Tooth Letter R: Lower Right Baby Canine

When does tooth R come in and fall out?

The lower baby canines usually come in at 17–23 months and fall out at 9–12 years (ADA). The AAPD chart gives 16–20 months to come in and 9–11 years to fall out.

In the ADA chart, they usually come in after the upper baby canines (16–22 months) and before the lower baby second molars (23–31 months), and they usually fall out after the lower baby first molars (9–11 years) and before the upper baby second molars (10–12 years).

Tooth R is replaced by tooth 27, the lower right canine, which usually comes in at 9–10 years (ADA). Under the gum, tooth R starts to harden in the 4th month of pregnancy and is fully formed by about 30–39 months (AAPD).

If tooth R is lost early

Losing one lower baby canine early has been reported to shift the middle of the lower teeth, and removing the other one is often recommended to even it out. But a review of the Iowa and Toronto growth studies found the lower midline did not change significantly after one baby canine was lost early.

Saving space. When lower baby canines are removed to relieve crowding, a holding wire (passive lingual arch) has been suggested. With one in place, about 9 in 10 children could fit all their adult teeth with 2 mm of extra arch length, and 60% needed no extra length at all.

Losing it early. If a baby tooth is lost early to decay or injury, nearby teeth can drift into the room the adult tooth needs. Dentists sometimes fit a space maintainer, though the AAPD notes the evidence on how well they prevent crowding is limited.

The same tooth on the left side, tooth M, has its own section on removing it to make room for crowded incisors.

Where is tooth R?

Tooth R is in your child's lower jaw on their right side. It is the third tooth from the middle: start at the gap between the two bottom front teeth and count 3 teeth toward the back on their right side.

"Left" and "right" always mean the child's own sides, so when you face your child, tooth R is on your left.

In front of it (toward the middle) is tooth Q, the lower right baby lateral incisor. Behind it is tooth S, the lower right baby first molar.

Its mirror twin on the left side is tooth M. The tooth in the same spot in the upper jaw is tooth C, the upper right baby canine.

Dental charts show the patient's right side on the left, so tooth R sits on the left half of the bottom row. Lower right teeth finish the circle, from P (the front tooth) to T (the back molar).

What does the lower baby canine do?

Baby canines are pointed teeth that help tear food and keep room for the adult canines. 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 R have?

One root.

Common problems with lower baby canines

• 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.

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 R in FDI and Palmer notation

Palmer stops at E. Palmer letters only run from A to E in each quarter, so an "R" can only be a Universal letter.

FDI baby teeth start with 5 to 8. The first digit 8 marks the lower right baby quarter, so FDI 83 can't be mixed up with an adult tooth.

Letters and numbers don't line up. R is letter 18 of the alphabet, but baby tooth R is replaced by adult tooth 27, not tooth 18.

All baby teeth in the lower right 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 R

• 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

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. 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.
5. World Health Organization. Oral health surveys: basic methods, 5th edition (tooth notation after ISO 3950). 2013. Accessed October 26, 2026.
6. Nelson SJ. Elsevier. Wheeler's Dental Anatomy, Physiology and Occlusion, 11th edition. 2019.
7. American Dental Association. ADA Dental Claim Form (tooth designation systems). Accessed October 26, 2026.
8. Dentalcare.com (continuing education course CE500). An Overview of Dental Anatomy: Types of Teeth and their Functions. Accessed October 26, 2026.
9. American Dental Association (MouthHealthy). Tooth Decay with Baby Bottles. Accessed October 26, 2026.

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