# Prediction of Dry Mouth Condition Using Radiomics Features from Tongue Diagnosis Image
## 1 Introduction  
Xerostomia, commonly referred to as dry mouth, is a condition characterized by reduced salivary secretion. This condition is particularly prevalent among the elderly and can significantly affect oral health and quality of life [1]. Water accounts for approximately 99% of saliva, and other components include inorganic salts such as sodium, potassium, calcium, magnesium, and organic materials such as amylase, lysozyme, lactoferrin, immunoglobulin, and glycoprotein. [2]. These components contained in saliva help maintain a proper pH in the oral cavity and enable antibacterial effects. Saliva has various physiological functions that are essential to oral hygiene, playing a crucial role in maintaining homeostasis in the tongue and mouth [3]. A reduction in saliva can lead to a range of oral health issues and discomfort. Symptoms associated with xerostomia include difficulty chewing and swallowing, a persistently dry or sore throat, and bad breath resulting from bacterial growth. Additionally, this condition increases the risk of dental caries, gum disease, and oral infections due to the diminished protective and cleansing properties of saliva [4, 5, 6, 7]. The prevalence of xerostomia is approximately 20% in the general population, rising to 30% in women and up to 50% in the elderly [8]. Xerostomia refers to the subjective sensation of dry mouth, while hyposulivation is defined as an objective reduction in salivary flow [1; 2], typically diagnosed when saliva production is equal to or less than 0.1-0.2 mL per minute. Hyposulivation may or may not be accompanied by the perception of dry mouth (xerostomia), a condition frequently reported among older adults. In the general population, the prevalence of hyposulivation ranges from 14.4% to 20%, but it exceeds 50% in individuals with autoimmune diseases [3; 4]. As life expectancy continues to rise, the prevalence of dry mouth is also increasing, driving greater interest in these conditions. The diagnosis of xerostomia involves several key factors, including symptoms, medication use, past medical history, and oral examination. Specifically, the symptoms associated with xerostomia include a persistent feeling of dry mouth, difficulty swallowing, intolerance to spicy or acidic foods, and discomfort when consuming crunchy foods [9]. To assess the presence of xerostomia, several research teams have proposed the use of structured questionnaires for patients, with diagnosis being based on the scoring results from these tools [10; 11; 12]. Additionally, careful oral examination for clinical pathognomonic signs--such as frothy saliva, the loss of papillae on the dorsal surface of the tongue, or a glassy appearance of the oral mucosa--serves as another diagnostic approach [13]. These approaches can be subjective, varying depending on the patient or physician, and therefore may have limitations in terms of objectively diagnosing the condition. One of the most straightforward and direct diagnostic methods currently used in clinical settings is the measurement of salivary flow. Depending on the targeted salivary gland, whether a major or minor salivary gland, salivary flow can be measured under stimulated or unstimulated conditions. Measurement methods vary according to the proposing research group, including differences in duration (ranging from 1 to 15 min) and technique (such as draining or absorbent strip methods) [14; 15; 16]. Generally, a flow rate of less than 0.1 mL per minute is considered indicative of dry mouth [17]. In addition, salivary gland function tests, such as scans or CT imaging, help detect structural or functional abnormalities. Biopsies of minor salivary glands can be used to differentiate autoimmune diseases, such as Sjogren's syndrome [18]. Blood tests are also employed to detect systemic or autoimmune conditions that may contribute to dry mouth. Despite these diagnostic methods, limitations exist. Diagnosis often relies on subjective patient reports, which can vary due to individual perceptions.