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 Table of Contents  
Year : 2019  |  Volume : 9  |  Issue : 1  |  Page : 5-8

Estimation of salivary flow in oral submucous fibrosis patients using vibrotactile stimulation

1 Department of Oral Medicine & Radiology, Kaher's KLE VK Institute of Dental Sciences, Belagavi, Karnataka, India
2 Department of Public Health Dentistry, Kaher's KLE VK Institute of Dental Sciences, Belagavi, Karnataka, India

Date of Web Publication17-May-2019

Correspondence Address:
Dr. Apurva Prashant Deshpande
Department Of Oral Medicine & Radiology, Kaher's KLE VK Institute of Dental Sciences, Belagavi, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijohs.ijohs_35_18

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Introduction: Xerostomia is encountered commonly in dentistry and also features in oral submucous fibrosis (OSMF), due to fibrosis and hyalinization in and around salivary glands. Vibrotactile stimulation of salivary glands is a new reliable noninvasive method for stimulation of saliva.
Purpose: The aim of this research is to determine the efficacy of vibrotactile stimulation in increasing salivary secretions.
Materials and Methods: Study was conducted on 20 individuals with OSMF and equal control group. Resting saliva was measured by asking the participants to accumulate saliva in the mouth for 3 min and then collect it in a container by spitting method. Later, masseter muscles were stimulated by extraoral vibrations of 90 Hz frequency through the apparatus for 3 min and stimulated saliva was collected immediately in a container. The volume of the stimulated and resting saliva was then compared.
Results: The study comprised of majority male subjects with average age of 35 years. On vibrotactile stimuli, there was a rise in stimulated saliva in both the groups with a statistically significant P value.
Conclusion: Although there is saliva blockage due to the fibrosis in minor salivary glands (MSGs) and ducts of major salivary glands in OSMF, this study showed increased salivary flow upon vibratory stimuli. Increase in salivation is assumed to be from tonic vibration reflex (TVR) of muscles and conduction of vibrations by the bone till the major salivary glands and MSG. The reported apparatus can be used to stimulate salivary flow by patients itself without any need of assistance.

Keywords: Oral submucous fibrosis, tonic vibration reflex, vibrotactile stimulation, xerostomia

How to cite this article:
Deshpande AP, Gokak KV, Jalihal S, Bagewadi A. Estimation of salivary flow in oral submucous fibrosis patients using vibrotactile stimulation. Int J Oral Health Sci 2019;9:5-8

How to cite this URL:
Deshpande AP, Gokak KV, Jalihal S, Bagewadi A. Estimation of salivary flow in oral submucous fibrosis patients using vibrotactile stimulation. Int J Oral Health Sci [serial online] 2019 [cited 2022 Aug 18];9:5-8. Available from: https://www.ijohsjournal.org/text.asp?2019/9/1/5/258572

  Introduction Top

Xerostomia is a condition that is frequently encountered in dental practice. The most common causes are patients seeking radiation therapy, certain drugs such as antihistamines, antihypertension (diuretics), anti-epilepsy, and antidepressants and diseases such as Sjogren's syndrome, rheumatoid arthritis, hypothyroidism, sarcoidosis, lupus erythematosus, and oral submucous fibrosis (OSMF). Xerostomia can lead to speech and eating difficulties, halitosis, increase in the number of dental cavities, fungal infections, etc.[1] It is known to be produced by salivary glands controlled by reflex arc of parasympathetic nerves through trigeminal or facial fibres related to mechanoreceptors in oral cavity or chemical receptors in taste Stimuli.[1],[2],[3]

OSMF is a chronic progressive disorder characterized by generalized fibrosis of submucosa and epithelial atrophy. Hyalinization in and around minor salivary glands (MSGs) with degenerative changes in mucous acini and also with intralobular fibrosis and hyalinization with ductal cells showing oncotic metaplasia (degenerative/age change).[4] It is precancerous and crippling condition of oral mucosa which is more prevalent in South- east Asian population commonly found in age group of 16-35 yrs.[5],[6],[7],[8],[9]

Areca nut is main etiological factor for OSMF. Treatment option for OSMF include Surgical Management, Nutritional Support, with micro nutrients and minerals, local drug delivery including injections of steroids, hyaluronidase, physiotherapy, etc.[8],[9],[10],[11]

Treatment for xerostomia includes the use of saliva substitutes and salivary stimulants. There are various side effects associated with artificial salivary substitutes and sialogues. A new, noninvasive, cost-effective method for stimulation of saliva is vibrotactile stimulation which is proving to be a reliable tool in xerostomia. A study conducted by Hiraba and Yamaoka [12] in 2008 stated that facial vibrotactile stimulation increased salivary secretions in the right and left sides and in the parotid and submandibular and sublingual glands. Furthermore, the study done by Masashi Uchikune in 1999 on effects of whole-body vibrations in low-frequency range concluded that there were changes in autonomic nervous system and effects on autonomic nervous system appeared as changes in heart rate ratio and respiratory rate and quantity of saliva secretions.[13] This study was done to determine if vibrotactile stimulations are helpful in increasing the saliva secretions in OSMF (Group I) and normal individuals (Group II).

