# Development and Proposal of a Novel Scoring System to Classify Dry Month Severity
## 1 Introduction  
Dry mouth is a common complaint, especially among the elderly, and refers both to xerostomia, the subjective feeling of dry mouth, and hyposalivation, an objectively measured reduction in salivary secretion, but there is often not a clear distinction between the two conditions in the literature. The most common cause of both xerostomia and hyposalivation is the anticholinergic side effects of drugs, such as antihistamines, antipsychotics, and antidepressants [1]. Other common causes are systemic diseases affecting the salivary glands like Sjogren's syndrome and connective tissue diseases (e.g., rheumatoid arthritis, systemic lupus erythematosusous), destroyed salivary secretory tissue due to radiotherapy of carcinomas in the head and neck area, and diseases causing dehydration such as diabetes mellitus and chronic renal failure [2; 3]. While xerostomia is bothersome for the patient, hyposalivation may lead to diseases like caries and yeast infections. Saliva substitutes to replace saliva in patients with hyposalivation come in many forms, such as gels and sprays based on various solutions withwater, hydrophilic polymers and glycerol. Unfortunately, most of these products have short-lasting effects due to the short residence time in the oral cavity. Therefore, there is a continuous search for new remedies to relieve and treat these conditions, demonstrated by the fact that there are more than 500 clinical studies on dry mouth registered on ClinicalTrials.gov [4]. When evaluating the various studies and the way patient inclusion and testing of the products are performed, it is striking that these parameters vary to a large extent. The inclusion criteria in the clinical trials may vary from no subjective or objective assessments to single-item questions to comprehensive clinical examinations, questionnaires, and measurements of salivary gland secretion [5; 6; 7]. There is no consensus on the inclusion of dry mouth patients into clinical studies, guidelines for standardized questionnaires to be used or specified clinical examinations to be performed. Thus, the effects of the various products to alleviate dry mouth cannot easily be compared. In the Dry Mouth Clinic at the Faculty of Dentistry, University of Oslo, established in 2015, in collaboration with the Norwegian Dry Eye Clinic, we have for years examined patients with complaints of dry mouth and dry eyes. We have reported clinical characteristics of the oral cavity and the ocular surface, as well as secretory rates and composition of saliva and tears in patients with various etiologies of dryness. During this collaborative work, it has become evident that there are far better screening tools for dryness in ophthalmology than in dentistry. A great tool for the definition and classification of dry eye disease is the dry eye severity grading scheme that grades the dry eye severity into four levels based on nine parameters [8]. No such tool exists for characterizing the severity of dry mouth. Accordingly, several systematic reviews evaluating the prevalence of dry mouth state that the diverse approaches to measure the condition may over- or underestimate the prevalence and that a standardized protocol or a consensus to diagnose dry mouth needs to be developed [9; 10; 11; 12]. At the Dry Mouth Clinic, we have previously examined four different groups of dry mouth patients: primary Sjogren's syndrome, non-Sjogren's syndrome, patients who had received radiation therapy for head and neck cancer, and medicated psychiatric patients [13; 14; 15]. [PERSON]'s syndrome is a systemic autoimmune disease with dry mouth and dry eyes as some of the most common symptoms, together with fatigue and joint pain [16]. The non-Sjogren's syndrome patients in this paper refer to patients with [PERSON]'s syndrome-like symptoms but who do not fulfil the classification criteria for primary Sjogren's syndrome [17]. A vast set of tests was used to characterize these dry mouth patients.