A random thought for the day....
Does fear of dentists highlight one of the many peculiarities of the human mind? When somebody has dental pain, perhaps letting a tooth become abcessed, before seeing a dentist, they suffer through a type of chronic pain that is far more prolonged than they would experience by obtaining prompt dental care. They will often require a more invasive dental procedure, have more discomfort during that procedure, and have a more complicated recovery... which, rather than convincing them to never again delay proper dental care, probably contributes to their phobia.
