Indian Journal of Dental ResearchIndian Journal of Dental ResearchIndian Journal of Dental Research
Indian Journal of Dental Research   Login   |  Users online:

Home Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size         


Table of Contents   
Year : 2011  |  Volume : 22  |  Issue : 4  |  Page : 547-551
Effects of milk curd on saliva secretion in healthy volunteer compared to baseline, 2% pilocarpine and equivalent pH adjusted acetic acid solutions

1 Department of Oral Medicine, Babol University of Medical Sciences, Babol, Iran
2 Department of Endodontics, Babol University of Medical Sciences, Babol, Iran
3 Faculty of Basic Sciences, Alzzahra University, Tehran, Iran
4 Department of Pharmacology, Babol University of Medical Sciences, Babol, Iran

Click here for correspondence address and email

Date of Submission03-Apr-2010
Date of Decision31-Aug-2010
Date of Acceptance11-Oct-2010
Date of Web Publication26-Nov-2011


Background: Dry mouth is a common clinical problem, and different products have been proposed to improve it. In this investigation, the effects of "milk curd" on the amount of saliva secretion were studied.
Materials and Methods: A total of 32 patients (aged 20-30) were selected from healthy volunteers. Milk curd concentrations of 0.5, 1, 2 and 4%, and 2% pilocarpine were prepared as drops. The impact of the drugs on the saliva weight was assessed after 1-5 min. To determine the effects of the pH of the milk curd on the amount of saliva secretion, different concentrations of acetic acid were used.
Results: At the end of the first minute, the differences between the data for all groups were statistically significant, and the difference between the 2% and 4% milk curd groups was higher than the others (P < 0.0001). The differences in the amount of the saliva secreted at the end of the second minute between the baseline and 4% milk curd groups and between the 0.5% and 4% MC groups were significant (P = 0.006 and P = 0.025, respectively). In total, there was no significant difference between the effect of various pH treatments and the amount of baseline saliva secretion.
Conclusion: Milk curd has a significant local impact, and the saliva increase depends on the dose. It seems that this effect is not only related to its acidic taste. As a result, factors other than pH are involved in the effect.

Keywords: Dry mouth, milk curd, pilocarpine, secretion of saliva

How to cite this article:
Babaee N, Gholizadehpasha A, Zahedpasha S, Moghadamnia Y, Zamaninejad S, Moghadamnia AA. Effects of milk curd on saliva secretion in healthy volunteer compared to baseline, 2% pilocarpine and equivalent pH adjusted acetic acid solutions. Indian J Dent Res 2011;22:547-51

How to cite this URL:
Babaee N, Gholizadehpasha A, Zahedpasha S, Moghadamnia Y, Zamaninejad S, Moghadamnia AA. Effects of milk curd on saliva secretion in healthy volunteer compared to baseline, 2% pilocarpine and equivalent pH adjusted acetic acid solutions. Indian J Dent Res [serial online] 2011 [cited 2021 Oct 19];22:547-51. Available from:
Saliva has a critical role in the natural oral cavity environment. Factors that affect salivary function may change hard and soft oral tissue integrity and function and may increase the prevalence of digestive illness.[1],[2]

Xerostomia or "dry mouth" is a common condition that may occur without a low salivary flow rate.[3],[4] Some conditions that may induce xerostomia include Sjögren's syndrome, diabetes mellitus, drugs, and radiation to the head or neck.[5]

Clinical studies have shown that 25% of geriatric individuals in the general population suffer from xerostomia and related problems in the absence of any disease.[6],[7]

The salivary function in patients with symptoms of xerostomia is improved with the use of moisturizing materials. In patients with salivary function deficiency, the use of some oral drugs increases saliva flow. The drugs that can improve symptoms of dry mouth should be administered as the drugs of choice.[1],[8] Pilocarpine is prescribed in cases of dry mouth and xerostomia.[9],[10]

