Maxillary lateral incisor: FDI 12 and 22
The upper incisor next to the canine: narrower than the central, with a palatal pit that can run down the root.
Quick answer
- FDI 12 and 22, Universal 7 and 10, Palmer UR2 and UL2.
- Maxillary lateral incisor erupts at 8 to 9 years.
The numbers on both sides
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Upper right lateral incisor | 12 | 7 | UR2 |
| Upper left lateral incisor | 22 | 10 | UL2 |
In FDI the first digit is the quadrant and the second is the position counted from the midline. 12 is quadrant 1, position 2: the upper right lateral incisor. 22 is the same position in quadrant 2, on the upper left. Universal numbers adult teeth from 1 at the upper right third molar around to 32 at the lower right third molar, which makes this tooth 7 on the upper right and 10 on the upper left. Palmer writes the position inside a bracket that shows the quadrant. In plain text that gives UR2 and UL2.
A plain number can name two different teeth, so the system matters. Universal 12 is the maxillary left first premolar, which is FDI 24. Universal 22 is the mandibular left canine, which is FDI 33.
Crown surfaces: mesial, distal, labial (facial), lingual and incisal.
Development and eruption
| Stage | Age |
|---|---|
| Calcification begins | 10 to 12 months |
| Crown completed | 4 to 5 years |
| Erupts | 8 to 9 years |
| Root completed | 11 years |
Calcification begins at 10 to 12 months, later than any other incisor, and the crown is finished by 4 to 5 years. Eruption at 8 to 9 years follows the central incisor by about a year. The root closes at about 11 years.
Read on 24 October 2026. Sources: Human tooth development, tables citing Ash and Nelson, Wheeler's Dental Anatomy, Physiology and Occlusion (Wikipedia); American Dental Association, Tooth development charts (primary and permanent). Figures are usual values, and teeth vary from person to person.
Crown
The lateral incisor copies the central incisor at a smaller scale. In the tabulated means it is 9.0 mm long and 6.5 mm wide at contact, and it has the smallest mesiodistal crown width of any maxillary tooth. Both incisal angles are rounded, and two mamelons are the usual count on a new tooth.
The lingual side is more pronounced than on the central incisor. The cingulum and the marginal ridges stand out more, the lingual fossa is deeper, and a palatal pit or a palatocervical groove is much more common. After the third molars, this is the tooth with the most variation in crown size and shape.
The mesial contact lies near the junction of the incisal and middle thirds, and the distal contact at the center of the middle third.
Read on 24 October 2026. Sources: Grawish and others, Permanent Maxillary and Mandibular Incisors, in Dental Anatomy (IntechOpen, 2017). Figures are usual values, and teeth vary from person to person.
Roots and canals
One root tapers to a pointed apex that tilts distally. Ingle's Endodontics gives one root and one canal. In the apical third the canal usually bends mainly distally and often palatally. A periapical film shows the distal bend and hides the palatal one.
The palatal groove can run from the lingual pit across the cingulum and down the root. A review of the literature quotes a study of 3,168 extracted maxillary incisors that found the groove in 5.6 percent of lateral incisors and 3.4 percent of central incisors. Over half of the grooves that ran more than 5 mm apical to the cementoenamel junction came with a localized periodontal lesion.
Read on 24 October 2026. Sources: Number of roots and canals, from Ingle's Endodontics (animated-teeth.com); MolarPath note Pulp chambers and root canal morphology (built on Cohen's Pathways of the Pulp, 12th ed.); Gaudex and others, Palatal groove associated with periodontal lesions: a systematic review, BMC Oral Health 2024. Figures are usual values, and teeth vary from person to person.
Neighbors and the baby tooth before it
Next to the canine it is the shorter crown, and next to the central incisor it is the narrower one. It is still wider than either mandibular incisor.
Its primary predecessor is narrower than the primary central incisor and has a crown taller than it is wide. The lateral incisor then guides the maxillary canine: when the lateral incisor is missing or small, the canine is at higher risk of palatal displacement.
Read on 24 October 2026. Sources: MolarPath note Primary tooth morphology (built on McDonald and Avery's Dentistry for the Child and Adolescent, 11th ed.); MolarPath note Eruption sequence and chronology (built on McDonald and Avery, 11th ed., and Proffit's Contemporary Orthodontics, 7th ed.). Figures are usual values, and teeth vary from person to person.
Local anesthesia
The anterior superior alveolar nerve supplies the pulp, and a buccal infiltration near the apex is the usual injection. Because the apex of this tooth often tilts palatally, it sits farther from a buccal deposit than the central incisor does, and a small palatal supplement may be needed when the tooth stays sensitive.
The palatal soft tissue is served by the nasopalatine nerve. Numbing the labial papilla first makes the palatal injection less painful.
Read on 24 October 2026. Sources: MolarPath note Maxillary techniques, local anesthesia (built on Malamed's Handbook of Local Anesthesia, 7th ed.). Figures are usual values, and teeth vary from person to person.
Clinical and exam points
Dens invaginatus is an enamel-lined fold of the crown or root, and the lateral incisor is by far the tooth that shows it most often. The fold can start at the palatal pit.
The AAPD lists the maxillary lateral incisor as the second most frequently missing permanent tooth after the mandibular second premolar, third molars excluded. A peg-shaped lateral incisor is one of the signs that raise suspicion of an impacted canine.
Read on 24 October 2026. Sources: MolarPath note Permanent tooth morphology (built on Wheeler's Dental Anatomy, 11th ed., and Sturdevant's Operative Dentistry, 8th ed.); American Academy of Pediatric Dentistry, Management of the Developing Dentition and Occlusion in Pediatric Dentistry (2024 revision). Figures are usual values, and teeth vary from person to person.
Questions and answers
What are the numbers for the maxillary lateral incisor?
FDI 12 and 22, Universal 7 and 10, Palmer UR2 and UL2.
How common is a palatal groove on this tooth?
A review reports 5.6 percent of lateral incisors and 3.4 percent of central incisors in one study of 3,168 extracted maxillary incisors.
Which permanent teeth are most often missing from birth?
Leaving out third molars, the AAPD names the mandibular second premolar first, the maxillary lateral incisor second and the maxillary second premolar third.
Why can a palatal injection help at this tooth?
The apex often tilts toward the palate, which places it farther from a buccal deposit.
Read on 24 October 2026. Sources: American Dental Association, Tooth development charts (primary and permanent); Gaudex and others, Palatal groove associated with periodontal lesions: a systematic review, BMC Oral Health 2024; American Academy of Pediatric Dentistry, Management of the Developing Dentition and Occlusion in Pediatric Dentistry (2024 revision); MolarPath note Maxillary techniques, local anesthesia (built on Malamed's Handbook of Local Anesthesia, 7th ed.). Figures are usual values, and teeth vary from person to person.
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