|Year : 2015 | Volume
| Issue : 1 | Page : 11-13
Effect of long-term smoking on salivary flow rate and salivary pH
Mala Singh1, Navin Anand Ingle1, Navpreet Kaur1, Pramod Yadav1, Ekta Ingle2
1 Department of Public Health Dentistry, K. D. Dental College and Hospital, Mathura, Uttar Pradesh, India
2 Department of Oral Medicine and Radiology, Vasantdada Patil Dental College, Sangli, Maharashtra, India
|Date of Web Publication||19-Mar-2015|
Dr. Mala Singh
K. D. Dental College and Hospital, Mathura, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Saliva is a complex and important body fluid which is very essential for oral health and it is the first biological fluid that is exposed to cigarette smoke, which contains numerous toxic compositions responsible for structural and functional changes in saliva. Aim: To evaluate the long-term effect of smoking on salivary flow rate (SFR) and salivary pH. Materials and Methods: The subjects of the study were divided into smokers and nonsmokers. Each group comprised of 35 male adults. The saliva of each subject was collected under resting conditions. They were asked to spit in a graduated container at an interval of 60 s for 5 min. Salivary pH was measured immediately after measuring SFR using the (Indikrom Paper) pH indicator and calibrated cylinder. Based on the color change of the indicator paper strip, the pH was assessed in comparison with a color chart. Data were analyzed by Student's t-test using SPSS 15. Results: The mean (±standard deviation) SFR and pH were 0.20 (±0.05) ml/min and 6.30 (±0.36) respectively in smokers while the mean SFR and pH were 0.36 (±0.06) ml/min and 7.10 (±0.24) in nonsmokers. The difference was statistically significant (P = 0.00). Conclusion: Long-term smoking significantly reduces the SFR and salivary pH.
Keywords: Saliva, salivary flow rate, salivary pH
|How to cite this article:|
Singh M, Ingle NA, Kaur N, Yadav P, Ingle E. Effect of long-term smoking on salivary flow rate and salivary pH. J Indian Assoc Public Health Dent 2015;13:11-3
|How to cite this URL:|
Singh M, Ingle NA, Kaur N, Yadav P, Ingle E. Effect of long-term smoking on salivary flow rate and salivary pH. J Indian Assoc Public Health Dent [serial online] 2015 [cited 2019 Aug 21];13:11-3. Available from: http://www.jiaphd.org/text.asp?2015/13/1/11/153549
| Introduction|| |
Saliva is a complex and important body fluid, which is very essential for oral health.  Saliva, the fluid in the mouth, is a combined secretion of the three pairs of salivary glands: The parotid, the submandibular and the sublingual; together with numerous small glands.  When flow is unstimulated, the parotid, submandibular, sublingual and minor mucous glands contribute about 25%, 60%, 7-8% and 7-8%, respectively, to whole saliva, but when flow is stimulated, the parotid glands contribution increases by at least 10%.  Approximately, 0.5 L of saliva is secreted per day. The salivary flow rates (SFRs) are 0.3 ml/min when unstimulated and rise to 1.5-2.0 ml/min when stimulated but flow rate is negligible during night.  Saliva plays a critical role in oral homeostasis, as it modulates the ecosystem within the oral cavity.  Saliva is required for lubrication of the alimentary bolus, protection against virus, bacteria and fungi, protecting the oral mucosa, teeth remineralization, digestion, taste sensation, pH balance and phonation.  Nicotine, tar, carbonmonoxide, formaldehyde, ammonia etc., is present is present in the cigarette smoke. Nicotine at first increases the flow of saliva in the mouth and with later doses it decreases the salivary flow. 
The smoke of tobacco spreads to about all parts of the oral cavity and therefore, the taste receptors, a primary receptor site for salivary secretion, are constantly exposed to this smoke during the smoking process. It has been discovered that smoking increases the activity of salivary glands and indeed, this observation has been made by everyone who begins smoking. It has also been observed that some tolerance develops to the salivatory effects of smoking because habitual smokers do not salivate as do novice smokers in response to smoking.  Saliva is the first biological fluid that is exposed to cigarette smoke, which contains numerous toxic compositions responsible for structural and functional changes in saliva.
The pH in the saliva plays an important role in the life, growth and multiplication of oral bacteria. The number of acidophilic bacteria is increased when the pH in the saliva is very low, whereas the number of the acid-sensitive bacteria is decreased. The increased number of acidophilic bacteria in the dental plaque and saliva above 10 5 colony forming units colonies, as well as a low pH and caries risk test-buffer capacity of the saliva, can indicate a high risk of caries. 
Therefore, altered whole-mouth SFR has an important role in the pathogenesis of oral and dental diseases.  Alterations in salivary function may lead to impairment of oral tissues and have a large impact on the patient's quality of life. A higher incidence of dental caries, oral mucositis, dysphagia, oral infections and altered taste has been reported in individuals with reduced salivary flow. 
In long-term smoking, the taste receptors, a primary site for salivary secretion, are repeatedly exposed to tobacco for long-time thus presumably affecting the salivary reflex.  Therefore, the aim of the present study was to analyze the long-term effects of smoking on SFR and salivary pH.
| Materials and Methods|| |
Examination was conducted in the outpatient department (OPD) of Oral Medicine and Radiology of K.D Dental College and Hospital. The duration of this study was 3 days. All the 35 smokers who were present at the time of examination were included in the study. Therefore, 35 nonsmokers were taken as a control group from the same OPD. Thus, the present study comprised of total 70 male adults (35 smokers and 35 nonsmokers) aged 20-50 years.
