|Year : 2015 | Volume
| Issue : 1 | Page : 85-89
Xerostomia: An overview
Jitender Reddy Kubbi, Loka Ravali Reddy, Lakshmi Srujana Duggi, Harisha Aitha
Department of Oral Medicine and Radiology, SVS Institute of Dental Sciences, Mahabubnagar, Telangana, India
|Date of Submission||29-Nov-2014|
|Date of Acceptance||21-Jul-2015|
|Date of Web Publication||12-Oct-2015|
SVS Institute of Dental Sciences, Appanapally, Mahabubnagar - 509 002, Telangana
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Xerostomia is a subjective sensation of dry mouth with objective evidence of decreased salivary flow. It is a multifactorial condition which increases the risk of oral diseases and has a significant effect on the person's quality of life. So, these patients need special care for maintenance of oral and general health. We, being oral health care professionals, it is our responsibility to diagnose and treat the condition accordingly using a multidisciplinary approach. This paper enlightens the etiology and management of xerostomia.
Keywords: Chemotherapy, diabetes mellitus, radiation therapy, saliva, xerostomia
|How to cite this article:|
Kubbi JR, Reddy LR, Duggi LS, Aitha H. Xerostomia: An overview. J Indian Acad Oral Med Radiol 2015;27:85-9
| Introduction|| |
Saliva plays a vital protective role in the oral cavity, and reduction in the quantity of saliva is known to increase the risk of oral diseases.  Xerostomia is the most common complaint found among patients during periods of anxiety, stress, depression, radiation therapy, chemotherapy, and systemic diseases.  Though it is multifactorial, diagnosis can be made from patient's history, examination of the oral cavity, and by various investigative procedures like sialometry.  Various treatment modalities have been proposed to treat xerostomia, which include preventive measures, management of symptoms, measures to increase the salivary flow, and use of salivary substitutes.  Sreebny (1988) defined xerostomia as the subjective feeling of oral dryness and it is the result of salivary gland hypofunction. This symptom is more common in elderly people, but is not caused by aging. The unstimulated/resting salivary flow rate is 0.3 ml/min, whereas the flow rate during sleep is 0.1 ml/min and during mastication, it increases to 4.0-5.0 ml/min. 
| Etiology|| |
Xerostomia is the subjective complaint of dry mouth due to lack of saliva caused by multitude of factors as given in [Table 1]. 
Xerostomia is one of the most common drug-related adverse effects in the oral cavity. Till date, more than 500 medications have been implicated in the etiology of xerostomia.  Use of medications and advancing age are significant risk factors that cause xerostomia in elderly individuals.  Drugs which are commonly implicated in xerostomia are: 
Anticholinergic agents: Atropine, scopalamine.
Antidepressants and antipsychotics: Citalopram, fluoxetine.
Antihypertensive agents: Captopril, clonidine.
Diuretic agents: Chlorothiazide, frusemide.
Muscle relaxant agents: Cyclobenzaprine, orphenadrine.
Sedative and anxiolytic agents: Alprazolam, diazepam.
Analgesic agents: Opioids: Codeine, meperidine.
Nonsteroidal anti-inflammatory drugs (NSAIDs): Ibuprofen, naproxen.
Antihistamines: Astemizole, chlorpheniramine.
Xerostomia is a common adverse effect of radiation therapy, when advised as primary, concomitant, or adjuvant treatment for head and neck tumors, as the salivary tissue is very sensitive to radiation.  The severity of xerostomia depends on the degree of radiation exposure of the salivary tissues. Of all the major salivary glands, parotid gland is most radiosensitive. Management of oral cancer requires administration of 60-70 Gy of radiation dose, which causes acute decrease in salivary flow in the 1 st week, with a gradual reduction to 95% and by the 5 th week, the salivary flow virtually stops which recovers rarely.  To protect the salivary function and improve the quality of life, radiation exposure can be minimized by using intensity-modulated radiation therapy (IMRT), three-dimensional treatment planning, and dose delivery techniques. Radiation-induced hyposalivation was decreased by using the radioprotective agent amifostine, which provides cytoprotection to the salivary glands. 
Many malignant tumors are treated either by chemotherapy alone or by a combination of radiation and chemotherapy.  Xerostomia is the fourth most common symptom reported due to chemotherapeutic agents in advanced cancer patients. A chemotherapeutic drug makes the saliva thick and causes dry mouth, which shoots up the incidence of dental caries.  If oral side effects are noticed due to these drugs, dental clinician should ask the patient's physician to treat the induced xerostomia jointly. 
