Introduction

With the advent of an ageing society, the number of patients with xerostomia and its related conditions is increasing rapidly. As a result, treatment demand in dental clinics is changing and will change even more rapidly in the near future.

Burning mouth, taste disturbance, and oral malodor are related to xerostomia. A decrease in salivation affects taste function and increases the severities of oral mucosal burning pain and malodor. These symptoms share the same or related etiologies, and therefore can be present together in the same patient. Patients with multiple diagnoses may experience greater severity of symptoms than patients with a single diagnosis. Therefore, in order to prepare for increasing treatment needs, information regarding the prevalence, severity, and relationships of xerostomia and its related conditions is needed.

Most studies regarding the prevalence of xerostomia have been performed in elderly residents and elderly hospitalized or institutionalized persons; in these studies, the prevalence has ranged from 17.0% to 62.9%. Studies involving adults of all ages have reported xerostomia to be a common condition at all ages with a prevalence ranging from 7.0% to 34.2%. These previous studies have shown that the prevalence of xerostomia increases with age and that xerostomia is more common in women than in men.

Burning mouth is a common symptom among middle-aged and elderly women who attend dental clinics. This distressing sensation results from a complex interaction among local, systemic, and/or psychogenic factors. When no local or systemic factors are found upon clinical and laboratory examinations, a diagnosis of burning mouth syndrome is suggested. According to criteria used in previous studies, the prevalence of burning mouth in the general population is highly variable, ranging from 0.7% to 14.8%.

Data concerning taste disturbance also usually come from patients in chemosensory clinics or patients with certain types of diseases or conditions, and not from the general population. The prevalence of taste disturbance in the general population was found to be 0.93–8.3% in studies using questionnaires. In studies using examination-based measures, the prevalence increased to 5.3–20%. Taste disturbance was found to increase with age, and a gender difference was not apparent.

Oral malodor is one of several very common symptoms in the general population, with a reported prevalence rate between 15% and 32%, mainly depending on the type of evaluation method used. Reports on prevalence according to age and gender have not been consistent.

Most available information on the prevalence of xerostomia and its related conditions concerns specific age or gender groups, or groups with specific diseases or conditions. Information about the prevalence in adults of all ages is limited and information about the relationships between xerostomia and its related conditions is sparse. The purpose of the present study was to investigate the prevalence, severity, and relationships between xerostomia and its related conditions in adults of all ages who attended hospital for general health examinations.