Which nerve fiber types are primarily responsible for the dull, lingering pain of symptomatic irreversible pulpitis and for the initial sharp response to electric pulp testing, respectively?

Dental pulp contains two main types of nociceptive nerve fibers: A-delta fibers — myelinated, fast-conducting (5-30 m/s), responsible for sharp, well-localized pain. They are sensitive to cold and electric stimuli and are responsible for the initial response to EPT and cold testing. They are found primarily in the odontoblast layer and respond to dentinal tubule fluid movement. C fibers — unmyelinated, slow-conducting (0.5-2 m/s), responsible for dull, aching, throbbing, poorly localized, lingering pain characteristic of pulpitis. They respond to inflammation, heat, and sustained stimuli. They are distributed throughout the pulp. In irreversible pulpitis, C fiber activity predominates, causing the characteristic dull, lingering pain.