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# Upper right second premolar

The upper right second premolar (tooth 15) is the tooth between the first premolar and the first molar; it helps crush and grind food.

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## What it is

A transition tooth with two cusps and one root, just in front of the molars.

## What it does

Crushes and tears food.

## Key points

- Its buccal and palatal cusps are almost the same height, unlike the upper first premolar, and it usually has a single canal (some have two)
- Its root tip is often very close to the floor of the maxillary sinus, so infection or extraction can involve the sinus

## 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 15, upper right second premolar: 1 root; two cusps of about equal height; erupts at about 10–12 years; nerve: middle superior alveolar nerve (V2)

## Relations

**In front**
The [upper right first premolar](https://durgical.com/en/anatomy/upper-right-first-premolar/)

**Behind**
The [upper right first molar](https://durgical.com/en/anatomy/upper-right-first-molar/)

**Above**
Floor of the [maxillary sinus](https://durgical.com/en/anatomy/maxillary-sinus/), separated from the root tip by thin bone or, at times, only by the sinus lining

**Below**
Opposes the [lower right second premolar](https://durgical.com/en/anatomy/lower-right-second-premolar/) and the [lower right first molar](https://durgical.com/en/anatomy/lower-right-first-molar/)

## How to find it

Fifth tooth from the midline on the upper right, in front of the first molar; its two cusps are nearly equal in height.

## On imaging

A periapical shows how near its apex lies to the sinus floor. In a child, a panoramic film shows its germ between the roots of the primary second molar and reveals whether it is missing.

## Clinical notes

- Middle superior alveolar nerve when present, otherwise the neighbouring superior alveolar branches; buccal infiltration reaches it through thin bone, while the palatal gum depends on the greater palatine nerve
- After extraction a thin sinus floor can open into the socket (oroantral communication), letting air or fluid pass between the mouth and the nose
- If the primary second molar above it is lost early, the first permanent molar drifts forward and can block this tooth's eruption; a space maintainer prevents this

## Development

Replaces the primary [upper right second molar](https://durgical.com/en/anatomy/upper-right-second-molar/) (FDI 55): a two-cusped premolar takes the place of a wider primary tooth with the shape of a molar.

## Related conditions

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

## Test yourself

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

## How does the upper right second premolar differ from the upper first premolar?

Its buccal and palatal cusps are almost the same height, and it usually has a single root and canal.

## Why can extraction of the upper right second premolar cause an oroantral communication?

Its root tip is often very close to the floor of the maxillary sinus, which can open into the socket.

## Which nerve supplies the palatal gum of the upper right second premolar?

The greater palatine nerve.

## What can happen to the upper right second premolar if the primary second molar is lost early?

The first permanent molar drifts forward into the gap and can block its eruption.

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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/).

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Representative model, for educational purposes only.

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