Tooth #15 in particular
About the upper left second molar
Tooth 15 is the upper left second molar. Count seven teeth back from the center of your upper jaw on the left and you are on it; the FDI system labels it 27 and Palmer notation UL7. In front is tooth 14, the first molar, and behind is tooth 16, the upper left wisdom tooth, when one exists. Its chewing partner below is tooth 18, the lower left second molar. It usually comes through at 12 to 13 years of age, well after the first molar, and takes on part of the grinding at the back of the mouth. Underneath the gum it typically has three roots, often set close together or fused, carrying three or four canals.
What tends to go wrong here
People who look up tooth 15 have often just been told about decay at the very back of the upper left, or about a wisdom tooth pressing on it. Both come down to the same thing: second molars are far back and harder to brush and floss. When tooth 16 comes in tilted or only partway, it rests against the rear surface of tooth 15 and creates a pocket where food and plaque collect. Decay or gum breakdown can start there, hidden between the two teeth. Sometimes the damage to the second molar is discovered only when the wisdom tooth is being assessed. Cavities in the grooves and along the cheek side near the gum are the other frequent findings here.
If it needs treatment
Working on tooth 15 means working with limited room, since access this far back is the main difficulty for any filling, crown or root canal. Its roots are near the sinus, so an x-ray is part of planning. When a wisdom tooth is involved, treatment often has to deal with both teeth, and the order matters. Questions worth raising with your dentist: is the wisdom tooth behind it causing or worsening the problem, and should it be removed first? How much of the back surface is affected? Would a specialist have better access for a root canal? And if the tooth is not restorable, what are the consequences of losing it for tooth 18 below?
What it does
What the upper left second molar is for
Second molars sit behind the first molars and share the grinding. Often called the "twelve-year molars".
Anatomy
Roots and canals of tooth #15
Typically three roots, often closer together or fused, 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 second molars
Being far back, second molars are harder to brush and floss. They are also the tooth a wisdom tooth leans against, which can cause decay or gum problems on their back surface.
If it needs treatment
Root canal, crown, or extraction on tooth #15
Access is the main difficulty: there is less room to work this far back. The roots are near the sinus.
| 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 second molar. It cannot tell you anything about your own tooth #15. 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