Pilocarpine stimulates the muscarinic receptors on secretary salivary glands and increases saliva secretion. [11] Previous studies have suggested that pilocarpine can improve the dry mouth and salivary gland dysfunction that result from radiotherapy. These studies reported that pilocarpine hydrochloride increases saliva secretion by 42%-52% compared to the placebo and that pilocarpine hydrochloride is more effective than artificial saliva. The effect is dose-dependent, but so are the side effects.[12] Despite the positive effect of pilocarpine on saliva secretion, there is limited evidence that supports the administration of pilocarpine to treat salivary gland dysfunctions.[12] Additionally, there is little evidence to support the use of other parasympathomimetic drugs in the treatment of salivary gland dysfunction,[12] and studies show that almost half of the patients give up on the treatment due to dose-dependent parasympathomimetic side effects.[12] It has been shown that the effect of pilocarpine on physiologic saliva secretion is not as strong as the effect of lemon juice.[13] Milk curd, the side product of the concentration of natural yogurt water by boiling, is dark brown in color and contains water, proteins, fats, carbohydrates, organic materials, and vitamins such as thiamine and riboflavin.[14] In traditional medicine, milk curd has been prescribed as a treatment for mouth ulcers. It has a sour and salty taste and is termed "Charah Choroot" in Persian.

In this study, the efficacy of the natural dairy product of milk curd on saliva secretion was investigated and compared with the effect of pilocarpine.

   Materials and Methods Top

Study type

This clinical trial was done as a crossover study.


This clinical study was approved by local research Ethics Committee at Babol University of Medical Sciences. A total of 32 females were selected among young volunteers aged 20-30 years who were healthy and had good oral hygiene conditions. They were mainly selected from the Dental School of the Babol University of Medical Sciences (Babol, Iran). Exclusion criteria were as follows : s0 pecific systemic disease; a history of drug administration that included anticholinergics, TCAs, or anticancer drugs; and a history of radiotherapy of the head and neck.

Milk curd preparation : S0 ince some additives are added to industrial milk curd, we purchased pure traditional milk curd from special local shops (Mashhad, Iran). A voucher specimen was deposited in the Department of Pharmacology, Babol University of Medical Sciences, under the number : C0 S_00238.

The samples were analyzed for their chemical compositions, and the percentages of some components such as inorganics were determined. Four different concentrations of milk curd were prepared in drop form by dissolving 0.5, 1, 2, and 4 g of milk curd in 100 ml water separately in four different bottles. They were kept in a cool place (4-8°C in a refrigerator) until the test day.


In order to collect saliva samples from each subject, 42 bottles were needed. Treatments were given in random order. Sampling of each volunteer was performed with six measurements including salivation without stimulation and salivation after being given different concentrations of milk curd (0.5, 1, 2, and 4%), pilocarpine and water as placebo (defined as baseline). All samplings were done over a time period of 5 min with 1 min intervals. Saliva samples were collected in well-sealed, capped containers and were labeled. In order to prevent the evaporation of saliva, the containers' caps were screwed tightly. The exact weight of each container was measured using a sensitive digital scale (Sartorius CP124S, Germany) before and after saliva collection. Differences between the weights before and after saliva collection were recorded for further analyses. Volunteers were asked to fast for one and half hour before starting the saliva collection. All steps of the study were started at 8:00 a.m.[15] Participants were given a brief description of the study, and they were asked to rinse their mouths with water and to sit with their heads at a 45° downward-facing angle. After 1 min, they were asked to collect the contents of their mouths in separate containers each minute for 5 min, without swallowing the saliva in between the measurements. After the collection of nonstimulated saliva, the volunteers were given a 5-min break. Stimulated saliva secretion by drugs or placebo was assessed by collecting saliva within 5 min, based on the Dawes technique.[15],[16] A half-hour wash-out period was implemented between each course of treatment. The collection of saliva lasted 3.5 h, and participants were not allowed to eat during this period. To detect the impact of pH on saliva secretion, different solutions of dilute acetic acid with pH values similar to the pH values of the different preparations of milk curd and pilocarpine were prepared and tested as above. Testing of the acetic acid series was done at another time with the same participants.

