When does tooth N come in and fall out?
The lower baby lateral incisors usually come in at 10–16 months and fall out at 7–8 years (ADA). The AAPD chart gives 7–10 months to come in and 7–8 years to fall out.
In the ADA chart, they usually come in after the upper baby lateral incisors (9–13 months) and before the upper baby first molars (13–19 months), and they fall out at the same time as the upper baby lateral incisors, after the lower baby central incisors (6–7 years) and before the upper baby first molars (9–11 years).
Tooth N is replaced by tooth 23, the lower left lateral incisor, which usually comes in at 7–8 years (ADA). Under the gum, tooth N starts to harden in the 4th month of pregnancy and is fully formed by about 18–24 months (AAPD).
Teething and early care for tooth N
Charts disagree on this tooth. The ADA and AAPD give quite different ages: 10–16 months (ADA) or 7–10 months (AAPD). The AAPD notes that many healthy babies don't follow the schedule exactly.
Teething. Babies may drool, chew more or get a rash around the mouth. The AAP says teething does not cause fever, diarrhea or excess crying, and warns that numbing gels with benzocaine and teething necklaces are not safe.
Brushing. The ADA says to brush with a smear of fluoride toothpaste the size of a grain of rice until age 3, and to book the first dental visit when the first tooth appears.
Not just the front teeth. Early childhood decay most often starts on the upper front teeth, but other teeth can be affected too.
Cavities. The AAPD advises repairing decayed baby teeth when possible, rebuilding each tooth to its original shape so it keeps its place until the adult tooth is ready.
The same tooth on the right side, tooth Q, has its own section on crowding as the adult front teeth come in.
Where is tooth N?
Tooth N is in your child's lower jaw on their 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 their left side.
"Left" and "right" always mean the child's own sides, so when you face your child, tooth N is on your right.
In front of it (toward the middle) is tooth O, the lower left baby central incisor. Behind it is tooth M, the lower left baby canine.
Its mirror twin on the right side is tooth Q. The tooth in the same spot in the upper jaw is tooth G, the upper left baby lateral incisor.
Dental charts show the patient's right side on the left, so tooth N sits on the right half of the bottom row. The letters then drop to the lower jaw: lower left teeth run from K (the back molar) to O (the front tooth).
What does the lower baby lateral incisor do?
Baby incisors are the front teeth young children use to bite and cut soft food. Baby teeth matter even though they fall out: children need them to chew, speak and smile, and they help the adult teeth come in correctly.
How many roots does tooth N have?
One small root, which dissolves as the adult tooth grows underneath.
Common problems with lower baby lateral incisors
- Injuries. Worldwide, about 1 in 5 children (22.7%) injure at least one baby tooth. In baby teeth the most common injury is a tooth pushed out of position (a luxation) rather than a broken tooth.
If a baby tooth is knocked loose or out in a fall, or your child has swelling, fever or pain, call your dentist. Never put a knocked-out baby tooth back in (Knocked-Out Tooth Rescue explains why). Swelling that 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 N in FDI and Palmer notation
| System | Tooth N is written | What it means |
|---|---|---|
| Universal (ADA, used in the US) | N | Baby teeth are lettered A–T around the mouth, starting at the upper right back molar. |
| FDI / ISO 3950 (international) | 72 | First digit 7 = lower left quarter (baby teeth use 5–8); second digit 2 = second baby tooth from the middle. Said "seven-two". |
| Palmer | ┌B (often typed LLB) | The ┌ bracket marks the lower left quarter; B = second baby tooth from the middle. |
Palmer stops at E. Palmer letters only run from A to E in each quarter, so an "N" can only be a Universal letter.
FDI baby teeth start with 5 to 8. The first digit 7 marks the lower left baby quarter, so FDI 72 can't be mixed up with an adult tooth.
Letters and numbers don't line up. N is letter 14 of the alphabet, but baby tooth N is replaced by adult tooth 23, not tooth 14.
All baby teeth in the lower left quarter
From the front of the mouth to the back:
| Universal | FDI | Palmer | Tooth |
|---|---|---|---|
| O | 71 | ┌A (LLA) | Baby central incisor |
| N | 72 | ┌B (LLB) | Baby lateral incisor (this tooth) |
| M | 73 | ┌C (LLC) | Baby canine |
| L | 74 | ┌D (LLD) | Baby first molar |
| K | 75 | ┌E (LLE) | Baby second molar |
The Tooth Number Chart & Converter converts any tooth between the three systems.
Tools for tooth N
- Teething Calculator: which baby teeth are due at your baby's age.
- Baby Teeth Tracker: log each tooth in and out.
- Kids Fluoride Calculator: how much toothpaste to use; the ADA says a rice-grain smear until age 3, then a pea-size amount.
- Tooth Fairy Calculator: what families give for a lost tooth.
- Dental Treatment Plan Decoder: plain English for treatment-plan shorthand like "#30 MOD comp".
Frequently asked questions
What tooth is letter N?
When does tooth N come in?
When does tooth N fall out?
Is it normal if tooth N is late?
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.
- American Dental Association (MouthHealthy). Tooth Decay with Baby Bottles. Accessed October 26, 2026.
- American Academy of Pediatrics (HealthyChildren.org). Teething Pain Relief: How to Soothe Your Baby's Discomfort. updated July 9, 2025. 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.
- Petti S, Glendor U, Andersson L. Dental Traumatology 34(2):71–86. World traumatic dental injury prevalence and incidence, a meta-analysis. 2018. Accessed October 26, 2026.
Last reviewed by the Dental Health Time editorial team, against the sources above. How we review.