Xerostomia in the older adult population, from diagnosis to treatment

| Saliva is important for the preservation and maintenance of normal physiological conditions of oral tissues, and factors influencing its decrease are associated with the risk for oral diseases. Xerostomia is the subjective sensation of oral dryness, which can be influenced by etiological factors including the use of several types of medications, Sjogren’s and metabolic syndromes, head and neck irradiation, among others. Treatment methods for xerostomia vary and can be local or systemic. The aim of this article is to present the results of a literature review addressing the correlation between xerostomia and its incidence and prevalence in the older adult population. Results of this review highlight the importance of diagnosis and appropriate management, and briefly describe treatment modalities and etiological factors such as medications, Sjogren’s syndrome, metabolic syndrome, and head and neck irradiation. DESCRIPTORS | Xerostomia; Dry mouth; Saliva. RESUMO | Xerostomia na população idosa, do diagnóstico ao tratamento: revisão da literatura • A saliva é importante para a preservação e manutenção das condições fisiológicas normais dos tecidos bucais, e os fatores que influenciam sua diminuição estão associados ao risco de doenças bucais. Xerostomia é a sensação subjetiva de secura oral, que pode ser influenciada por fatores etiológicos, incluindo o uso de vários tipos de medicamentos, síndromes metabólicas e de Sjögren, irradiação de cabeça e pescoço, entre outros. Os métodos de tratamento para xerostomia variam e podem ser locais ou sistêmicos. O objetivo deste artigo é apresentar os resultados de uma revisão bibliográfica abordando a correlação entre xerostomia e sua incidência e prevalência na população idosa. Os resultados desta revisão destacam a importância do diagnóstico e do manejo adequado e descrevem brevemente as modalidades de tratamento e fatores etiológicos, como medicamentos, síndrome de Sjögren, síndrome metabólica e irradiação de cabeça e pescoço. DESCRITORES | Xerostomia; Boca seca; Saliva. CORRESPONDING AUTHOR | • Wladimir Gushiken de Campos Department of Oral Medicine, Faculdade de Odontologia, Universidade de São Paulo • Av. Prof. Lineu Prestes, 2227 • São Paulo, SP, Brazil • 05508-00 • E-mail: wgushiken@hotmail.com • Received May 06, 2019. • Accepted Aug. 05, 2019. • DOI http://dx.doi.org/10.11606/issn.2357-8041.clrd.2019.157759 Xerostomia in the older adult population, from diagnosis to treatment: a literature review 2 ● Clin Lab Res Den 2019: 1-7 INTRODUCTION Xerostomia is characterized as the subjective sensation of dry mouth, whereas hyposalivation describes a reduction in salivary flow. Xerostomia, however, does not necessarily imply in a decrease in salivary flow because patients who do not exhibit hyposalivation may exhibit xerostomia.1 Salivary function remains remarkably intact in healthy older adults; however, numerous etiological factors can induce and/or maintain xerostomia, including dehydration, mouth breathing, hormonal changes, autoimmune diseases – e.g., Sjogren’s syndrome –, chronic mouth breathing caused by disease, head and neck irradiation, diseases such as diabetes mellitus, nephritis, thyroid dysfunction, HIV infection, kidney diseases, and continuous use of numerous medications. The latter seems to be the most common cause of xerostomia in older adults because most are treated with at least one medication that causes salivary hypofunction.2 Xerostomia is not directly associated with the normal aging process in older adults but as a consequence of disease, or as a side effect of medication(s).1,3 Approximately 30% of the population ≥ 65 years of age experience some type of dry mouth-related disorder.1 The objective of this study was to perform a review of the literature addressing xerostomia to demonstrate the importance of diagnosis and appropriate management, and to describe applicable treatment modalities. MATERIALS AND METHODS A bibliographic search of the scientific literature indexed in the PubMed and Google Scholar databases was performed using the keywords “Xerostomia”, “Dry mouth”, “Saliva”, and “Elderly”. Articles published in Portuguese and/or English, available in full-text, and published in the past 15 years were included. After screening, 26 articles were selected. Literature review Xerostomia and hyposalivation The term “xerostomia” is related to several concepts and often correlated with decreased salivary flow or simply the subjective sensation of dry mouth, thus causing confusion regarding the term.4 Xerostomia may result from decreased or altered salivary gland function, with changes in salivary quality/quantity.4 Hyposalivation, with or without the sensation of dry mouth, can result from several causes, although its main etiological factors are the inhibition of salivation reflex and alterations in the salivary glands.5 Prevalence of xerostomia Studies addressing the prevalence of xerostomia in diverse