As you probably are already aware of, the trigeminal nerve is quite a vast one. It itself has three major branches which innervate a vast region of the head, including such internal parts as the sinuses and dura mater, and, of course, big part of the upper digestion earns credit to the trigeminal nerve – including the muscles involved in chewing and swallowing as well as the sense of your gums and teeth.
All of this is done via smaller branches which furthermore innervate their target structures. The dental plexus is one of those branches, which actually consist of two quite different parts (see the image below, precisely demonstrated by Anatomy Next).
Although they do innervate teeth, the superior branch comes from the maxillary nerve and the inferior branch originates from the mandibular nerve. The superior dental plexus arises from the infraorbital nerve in the infraorbital canal. This branch of nerves furthermore innervates superior molar, premolar, canine and incisor teeth together with gingiva surrounding them before the infraorbital nerve exits the canal via the infraorbital foramen and innervates the skin of the upper lip, cheek, nasal ala, lower eyelid and conjunctiva.
It is always worth remembering the close location of the maxillary sinus. Not only the nerves can be a common thing between the teeth and the maxillary sinus, but part of the dental infections can spread in the sinus as well.
The inferior dental plexus, however, arises from the mandibular branch of the trigeminal nerve as it travels through the mandibular canal on its way to become the mental nerve before giving a branch to the incisive teeth. It is worth noting though, that the gingiva is innerved via the inferior dental plexus just as it is with the upper dental plexus. The incisive branch, as the name suggests, innervates the incisors, and the inferior dental branches innervate the premolars and molars together with the canines.
Although the anatomy of teeth innervation might seem challenging to learn and remember, for me it is a piece of art. Such complex structures are amazing to explore and we really do hope that the illustrations and renders will make it easier for students out there as well. If you want to see the nerve in greater 3D detail, visit anatomynext.com!