Anosmia: A review in the context of coronavirus disease 2019 and orofacial pain

Olfaction is the sense of smell. It is one of the chemical senses, involving the detection of chemical stimuli and conversion of these stimuli into electrical energy for perception via the central nervous system.1 Apart from playing a role in the determination of the flavor of food and beverages, olfaction has a role in acting as an early warning system to detect hazards. Reduction of olfactory function has been shown to be associated with loss of appetite, consumption of bad food, and, in many people, problems with cooking.2 It has been hypothesized that olfaction aids in possible avoidance of food poisoning.3 Olfaction also plays a significant role in the process of enjoyment of food. Most information regarding the flavor of food is thought to come from olfaction.4 Lack of proper olfaction also has been associated with weight loss and weight gain.5,6 The sense of smell is reported in the literature as connected to emotions, either positive or negative.7 Quality of life is reduced significantly in patients with olfactory disorders.8 Olfactory disorders have been reported as prominent features that can be possible early signs of neurodegenerative (ND) diseases.9 Loss of this sensation has been attributed to be one of the first manifesting symptoms in COVID-19.10 In our article, we highlight the basic principles underlying the physiology and pathophysiology of olfaction and its possible relationship with disease entities. We also look at the significance of olfaction as it relates to dentistry and orofacial pain.