53 Introduction Oral dyskinesia is a condition in which oral organs exhibit involuntary movements. It is most commonly observed as tardive dyskinesia in patients taking certain neuroleptic drugs. It is also observed in edentulous patients not receiving these medications, which is sometimes termed as edentulous dyskinesia [1,2]. Unlike oral dyskinesia in tardive dyskinesia, edentulous dyskinesia is caused by ill-fitting dentures, malocclusion, and a lack of sensory contact, although the mechanism remains ill defined. However, it was reported that edentulous patients exhibit increased severity of oral dyskinesia when experiencing tardive dyskinesia [3]. Thus, oral sensation plays an important role in the occurrence or deterioration of oral dyskinesia, but the mechanism and oral factors have not yet been elucidated. Role of Oral Sensory and Serotonergic Neurons in Dopamine-induced Tongue Movement in Rat
