INTRODUCTION:

Xerostomia (also termed as dry mouth) is the medical term for the subjective symptom of dryness in the mouth, which may be associated with a change in the composition of saliva or reduced salivary flow (hyposalivation) or have no identifiable cause.⁽¹⁾Xerostomia is the subjective feeling of oral dryness, which is often (but not always) associated with hypofunction of the salivary gland.⁽²⁾The term is derived from the Greek word (xeros) meaning “dry” and (stoma) meaning “mouth”.⁽³⁾This symptom is very common and is often seen as a side effect of many types of medication. Dry mouth can change speech patterns, allow dentures to rub, and contribute to dental caries. It also changes dietary preferences too. It even causes vitamin deficiencies and caloric insufficiency.

Once if the salivary flow is reduced to half, chewing and swallowing becomes problematic. It is more common in older people (mostly because this group tend to take several medications) and in persons who breathe through their mouths (mouth breathing). ⁽¹⁾

ROLE OF SALIVA:

Saliva is the viscous, clear, watery fluid secreted from the parotid, sub mandibular, sub lingual and smaller mucous glands of the mouth. Saliva contains two major types of secretions, a serous secretion containing the digestive enzyme ptyalin and a mucous secretion containing the lubricating aid mucin.⁽³⁾ Saliva is a watery substance located in the mouths of organisms, secreted by the salivary glands. Human saliva is 99.5%water, while the other 0.5%consists of electrolytes, mucus, glycoprotein, enzymes, and antibacterial compounds such as secretory IgA and lysozyme.⁽⁴⁾The enzyme found in saliva are essential in beginning the process of digestion of dietary starches and fats. These enzymes also play a role in breaking down food particles entrapped within dental crevices, protecting teeth from bacterial decay. ⁽⁵⁾Furthermore, saliva serves a lubricative function, wetting food and permitting the initation of swallowing, and protecting the mucosal surfaces of the oral cavity from desiccation. ⁽⁶⁾ Saliva contributes to the digestion of food and to the maintenance of oral hygiene. Without normal salivary function the frequency of dental caries, gum diseases and other oral problem increases significantly. It has various functions like lubricating of oral cavity for protecting it from trauma during eating, swallowing and speaking. In persons with little saliva (Xerostomia), Soreness of the mouth is very common, and the food sticks to the inside of the mouth.⁽⁶⁾ Saliva possesses many important functions including anti microbial activity, mechanical cleansing action, control of pH, removal of food debris from the oral cavity, lubrication of the oral cavity, remineralization and maintaining the integrity of the oral mucosa.⁽⁷⁾

Fig no: 1 Anatomic representation of glands.

ABSENCE OF SALIVA:

If the salivary flow is absent (Xerostomia) or less (hyposalivation) in the oral cavity it may lead to many sort of diseases and problems some are dental caries, oral candidiasis, dysgeuia- altered taste sensation, intra oral halitosis, oral dysesthesia-mucosa appears dry, dysphagia-difficulty swallowing and chewing, difficulty in wearing dentures, mouth soreness, oral mucositis, food may stick to the teeth, dry, sore, and cracked lips and angles of mouth.⁽⁸⁾ Xerostomia may be a symptom of a serious systemic disease, such as systemic lupus erthymatosus, rheumatoid arthritis, scleroderma, sarcoidosis, amyloidosis, Sjogren`s syndrome and hypothyroidism. A systemic disease is the one that affects the entire body. In fact, Xerostomia is not a disease it is a symptom, just like headache is a headache is a symptom and not a disease.⁽⁹⁾

DRUGS WITH ACTIONS ON SALIVATION:

There is usually a fairly close temporal relationship between starting the drug treatment or increasing the dose, and experiencing dry mouth. However, remarkably few studies on drug-related oral dryness have examined salivary flow, much of the data, unfortunately, being based on a subjective complaint of ‘dry mouth’. ⁽¹⁰⁾

MECHANISMS OF ACTION OF XEROGENIC DRUGS:

A number of different mechanisms account for drug-related dry mouth, but an anticholinergic action underlies many. Muscarinic acetylcholine receptors consist of five distinct subtypes. In the periphery, Muscarinic acetylcholine receptor mediate cholinergic signals to autonomic organs, but specific physiological functions of each subtype remain poorly elucidated. ⁽¹¹⁾ The M3-muscarinic receptors mediate parasympathetic cholinergic neurotransmission to salivary glands. Many types of other receptors for endogenous substances in salivary glands exist, suggesting that salivary glands may contain target systems for many drugs. Alpha 1A, beta1, M3, H2 and some other receptors mediate exocytosis via the Camp-protein kinase A pathway; NK-1 and M3Rs via another pathway, diacylglycerol and protein kinase C; and gamma amino butyric acid and benzodiazepines are involved in decreasing fluid secretion and amylase release elicited by secretagogues. ⁽¹²⁾

DRUGS INDUCING XEROSTOMIA:

Several hundred medications can cause or exacerbate xerostomia, ⁽¹³⁾including antihypertensive, anorexiants, antiacne agents, antianxiety agents, anticholinergic, anticonvulsants, antidiarrheals, antiemetics, anti-inflammatory, antinauseants, antiparkinsonian agents, antipsychotics, antidepressants, analgesic, bronchodilators, decongestants, muscle relaxants, sedatives, tranquilizers, diuretics, and antihistamines. ⁽¹⁴⁾ These drugs affect the saliva`s quantity and possibly quality, but usually the problem is temporary or reversible. The most common cause of drug-induced xerostomia is the altering of neural pathways that stimulate salivary glands secretion.⁽¹⁵⁾ Some of the medications causing xerostomia are Abciximab, Adenosine, Alprazolam, Atenolol, Clozapine, Codeine, Cyclosporine, Diazepam, Diaoxide, Diclofenac potassium, Enoxacin, Lovastatin with niacin, Modafinil, Thalidomide, Tolcapone. The list of medications associated with xerostomia continues to grow as new drugs are released. Other drug classes now known to cause xerostomia include the proton pump inhibitors, protease inhibitors and reverse transcriptase inhibitors for HIV infection, analgesic and narcotics for pain control, a variety of anti-infective agents, and some anti-neoplastic agents. ⁽¹⁶⁾

Fig no: 2 Drugs inducing Xerostomia.

NON-PHARMACOLOGICAL CAUSES OF DRY MOUTH:

~ Accidental or surgical trauma.

~ Autoimmune or chronic disease.

~ Bone marrow transplant.

~ Endocrine disorders.

~ Hyposecretory conditions.

~ Mental illness.

~ Radiation.⁽¹⁷⁾

TREATMENT:

Systemic treatment:

Pilocarpine:

This is the only licensed oral treatment available. ⁽¹⁸⁾ The tablets are licensed for the treatment of Xerostomia following:

*Irradiation for head and neck cancers.

*Dry mouth and dry eyes in Sjogren’s syndrome.

Salivary stimulant:

Salivary stimulant can be achieved mechanically by chewing sugarless gum and by chewing (gustatory) stimulation by sucking on sugarless candies or products that contain citric acid, such as vitamin C tablets, lemon drops, or lozenges. ⁽¹⁹⁾

Artificial salivary substitute:

1. Carboxymethyl.

2.Entertainer`s secret, spray

3. Optimoist.

4. Aquoral.

5. Caphosol.

6. Salese.

7. Xylitol.⁽²⁰⁾

PHYSICAL TREATMENT:

Acupuncture has been found useful in the prevention of Xerostomia when administered concurrently with radiotherapy.⁽²¹A technique called acupuncture like transelectrical nerve stimulation is currently being investigated. ⁽²²⁾

PREVENTION:

Surgical transfer of one submandibular gland to the submental space facilitates shielding of the gland during postoperative radiation therapy. Studies have been confirmed that there is no adverse effect on the function of the gland in this position.⁽²³⁾

CONCLUSION:

From the above review, we have evidence that a number of drugs, especially antimuscarinic agents, some sympathomimetic agents, and agents affecting serotonin and noradrenaline uptake, as well as miscellany of other drugs such as protease inhibitors and appetite suppressants, may produce subjective dry mouth. Xerostomia is a common problem and if not recognized and treated, can have a significant effect on a patient’s quality of life. Through proper education, assessment, prevention, referral and appropriate treatment, patients with dentists help, can minimize xerostomia and its effect on dental health and quality of life.

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