Statistical analysis

All data in the table are shown as means ± S.D. A one-way ANOVA test was used to compare the data for the placebo, milk curd, and acetic acid groups. A repeated measurement test was applied to analyze the trend for the changes in saliva secretion within each group and also between different groups. A 5% level of significance was used.

   Results Top

In this study, 32 healthy volunteer (aged between 20 and 30 year) were selected. First, each participant collected his/her nonstimulated saliva as a baseline. Then, subjects were divided into placebo or drug treatment.

Composition of milk curd

A sample of purchased milk curd was analyzed based on some physiochemical parameters. [Table 1] shows the composition of the milk curd sample in 100 g of the dry milk curd.
Table 1: Characteristics and composition of 100 g of milk curd

Click here to view

Effect of milk curd and pilocarpine on saliva secretion

Comparisons between baseline saliva secretion and the saliva secretions induced by milk curd and pilocarpine (using the ANOVA test) showed that there was a significant increase after milk curd treatment at the end of first minute of the experiment for all groups. All groups showed a significant increase in saliva secretion compared to baseline. Greater differences were seen for 2% (1.062 ± 0.5 vs. 0.53 ± 0.42) and 4% (1.27 ± 0.6 vs. 0.53 ± 0.41) milk curd than for the other groups [Table 2].
Table 2: pH and mean (±S.D.) of saliva weight (g) at the end of the first minute for the various treatment groups

Click here to view

At the end of the second minute, a significant increase in saliva secretion was observed in the group receiving 4% milk curd compared to baseline ([Table 3] P = 0.006). The difference between the group receiving 0.5% milk curd and the group getting 4% milk curd was also significant (P = 0.025) after 2 min, with the secretion of saliva in the 4% milk curd group being significantly higher than that in the 0.5% milk curd group. The repeated measurement test showed statistically significant changes in saliva secretion within each group ( P < 0.0001 [Figure 1]). However, the changes in saliva secretion between the study groups were not statistically significant (P = 0.07).
Figure 1: Comparison of weight differences (g) over time between the milk curd and pilocarpine treatment groups

Click here to view
Table 3: Mean (±S.D.) saliva weight (g) of pilocarpine and milk curd groups at the end of the each minute

Click here to view

The effect of acetic acid solutions with equivalent pHs on saliva secretion

No significant differences were seen in the saliva secretion rates at any sampling time point between the baseline and after administration of acetic acid drops with pH levels equivalent to those of the milk curd drops. The effect of pH on the amount of saliva secretion has not been documented. Despite the significant differences within groups seen here (using the repeated measured test, P<0.0001), no differences were detected between groups [Table 4] and [Figure 2].
Figure 2: The effect of pH on the saliva weight. Comparison of weight differences (g) over time for the different pH groups

Click here to view
Table 4: Mean (±S.D.) saliva weight (g) in the groups after administration of different concentrations of acetic acid solutions with equivalent pH to four concentration of milk curd at the end of each minute

Click here to view

Comparing the effects of milk curd, pilocarpine and various acetic acid drops with equivalent pH levels

Milk curd at 1% showed a significant increase in saliva secretion at minutes 1 and 5 compared to the equivalent p. group (P = 0.018 and P = 0.02, respectively). Similar increases in saliva secretion were seen in the 2% milk curd group at the end of the second minute (P = 0.004) and in the 4% milk curd group at the end of the first and second minutes of saliva sampling (P = 0.017 and P = 0.027, respectively).

