The prevalence of atypical facial pain and other disturbances of oral sensation (glossalgia, subjective xerostomia and dysgeusia) will be studied in several population samples of dental and medical patients. Each sample will be surveyed by questionnaire relating to persistent oral and facial pain, burning sensations, dry mouth, and taste and other sensation abnormalities. Patients reporting these chronic symptoms will be investigated in detail as to the nature of their complaint and any associated local and systemic diseases. The survey will include the entire census of patients coming to the clinics of a dental school, as well as samples of patients receiving endodontic treatment, patients with diagnosed depression and patients attending gastro-intestinal, rheumatology and metabolic clinics of a community hospital. Patients with disturbed oral sensation who are identified in the survey, as well as similar patients referred to the investigators, will be further studied for their response to experimentally-induced pain, for their taste sensitivity, their salivary gland function and the rate of electrical discharge from their oro-facial musculature. On the basis of these data, a comparison will be made between patients with different types of disturbed oral sensation, and between these patients and matched controls, to test the hypothesis that atypical facial pain, glossalgia, subjective xerostomia and taste aberrations are variants of a single syndrome and not independent problems. The association of diabetes, TMJ myofascial dysfunction syndrome, depression and mental cation (Zn ions) metabolism with each of these syndromes will also be studied.