|Year : 2019 | Volume
| Issue : 3 | Page : 276-280
Dry mouth: An emerging epidemic
S Sujatha, R Priyadharshini, Rizwana Azmi
Department of Oral Medicine and Radiology, Faculty of Dental Sciences, Ramaiah University of Applied Sciences, Bengaluru, Karnataka, India
|Date of Submission||12-May-2019|
|Date of Decision||16-Jul-2019|
|Date of Acceptance||30-Jul-2019|
|Date of Web Publication||2-May-2020|
Dr. S Sujatha
Department of Oral Medicine and Radiology, Faculty of Dental Sciences, Ramaiah University of Applied Sciences, Bengaluru - 560 054, Karnataka
Source of Support: None, Conflict of Interest: None
Dry mouth is a common and emerging concern among the young and old alike, causing significant discomfort and oropharyngeal infections and impairing the quality of life of the individual. The etiology ranges from simple obstruction of salivary gland ducts, physiological stress and anxiety to a plethora of underlying salivary gland pathologies and systemic conditions. This review is focused to discuss the various clinical conditions predisposing to dry mouth. Understanding the etiology of the condition prompts appropriate early intervention to treat the underlying pathology, alleviate symptoms and prevent undesirable consequences that compromise the quality of life of an individual. Prompt diagnosis helps to alleviate symptoms in both curable and noncurable conditions contributing to dry mouth.
Keywords: Dry mouth, etiology, hyposalivation, xerostomia
|How to cite this article:|
Sujatha S, Priyadharshini R, Azmi R. Dry mouth: An emerging epidemic. J Datta Meghe Inst Med Sci Univ 2019;14:276-80
| Introduction|| |
Saliva plays a critical role in maintaining the oropharyngeal health. It preserves the homeostasis of the oral environment and helps in mastication, taste perception, deglutition, digestion, speech, immunity, caries protection, lubricates oral mucosa and protects it from desiccation. Three paired major salivary glands (parotid, sublingual, and submandibular) and hundreds of minor salivary glands distributed throughout the oral cavity, contribute to secretion of saliva, under the regulation of the sympathetic and parasympathetic divisions of the autonomic nervous system. The daily secretion of saliva normally ranges between 1.0 and 1.5 L at a rate of 0.5 mL/min.
Conditions that interfere with the normal composition or quantity of saliva can cause significant discomfort and adversely affect oral and systemic health. Salivary gland hypofunction (SGH) or hyposalivation is a condition of reduced saliva production due to numerous causes. Dry mouth is a condition when unstimulated submandibular/sublingual or parotid saliva flow of < 0.05 mL/min; stimulated submandibular/sublingual or parotid saliva flow < 0.15 mL/min is present. It usually leads to the subjective complaint of oral dryness which is termed xerostomia.,
Xerostomia is a subjective complaint of dry mouth, whereas hyposalivation is an objective decrease in salivary flow. Xerostomia is often associated with hyposalivation, but not always, and many cases of xerostomia have been described in patients with a normal salivary flow rate and their symptoms may be secondary to qualitative and/or quantitative changes in the composition of saliva., Affecting 10%–30% of the general population, dry mouth is considered to be one of the most common yet underappreciated, underdiagnosed and undermanaged oral health conditions, which can significantly diminish the quality of life.
Decreased salivation is associated with generalized oral discomfort, halitosis, difficulty in chewing and swallowing, altered taste perception, altered speech and compromises retention of prosthesis. It contributes to increased risk of dental caries, gingivitis, periodontitis, candidiasis, poor oral hygiene, decreased lubrication, dehydration and atrophy of the mucosal surfaces leading to loss of integrity, injury and ulceration, infection risk, difficulty in tolerating dentures, delayed wound healing, and pain. One of the most disturbing consequences of persistent mouth dryness is the rapid and preventable loss of dentition which results from increased risk of dental caries and erosion posed by the dry mouth environment. Intolerance to spicy foods and food sticking on to the teeth impairs social engagements. Serving many roles, saliva is vital not only to one's daily functioning but also to one's general wellbeing. Patients with dry mouth also experience disordered sleep pattern with poor quality of sleep and frequent interruptions in sleep to drink water owing to dryness of the mouth. Persistent xerostomia and salivary dysfunction can induce significant and permanent oropharyngeal disorders and can impair the routine life of an individual.
Salivary dysfunction and ensuing dry mouth has a multifactorial etiology. Medications, poor general health, female sex, and old age influence the development of the condition. Vulnerable elders often suffer from chronic diseases and use multiple medications, both of which can impair the function of salivary glands. Understanding these causes is important because in some cases, the etiology can be addressed and early intervention can eliminate mouth dryness [Table 1].
| Etiology|| |
Diabetes is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Diabetes mellitus (DM) has become a worldwide public health problem and in recent years, the global prevalence of DM has increased substantially. DM is probably the most common metabolic disease with salivary implications, due to its high frequency. Thus, with a rise in the prevalence of DM, there is a greater risk of larger proportion of this population to develop dry mouth. Dry mouth may be a warning sign of diabetes. Chronic hyperglycemia-induced polydipsia and polyuria, neuropathy, microvascular abnormalities, damage to the gland parenchyma, endothelial dysfunction and medication that is being consumed to keep the diabetes under control may contribute to decreased salivary flow in these individuals. Hyposalivation is also related to the level of hemoglobin A1c (HbA1c) with a significant decrease in the quantity of saliva with increase in HbA1c levels, particularly in poorly controlled DM (>9% HbA1c). Increased expression of sodium-glucose cotransporter 1 protein in ductal cells is known to repress salivation by increasing salivary water reabsorption. It is strongly associated with objective measurements of poor salivary flow and with other oral and extraoral symptoms of desiccation.