  Materials and Methods Top

Development of vibratory apparatus

The vibrator is a hand-held plastic tool of the size of a typical hairbrush massager which houses a vibratory motor whose frequency and amplitude can be altered by rotating the trimpot (variable resistor) that regulates the battery power to the motor [Figure 1]. The voltage is varied with the help of trimpot, to adjust frequency of vibratory motors. The motor can be controlled by pulse width modulation controller, but a simple trimpot is employed here which oscillates the vibrator at the fundamental frequency of 90 Hz. The vibration acoustics are captured on a smartphone using “Frequensee” App to adjust the rpm of the motor, thereby fine-tuning the fundamental vibration frequency to 90 Hz.
Figure 1: Circuit diagram

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Vibration amplitude is directly related to the speed of the vibratory motor. The speed of direct current motor has a small tolerance, which will cause a variation in the amplitude, hence, the specification of minimum vibration strength that is possible for a conformant motor. However, the characteristic of typical normalized amplitude is the level of vibration that can be expected from a typical motor running at the rated speed.

Source of data

The study included a total of 40 participants in the age group of 30–45 years, divided into two groups of 20 participants in each group. Group I comprised participants having OSMF and Group II comprised normal participants.


Spitting method was used to collect saliva. Resting saliva was measured by asking the participants to accumulate saliva in the mouth for 3 min and then spit it out in measuring container labeled “R.” Then, the extraoral vibratory stimulus was applied on masseter muscle with the help of vibratory apparatus for 3 min, and then, stimulated saliva was then collected at the end of 3 min in a container labeled “S.” The volume of stimulated and resting saliva was then compared. Measurements were collected in the morning (about 9 am to 11 am).

Vibration aided salivation

Vibration is the sensation produced by sinusoidal oscillation of objects placed against the skin. The vibratory frequency is signaled by the frequency of action potentials fired by the sensory nerves, and individual mechanoreceptors differ in their threshold sensitivity to vibration. The Pacinian corpuscles are best at detecting vibration. The Pacinian corpuscles are best at detecting vibrations in the range of 40–800 Hz range. In addition, muscle spindles of masseter muscles show the activation of tonic vibration reflex (TVR) with the 80–100 Hz vibrations, and hence, the parotid gland on the belly of masseter muscle will produce the salivary secretion with activation and/or contraction of the muscles through muscle spindles. Vibration accompanied by the bone conduction provides activation of a group of suprahyoid muscles and produces increased salivation in submandibular and sublingual glands.

  Results Top

In the present study, a majority of the participants were male with the mean age of 35 years.

On comparison of OSMF group and the control group, resting salivary secretion was decreased in OSMF group below the normal range. On vibrotactile stimuli, there was a rise in stimulated saliva in both the groups. There were also more rises noted in stimulated saliva in the control group compared to OSMF group. For comparing resting and stimulated salivary flow within the groups, Wilcoxon signed-rank test was used [Table 1]. P was statistically significant in both the groups.
Table 1: Comparison of resting and stimulated salivary flow within the groups

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For comparison of resting and stimulated saliva between the groups, Mann–Whitney test was used. Both the resting and stimulated saliva were found to be high in the control group when compared to OSMF group [Table 2].
Table 2: Comparison of resting and stimulated saliva between the groups

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  Discussion Top

Findings of this study revealed increased salivary flow in both the groups upon vibratory stimuli.

Possible reasons favoring increased salivation upon vibrotactile stimuli include the following:

In a de-efferent passive muscle, the spindle primary endings are highly sensitive to vibration.[14] Four classes of mechanoreceptors inform the brain about the form, weight, motion, vibration, and hand posture that define each object. Parallel messages from ~20,000 nerve fibers are integrated by neurons in the cerebral cortex that detect specific object classes.[15] Takata et al.[16] study, in 1996, evaluated the efficacy of the TVR elicited by high-frequency vibration in evaluating masticatory muscle excitability and concluded that TVR may be of use in evaluating masseter muscle excitability. Thus, we have solicited a vibrotactile apparatus which causes muscle excitation and also stimulates the salivary flow. A study done by Hiraba and Yamaoka [2] in 2008 found an effective increase in the whole saliva after vibratory stimuli which is consistent with the present study. Vibration of 90 Hz produced increased salivation in both the groups. Salivation increased in parotid gland due to masseter muscle excitability upon vibrotactile stimulation. In particular, the muscle spindles of the masseter muscles show the activation of TVR with the 80–100 Hz vibrations.[17] However, there are various mechanoreceptors in the facial skin; the four principal ones are Meissner's corpuscles, Merkel disk receptors, Pacinian corpuscles, and Ruffini endings.[15] Hence, we conclude that Pacinian corpuscles were responsible for the detection of vibration in our study. In addition, we assume that salivation from submandibular glands, sublingual glands, and MSGs was due to the proprioceptive property of bone causing bone conduction of vibration.

