Tooth Number 12: Upper Left First Premolar

Tooth 12: braces and cracked roots

Removed for braces. First premolars are often the teeth removed when braces need more room to straighten crowded teeth.

Cracked roots. A crack that runs down the root (a vertical root fracture) is a common reason teeth are pulled. In a study of 736 teeth removed at 24 clinics in Tokyo, it was the main reason for 31.7% of extractions, and 93.6% of those teeth had had a root canal.

Among women in that study, a cracked root was the reason for 43.3% of upper first premolar extractions.

The same tooth on the right side, tooth 5, has its own section on root canals and how often the two sides match.

Where is tooth 12?

Tooth 12 is in your upper jaw on your left side. It is the fourth tooth from the middle: start at the gap between the two top front teeth and count 4 teeth toward the back on your left side.

In a mirror, tooth 12 shows on the left side of your reflection. Someone looking into your mouth sees it on their right.

In front of it (toward the middle) is tooth 11, the upper left canine. Behind it is tooth 13, the upper left second premolar.

Its mirror twin on the right side is tooth 5. The tooth in the same spot in the lower jaw is tooth 21, the lower left first premolar.

Dental charts show the patient's right side on the left, so tooth 12 sits on the right half 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 first premolar do?

Premolars (also called bicuspids) sit between the canines and the molars and help crush and grind food. They have features of both their neighbors. Each upper premolar has two cusps (points), one on the cheek side and one on the tongue side.

It is also called the "first bicuspid".

Adult premolars replace the baby molars. There are no premolars among the 20 baby teeth.

How many roots does tooth 12 have?

Usually 2 roots, one on the cheek side and one on the palate side. It is the premolar that most often has two roots.

When does tooth 12 come in?

Both the ADA and AAPD charts give 10–11 years for the upper first premolars.

Tooth 12 replaces the upper left baby first molar (tooth I), which usually falls out at 9–11 years (ADA).

In the ADA chart, they usually come in after the lower canines (9–10 years) and before the upper second premolars (10–12 years). In the AAPD's 13-step order, from the first molars (step 1) to the wisdom teeth (step 13), they are step 7.

Under the gum, according to the AAPD chart, it starts to harden (calcify) at about 18–24 months, has a finished crown by 5–6 years and has a finished root by about 12–13 years, a few years after it comes into the mouth.

Common problems with upper first premolars

• Cavities and cracks. 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 12 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.

Tooth 12 in FDI and Palmer notation

"12" in FDI is a different tooth. Read as an FDI code, 12 means the upper right lateral incisor (tooth 7 in Universal). Charts and X-ray reports from outside the US often use FDI, so check which system is in use.

On a US chart, "24" is a different tooth. Universal 24 is the lower left central incisor (tooth 24), so "tooth 24" only means this tooth when the chart uses FDI.

Palmer needs the bracket. Every quarter of the mouth has a tooth 4 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:

The Tooth Number Chart & Converter converts any tooth between the three systems.

Tools for tooth 12

• Dental Emergency Checker: how soon to see a dentist if it hurts or breaks.
• Dental Numbness Calculator: how long numbness lasts after a filling.
• Dental Insurance Calculator: what your plan may pay for a crown or root canal.
• 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

Sources

1. American Dental Association (MouthHealthy). Permanent Tooth Development (eruption chart). 2012. Accessed October 26, 2026.
2. American Dental Association (MouthHealthy). Primary Tooth Development (eruption chart). 2012. Accessed October 26, 2026.
3. American Academy of Pediatric Dentistry. Dental Growth and Development (chronology after Logan & Kronfeld 1933, adapted 2003). Accessed October 26, 2026.
4. World Health Organization. Oral health surveys: basic methods, 5th edition (tooth notation after ISO 3950). 2013. Accessed October 26, 2026.
5. Nelson SJ. Elsevier. Wheeler's Dental Anatomy, Physiology and Occlusion, 11th edition. 2019.
6. American Dental Association. ADA Dental Claim Form (tooth designation systems). Accessed October 26, 2026.
7. Dentalcare.com (continuing education course CE500). An Overview of Dental Anatomy: Types of Teeth and their Functions. Accessed October 26, 2026.
8. Dentalcare.com (continuing education course CE500). An Overview of Dental Anatomy: Permanent Dentition. Accessed October 26, 2026.
9. Cleveland Clinic. Teeth: Anatomy, Types, Function & Care. last updated January 26, 2023. Accessed October 26, 2026.
10. Yoshino K, Ito K, Kuroda M, Sugihara N. Clinical Oral Investigations 19(6):1405–1409. Prevalence of vertical root fracture as the reason for tooth extraction in dental clinics. 2015. Accessed October 26, 2026.

Last reviewed October 26, 2026 by the Dental Health Time editorial team, against the sources above. How we review.