Tooth number 17 is the lower left third molar, a permanent (adult) tooth. In the FDI (ISO 3950) system it is 38, and in Palmer notation it is ┌8. It is one of the four wisdom teeth.
Tooth #17 at a glance
| Universal (US) | 17 |
| FDI / ISO 3950 | 38 |
| Palmer | ┌8 |
| Name | Lower left third molar |
| Type | Third molar (adult tooth) |
| Jaw | Lower (mandible) |
| Side | Patient’s left |
| Comes in | 17-21 yrs |
| Roots | 2, often fused together |
| Root canals (usual) | varies |
| Chewing surface | Varies, often 4 or 5 |
Where it is and what it does
It sits in the lower jaw on the patient’s left side, at the very back of the mouth. Third molars (wisdom teeth) are the last teeth to come in. Many jaws do not have enough room for them, so they can come in at an angle, stay partly under the gum, or never appear at all.
Neighbouring and related teeth
- In front of it (toward the midline): Tooth number 18, the lower left second molar
- Same tooth on the other side: Tooth number 32
- The matching tooth in the upper jaw: Tooth number 16
- It does not replace a baby tooth. Adult molars grow in behind the baby teeth.
Common dental work on this tooth
Wisdom teeth are the teeth most often removed. Dentists may suggest removal when a wisdom tooth is impacted (stuck), keeps getting infected, or is hard to keep clean. Many people keep healthy wisdom teeth for life.
Questions
What tooth is number 17?
Tooth number 17 is the lower left third molar. Numbers 1 to 32 are used for adult teeth in the Universal system used in the United States, starting with the upper right wisdom tooth.
What is tooth number 17 in the FDI and Palmer systems?
In FDI it is 38, said digit by digit (“three-eight”). The first digit is the quadrant and the second is the position from the midline. In Palmer notation it is ┌8.
When does tooth 17 come in?
Usually at about 17-21 yrs. Timing varies from person to person, and some people never develop wisdom teeth at all.
For education only. This is not dental advice; your dentist can tell you what is right for your own teeth.