[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/) › Lower 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/)

# Lower left third molar

The lower left third molar (tooth 38) 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_38&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

- The most often impacted tooth; Winter's classification describes its tilt (mesioangular, the most common, vertical, horizontal or distoangular)
- The lingual nerve runs against the thin inner (lingual) plate beside it, sometimes above the bone; injury during surgery numbs that side of the [tongue](https://durgical.com/en/anatomy/tongue/) and can disturb taste in its front two thirds
- Its roots often lie close to or across the inferior alveolar canal; nerve injury after removal leaves the lower lip and chin numb on that side
- Dry socket (alveolar osteitis), loss of the clot with severe pain starting a few days later, is most common after lower third molar removal

## Key facts

**Joints with**
Alveolar socket of the mandible (gomphosis held by the periodontal ligament); bites against the opposing teeth

**Landmarks**
FDI 38, lower left third molar (wisdom tooth): roots often fused or variable; often impacted or missing; erupts at about 17–25 years; nerve: inferior alveolar nerve (V3); close to the inferior alveolar canal and the lingual nerve

## Relations

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

**Behind**
Front edge of the ramus of the [mandible](https://durgical.com/en/anatomy/mandible/) and the retromolar area

**Above**
The [upper left second molar](https://durgical.com/en/anatomy/upper-left-second-molar/) and the [upper left third molar](https://durgical.com/en/anatomy/upper-left-third-molar/), when erupted

**Below**
Inferior alveolar canal with the [inferior alveolar nerve](https://durgical.com/en/anatomy/inferior-alveolar-nerve/), artery and vein, often touching the root tips

**Medial**
[Lingual nerve](https://durgical.com/en/anatomy/lingual-nerve/) inside the thin lingual plate; lower down, the submandibular space below the [mylohyoid](https://durgical.com/en/anatomy/mylohyoid-muscle/) line

## How to find it

The last tooth on the lower left, eighth from the midline, against the front of the ramus; when partly erupted only a cusp shows through a flap of gum.

## On imaging

Panoramic radiograph signs of a close canal: darkening of the root where the canal crosses it, a break in the canal's white lines or a diverted canal; cone-beam CT then shows the exact relation.

## Common problems

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

## Clinical notes

- Pericoronitis starts under the gum flap (operculum) over a partly erupted crown; spread into the chewing-muscle spaces brings trismus
- Pell and Gregory grade the impacted tooth by the room left by the ramus (I–III) and its depth against the second molar (A–C)
- Coronectomy, taking off the crown and leaving the roots, is an option when the roots are bound to the canal
- Lower third molars are the most common site of a dentigerous cyst, which forms around the crown of an unerupted tooth

## Anatomical variants

- Crown and roots vary widely: extra or fewer cusps, and roots that are often fused into one cone or curved sharply

## Development

The last teeth to form: calcification begins around 9–10 years and the roots close in the early twenties, so their stage helps estimate age in forensic work.

## Memory aid

FDI 38 = quadrant 3 (lower left), tooth 8. In the US Universal system it is #17, where the lower count begins.

## Related conditions

- [Dental caries](https://durgical.com/en/conditions/dental-caries/)

## Test yourself

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

## What does Winter's classification describe for the lower left third molar, and which form is most common?

Its tilt when impacted: mesioangular (the most common), vertical, horizontal or distoangular.

## Which nerve on the lingual side is at risk in removal of the lower left third molar, and what is the deficit?

The lingual nerve, against the thin lingual plate: numbness of that side of the tongue and possibly altered taste in its front two thirds.

## Which panoramic radiograph signs suggest the roots of the lower left third molar are close to the inferior alveolar canal?

Darkening of the root where the canal crosses it, a break in the canal's white lines or a diverted canal; cone-beam CT then shows the exact relation.

## What is a dry socket after removal of the lower left third molar?

Alveolar osteitis: the clot is lost and severe pain starts a few days after extraction.

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

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

## Related

- [Mandible](https://durgical.com/en/anatomy/mandible/)

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/lower-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/lower-left-third-molar/