Making room for a crowded tooth 23
When the lower lateral incisors come in crowded, dentists sometimes make room by slimming the sides of the baby canines next to them, or by removing those baby canines. A holding wire (a passive lingual arch) may then keep the space.
There is a trade-off. Removing the lower baby canines straightens the incisors, but studies show it also costs up to 2.7 mm of arch length, so dentists weigh one against the other.
The same tooth on the right side, tooth 26, has its own section on hidden second canals.
Where is tooth 23?
Tooth 23 is in your lower jaw on your left side. It is the second tooth from the middle: start at the gap between the two bottom front teeth and count 2 teeth toward the back on your left side.
In a mirror, tooth 23 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 24, the lower left central incisor. Behind it is tooth 22, the lower left canine.
Its mirror twin on the right side is tooth 26. The tooth in the same spot in the upper jaw is tooth 10, the upper left lateral incisor.
Dental charts show the patient's right side on the left, so tooth 23 sits on the right half of the bottom row. The numbers then drop to the lower jaw: lower left teeth run from 17 (the wisdom tooth) to 24 (the front tooth).
What does the lower lateral incisor do?
Incisors have a thin, straight biting edge for cutting into food. They are the most visible teeth in the mouth. Lower lateral incisors are slightly wider than the lower central incisors beside them, but still among the smallest adult teeth.
Common problems with lower lateral incisors
- Tartar. Hard tartar (calculus) builds up most easily on the tongue side of the six lower front teeth. Brushing and flossing behind these teeth, and regular cleanings, help keep it under control.
- Cavities and chips. 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 23 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 23 come in?
Both the ADA and AAPD charts give 7–8 years for the lower lateral incisors.
Tooth 23 replaces the lower left baby lateral incisor (tooth N), which usually falls out at 7–8 years (ADA).
In the ADA chart, they come in at the same time as the upper central 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 4.
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 10 years, a few years after it comes into the mouth.
How many roots does tooth 23 have?
One narrow root.
Tooth 23 in FDI and Palmer notation
| System | Tooth 23 is written | What it means |
|---|---|---|
| Universal (ADA, used in the US) | 23 | Adult teeth are numbered 1–32 around the mouth, starting at the upper right wisdom tooth. |
| FDI / ISO 3950 (international) | 32 | First digit 3 = lower left quarter; second digit 2 = second tooth from the middle. Said "three-two". |
| Palmer | ┌2 (often typed LL2) | The ┌ bracket marks the lower left quarter; 2 = second tooth from the middle. |
"23" in FDI is a different tooth. Read as an FDI code, 23 means the upper left canine (tooth 11 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, "32" is a different tooth. Universal 32 is the lower right wisdom tooth (tooth 32), so "tooth 32" only means this tooth when the chart uses FDI.
Palmer needs the bracket. Every quarter of the mouth has a tooth 2 in Palmer notation; only the ┌ (or the letters LL) makes it this one.
All adult teeth in the lower left quarter
From the front of the mouth to the back:
| Universal | FDI | Palmer | Tooth |
|---|---|---|---|
| 24 | 31 | ┌1 (LL1) | Central incisor |
| 23 | 32 | ┌2 (LL2) | Lateral incisor (this tooth) |
| 22 | 33 | ┌3 (LL3) | Canine |
| 21 | 34 | ┌4 (LL4) | First premolar |
| 20 | 35 | ┌5 (LL5) | Second premolar |
| 19 | 36 | ┌6 (LL6) | First molar |
| 18 | 37 | ┌7 (LL7) | Second molar |
| 17 | 38 | ┌8 (LL8) | Wisdom tooth |
The Tooth Number Chart & Converter converts any tooth between the three systems.
Tools for tooth 23
- Adult Teeth Predictor: likely dates for your child's adult teeth.
- Dental Emergency Checker: how soon to see a dentist if it hurts or breaks.
- Knocked-Out Tooth Rescue: first aid for a knocked-out adult tooth.
- 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 23?
Is tooth 23 the same as tooth 32?
At what age does tooth 23 come in?
What if tooth 23 comes in crowded?
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.
- Dawes C. Journal of the Canadian Dental Association 72(10):923–926. Why does supragingival calculus form preferentially on the lingual surface of the 6 lower anterior teeth?. 2006. Accessed October 26, 2026.
Last reviewed by the Dental Health Time editorial team, against the sources above. How we review.