Because with a tooth nerve fiber distribution, therefore when damage teeth, teeth of the stimulation of nerve tissue is directly or indirectly, to the central, people will feel a toothache.
Tooth the tooth itself, including the enamel, dentine, cementum three calcification of hard tissue and a kind of soft tissue of the pulp.Dentin constitute the main body of teeth, tooth enamel covers the surface of dental crowns, cementum covering on the root surface, the central cavity is there for the pulp cavity, the pulp cavity with dental pulp tissue, blood vessels and nerves which associated with periodontal tissue by narrow root hole.
Dentin to external mechanical, temperature and chemical stimulation has obvious reaction.There are nerve fibers in the dentin small tube.Dentin feeling passed to external stimuli commonly direct stimulation of nerve endings of dentin, then transfer to central, or external stimuli causing dentin tubule content flows, indirect make pulp dentine border nerve endings impulses (fluid mechanics hypothesis), or irritation of the outburst made dental cells will be caused to the cell body cell body changes and surface charge of contact with nerve endings.
Nerve is very rich, and dental pulp cavity from alveolar nerve branches with holes into the dental pulp, blood vessels from the apex and then divided into many thin and more thin branches.Enter the dental pulp nerve mostly myelinated nerve, conduction of pain, a few to no myelinated nerve, for the sympathetic nerve, adjustable in systolic and diastolic blood vessels.So when the tooth damage and dentine and dental pulp, the patient will feel a toothache.