   Discussion Top

The present study shows that milk curd can considerably increase saliva secretion compared to the baseline secretion levels. In traditional medicine, some plants and medications have been recommended to patients who suffer from dry mouth; these plants and medications are often stimulators of appetite and, in turn, of saliva secretion.[17],[18]

Milk curd derived from concentrated yogurt is considered by many Iranian ethnic groups to be a special sauce. Studies have shown that a sour taste in combination with an organic stimulus has a strong role in the secretion of saliva. It is obvious that organic acids, including acetic acid, lactic acid, citric acid, and malic acid, at equal pHs and equal concentrations cause greater effects in the perception of sour taste.[15] It is believed that milk curd increases saliva secretion due to its sour taste, but there is no scientific evidence to support this notion. This study was designed to examine this issue.

In one study using 1% citric acid, it was determined that the highest flow of saliva was reached at the end of the first minute and that after six minutes saliva secretion returned to normal.[19] In the present study, significant increases in saliva flow were observed at the end of the first and second minutes. Our study was limited to a 5-min duration, but no significant differences were seen in saliva secretion at minutes 3, 4, and 5, as compared to baseline. The saliva flow reached nearly the normal limit at those time points. In the present study, pilocarpine was used in topical drop form. It is commonly used as a systemic treatment for dry mouth. The results of this study did not show meaningful differences in saliva flow after topical pilocarpine administration, compared with different milk curd concentrations.

The salivary flow rate and composition are affected by the type of stimulation. Sour taste, sour pickles, and foods increase the flow of saliva and the Na+ concentration.[20] Since the pH of the milk curd solutions applied in this study ranged from 4.27 to 4.39, different concentrations of acetic acid with equal pH values were prepared. This part of the study was done to test whether or not the acidic properties of milk curd are responsible for the salivary secretion. Based on the findings, there was a significant increase in the salivary secretion rate using 4% milk curd compared to acetic acid with an equal pH. The results show that the salivary secretion enhancement caused by milk curd is not just a result of its acidic nature, and other possible mechanisms may contribute. The components of milk curd, including fat, protein, sodium, phosphorus, potassium, calcium, and water, are shown in [Table 1].

The results of this study emphasize the positive role of milk curd on saliva secretion, independent of its acidic taste or pH. The pH. is not the only factor that is responsible for the increase in saliva secretion, especially in the first and second minutes. Milk curd contains ions including sodium, potassium, calcium, and phosphorus. The increase in saliva production effect may be related to the sodium and calcium ions in the milk curd, or perhaps the milk curd increased the secretion of saliva via pharmacological mechanisms.

To date, we could not obtain any data on the possible pharmacological mechanisms of milk curd action in salivary secretion. Many people suffer from dry mouth or xerostomia due to diseases such as Sjögren's syndrome, radiation therapy for head and neck tumors or increases in age. Making products such as mouthwash, candy or gum using milk curd can help to reduce dry mouth.

   Conclusion Top

Milk curd has a significant local impact on increasing saliva volume. The effect is dose-dependent, and it seems that this effect does not just depend on its acidic taste.

