EM evidence on the innervation of dentine and length of odontoblast processes
Holland showed that odontoblast processes extend no more than 1/3 to 1/2 the length of the dentinal tubules in the coronal dentine of cat canines.
Hughes and Matthews showed that, above the pulp cornu in the cat canine, the process was even shorter (c. 1/6 tubule length).
Outer ends of tubules in cat dentine appear to contain extracellular fluid with maybe added protein and cell debris
Lamina limitans confused with odontoblast process in outer dentine in some EM studies.
Denervation studies in cats identified the nerve terminals and showed that they penetrated no more than 100 µm into some tubules, mainly over the pulp cornu.
Human dentine assumed to be similar, although no quantitative studies.
Some evidence for gap junctions between nerve terminals and odontoblast cell bodies. Maybe odontoblast is involved.