This is true.  In fact I almost certainly did a root canal treatment on
my mother that was unnecessary early in the stages of her trigeminal
neuralgia.
    Symptoms of trigeminal neuralgia can vary--not all are classical, and
many patients run the gamut of many different specialties before a
diagnosis is reached.  Often there are overlapping clinical entities
that make things even more challenging for the clinician, and more
frustrating to the patient.
    By far the majority of pain of dental origin can be identified as such.
 When in doubt, the good dentist will always make an appropriate referral.

Steve