Psychophysical Assessment of Gustatory Function in Burning Mouth Syndrome: A Systematic Review.

OBJECTIVE: To evaluate whether psychophysically assessed gustatory function differs between adults with burning mouth syndrome and age- and sex-matched healthy controls, and to explore related sensory and physiological factors. METHODS: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol was prospectively registered on the Open Science Framework. MEDLINE, Scopus, and Embase were searched up to 3 November 2025. Observational studies assessing gustatory function in patients with burning mouth syndrome and healthy controls were included. Methodological quality was assessed using the Newcastle-Ottawa Scale. RESULTS: Seven studies of acceptable methodological quality were included. Gustatory function was assessed using electrogustometry and chemogustometry. Electrogustometry indicated elevated gustatory thresholds and increased taste-to-tingling ratios in burning mouth syndrome, suggesting reduced sensitivity. Chemogustometric findings were heterogeneous, ranging from reduced scores or altered thresholds for specific gustatory qualities to no significant group differences. Substantial overlap between groups was observed. Salivary parameters and peripheral gustatory structures appeared largely preserved, whereas findings for related sensory modalities were inconsistent. CONCLUSION: Current evidence does not support uniform gustatory dysfunction in burning mouth syndrome. Findings are heterogeneous and appear dependent on diagnostic criteria and assessment methods. Standardised approaches are needed to clarify their clinical relevance.