Although they seem pretty solid, our teeth are hollow inside – all the way to the roots. The core is filled with nerves, blood vessels and a connective tissue called dental pulp. In the actual tooth, this space is known as the coronal chamber, but when you get down to the roots, they’re called canals. The blood vessels run through the centres like graphite in a pencil. A ‘root canal’ is also used to describe a dental procedure in which the pulp and other tissues are removed and replaced with a filler. This is usually done when the tooth is severely infected, and while considered ‘dead’, the tooth can at least be preserved.