Tooth #19 in particular
About the lower left first molar
Tooth 19 is the lower left first molar, the sixth tooth from the midline in the lower jaw on your left. The same tooth is 36 in FDI numbering and LL6 in Palmer. It stands between the second premolar, tooth 20, and the second molar, tooth 18, and its chewing surface meets tooth 14, the upper left first molar. Like the other first molars it is among the largest teeth and does most of the grinding, and it is one of the first permanent teeth to appear, usually at 6 to 7 years, behind the baby teeth and without taking the place of any. Below the gum it typically has two roots, one toward the front and one toward the back, containing three or four canals.
What tends to go wrong here
Two things work against tooth 19. The first is time: it arrives around age six with deep grooves, and first molars end up being the teeth most often filled, crowned and root-canal treated over a lifetime. The second is force. Lower molars take the heaviest chewing load, which is why cracks are common in them, particularly in a tooth already hollowed by a wide filling. A cracked lower first molar often announces itself as a sharp pain when you bite on something firm or let go of a bite, with sensitivity to cold that comes and goes. Because a crack can deepen with use, that pattern on the lower left is a reason to book a dental exam soon.
If it needs treatment
Numbing a lower molar usually involves an injection further back in the jaw that also numbs the lip and tongue on that side for a few hours, so plan meals around it. For a root canal, the dentist needs to find and clean all three or four canals within the two roots. Because of the chewing load on this tooth, a crown is usually recommended afterward. Ask your dentist whether a crack has been seen or is suspected, how far it extends, whether the tooth should be protected with a temporary crown in the meantime, and how long you can safely wait between the root canal and the final crown.
What it does
What the lower left first molar is for
First molars are the largest teeth and do most of the grinding. They are the first permanent teeth to arrive, behind the baby teeth, without replacing any of them. Often called the "six-year molars".
Anatomy
Roots and canals of tooth #19
Typically two roots with three or four canals. These are typical patterns. The only way to know the anatomy of your own tooth is an x-ray, which is why one is taken before a root canal or extraction.
Common problems
What tends to go wrong with first molars
Because they arrive around age six and have deep grooves, first molars are the teeth most often filled, crowned, and root-canal treated over a lifetime.
If it needs treatment
Root canal, crown, or extraction on tooth #19
Lower molars take the heaviest chewing load, which is why cracks are common and why a crown is usually recommended after a root canal.
| Root canal: what to expect |
| Tooth extraction: what to expect |
| Dental crown: what to expect |
| Extraction or root canal? |
General information · Not dental advice
This page describes a typical first molar. It cannot tell you anything about your own tooth #19. We always recommend seeing a dentist. Nothing on this site can examine your mouth or tell you what is wrong. If something hurts, looks wrong, or worries you, book an exam, and go sooner if it is getting worse.
Emergency? If you have trouble breathing or swallowing, swelling that is spreading toward your eye or neck, a fever with facial swelling, or bleeding that will not stop, call 911 or go to your nearest emergency room immediately. Full disclaimer