populations have reported significant variability, possibly due to the different definitions and instruments used to measure it. As such, prevalence varies from 10% to 46%, with a lower prevalence in men (9.7-25.8%) than in women (10.3-33.3%).6 A recent systematic review suggests a prevalence of approximately 20%, although this figure appears to be higher in older and institutionalized populations.7 It is generally accepted that aging alone has no significant clinical impact on salivary flow; however, the prevalence of xerostomia appears to increase with age, affecting mainly middle-aged and older individuals,8 which can be explained by the greater number of drugs used by these populations. Etiological factors of xerostomia Medication Although aging does not correlate with a higher prevalence of xerostomia, its occurrence may be the result of certain types of drugs used by older populations or the combination of many drugs (i.e., polypharmacy).7 Several studies3,6,9 have reported Campos WG • Esteves CV • Costa K • Andrade ACP • Domaneschi C • Lemos CA Clin Lab Res Den 2019: 1-7 ● 3 that groups of drugs, such as antidepressants, anticholinergics, antihistamines, and anxiolytics and antihypertensives, may largely explain the prevalence of xerostomia. Sjogren’s syndrome Sjogren’s syndrome is a systemic autoimmune disease that generates chronic inflammation of the exocrine glands and usually affects the salivary and lacrimal glands,9 leading to dryness of the major mucosal surfaces including the mouth, eyes, nose, pharynx, larynx, and vagina.8 The etiology of Sjogren’s syndrome appears to have a genetic and environmental basis. The disease affects mostly middle-aged women but can also affect children, men, and older adults. When symptoms of dryness appear in a previously healthy individual, the syndrome is classified as primary Sjogren’s syndrome. Sjogren’s syndrome associated with other underlying systemic autoimmune diseases – e.g., systemic lupus erythematosus, rheumatoid arthritis or scleroderma – is known as secondary Sjogren’s syndrome.10 Metabolic syndrome Metabolic syndrome has received worldwide attention in recent years due to its increasing prevalence (20% to 30%) in the adult population of virtually all Western countries, and has grown in parallel with obesity.11 This syndrome is characterized as a group of related diseases, including hyperglycemia, obesity, hypertension, dyslipidemia, diabetes mellitus and cardiovascular disease, all of which are related to insulin resistance.1 Salivary pH and flow rate are affected by several components of the metabolic syndrome.1 Head and neck irradiation Salivary tissue is highly vulnerable to radiation damage, and the parotid glands are the most easily damaged. Radiation doses as low as 20 Gray (Gy) may cause permanent discontinuation of salivary flow if applied in a single dose. Salivary dysfunction is severe at > 52 Gy doses. Oral cancer treatment usually involves the administration of 60 Gy and 70 Gy doses, which may lead to a rapid decrease in flow during the first week of radiation, with a possible 95% reduction in the region. After 5 weeks of radiation, salivary flow virtually ceases and rarely recovers completely, and stimulated and resting salivary flow is inhibited. The degree of xerostomia depends on the degree of salivary tissue exposed to radiation, with partially irradiated glands exhibiting greater salivary flow than fully irradiated glands.8 Radioiodine treatment has been used to treat thyroid cancer for > 70 years. One of its main complications is xerostomia, which is caused by radiation damage to the salivary glands. Xerostomia rates in these patients are high, ranging from 42.9% to 54%.12 Xerostomia in these patients can lead to an increased susceptibility to dental caries, a higher tendency to develop opportunistic fungal infections (Candida albicans), and loss of denture retention.13 Other conditions Dehydration due to reduced fluid intake, vomiting, and diarrhea may result in xerostomia. Dry mouth is also a common complaint in patients with diabetes mellitus. Psychogenic causes – e.g., fear, stress, depression and anxiety – can also result in xerostomia. In cases of Alzheimer’s disease or stroke, patients may complain of dry mouth in the presence of normal salivary secretion due to altered perception.14 Treatment The first step in treating patients with xerostomia is to establish a correct diagnosis. This often involves a multidisciplinary team of health professionals, among whom communication is essential because many older individuals have concomitant medical problems and polypharmacy complications. The Xerostomia in the older adult population, from diagnosis to treatment: a literature review 4 ● Clin Lab Res Den 2019: 1-7 second step is to schedule frequent dental evaluations of patients at risk of oral complications due to low salivary flow.6 The surfaces of dried mucous membranes and dysphagia are treated with oral moisturizers and lubricants, artificial saliva, and th