 31.53 ± 2.90 with a significant P value (P < 0.0001). There is a gradual increase in all groups' unstimulated mean salivary flow rate with increased time intervals. But the salivary flow rate when compared between the groups-Groups A and B: the salivary flow rate in group A (reverse smokers) was comparatively less than in group B (conventional smokers) at all the time intervals. [Table 3] [Graph 1]
Table 3: Mean salivary flow rates at 1-minute intervals in each group

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When all the groups were compared, group A (reverse smokers) subjects followed by group B (conventional smokers) showed less unstimulated salivary flow rate than the group C subjects (healthy individuals).


   Discussion Top


Smoking is a practice in which smoke is drawn from the burning tobacco into the mouth and lungs.[10] Tobacco smoking has been a popular practice among billions of people with 47% of males and 20% of females.[6]

Tobacco consists of nearly 7000 different chemicals, out of which, 60 can cause cancer, and 250 are harmful to humanity.[11] The active ingredient and the chemical nicotine, found in tobacco, is highly addictive; it is quickly taken into the bloodstream via the skin and lungs and travels to the brain in fractions of seconds. It also stimulates cholinergic receptors in the brain and other organs and causes neural activation, leading to altered salivary secretion.[11],[12] The toxin carbon monoxide affects the salivary parenchyma and destroys the salivary glands, causing salivary flow reduction.[13]

Reverse smoking is a peculiar form of smoking, in which the lit end of the smoke is kept in the mouth and the smoke is inhaled. The female predilection is more (1.7:1) similar to our study. This habit is peculiar in Sri Lanka, Venezuela, Sardinia, Panama, and India. The most noticeable changes were detected on the palate and tongue because of the near proximity of heat and tobacco materials during smoking and various other mucosal changes like hyperpigmentation, depigmentation, stomatitis nicotina, preleukoplakia, leukoedema, melanosis, smoker's palate, leukoplakia, erythroplakia and can sometimes lead to cancer.[6]

Saliva plays an important part in maintaining oral cavity balance. Saliva secretion varies from 0.75 to 1.5 L/day. The total salivary flow rate is typically 0.3–0.5 ml/min with a pH of 6.7–7.3. A decrease in flow rate tends to decrease buffering capacity, lowering salivary pH (acidic), making the oral mucosa and dental structures more vulnerable to changes[1] like accumulation of microorganisms on oral surfaces, dental demineralization, and periodontal and mucosal problems. Thus, early detection of hyposalivation will be helpful to improve the quality of life.[14]

Various methods are used for measuring the volume and weight of saliva, like the Carlson-Crittenden cup, Lashley cup for collecting saliva from major salivary glands, and filter paper strips of predetermined size test from minor salivary glands for volumetric analysis. Modified Schirmer test (MST), another method, has shown promising results in screening the resting whole saliva wetting. The ophthalmologist uses the Schirmer test to measure the wetness of the eye. This test was modified to differentiate between healthy patients and patients with xerostomia and hyposalivation by utilizing paper strips to measure the saliva secretions, similar to the Schirmer test.[8]

In a study by López-Jornet P et al., (1996),[15] they used a Whatman paper strip measuring 1 × 17 cm encased in a sterilized polyethylene bag to do a whole saliva test similar to the Schirmer test. The study included 159 healthy subjects divided into three different test groups, including the Schirmer test, draining test, and swab test. In the Schirmer test, the paper's one end was placed in the patient's mouth for five minutes, and the wetting of the strip was measured. Results showed all the tests had similar responses, but the swab and draining test required special equipment, and it caused discomfort to the patients, whereas the Schirmer test was easy, and required no special equipment. Similarly, another study by Dyasanoor and Saddu,[2] used the Modified Schirmer test (MST) to compare dryness of mouth and salivary flow in 60 smokers and 60 non-smokers. The results showed that xerostomia symptoms were significant with the reduced non-stimulated salivary flow in chronic smokers. Thus, smoking has a greater effect on unstimulated salivary flow than on stimulated salivary flow.[2] Hence, the unstimulated salivary flow rate was assessed in smokers and non-smokers using the Modified Schirmer test in the present study.

The idea of using Schirmer strips to measure salivary flow is not new. A study by Davis and Marks[16] used the Schirmer test to evaluate saliva flow rates. They placed the test strip between two tongue depressors, with its 3 mm end against the parotid papilla for 5 mins. As they took the saliva measurements from a single parotid duct but not the whole saliva, the wetting of the strip was slow. The study did not collect the whole saliva for measurements.[14],[16] However, López-Jornet and colleagues did a study on the whole saliva. The study showed faster wetting rates than the wetting rate from the Davis and Mark study.[14] Thus, it can be concluded that the ideal location for placing Schirmer's strip for measuring unstimulated salivary flow rate was the floor of the mouth.

MST was found to be more simple, practical, inexpensive, standardized, reliable, and easy to perform in clinical practice for testing hyposalivation.[2] According to Fontana et al. (2005)[17] and Austin Chen et al. (2005),[8] MST value of <25 at 3 minutes suggests 'Hyposalivation,' whereas MST value of >28 per 3 minutes is considered normal. Therefore, this present study included MST to measure the unstimulated salivary flow.[14]

Several studies have shown that salivary flow is reduced in smokers compared to non-smokers. According to Dyasanoor S et al.,[2] the mean values of salivary flow rate in smokers are low (25.08 ± 5.94) compared to healthy individuals (31.07 ± 5.48), which was also similar to the results of the present study. According to Rad M et al.,[3] the mean resting salivary flow rate in smokers was 0.38 ml/minute and 0.56 ml/minute in non-smokers, which indicates a significant decrease in salivary flow rate in smokers compared to the control group similar to the present study. But very few studies compared the salivary flow rate between reverse and conventional smokers.

