Jingszo !

Immunofluorescence analysis shows that the external odontodes of extant chondrichthyans and teleosts retain extensive innervation suggestive of a sensory function akin to teeth These patterns of convergence and innervation reveal that dentine evolved as a sensory tissue in the exoskeleton of early vertebrates, a function retained in modern vertebrate teeth.

Middle-Ordovician fossils now represent the oldest known evidence for vertebrate dental tissues.

An ancestral sensory function of dentine reveals that independent vertebrate dental specializations, or autapomorphies, reflect a shared history. Notably, there are numerous reports of modern vertebrates with sensitive external odontodes. Blind catfish have specialized dermal odontodes that have a purported sensory function.

Several mammals, such as narwhals, have specialized dentition that serves a sensory function.

Odontoblasts themselves are widely recognized to be sensory cells.

When viewed through this evolutionary lens, the fact that teeth in the mouth are extremely sensitive is less of a mystery, and more a reflection of their evolutionary origins within the sensory armour of early vertebrates.