Chipped tooth 9 and extra teeth
Chips. In adult teeth, broken crowns are the most commonly reported injury. Small chips are usually repaired with tooth-colored bonding; bigger breaks may need a crown.
An extra tooth (mesiodens). Sometimes an extra tooth forms between the two upper central incisors. Between 80% and 90% of all extra teeth are in the upper jaw, and only about 1 in 4 of these middle extra teeth come through the gum on their own. One can block a central incisor or push it off course.
When one front tooth is late. If one upper front tooth comes in long after the other, or a baby front tooth stays too long, dentists look for an extra tooth on X-rays. Removing an erupted extra tooth let the blocked incisor come in on its own in 75% of cases, and the AAPD notes that removing an unerupted one at about age 6 to 7 works better than waiting.
The same tooth on the right side, tooth 8, has its own section on front-tooth injuries and mouthguards.
Where is tooth 9?
Tooth 9 is one of the two top front teeth right in the middle of your mouth: the one on your left side.
In a mirror, tooth 9 shows on the left side of your reflection. Someone looking into your mouth sees it on their right.
Right next to it, across the middle, is tooth 8, the other upper central incisor. Behind it is tooth 10, the upper left lateral incisor.
Its mirror twin on the right side is tooth 8. The tooth in the same spot in the lower jaw is tooth 24, the lower left central incisor.
Dental charts show the patient's right side on the left, so tooth 9 sits just right of the center line of the top row. Universal numbers continue across the top: upper left teeth run from 9 (the front tooth) to 16 (the wisdom tooth).
What does the upper central incisor do?
Incisors have a thin, straight biting edge for cutting into food. They are the most visible teeth in the mouth. The two upper central incisors are your big front teeth. They are larger than the lower central incisors and the widest of all the front teeth.
Common problems with upper central incisors
- Knocked-out tooth. An adult front tooth that is knocked out is a dental emergency. See Knocked-Out Tooth Rescue for first aid.
- Cavities between the front teeth. Small cavities are fixed with a filling. If decay or an injury reaches the nerve, root canal treatment can save the tooth, often followed by a crown.
If tooth 9 hurts, feels loose, or the gum around it swells, the Dental Emergency Checker can help you decide how soon to see a dentist. Swelling that spreads to the eye or neck, or makes it hard to breathe or swallow, is an emergency: call 911. These are typical problems for this kind of tooth, not a diagnosis.
When does tooth 9 come in?
Both the ADA and AAPD charts give 7–8 years for the upper central incisors.
Tooth 9 replaces the upper left baby central incisor (tooth F), which usually falls out at 6–7 years (ADA).
In the ADA chart, they come in at the same time as the lower lateral incisors, after the lower central incisors (6–7 years) and before the upper lateral incisors (8–9 years). In the AAPD's 13-step order, from the first molars (step 1) to the wisdom teeth (step 13), they are step 3.
Under the gum, according to the AAPD chart, it starts to harden (calcify) at about 3–4 months, has a finished crown by 4–5 years and has a finished root by about 9–10 years, a few years after it comes into the mouth.
How many roots does tooth 9 have?
One straight, cone-shaped root.
Tooth 9 in FDI and Palmer notation
| System | Tooth 9 is written | What it means |
|---|---|---|
| Universal (ADA, used in the US) | 9 | Adult teeth are numbered 1–32 around the mouth, starting at the upper right wisdom tooth. |
| FDI / ISO 3950 (international) | 21 | First digit 2 = upper left quarter; second digit 1 = first tooth from the middle. Said "two-one". |
| Palmer | └1 (often typed UL1) | The └ bracket marks the upper left quarter; 1 = first tooth from the middle. |
A lone "9" can only be Universal. FDI codes always have two digits, so 9 on its own is never an FDI number.
On a US chart, "21" is a different tooth. Universal 21 is the lower left first premolar (tooth 21), so "tooth 21" only means this tooth when the chart uses FDI.
Palmer needs the bracket. Every quarter of the mouth has a tooth 1 in Palmer notation; only the └ (or the letters UL) makes it this one.
All adult teeth in the upper left quarter
From the front of the mouth to the back:
| Universal | FDI | Palmer | Tooth |
|---|---|---|---|
| 9 | 21 | └1 (UL1) | Central incisor (this tooth) |
| 10 | 22 | └2 (UL2) | Lateral incisor |
| 11 | 23 | └3 (UL3) | Canine |
| 12 | 24 | └4 (UL4) | First premolar |
| 13 | 25 | └5 (UL5) | Second premolar |
| 14 | 26 | └6 (UL6) | First molar |
| 15 | 27 | └7 (UL7) | Second molar |
| 16 | 28 | └8 (UL8) | Wisdom tooth |
The Tooth Number Chart & Converter converts any tooth between the three systems.
Tools for tooth 9
- Knocked-Out Tooth Rescue: first aid for a knocked-out adult tooth.
- Dental Emergency Checker: how soon to see a dentist if it hurts or breaks.
- Adult Teeth Predictor: likely dates for your child's adult teeth.
- How Long Does Dental Work Last?: how long fillings, crowns, veneers and implants usually last, from long-term studies.
- Dental Treatment Plan Decoder: plain English for treatment-plan shorthand like "#30 MOD comp".
Frequently asked questions
What tooth is number 9?
Is tooth 9 the same as tooth 21?
At what age does tooth 9 come in?
Can an extra tooth stop tooth 9 from coming in?
Sources
- American Dental Association (MouthHealthy). Permanent Tooth Development (eruption chart). 2012. Accessed October 26, 2026.
- American Dental Association (MouthHealthy). Primary Tooth Development (eruption chart). 2012. Accessed October 26, 2026.
- American Academy of Pediatric Dentistry. Dental Growth and Development (chronology after Logan & Kronfeld 1933, adapted 2003). Accessed October 26, 2026.
- American Academy of Pediatric Dentistry. Management of the Developing Dentition and Occlusion in Pediatric Dentistry (Reference Manual of Pediatric Dentistry). latest revision 2024. Accessed October 26, 2026.
- World Health Organization. Oral health surveys: basic methods, 5th edition (tooth notation after ISO 3950). 2013. Accessed October 26, 2026.
- Nelson SJ. Elsevier. Wheeler's Dental Anatomy, Physiology and Occlusion, 11th edition. 2019.
- American Dental Association. ADA Dental Claim Form (tooth designation systems). Accessed October 26, 2026.
- Dentalcare.com (continuing education course CE500). An Overview of Dental Anatomy: Types of Teeth and their Functions. Accessed October 26, 2026.
- Cleveland Clinic. Teeth: Anatomy, Types, Function & Care. last updated January 26, 2023. Accessed October 26, 2026.
- Levin L et al. (International Association of Dental Traumatology). Dental Traumatology 36(4):309–313. IADT guidelines for the management of traumatic dental injuries: General introduction. 2020. Accessed October 26, 2026.
Last reviewed by the Dental Health Time editorial team, against the sources above. How we review.