Psychoneurobiological Aspects of Burning Mouth Syndrome and Oral Lichen Planus: A Narrative Review.

Burning mouth syndrome (BMS) and oral lichen planus (OLP) are two chronic oral diseases/disorders that continue to pose a challenge for conventional diagnosis and treatment. Both diseases do not occur in isolation but rather appear to reflect a broader interplay of psychological, neurological, endocrine, and immunological factors, i.e., complex disorders in interconnected biological and psychological systems. In BMS, patients often suffer from persistent burning sensations without visible lesions, which may be related to altered pain processing, emotional stress, and dysregulation in the brain regions responsible for interoception and perception. Although OLP is primarily characterised by immune-mediated mucosal damage, it often has significant psychological comorbidity, particularly in the erosive form. Common features such as cortisol imbalance, disturbed cytokine patterns, and high levels of anxiety and depression suggest that these conditions may be due to overlapping systemic disorders. It is no longer sufficient to focus only on the visible lesions or symptom relief. Understanding these diseases/disorders through a more comprehensive psychoneuroendocrine immune system (PNEI) opens up new opportunities for early intervention, improved diagnostics, and more personalised therapeutic strategies that go beyond treating symptoms. Ultimately, these diseases/disorders require a more integrated and patient-centred approach, where understanding the whole system is as important as treating its individual parts.