Taste changes in orofacial pain conditions and coronavirus disease 2019: a review

Taste sensation has a significant evolutionary, nutritional and protective role in human beings. Changes in the perception of taste can significantly affect the overall quality of life of an individual. A significant proportion of patients with taste changes such as ageusia (complete loss of taste), hypogeusia (diminished taste sensation), dysgeusia (altered/distorted taste sensation including taste phantoms like metallic/bitter taste) present to the dental and medical healthcare professionals. Taste changes may occur as a consequence of normal physiological changes or secondary to pathology. Taste alterations secondary to pathology encompasses various local, systemic factors such as coronavirus disease 2019 (COVID-19), burning mouth syndrome (BMS) and damage or disease of the peripheral or central nervous system (CNS). BMS is one of the most enigmatic and poorly understood orofacial pain condition. Significant proportion of the patients with BMS present with taste changes, taste phantoms, subjective oral dryness and burning sensation. Various local and systemic factors such as local irritants (chemical/mechanical), mucosal lesions, radiation therapy, medications, iatrogenic injury, deficiencies, infections (bacterial, fungal, viral), trauma, endocrine, neuromuscular and autoimmune disorders may induce changes in taste. Taste loss may be a key cardinal clinical feature associated with the COVID-19. The manuscript aims to familiarize the dental and medical healthcare professionals with the taste pathway and pathophysiological mechanisms, diagnostic testing and management.