Uncontrolled diabetic patients often report dry mouth, due to polyuria and poor hydration. Poorly controlled diabetic patients have reduced parotid flow rates when compared to those in patients with well-controlled diabetes mellitus. Xerostomia is one of the primary predisposing causes for oral candidiasis, median rhomboid glossitis, denture stomatitis, and angular chelitis with denture use in diabetic patients. 
| Clinical Features|| |
Xerostomia causes dysphagia, dysgeusia, and dysarthria by affecting patient's quality of life.  The patients also have unpleasant, altered taste perception, bad breath, and increased incidence of infections like oral thrush and ulcerations.  The condition causes dry, cracked lips with fissuring at the corners of the mouth, fissured tongue, and burning sensation.  Xerostomia has a devastating effect on denture wearers by affecting the retention and comfort of the prosthesis.  Xerostomia predisposes patients to increased incidence of dental caries leading to increased tooth extraction.  Due to reduced salivary flushing activity, xerostomic patients show considerable accumulation of plaque and calculus leading to periodontal disease. Thus, xerostomia has a direct impact on oral and general health status. 
| Diagnosis and Investigations|| |
Diagnosis of xerostomia can be made by detailed patient's history, examination of the oral cavity, and clinically by mouth mirror test and wafer test. In mouth mirror test, back of the mouth mirror is drawn along the buccal mucosa and the friction is registered accordingly. Wafer test is a semi-quantitative test in which the time taken for dissolution of wafer is noted in minutes and is recorded in grades to screen for xerostomia.  Clinical salivary gland hypofunction predictors are dryness of the lips and buccal mucosa, absence of saliva production during gland palpation, and increased DMFT score. Sialometry measures the salivary flow rate. Salivary gland imaging techniques like sialography demonstrate ductal structures, detect salivary gland calculi and masses, and also find application in the identification of long-standing xerostomia. Salivary scintigraphy helps in assessing salivary gland function. Ultrasonography demonstrates acinar and ductal structures. CT and MRI demonstrate parenchymal structure of the salivary gland tissue. But MRI is preferred to CT because it has better resolution for soft tissues. Other investigational tools like Schirmer's test and Rose Bengal staining can be used.  Minor and major salivary gland biopsy is helpful for the diagnosis of Sjogren's syndrome, HIV-associated salivary gland disease, sarcoidosis, amyloidosis, and in case of malignancy. 
| Management|| |
Management of dry mouth should begin with proper patient education and the identification of the underlying cause. ,
Preventive care should be instituted to avoid oral complications due to xerostomia. This begins with oral evaluation and examination for every 4-6 months. Thorough oral hygiene, a low-sugar diet, topical fluoride, neutral pH, and 1% sodium fluoride are efficient ways of preventing hyposalivation-induced dental caries. 
In xerostomic patients, functional salivary gland tissue can be stimulated either mechanically or chemically.  Salivary stimulation can be achieved by frequent meals, ingestion of lemonade or acid drinks, sugar-free chewing gums, mints, and candies. Sialogogues that directly stimulate salivary glands are Pilocarpine, Cevimeline, Bethanecol, and Anethole trithone. , Electrostimulation may increase the salivary flow in patients with Sjogren's syndrome. 
Lubricating agents in the form of gels, mouthwashes, lozenges, and toothpaste have been used for both subjective and objective improvement in the signs and symptoms of xerostomia. Recently, a mucin spray was found to be useful against xerostomia in a patient who had undergone irradiation. 
Cholinergic agonists i.e., pilocarpine and cevimeline, have been successfully used orally to increase salivary secretion. Pilocarpine has a potential benefit in limiting drug-induced xerostomia in patients using antihypertensive drugs and tricyclic antidepressants. The optimal dosage of pilocarpine is 5 mg given 4 times daily or 10 mg given thrice daily. Cevimeline 30 mg thrice daily is used in the management of xerostomia secondary to irradiation, Sjogren's syndrome, HCV infection, and drug therapy.  Bethanecol 25 mg thrice daily orally increases both the unstimulated and stimulated salivary flow rates in patients with xerostomia secondary to radiation. Other drugs like carbacholine, anethole trithione, and pyridostigmine can also be used. Bromhexine (32-48 mg daily) and zidovudine are found to increase salivary flow rates and limit xerostomia symptoms in Sjogren's syndrome patients. Antiretroviral therapy reduces salivary gland enlargement of HIV-related salivary gland disease. Regular infusion of infliximab for 1 year reduces xerostomia significantly. 
Parenteral (3 × 10 6 IU/week) and IM (1 × 10 6 IU/week) administration of interferon-α increases the salivary and lacrimal flow in primary and secondary Sjogren's syndrome patients by increasing the transcription and production of aquaporin-5, which is a membrane-bound protein. Interferon-α lozenges (150 IU thrice daily) reduce the severity of xerostomia. 
Systemic corticosteroids may be of benefit in reducing the oral and ocular symptoms of Sjogren's syndrome. Corticosteroid irrigation (with prednisolone 2 mg/ml in normal saline) is clinically helpful by increasing the salivary flow rates in early stages of disease. 