The exclusion criteria included subjects who wore denture, had a history of radiotherapy, patients with systemic or salivary gland disease, alcohol consumption or those who consumed smokeless tobacco in any form. The subjects who smoked 10-15 cigarettes daily or 1-2 bundles of bidi per day for >6 months were considered in smokers group and those who do not smoked tobacco were considered in nonsmokers group. Before the start of the study, the purpose and methodology of the study had been explained to each of the subject and informed consent was obtained.
Saliva collection was done between 9:00 am and 12:00 pm to avoid diurnal variation. To avoid this effect, it is advised to collect all saliva sample at the same, fixed time of the day. Each subject was requested not to eat, drink or perform oral hygiene or chew or smoke 60 min before and during the entire study. Subjects were comfortably seated in the dental chair and a few minutes of relaxation asked to spit in a graduated test tube through a glass funnel every 1 min for 5 min. During saliva collection, subjects were instructed not to speak or swallow. After the collection, the SFR was measured and expressed in ml/5 min.
Salivary pH was then measured using the (Indikrom Paper) pH indicator. The whole mouth resting saliva was collected in graduated test tube, and the indicator strip was dipped in the saliva for 30 s and the color on the strip was compared with the standard color chart provided by the manufacturer. Based on the color change of the indicator paper strip, the pH was assessed in comparison with a color chart. Manufacturer's instructions were followed while measuring salivary pH.
Data were analyzed using Statistical Package for Social Science 15 (SPSS Inc.Chicago, IL, USA) computer software. Student's unpaired t-test was applied to assess between-group differences. P ≤ 0.05 was considered as statistically significant.
| Results|| |
The mean SFR is found to be 0.20 ± 0.05 ml/min in smokers and 0.36 ± 0.06 ml/min in nonsmokers. And the mean salivary pH is found to be 6.30 ± 0.36 in smokers and 7.10 ± 0.24 in nonsmokers. The difference is found to be statistically significant (P = 0.00) [Table 1].
|Table 1: Distribution of study subjects based on mean salivary flow rate and salivary pH |
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| Discussion|| |
The salivary secretion is a complex process, and its flow and composition vary greatly under different conditions.  Resting whole saliva is the mixture of secretions, which enter the mouth in the absence of exogenous stimuli. 
Unstimulated whole saliva reflects basal SFR, is present in the oral cavity 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 while stimulated saliva is useful for the study of the functional reserve. 
There are clinical and epidemiological evidences regarding the adverse effect of tobacco on oral health.  The adverse effect of cigarette smoking and other forms of tobacco are numerous, and tobacco use has been associated with gingival, oral mucosa and dental alterations. 
In this study, the mean SFR was 0.20 ± 0.05 ml/min in smokers and 0.36 ± 0.06 ml/min in nonsmokers, which was in accordance to the study conducted by Rad et al.  in which the mean SFR was lower in smokers that is, 0.38 ± 0.13 ml/min as compared to nonsmokers that is, 0.56 ± 0.16 ml/min.
On the contrary, in the study conducted by Fenoll-Palomares et al.  the mean SFR was higher in smokers that is, 0.52 ml/min as compared to nonsmokers that is, 0.45 ml/min (P = 0.14).
Similarly, Khan et al.  showed that SFR was 0.46 ± 0.05 ml/min in smokers while 0.43 ± 0.05 ml/min in nonsmokers. There was no statistically significant difference was observed. Furthermore, Rooban et al.  revealed that SFR was 3.88 ml/min ± 1.32 in smokers while the mean SFR was 3.52 ± 1.41 in nonsmokers.
A no. of studies shown that while cigarette smoking would typically cause a noticeable short-term increases in SFRs because it increases the activity of salivary glands in anyone who begins smoking, but in long-term use it has been observed that some individuals develop tolerance to the salivary effect of smoking so it reduces SFR. And also smoking is one of the risk factors for reducing saliva and xerostomia. 
Present study revealed that the mean salivary pH was 6.30 ± 0.36 in smokers and 7.10 ± 0.24 in nonsmokers which is in accordance to the study conducted by Fenoll-Palomares et al.  in which the mean salivary pH was lower in smokers that is, 6.7 ± 0.27 as compared to nonsmokers that is, 6.8 ± 0.29. No statistically difference was seen. Similarly, Rooban et al.  also observed a lower salivary pH in smokers that is, 6.48 ± 0.36 in comparison to 6.59 ± 0.56 in nonsmokers. The difference was statistically significant (P = 0.03).
On the contrary, the study conducted by Al-Weheb  showed that the mean salivary pH was higher in smokers that is, 7.32 as compared to nonsmokers that is, 7.27.
The decrease in SFR alters salivary pH by decreasing bicarbonate secretion and this decrease in saliva bicarbonate in turn decreases the salivary pH. The sample size was small, and the SFR and salivary pH can vary are the limitations of the present study.
Further studies should be carried out to correlate the SFR and salivary pH with various oral diseases like oral candidiasis, that can manifest itself as erythema, white plaque, thrush, median rhomboid glossitis, and angular cheilitis (deep furrow at the mouth of corners from years of smoking can predispose). 
| Conclusion|| |
From the present study, it can be concluded that the long-term smoking significantly reduces the SFR and salivary pH. Further studies should be carried out to correlate the SFR and salivary pH with various oral diseases like oral candidiasis, which can manifest itself as erythema, white plaque, thrush, median rhomboid glossitis, and angular cheilitis.
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