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Year : 2019  |  Volume : 7  |  Issue : 2  |  Page : 56-59

Changes in salivary flow rate, pH, and viscosity among working men and women

Department of Oral Medicine and Radiology, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Puducherry, India

Date of Submission04-Sep-2019
Date of Decision09-Nov-2019
Date of Acceptance11-Sep-2019
Date of Web Publication22-Oct-2019

Correspondence Address:
Sethuraman Govindaraj
Department of Oral Medicine and Radiology, Mahatma Gandhi Postgraduate Institute of Dental Sciences, Puducherry
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/dmr.dmr_20_19

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Introduction: Salivary gland secretion is mainly under autonomic nervous control, but various hormones may also modulate the salivary composition. Psychological stress exerts its effect on salivary composition, increasing the value of saliva as a dynamic biological fluid determining the overall psychological health of an individual and also in maintaining adequate oral health. Aim and Objective: To determine the salivary flow rate, pH, and viscosity among working men and women. Materials and Methods: The present study consisted of 50 patients, of them 25 were working men and 25 working women. The levels of stress among them were assessed by job stress scale (Shukla and Srivastava, Cogent Business and Management, 2016). Results: The mean flow rate of saliva in working men and women was 0.36 ml/min and 0.25 ml/min and flow rate in men and women with stress was 0.2 ml/min and 0.15 ml/min, respectively. pH in working men and women was 7.1 and 6.7, respectively. pH in men and women with stress was 6.5 and 6.4, respectively. The viscosity of saliva in working men and women was 1.05 cP and 1.29 cP, respectively, whereas the viscosity of saliva in men and women with stress was 1.3 cP and 1.5 cP, respectively. Flow rate in working men and women with stress was found to be significant. Conclusion: To conclude, the stress job exerts its influence on salivary gland function, creating an impact on the quantity and quality of saliva in maintaining the oral health.

Keywords: pH, salivary flow rate, stress, viscosity

How to cite this article:
Govindaraj S, Daniel M J, Vasudevan SS, Kumaran JV. Changes in salivary flow rate, pH, and viscosity among working men and women. Dent Med Res 2019;7:56-9

How to cite this URL:
Govindaraj S, Daniel M J, Vasudevan SS, Kumaran JV. Changes in salivary flow rate, pH, and viscosity among working men and women. Dent Med Res [serial online] 2019 [cited 2023 Apr 1];7:56-9. Available from: https://www.dmrjournal.org/text.asp?2019/7/2/56/269668

  Introduction Top

Saliva is a unique biologic fluid produced by different salivary glands. It is composed of approximately 99% water and 1% protein and salts.[1] It is critical in preservation and maintenance of oral health, yet it receives little attention until quantity or quality is diminished.[2] The complex patterns of salivary responsiveness during mental stress are reflected by an increase in total salivary protein concentration and changing cortisol levels.[3] Viscosity is a rheological property of complex salivary fluid, which is related to its glycoprotein content. Viscoelastic properties are essential for lubrication and humidification, thus providing mucosal integrity.[1] Changes in salivation often accompany the stress response; therefore, it is important to establish whether these changes truly mirror the physiological response to stress or merely confound altered salivary changes.

  Materials and Methods Top

This cross-sectional study was carried out in the Inpatient Department of Oral Medicine and Radiology, Mahatma Gandhi Postgraduate Institute of Dental Science, Puducherry. The present study included fifty individuals of both sexes under two groups: Group 1: working men and Group 2: working women. The age range of working men and women was between 20 and 40 years. We excluded the individuals with acute infectious diseases, periodontitis, systemic illness (i.e., cardiac, renal, respiratory or hepatic failure), and therapeutic radiation to the head or neck region and pregnant women. Informed consent was obtained from all the patients before the interview and examination. Along with the patient's demographic details, stress among them was assessed by job stress scale (Shukla and Srivastava, Cogent Business and Management, 2016).[4] After assessing the stress, unstimulated saliva was collected in a sterile container. The data were entered into a pro forma and then were analyzed using inferential statistics such as Chi-square, t-test, and Pearson's correlation. All the analyses were carried out with SPSS 20. The level of statistical significance was set at P < 0.05.


[Figure 1] shows armamentarium required for the study: sample container, measuring jar, weighing jar, pH strip, digital weighing, and Ostwald viscometer.
Figure 1: (A) Sample container, (B) measuring jar, (C) weighing jar, (D) pH strip, (E) digital weighing, (F) Ostwald viscometer

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Sample collection

All samples were taken between 9:00 and 11:00 am. Unstimulated whole saliva was collected from all individuals by direct expectoration into a sterile container over a period of 10 min by spitting method, so that the flow rate could be calculated. The patient was instructed to do initial swallowing to remove the excess of the deionized water (presampling period was 1 min). Patients were asked to refrain from smoking, eating, and drinking for 2 h before the test session.

Flow rate and pH measurement: The collected saliva was immediately measured for quantity and pH was measured within 30 min using pH strips.