Several epidemiologic studies have suggested that xerostomia is frequent among DM patients than non-DM population., This salivary disorder in DM patients could be associated with increased susceptibility to caries and oral infections, particularly when there has been dehydration and inadequate blood glucose control.
Sjogren's syndrome is an autoimmune disorder characterized by lymphocytic infiltration of the exocrine glands, mainly the lacrimal and salivary glands, resulting in reduced secretory functions with oral and ocular dryness. It may be seen alone or in association with other connective disorders such as rheumatoid arthritis. The misdirected immune system in autoimmunity tends to lead to inflammation of glands that produce the saliva in the mouth (salivary glands, including the parotid glands) which leads to dry mouth and dry lips. Dryness of eyes and mouth, in patients with or without Sjogren's syndrome, is sometimes referred to as sicca syndrome.
Patients suffering from rheumatoid arthritis also have shown decreased resting whole saliva and stimulated parotid saliva rates in the absence of Sjogren's syndrome. Decreased salivary secretion has also been noted in patients suffering from familial amyloidotic polyneuropathy with hyposalivation being positively correlated to the progress of familial amyloidotic polyneuropathy. Fibrosis of the salivary glands and lack of pooling of saliva in the floor of the mouth have also been reported in patients suffering from scleroderma. Primary biliary cirrhosis is a chronic cholestatic disorder predominantly affecting middle-aged women, often presenting with autoimmune associations. In a prospective study of 95 patients with Primary biliary cirrhosis, 47.4% presented with dry mouth while 68.4% presented with sicca complex.,
Xerostomia and SGH are common side effects of prescription drugs. In addition, polypharmacy has been shown to significantly influence patients’ saliva flow. More than 500 medications that are currently in use list mouth dryness as a side effect; however, in the majority of cases, the mechanisms are unknown. Nonetheless, it is predominantly believed to be the result of changes in salivary quality more so than the quantity. Drug-induced hyposalivation may be due to inhibition of parasympathetic nervous system with decreased salivation or through sympathetic stimulation that produces little saliva, high in protein content, thus giving a sensation of dry mouth. Drug-induced hyposalivation accounts for 80.5% of the adverse drug reactions. “Xerogenic” medications most commonly implicated in dry mouth are the tricyclic antidepressants, antipsychotics, atropinics, beta blockers, and antihistamines, and therefore the complaint of dry mouth is common particularly in patients treated for hypertensive, psychiatric or urinary problems.
Drugs used to treat cancer can make saliva thicker, causing the mouth to feel dry. The drugs implicated to cause dry mouth have an anticholinergic, sympathomimetic action or both. Diuretics limit the transport of water and electrolytes through the cell membrane of salivary acinar cells by causing vasoconstriction in salivary glands.
Radiotherapy is commonly employed as the mainstay or as an adjunct with chemotherapy and surgery for treatment of head and neck cancers. Incidental radiation also occurs to the salivary glands in such conditions. Depending on the site and extension of primary tumors and the path of lymphatic spread, all or part of the major and minor salivary glands are included within the radiation field. The first few weeks of radiotherapy witness a marked and progressive reduction in the salivary flow. Xerostomia affects 80% of the patients who need radiotherapy as a primary treatment, as an adjunct to surgery, in combination with chemotherapy, or as palliation. Radiation dose as low as 20 Gy can cause permanent cessation of salivary flow if given as a single dose. At doses above 52 Gy, salivary dysfunction is severe and may essentially reach zero at 60 Gy. Serous acinar cells appear to be more sensitive to radiation than mucous cells. Free radical-induced disruption of cellular metabolism results in the damage of acinar cells.,
The quality of saliva is also affected owing to a decrease in its pH that predisposes to demineralization of teeth, dental caries and a change in its consistency. Compensatory hypertrophy of residual salivary gland tissue not exposed to radiation might partially alleviate the symptoms of dry mouth. A change in the buffering capacity, electrolyte composition as well as physical properties ensues that may contribute to change in oral microflora. Following radiotherapy, there is an increase in the viscosity of saliva with a change in the color that can be yellow, brown, or even white. Radiation-induced dry mouth affects the overall quality of life of individual during and after radiotherapy. A decrease in the quantity of saliva is associated with difficulty in chewing and swallowing and inadequate oral clearance leading to angular cheilitis, cracked lips, periodontal disease, stomatitis, and halitosis.
