Tooth number 9 is the upper left central incisor, a permanent (adult) tooth. In the FDI (ISO 3950) system it is 21, and in Palmer notation it is └1.
Tooth #9 at a glance
| Universal (US) | 9 |
| FDI / ISO 3950 | 21 |
| Palmer | └1 |
| Name | Upper left central incisor |
| Type | Central incisor (adult tooth) |
| Jaw | Upper (maxilla) |
| Side | Patient’s left |
| Comes in | 7-8 yrs |
| Roots | 1 |
| Root canals (usual) | 1 |
| Chewing surface | An incisal (biting) edge |
Where it is and what it does
It sits in the upper jaw on the patient’s left side, right at the front, next to the midline. Incisors are cutting teeth. Their thin, flat edges bite through food, and they matter a lot for speech and for how a smile looks.
Neighbouring and related teeth
- Across the midline: Tooth number 8, the upper right central incisor
- Behind it: Tooth number 10, the upper left lateral incisor
- The matching tooth in the lower jaw: Tooth number 24
- Replaces: Baby tooth F, the baby upper left central incisor
Common dental work on this tooth
Front teeth are often chipped or knocked. Common treatments include bonding (tooth-coloured filling material), veneers, crowns and, after an injury that reaches the nerve, a root canal.
Questions
What tooth is number 9?
Tooth number 9 is the upper left central incisor. 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 9 in the FDI and Palmer systems?
In FDI it is 21, said digit by digit (“two-one”). The first digit is the quadrant and the second is the position from the midline. In Palmer notation it is └1.
When does tooth 9 come in?
Usually at about 7-8 yrs. Timing varies from person to person.
For education only. This is not dental advice; your dentist can tell you what is right for your own teeth.