Salivary viscosity

Salivary viscosity was determined by allowing saliva to flow through a tube of circular cross section and measuring the rate of flow. This was done using the Ostwald viscometer [Figure 1], which is a simple device and accurate for measuring the viscosity of the liquid. The viscosity of the liquid was determined by a comparison with a standard such as water:

η12= t1d1/t2d2

where η1 is viscosity of liquid 1.

η2 is viscosity of liquid 2.

t1 flow time of liquid 1.

t2 flow time of liquid 2.

d1 density of liquid 1.

d2 density of liquid 2.

  Results Top

A total of fifty patients were enrolled in the study. There were 25 men and 25 women. Salivary flow rate, pH, and viscosity of saliva in working men and working women are shown in [Table 1], with mean flow rate of saliva being 0.36 ml/min for men and 0.2 ml/min for women, pH of saliva being 7.1 for men and 6.7 for women, the viscosity of saliva being 1.05 for men and 1.29 for women, and no significant difference was found in flow rate, pH, and viscosity between men and women.
Table 1: Salivary flow rate, pH, and viscosity in men and women

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On comparison of various parameters, women with stress show a statistically significant reduced salivary flow rate [Table 2]. On comparing correlation between stress and other parameters studied among working men and women, a statistically significant relationship was found between the stress, flow rate, PH, and viscosity in working women and a statistically significant relationship found between the stress, PH, and viscosity in working men [Table 3].
Table 2: Comparison of various parameters between men and women with stress

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Table 3: Correlation between stress and Flow rate, pH, Viscosity in working men and women

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  Discussion Top

Saliva plays a critical role in oral homeostasis, as it modulates the ecosystem within the oral cavity.[5] Salivary gland secretion is mainly under autonomic nervous control, but various hormones may also modulate the salivary composition. Saliva consists of two components that are secreted by independent mechanisms: first component includes ions, which is produced mainly by parasympathetic stimulation, and the second is protein component, which is released mainly in response to the sympathetic stimulation.[6] Under chronic exposure to stress conditions, a “wear and tear” of the allostatic systems (central nervous system, the autonomic nervous system [ANS], the hypothalamus–pituitary–adrenal axis [HPA]) accumulates. Over time, the ANS system and HPA axis become dysregulated.

Stress can be defined as a real or interpreted threat to the physiological or psychological integrity of an individual that results in a cascade of physiological and/or behavioral responses of the body to maintain homeostasis.[7] Numerous epidemiological studies have tried to define the effects of social, workplace, and lifestyle on stress, health, and well-being.[8]

Job stress is defined as the harmful physical and emotional responses that occur when role (job) requirements do not match with the employees' capabilities, resources, and needs. Job stress is a major concern for Indian employers, due to demanding schedules and high level of stress; nearly 78% of corporate employees in India sleep <6 h a day, leading to severe sleep disorders. The organizational stress framework includes sources of work stress, such as role conflict, role ambiguity, work overload, and role expectations. The demographic variables such as age, sex, occupation, health status, education, and social support can also influence occupational stress. Men and women experience many of the same stressors.[4]

We have taken the young adult population in our study, i.e. 20–40 years. After the age of 40 years, a number of systemic disorders occur, and it is rare to find any adult above 40 years without any oral mucosal disorders. Hence, this age group was chosen to avoid any discrepancies and to include only healthy adults.

Unstimulated whole saliva reflects basal salivary flow rate, is present in our mouths for about 14 h a day, and is the secretion that provides protection to oral tissues. Stimulated saliva represents the secretion during food intake (physiologic stimulation) and is present in our mouths for up to 2 h. Hence, the study of unstimulated salivary secretion is an accurate method to analyze salivary gland status, whereas stimulated saliva is useful for the study of the functional reserve.[5] In our study, we have chosen to measure unstimulated saliva, as it is an easy, noninvasive, and comfortable procedure, which favors its use in population studies.

In the present study, we measured unstimulated saliva in working men and women. The mean flow rate in men was 0.36 ml/min and in women was 0.25 ml/min, which was found to be normal based on the study done by Humphrey and Williamson and states that accepted range of normal flow for unstimulated saliva is anything above 0.1 mL/min. For stimulated saliva, the minimum volume for the accepted norm increases to 0.2 ml/min.[2] According to our study, salivary flow is greater in men than in women. Our results are consistent with the studies done by Chauhan et al.[5] and Al-Azzawi et al.[9] This difference in men and women may be due to the smaller size of parotid and submandibular glands in women as compared to the men based on the study by Inoue et al.[10]

In a patient with stress, the mean flow rate in men and women was 0.27 ml/min and 0.15 ml/min, respectively, which is found to be statistically significant. Compared to men, women have reduced flow rate, which is similar to the study conducted by Kim and Suh[11] and Matos-Gomes et al.[12] This difference was due to emotional states, e.g., anxiety and depression which are known to affect salivary gland function. These effects illustrate the overriding control of higher central nervous system centers on salivary function.

The mean pH for men and women was 7.1 and 6.7, respectively, and the mean PH of men and women with stress was 6.5 and 6.4, respectively, which was similar to the study conducted by Kim and Suh[11] and Chauhan et al.,[5] but was not significant. This difference was because, in both the studies, they had used a pH meter to assess the salivary pH, but we had used a pH strip to assess the salivary Ph.

