Xerostomia is a subjective sensation of dry mouth that may or may not be accompanied by a decrease in the amount of saliva. Hyposialia is a reduction in salivary flow, as measured by sialometry. The aims of the study were to establish the total percentage of patients with actual reduced saliva flow (hyposialia) in a group of patients with perceived reduced saliva flow (xerostomia) and analyse the differences between patients with xerostomia associated with hyposalia and patients with subjective xerostomia.

28 patients with xerostomia were part of the study between November and March 2020-2021 at the Polyclinic of the European University of Madrid. A comprehensive medical history was prepared, 3 questionnaires were completed (Xerostomia Inventory, Perceived Stress Scale and OHIP- 14) and unstimulated sialometry was performed for 5 minutes. Data analysis was performed with the Stata IC v 14 statistics program.

82% of the total patients who reported dry mouth were women, with a mean age of 59.14 years. Less than half of the patients (46%) had hyposialia as evidenced by sialometry. There were more patients with dental prostheses in the group suffering from hyposialia compared to the group with normal salivary flow. Both groups showed a similar number of xerostomising disorders and drugs. There were no significant differences between either group regarding the completed questionnaires.

Xerostomia is the subjective sensation of a dry mouth; whereas hyposalivation is an objectively measured lower volume of saliva produced, according to accepted, standardised values. These two conditions are often confused and misused; they may complementary to each other, but not always. This pathology affects speech, chewing, swallowing and general status. It is also uncomfortable for wearers of prostheses; increases the incidence of tooth decay and periodontal disease; changes the taste of food; leads to halitosis and other symptoms that greatly affect the quality of a patient’s life¹ . The literature establishes the prevalence of xerostomia at around 20% of the population, although studies that place it in a range of 10-46% have been published2 . Among such patients, 30% are women and there is a higher percentage of those with advanced age² . A study conducted in an Australian elderly population found 1 in 5 had xerostomia or hyposalivation, with 1 in 6 having both pathologies: 5.6% of the total sample³ .

Given the known aetiology of xerostomia and hyposalivation, there are many studies that focus on the high percentage of the elderly with this pathology due to their polymedicated status, as this is a risk factor for the change in the composition of saliva, leaving aside any general problems of ageing⁴ . Among the 14 firstlevel medication groups of the Anatomical Therapeutic Chemical (ATC) classification system, 9 were reported as xerostomising medications. The most common are anticholinergics, antidepressants, antihistamines, antiParkinsonians, anti-hypertensive and sedative agents such as benzodiazepines. All of them are very common drugs in the clinical histories of people of all ages, not just the elderly⁵ .

Many common diseases have xerostomia among their symptoms, such as diabetes or depression, with this symptom getting worse with increasing prescribed medication, as is the case with Sjogren’s syndrome and uncontrolled Parkinson’s^6-8. Even certain treatments, such as head and neck radiation, have this type of side effect in most patients who receive it^9,10.

Stress is a risk factor for xerostomia; it is evaluated with questionnaires and is considered related to it¹¹. Smoking also plays a crucial role in this pathology, where it thickens the texture of saliva instead of reducing its volume. The effects of smoking are dependent on the amount consumed¹².

As these two pathologies are different, they have to be diagnosed differently. Xerostomia is a subjective disorder, and is evaluated by a questionnaire, of which here are several in the literature. Predominantly used is the xerostomia inventory, which contains 11 questions and gives a maximum score of 55. It is written in the first person: e.g. “I drink liquids to swallow the food”, “My eyes are so dry”¹³. Another simple diagnostic method to evaluate clinical signs is the Clinical Oral Dryness Score (CODS). This evaluates several parameters in a scoring scale of 10; among them are if the dental mirror adheres to the tongue, if there is saliva on the floor of the mouth and if there is a loss of papillae in the tongue¹⁴. However, to test for hyposalivation, an objective salivary flow measurement, sialometry, is required by. This is a simple test in which the patient expectorates into a container for an average of 5 minutes. This can be unstimulated sialometry or stimulated, using a sugar-free lemon sweet or chewing gum, for example¹⁵. Normal values for unstimulated sialometry are greater than or equal to 0.1 mL/min, and 0.7mL/min for stimulated^16,17.

Currently, there are few effective treatments available. Initially, a change of habits; stress control; stopping or reducing smoking; reducing the dose of medication or replacing it with another less xerostomising; proper hydration; and eating acidic sweets or chewing gum to stimulate the glands¹⁸. Another more palliative treatment option is to use topical sialagogues, such as 1% malic acid, which has been shown to significantly increase saliva volume¹⁹. Systemic sialagogues, such as pilocarpine and cevimeline, parasympathomimetic and muscarinic agonists, have proven effective in the relief of hyposialia even in extreme cases such as patients receiving head and neck radiation. The disadvantages they have are that the stimulation duration is an average of two hours, and numerous side effects can appear²⁰.

Given the confusion that exists between xerostomy and hyposalivation, and considering that they are not always linked and are managed differently in the clinic, the objectives of this study were to determine the proportion of xerostomic patients actually with hyposialia; the frequency of the disease in the different age groups and their distribution by sex. Their association with habits, stress levels, presence of xerostomising disorders and medications was also assessed.