Burning Mouth Disorder (BMD) - a Neuropathic Pain Disorder? An Investigation Using Qualitative and Quantitative Sensory Testing (QST)

Oral burning can have many different etiologies. Secondary burning mouth disorders (BMD) due to systemic (i.e. diabetes, nutritional deficiencies, allergies), local (i.e. Candidiasis, Lichen planus) or functional factors (i.e. tongue parafunctional activities, mouth breathing) are usually fairly easy to identify and are treated by eliminating the respective cause. A primary BMD as a specific disease is a challenging disorder with regard to assessment and treatment for both, the patient and the dentist. The prevailing hypothesis of a predominantly psychological cause is questioned by recent research results. The typical burning sensation, the partly efficacy of medication that is usually used in chronic, neuropathic pains and recent neurophysiologic studies and finally the finding of a degeneration of epithelial nerve fibers in BMD patients give reason to assume a peripheral and/or central neuropathic etiology. That is, the transduction of nociceptive stimuli in the orofacial region and the transmission and modulation of the nociceptive input might be altered. The hypothesis of a disorder of the gustatory system assumes that gustatory input has an inhibitory influence on the trigeminal nociceptive system. A hypogeusia or ageusia, maybe caused by peripheral nerve degeneration that has been found in BMD patients would therefore lead to a decreased gustatory input which in turn gives way to a central disinhibition of trigeminal nociception, leading to a more painful perception in the oral region. The aim of this study is to first identify patients with a primary burning mouth disorder by excluding other possible causes for oral burning. By means of qualitative and thermal quantitative sensory testing and a gustatory examination in the individual patient we want to find out whether neurosensory differences exist between patients with a primary BMD and controls and whether gustatory and neurosensory deficits always coexist in BMD-patients.