Pain in the trigeminal system, including dental pain, is ‘special’. Not only is the trigeminal nerve the largest sensory nerve in the body, represented by over 50% of the sensory cortex, but it is the only sensory nerve with an intracranial distal root ganglion: the trigeminal ganglion. It is also the ‘great protector’ of many vital structures, including the meninges, eyes, ears, nose, and mouth, underpinning survival and enjoyment of life. As such, any pain within the trigeminal system is met with varying degrees of angst, fear, and trepidation. This explains, in part, why phobia of dentists and dental procedures is so common. In addition, chronic pain within the trigeminal system has a significant negative quality-of-life impact, including suicidal tendencies in some patients.1
Healthy (nociceptive and inflammatory) and unhealthy (neuropathic and dysfunctional) pains in the trigeminal system tend to be interpreted and reacted to in many different ways under different circumstances.2
Dental pain is unique, given that pulpal nerves experience pain only on stimulation. Thus, the teeth are the only parts of the body within which allodynia is ‘normal’. Dental pain is amongst the most common forms of pain known to humankind, elicited typically by dental caries, resulting in inflammation of the dental pulp (Figure 1). Initially, symptoms are temporary acute allodynic pain (lasting seconds) well localised to the affected tooth, elicited by hot and cold stimuli and sugary and acidic foods (reversible pulpitis); subsequently, there is spontaneous, acute allodynic pain of variable duration (minutes), possibly poorly localised to the affected tooth (irreversible pulpitis). The treatment for reversible pulpitis is to manage dental decay and restore the tooth with a restoration; for irreversible pulpitis it is to remove the decay and the dental pulp, and place a restoration following endodontic …