   References Top

1.Fenoll-Palomares C, Muñoz Montagud JV, Sanchiz V, Herreros B, Hernández V, Mínguez M, et al. Unstimulated salivary flow rate, pH and buffer capacity of saliva in healthy volunteers. Rev Esp Enferm Dig 2004;96:773-83.  Back to cited text no. 1
2.Pedersen AM, Bardow A, Jensen SB, Nauntotte B. Saliva and gastro intestinal functions of taste, mastication, swallowing and digestion. Oral Dis 2002;8:117-29.  Back to cited text no. 2
3.Navazesh M. Dry mouth : A0 ging and oral health. Compend Contin Educ Dent 2002;23:41-8.  Back to cited text no. 3
4.Sreebny LM, Valdini A. Xerostomia. Part I. Relationship to other oral symptoms and salivary gland hypofunction. Oral Surg Oral Med Oral Pathol 1998;68:451-8.  Back to cited text no. 4
5.Guggenheimer J, Moore PA. Xerostomia : E0 tiology, recognitionand treatment. J Am Dent Assoc 2003;134:61-9.  Back to cited text no. 5
6.Elishoov H, Wolff A, Volovikov A, Gorskiy M. Evaluation of unstimulated and stimulated parotid salivary flow rate in Israeli healthy subjects aged 60 years and older. Refuat Hapeh Vehashinayim 2005;22:44-8.  Back to cited text no. 6
7.Astor FC, Hanft KL, Ciocon JO. Xerostomia : A0 prevalent condition in the elderly. Ear Nose Throat J 1999;78:476-9.  Back to cited text no. 7
8.Guachelaar HJ, Vermes A, Meerwaldt HJ. Radiation-induced xerostomia : P0 athophisiology, clinical course and supportive treatment. Support Care Cancer 1997;5:261-2.  Back to cited text no. 8
9.Vidal E, Liozon E, Soria P. Dry mouth. Rev Prat 2001;51:148-54.  Back to cited text no. 9
10.Bryfield A. Martindale's the completed drug. 32 nd ed. : P0 harmaceutical Press, London; 1999. p. 1396-7.  Back to cited text no. 10
11.Ferguson MM. Pilocarpine and other cholinergic drugs in the management of salivary gland dysfunction. Oral Surg Oral Med Oral Pathol 1993;75:186-91.  Back to cited text no. 11
12.Davies AN, Shorthose K. Parasympathomimetic drugs for the treatment of salivary gland dysfunction due to radiotherapy. Cochrane Database Syst Rev 2007;18 :C0 D003782.  Back to cited text no. 12
13.Dawes C. The composition of human saliva secreted in response to a gustatory stimulus and to pilocarpine. J Physiol 1966;183:360-8.  Back to cited text no. 13
14.Vaqefi S, Aqeli N, Nafisi N. The composition of cure, cooked and produced foods. Inst Diete Sci Food Indus 1978;130:43.  Back to cited text no. 14
15.Lugaz O, Pilliaz AM, Boireau N. Time-intensity evaluation of acid taste in subjects with saliva high flow and low flow rates for acids of various chemical properties. Chem Senses 2005;30:89-103.  Back to cited text no. 15
16.Torres SR, Nucci M, Milanos E, Pereira RP, Massaud A, Munhoz T. Variations of salivary flow rates in Brazilian school children. Oral Res 2006;20:8-12.  Back to cited text no. 16
17.Ciancio SG. Medications' impact on oral health. J Am Dent Assoc 2004;135:1440-8.  Back to cited text no. 17
18.Murakami M, Wei MX, Ding W, Zhang QD. Effects of Chinese herbs on salivary fluid secretion by isolated and perfused rat submandibular glands. World J Gastroenterol 2009;15:3908-15.  Back to cited text no. 18
19.Millward A, Shaw L, Harrington E, Smith AJ. Continuous monitoring of salivary flow rate and pH at the surface of the dentition following consumption of acidic beverage. Caries Res 1997;31:44-9.  Back to cited text no. 19
20.Spielman AL. Interaction of saliva and taste. J Dent Res 1990;69:838-43.  Back to cited text no. 20

Correspondence Address:
Neda Babaee
Department of Oral Medicine, Babol University of Medical Sciences, Babol
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.90294

Rights and Permissions


  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3], [Table 4]

This article has been cited by
1 Physico-chemical and antimicrobial evaluation of chitosan and hydroxypropyl methylcellulose biofilms for prolonged release of pilocarpine.
Jesús Israel Rodríguez,Rosa Isela Sánchez,Marianela Garza,María Argelia Nakagoshi,Juan Manuel Solis,Katiushka Arévalo,Emmanuel Garza
Journal Oral Of Research. 2014; 4(1): 25
[Pubmed] | [DOI]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  

    Materials and Me...
    Article Figures
    Article Tables

 Article Access Statistics
    PDF Downloaded144    
    Comments [Add]    
    Cited by others 1    

Recommend this journal