In this present study, the results showed that the mean value of salivary flow rate in reverse smokers per 3 minutes (19.73 ± 4.16) is less when compared to conventional smokers (22.53 ± 2.75) and healthy individuals (31.53 ± 2.90), with a significant P value. Results also showed a reduced salivary flow rate in reverse smokers compared to conventional smokers and healthy individuals, proving that the salivary rate is less in reverse smokers than in conventional smokers. They indicate that the smokers, mainly the reverse smokers, have a higher susceptibility to hyposalivation than the conventional smokers. And long-term reverse smoking can deteriorate the quality of life by causing various harmful oral manifestations secondary to hyposalivation.

Limitations of the study and prospects

The shortcoming of this study is that it included a small sample size. Therefore, further studies with a large sample size should authenticate our results.


   Conclusion Top


The results significantly reduce unstimulated salivary flow rate in reverse smokers compared to conventional smokers and healthy individuals. As in reverse smoking, the lit end of the chutta is kept inside the mouth, leading to more heat generation and more damage to the salivary glands than conventional smokers. So, we hypothesize that the lethal effects of the chutta on the salivary glands lead to more hyposalivation in reverse smokers than in conventional smokers. This study also suggests that the Modified Schirmer Test is an easy, inexpensive, and accurate measure of salivary flow rate in dental clinics.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Shubha G, Fasalkar SS, Praveen BN, Patrick S, Shubhasini AR, Keerthi G. Assessment of salivary flow rate and salivary pH in subjects with smoking and smokeless form of tobacco habits. J Med Radio Pathol Surg 2018;5:11–5.  Back to cited text no. 1
    
2.
Dyasanoor S, Saddu SC. Association of xerostomia and assessment of salivary flow using modified schirmer test among smokers and healthy individuals: A preliminary study. J Clin Diagn Res 2014;8:211-3.  Back to cited text no. 2
    
3.
Rad M, Kakoie S, NiliyeBrojeni F, Pourdamghan N. Effect of long-term smoking on whole-mouth salivary flow rate and oral health. J Dent Res Dent Clin Dent Prospects 2010;4:110-4.  Back to cited text no. 3
    
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Niklander S, Veas L, Barrera C, Fuentes F, Chiappini G, Marshall M. Risk factors, hyposalivation and impact of xerostomia on oral health-related quality of life. Braz Oral Res 2017;16:e14.  Back to cited text no. 4
    
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Petrušić N, Posavac M, Sabol I, Mravak-Stipetić M. The effect of tobacco smoking on salivation. Acta Stomatol Croat 2015;49:309-15.  Back to cited text no. 5
    
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Harini G, Krishnam Raju KV, Raju DK, Chakravarthy KK, Kavya SN. Psychosocial factors associated with reverse smoking: A qualitative research. J Int Soc Prev Community Dent 2016;6:529-34.  Back to cited text no. 6
    
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Khan GJ, Mehmood R, Salah-ud-Din, Ihtesham-ul-Haq. Effects of long-term use of tobacco on taste receptors and salivary secretion. J Ayub Med Coll Abbottabad 2003;15:37-9.  Back to cited text no. 7
    
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Chen A, Wai Y, Lee L, Lake S, Woo SB. Using the modified Schirmer test to measure mouth dryness: A preliminary study. J Am Dent Assoc 2005;136:164-70.  Back to cited text no. 8
    
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Van der Eb MM, Leyten EM, Gavarasana S, Vandenbroucke JP, Kahn PM, Cleton FJ. Reverse smoking as a risk factor for palatal cancer: a cross-sectional study in rural Andhra Pradesh, India. Int J Cancer 1993;54:754-8.  Back to cited text no. 9
    
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West R. Tobacco smoking: Health impact, prevalence, correlates and interventions. Psychol Health 2017;32:1018-36.  Back to cited text no. 10
    
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Akshita C, Showket H, Shazia R. Recent trends of tobacco use in India. J Public Health 2021;29:27–36.  Back to cited text no. 11
    
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Rehan F, Khan RS, Khurshid Z, Memon MS, Naqvi S, Zafar MS. Analysis of resting mouth salivary flow rate and salivary pH of tobacco chewers and smokers. J Pak Dent Assoc 2016;25:158-63.  Back to cited text no. 12
    
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Alaee A, Azizi A, Valaei N, Moeini SH. The correlation between cigarette smoking and salivary flow rate. J Res Dentomaxillofac Sci 2017;2:5-9.  Back to cited text no. 13
    
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Lo'pez-Jornet P, Camacho-Alonso F, Bermejo-Fenoll A. A simple test for salivary gland hypofunction using oral Schirmer's test. J Oral Pathol Med 2006;35:244–8.  Back to cited text no. 14
    
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López-Jornet P, Bermejo-Fenoll A, Bagan-Sebastian JV, Pascual Gomez E. Comparison of a new test for the measurement of resting the whole saliva with the draining and the swab techniques. Braz Dent J 1996;7:81-6.  Back to cited text no. 15
    
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Davis CC, Marks JE. The use of the Schirmer tear test in evaluating mouth dryness. Dent Hyg 1986;60:116-9.  Back to cited text no. 16
    
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Fontana M, Zunt S, Eckert GJ, Zero D. A screening test for unstimulated salivary flow measurement. Oper Dent 2005;30:3–8  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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