The activation of the sympathetic system in conditions of anxiety, stress produces viscous saliva and hence contributes to the symptom of dry mouth. Dawes in 1987 proposed that when the amount of water absorption and evaporation exceeds the salivary flow rate, the sensation of a dry mouth will be perceived. Individuals with mouth breathing also experience dry mouth as the rate of evaporation exceeds the salivary flow rate. The progressive age-dependent acinar degeneration and atropy accompanied by replacement of functional parenchyma by fibrous tissue and fatty infiltration may result in hyposalivation in elderly. There is 30%–40% decrease in the number of acinar cells of salivary glands from age 34 to75 years. Xerostomia remains an unresolved common complaint especially among the geriatric population, despite seeking medical or dental consultation.
Personal habits like mouth breathing, drinking alcohol, or using tobacco products can cause dry mouth. Chronic alcoholism is associated with hyposalivation and oral dryness. Ethanol-induced fatty infiltration of the salivary glands, tumor necrosis factor-alpha mediated acinar cell apoptosis causes a change in salivary flow. Similarly, a significant decrease in salivary flow rate has also been reported among tobacco users.,
The association of salivary secretion and psychological status of the individuals have been elucidated. Various psychological disorders such as depression, obsessive-compulsive disorder, cancer phobia, and anxiety states have been associated with dry mouth. Depression and anxiety are the two most common mental disorders in the global platform. Depression continues to be the foremost illness and disability among young and middle-aged populations, with 322 million people affected with depression on the global scale with 18% of them from India.,,,
Patients with long-term psychiatric illness are on prolonged medications that subjects them to a high risk of xerostomia. Dry mouth is considered as a psychophysiological expression of depression and hence one of the symptoms of depression. Thus the underlying psychological illness could contribute to the sensation of dry mouth.
Disruption in the neuronal pathway for salivation following trauma and head and neck surgery can also lead to hyposalivation. Nutritional deficiencies like Vitamin A can decrease salivation due to squamous keratinizing metaplasia of the major and minor salivary glands.,, Hyposialia caused by functional impairment of the salivary glands has also been reported in cases of hereditary hemochromatosis with a decline in total stimulated salivary flow consistent with the increase in serum ferritin levels. Self-induced vomiting, misuse of diuretics and laxatives, and excessive exercise may cause body dehydration resulting in decreased salivary flow in individuals suffering from bulimia nervosa and anorexia nervosa., Conditions like Alzheimer disease, cerebral vascular accident, hepatitis, HIV, hypertension, liver transplant candidates, menopause, osteoarthritis, parkinsonism, renal disease/dialysis, spinal cord injury, stroke, systemic lupus erythematosus, systemic sclerosis have also shown to be associated with dry mouth. Chronic sialadenitis secondary to sialolith, salivary duct stricture, external duct compression, systemic disease, or stasis may lead to progressive acinar destruction combined with lymphocytic infiltrate resulting in symptoms of xerostomia.,
| Diagnosis|| |
Understanding the etiology of the condition is critical for appropriate management. A systematic approach with detailed clinical history with an emphasis on the general medical condition of the patient along with the drugs taken is mandatory. Oral examination is fundamental to identify clinical signs that are pathognomonic for hyposalivation. Examination of oral mucosa can reveal sticking of an intraoral mirror to the buccal mucosa or tongue; frothy, viscous saliva; absence of saliva pooling in floor of the mouth; loss of papillae of the tongue dorsum; smooth gingival architecture; glassy appearance of the oral mucosa (especially the palate); lobulated or deeply fissured tongue; cervical caries involving more than two teeth; and mucosal debris on palate. Examination of the salivary gland function with measurement of salivary flow rates (stimulated and unstimulated), sialography, magnetic resonance imaging and ultrasonography to visualize architecture and pathology associated with the salivary gland and its ducts are of diagnostic importance.,
| Treatment|| |
The treatment should increase the existing salivary flow or replace the lost secretions, control the state of oral health, arrest dental caries, and other associated conditions. Depending on the etiology and patient associated factors, patient-specific treatment is preferred. Pharmacological agents, saliva substitutes and/or lubricants in the form of gel or oral rinses, Transcutaneous electric nerve stimulation, acupuncture, low-level laser therapy, and herbal medicines are commonly employed to alleviate symptoms by stimulating and/or substituting for the secretion of saliva.,,,, None of the currently available management approaches are entirely satisfactory. They provide temporary and intermittent relief with the recurrence of symptoms when the treatment is interrupted. Addressing the causative or contributing factors is, therefore, of paramount importance. Professional judgment and patient preferences should ultimately decide the line of treatment. Medical management of underlying condition along with lifestyle modifications improves the symptoms.
| Conclusion|| |
With changing lifestyles, increase in stress and anxiety, Type II DM, dry mouth is emerging as an epidemic condition. Prompt diagnosis, thus, helps in early intervention to alleviate symptoms in both curable and noncurable conditions contributing to dry mouth. Being aware of the causes and clinical presentation helps oral medicine specialists to treat this condition at an early stage, thus halting further complications.
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