[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) › Upper left third molar

[Digestive system](https://durgical.com/en/anatomy/system/digestive-system/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/)

# Upper left third molar

The upper left third molar (tooth 28) is the wisdom tooth, last at the back; it often lacks room to come in and stays stuck (impacted).

[See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=teeth_28&side=r)

Opens in the Durgical app, no sign-up needed.

## What it is

The wisdom tooth: the last molar, usually coming in between the ages of 17 and 25.

## What it does

Grinds food when it erupts fully; often it does not.

## Key points

- Most often impacted upright or tilted backward (distoangular), high in the maxillary tuberosity
- Its removal risks an oroantral communication, displacement of the tooth into the maxillary sinus or the infratemporal fossa, and fracture of the tuberosity
- The last tooth of the upper left arch to erupt, typically at about 17–21 years when it erupts at all

## Key facts

**Joints with**
Alveolar socket of the [maxilla](https://durgical.com/en/anatomy/maxilla/) (gomphosis held by the periodontal ligament); bites against the opposing teeth

**Landmarks**
FDI 28, upper left third molar (wisdom tooth): roots often fused or variable; often impacted or missing; erupts at about 17–25 years; nerve: posterior superior alveolar nerve (V2); roots near the floor of the maxillary sinus

## Relations

**In front**
The [upper left second molar](https://durgical.com/en/anatomy/upper-left-second-molar/)

**Behind**
Maxillary tuberosity and, beyond it, the infratemporal fossa

**Above**
[Maxillary sinus](https://durgical.com/en/anatomy/maxillary-sinus/) floor

**Below**
Opposes only the [lower left third molar](https://durgical.com/en/anatomy/lower-left-third-molar/)

## How to find it

Eighth and last tooth on the upper left, tucked against the maxillary tuberosity behind the second molar; frequently missing or still buried in bone.

## On imaging

A panoramic radiograph shows its angle, its depth in the tuberosity and the sinus floor above it; CBCT is added when the relation to the sinus is unclear.

## Common problems

- Impacted wisdom tooth: stuck under the gum or against the second molar, with pain, swelling or infection (pericoronitis).

## Clinical notes

- Supplied by the posterior superior alveolar nerve; the buccal gum around it is shared with the buccal nerve and the palatal gum with the greater palatine nerve
- Without a lower tooth to bite against it tends to over-erupt (extrude), which can catch food and disturb the bite
- It is hard to clean, so decay is common on it and on the back of the second molar in front

## Anatomical variants

- A small extra tooth can sit behind it (distomolar, a fourth molar) or on its cheek side (paramolar)

## Development

Its germ is one of the last to form, starting to calcify at about 9–10 years; the roots are complete in the early twenties. Absence of one or more third molars is common, at rates that vary by population.

## Memory aid

FDI 28 = quadrant 2, tooth 8. In the US Universal system it is #16, the last tooth of the upper count.

## Test yourself

Think of the answer, then tap the question to see it.

## What are the risks of removing an impacted upper left third molar?

An oroantral communication, displacement into the maxillary sinus or infratemporal fossa, and fracture of the maxillary tuberosity.

## What are a distomolar and a paramolar?

Small extra teeth near the upper third molar: a distomolar (fourth molar) sits behind it, a paramolar on its cheek side.

## What is the US Universal number of the upper left third molar (FDI 28)?

#16, the last tooth of the upper count.

## When does the germ of the upper left third molar begin to calcify?

At about 9–10 years; its roots are complete in the early twenties.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/upper-left-third-molar/)

Educational information, not medical advice. For any symptom, see a health professional.

## Related

- [Maxillae](https://durgical.com/en/anatomy/maxilla/)

Sources: [Anatomy, Head and Neck, Teeth](https://www.ncbi.nlm.nih.gov/books/NBK557543/); [Anatomy, Permanent Dentition](https://www.ncbi.nlm.nih.gov/books/NBK570590/); [Anatomy, Head and Neck, Tooth Eruption](https://www.ncbi.nlm.nih.gov/books/NBK549878/); [Anatomy, Head and Neck: Alveolar Nerve](https://www.ncbi.nlm.nih.gov/books/NBK546712/); [23.3 The Mouth, Pharynx, and Esophagus](https://openstax.org/books/anatomy-and-physiology-2e/pages/23-3-the-mouth-pharynx-and-esophagus) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/anatomy/upper-left-third-molar/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/upper-left-third-molar/