The inclusion criteria were as follows: (a) oral burning sensation, at least in the last 6 months; (b) no detection of oral mucosal lesions; and (c) ability to complete the present clinical trial. The exclusion criteria were as follows: (a) diagnosis of Sjögren syndrome on the basis of European criteria ; (b) previous head and neck radiotherapy; (c) diagnosed lymphoma; (d) hepatitis C infection; (c) pregnant or breast-feeding women