  Conclusion Top

Although there is fibrosis of MSGs and ducts of major salivary glands in OSMF, this study showed increased salivary flow upon vibratory stimuli.

Advantages of using vibratory stimuli are as follows: the vibratory apparatus is cost-effective and can be used by patients itself reducing any need of assistance. It also increases blood supply and relaxes muscular tension. Furthermore, there is no need to take any salivary stimulants and hence no side effects.

Apart from xerostomia associated with OSMF, vibratory stimuli can also be used to increase salivation in patients suffering from Sjogren's syndrome, xerostomia due to use of diuretics, antidepressants, radiation therapy, and geriatric population.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Bridges RB. Salivary glands and saliva. Oral Biology. St. Louis: Mosby; 1981. p. 196-236.  Back to cited text no. 1
Iverson S, Iverson L, Saper C. The autonomic nervous system and the hypothalamus. In Principles of Neural Science, E.R. Kandel, J.H. Schwartz, and T.M. Jessell, eds. (New York: McGraw-Hill), 2000. p. 960-81.  Back to cited text no. 2
Lashley KS. Reflex secretion of the human parotid gland. J Exp Psychol 1916;1:461.  Back to cited text no. 3
Sarode SC, Sarode GS. Burning sensation in oral submucous fibrosis and its possible association with mucin secreted by affected minor salivary glands. Oral Oncol 2013;49:e16-7.  Back to cited text no. 4
Dawes C. Rhythms in salivary flow rate and composition. Int J Chronobiol 1974;2:253-79.  Back to cited text no. 5
Domaracki LS, Sisson LA. Decreasing drooling with oral motor stimulation in children with multiple disabilities. Am J Occup Ther 1990;44:680-4.  Back to cited text no. 6
Fox PC, Busch KA, Baum BJ. Subjective reports of xerostomia and objective measures of salivary gland performance. J Am Dent Assoc 1987;115:581-4.  Back to cited text no. 7
Rajendran R. Oral submucous fibrosis: Etiology, pathogenesis, and future research. Bull World Health Organ 1994;72:985-96.  Back to cited text no. 8
More CB, Gupta S, Joshi J, Varma SN. Classification system for oral submucous fibrosis. J Indian Acad Oral Med Radiol 2012;24:24-9.  Back to cited text no. 9
  [Full text]  
Canniff JP, Harvey W, Harris M. Oral submucous fibrosis: Its pathogenesis and management. Br Dent J 1986;160:429-34.  Back to cited text no. 10
Tilakaratne WM, Klinikowski MF, Saku T, Peters TJ, Warnakulasuriya S. Oral submucous fibrosis: Review on aetiology and pathogenesis. Oral Oncol 2006;42:561-8.  Back to cited text no. 11
Hiraba H, Yamaoka M, Fukano M, Fujiwara T, Ueda K. Increased secretion of salivary glands produced by facial vibrotactile stimulation. Somatosens Mot Res 2008;25:222-9.  Back to cited text no. 12
Burdette BH, Gale EN. The effects of treatment on masticatory muscle activity and mandibular posture in myofascial pain-dysfunction patients. J Dent Res 1988;67:1126-30.  Back to cited text no. 13
Clark FJ, Matthews PB, Muir RB. Response of soleus Ia afferents to vibration in the presence of the tonic vibration reflex in the decerebrate cat. J Physiol 1981;311:97-112.  Back to cited text no. 14
Gardner EP, Martin JH, Jessell TM. The bodily senses. In Principles of Neural Science, 4th edn (ed. Kandel ER, Schwartz JH, Jessell TM). Vol. 4. New York: McGraw-Hill; 2000. p. 430-50.  Back to cited text no. 15
Takata Y, Nakajima T, Yamada Y. Quantitative evaluation of the tonic vibration reflex (TVR) in the masseter muscle. J Oral Maxillofac Surg 1996;54:1307-13.  Back to cited text no. 16
Desmedt JE, Godaux E. Vibration-induced discharge patterns of single motor units in the masseter muscle in man. J Physiol 1975;253:429-42.  Back to cited text no. 17


  [Figure 1]

  [Table 1], [Table 2]


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