Cyclosporine, cyclophosphamide, and thalidomide when administered systemically produce marked improvement in xerostomia. 
In prolonged xerostomic patients, artificial salivary substitutes can be used which humidify the oral cavity and replace lost salivary function and components.  Such preparations do contain aqueous solutions like mucins, glycoproteins, salivary enzymes, and polymers such as carboxymethycellulose used to protect soft tissues or ions such as calcium, phosphates, or fluorides for protecting the hard structures of the teeth. Milk helps in moistening and lubricating the oral mucosa, buffering oral acids, reducing enamel solubility, and contributes to enamel remineralization as it contains calcium, phosphate, and phosphoproteins that adsorb to enamel; hence, it is recommended as a salivary substitute. Pig products such as bovine/porcine and home remedies such as margarine and linseed oil are also used as salivary substitutes. Commercially available products are luborant (which contains lactose peroxidase, glandosane), saliva orthona (an oral spray containing porcine mucin), and biotene (contains components like polyglycerol methacrylate, lactoperoxidase, glucose oxidase), which decrease oral dryness and improve oral function. Medications like Salivix pastilles can also be used, which act as local salivary stimulants. 
Dentures should be cleaned with chlorhexidine solution 0.2% overnight or chlorhexidine gel 1% two times a day.  In dry mouth patients, fixed non-tissue-bearing prosthesis with full-coverage retainers with supragingival margins, easily cleaned pontics, and connectors are recommended.  Complete or partial dentures incorporating metal bases exhibit improved retention and stability. Metal-based prostheses are easy to maintain and have less plaque accumulation. Soft denture liners and adhesives are used to enhance comfort, retention, cushioning, and lubricating effect. Xerostomic patients wearing implant-supported dentures report improved oral comfort and function, as compared with conventional, mucosa-supported prosthesis users. 
Neuroelectrostimulation increases salivary secretion, and thus the device salitron has been introduced. The first-generation stimulator has a probe which is applied intraorally to the mucosal surface for a few minutes daily which signals the neurons to induce salivation.  The second-generation salivary neuroelectrostimulator is a removable intraoral appliance produced for individual patients, which is similar to a mouthguard used to treat temporomandibular joint (TMJ) disorders and bruxism. Significant moistening of oral mucosal membranes and diminished xerostomia are reported during its application and 10 min after its removal.  Dental implant-based third-generation intraoral device is a miniature neuroelectrostimulating device to be implanted into the oral cavity. It generates frequent stimuli, does not interfere with regular oral functions, senses the wetness/dryness of the mouth, and can be controlled by the patient via remote control. 
Psychological factors causing xerostomia must be evaluated and treated. Use of benzodiazepines such as ketazolam 15-30 mg at bed time, followed by gradual dose reduction is advised. , It is important to avoid irritants such as coffee, alcohol, or tobacco smoking. The patients are suggested to place ice chips in the mouth and sip water frequently to provide relief and moisture to dry mouth symptoms. ,
Acupuncture is known to increase parasympathetic action, causing a release in neuropeptide and stimulating salivary flow and secretions, thereby reducing the incidence of xerostomia. 
Hyperbaric oxygen (HBO) therapy
HBO therapy is also gaining popularity in the treatment of xerostomia in radiation-induced cancer patients owing to its angiogenetic and revascularization effects, but the exact mechanism is poorly understood.  Gerlach et al. conducted a study on the effect of HBO therapy in a series of 21 xerostomic patients with head and neck cancer at 1 and 2 years post administration of HBO. Their results were promising as they showed a quantitative improvement in symptoms of xerostomia at 1 year post HBO therapy. Notable finding from their study was reduced symptoms of xerostomia in patients who received HBO therapy within 1 year of radiation therapy than in those who received HBO 1 year after radiation therapy. 
A combination of principles and methods of life sciences with those of engineering to develop materials and methods that can repair damaged and diseased tissue or to create entire tissue replacements is called tissue engineering.  This procedure has manufacturing and ethical concerns. Ethically, there is a significant debate on tissue procurement. The molecular mechanisms underlying regenerating process for salivary gland are unknown and further studies are required. , Artificial salivary gland is fabricated based on the principles of tissue engineering. The device consists of a blind-end tube fabricated from porous, slowly biodegradable substratum, coated with matrix components on the inner surface of the tube, in order to allow formation of polarized epithelial cell monolayer, providing unidirectional fluid secretion, and is surgically implanted in the buccal mucosa with an opening in the oral cavity, similar to the natural duct system. ,
| Conclusion|| |
Since ages, xerostomia has become a concern for dental professionals. This concern along with increased risk of oral diseases in these patients has led the clinicians to be able to diagnose, and provide preventive and definitive treatment to achieve oral comfort and function. At present, management of xerostomic patients is quite challenging. So, a combination of various treatment modalities has become a better approach.
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Conflicts of interest
There are no conflicts of interest.
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