The mean viscosity for men and women was 1.05 cP and 1.29 cP, respectively. In patients with stress, the mean viscosity for men and women was 1.3 cP and 1.5 cP, respectively, which is similar to a study conducted by Foglio-Bonda et al.,[13] which was not significant because most of the patient stress score was mild to moderate.

Pearson's correlation was assessed in both the groups. In men, it was found to have negative correlation with stress and pH and positive correlation between stress and viscosity. In women, it had negative correlation between stress, flow rate, pH, and positive correlation between stress and viscosity, which is similar to the study by Morse et al.[14] Reduced flow rate in stress is due to increased anticholinergic and sympathetic activity, which leads to decreased secretion of saliva and increased in salivary protein secretion.[6]

Reduced pH during stress is due to the fact that the flow rate is reduced, which affects the inorganic constituent of saliva, especially decrease in bicarbonate and calcium and increase in phosphate.[6] The increase in viscosity of saliva with stress is due to the increase in the total protein concentration of saliva by activation of sympathetic system.[3]

Limitations of this study include we used pH strips to asses pH which gives approximate value and it was not precise compared to digital pH meter. We used manual method to asses viscosity of saliva, In case of digital viscometer values were precise e.g. Brookfield viscometer.

  Conclusion Top

Human body undergoes a series of chemical events during stress, which affects various organs enabling us for bearing these unpleasant stimuli. As a side effect of prolonged exposure to these chemical changes, the body develops various homeostatic/metabolic/endocrinal/immunological disturbances. These disturbances also influence on salivary gland function. In the present study, women experienced more stress when compared with men, which influences on salivary flow rate. To conclude, the job stress exerts its influence on the salivary gland function and this may lead to an impact on the quantity and quality of saliva in maintaining the oral health.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Ahmed Yas B, Nada Jafer MH, Njmh R. Salivary viscosity in relation to oral health status among a group of 20-22 years old dental students: Iraqi J Comm Med 2013;3:219-24.  Back to cited text no. 1
Humphrey SP, Williamson RT. A review of saliva: Normal composition, flow, and function. J Prosthet Dent 2001;85:162-9.  Back to cited text no. 2
Naumova EA, Sandulescu T, Bochnig C, Al Khatib P, Lee WK, Zimmer S, et al. Dynamic changes in saliva after acute mental stress. Sci Rep 2014;4:4884.  Back to cited text no. 3
Shukla A, Srivastava R. Development of short questionnaire to measure an extended set of role expectation conflict, coworker support and work-life balance: The new job stress scale. Cogent Bus Manag 2016;3:1-19.  Back to cited text no. 4
Chauhan S, Mohan V, Kumar JS, Garg N, Mathew SM. Evaluation of flow rate, ph and buffering capacity of saliva in healthy volunteers. Univ J Dent Sci 2015;1:1.  Back to cited text no. 5
Nuaimy KM, Al-Hamdani IH, Tawfik NO. Effect of stress on the composition and flow rate of saliva. Al-Rafidain Dent J 2012;12:66-70.  Back to cited text no. 6
Tikhonova S, Booij L, D'Souza V, Crosara KT, Siqueira WL, Emami E. Investigating the association between stress, saliva and dental caries: A scoping review. BMC Oral Health 2018;18:41.  Back to cited text no. 7
Fink G. Stress: concepts, definition and history. In: Reference Module in Neuroscience and Biobehavioral Psychology. Amsterdam, Nertherland: Elsevier; 2017. p. 1-9.  Back to cited text no. 8
Al-Azzawi SI, Mahmood Alwan A, Hatim Salal R. Influence of age and gender on salivary flow rate in completely edentulous patients. MDJ 2013;10:1.  Back to cited text no. 9
Inoue H, Ono K, Masuda W, Morimoto Y, Tanaka T, Yokota M, et al. Gender difference in unstimulated whole saliva flow rate and salivary gland sizes. Arch Oral Biol 2006;51:1055-60.  Back to cited text no. 10
Kim HJ, Suh B. Changes in salivary flow rate and PH in stressful condition. Korea Buccal Cavity Intern Med Newsl 2001;26:11-16.  Back to cited text no. 11
Matos-Gomes N, Katsurayama M, Makimoto FH, Santana LL, Paredes-Garcia E, Becker MA, et al. Psychological stress and its influence on salivary flow rate, total protein concentration and IgA, IgG and IgM titers. Neuroimmunomodulation 2010;17:396-404.  Back to cited text no. 12
Foglio-Bonda A, Pattarino F, Foglio-Bonda PL. Kinematic viscosity of unstimulated whole saliva in healthy young adults. Eur Rev Med Pharmacol Sci 2014;18:2988-94.  Back to cited text no. 13
Morse DR, Lawrence Furst M, Schacterle GR. Saliva: The misunderstood and underrated fluid. Stress Med 1986;2:13-25.  Back to cited text no. 14


  [Figure 1]

  [Table 1], [Table 2], [Table 3]

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