Digestive system · Head and neck
Lower left central incisor !
The lower left central incisor (tooth 31) is a small flat front tooth beside the midline that cuts food.
Opens in the Durgical app, no sign-up needed.
What it is
A front tooth with a thin, straight cutting edge and one root.
What it does
Bites into and cuts food; shapes some speech sounds (f, v, th).
Key facts
- Joints with
- Alveolar socket of the mandible (gomphosis held by the periodontal ligament); bites against the opposing teeth
- Landmarks
- FDI 31, lower left central incisor: 1 root; chisel-shaped crown for cutting; erupts at about 6–7 years; nerve: inferior alveolar nerve (V3)
Relations
- Medial
- The lower right central incisor, across the midline
- Lateral
- The lower left lateral incisor
- Above
- The upper left central incisor, whose palatal surface overlaps it in front
- Behind
- Tip and underside of the tongue; the submandibular gland ducts open on the floor of the mouth just behind it
How to find it
Just left of the lower midline (the patient's left), the narrowest tooth in the mouth; pull down the lower lip to see it, or look from behind with a mirror for tartar on its tongue side.
On imaging
A periapical shifted sideways (angled) separates the labial and lingual canals that overlap on a straight view. On a panoramic film this narrow front region is often blurred, so periapicals are preferred.
Common problems
- Chipped or broken front teeth after falls or blows.
Clinical notes
- Supplied by the incisive branch of the inferior alveolar nerve (V3), with fibres crossing from the other side at the midline; the labial bone is thin here, so infiltration works, unlike for the lower molars
- Thin labial bone and gum make this area prone to gum recession, more so with crowding or a strong lower labial frenum
- Periodontitis in teenagers and young adults may concentrate on the incisors and first molars (molar-incisor pattern), and the thin bone here shows the loss early
Development
Replaces the primary lower left central incisor (FDI 71); the permanent germ develops lingual to the primary root.
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
Which is the smallest permanent tooth, and what root canal feature is easy to miss?
The lower central incisor, such as the lower left central incisor; its flattened root often holds 2 canals (labial and lingual).
Which is the only lower tooth that meets a single upper tooth?
The lower central incisor, such as the lower left central incisor: it meets only the upper central incisor.
Why does infiltration numb the lower left central incisor, unlike the lower molars?
Its labial bone is thin; it is supplied by the incisive branch of the inferior alveolar nerve (V3), with fibres crossing from the other side.
Why is the lower left central incisor better seen on a periapical than on a panoramic film?
The narrow front of the panoramic image layer often blurs this region; an angled periapical also separates its two canals.
Educational information, not medical advice. For any symptom, see a health professional.
Related
Sources: Anatomy, Head and Neck, Teeth; Anatomy, Permanent Dentition; Anatomy, Head and Neck, Tooth Eruption; Anatomy, Head and Neck: Alveolar Nerve; 23.3 The Mouth, Pharynx, and Esophagus (OpenStax (Rice University), 2022) · adapted, CC BY 4.0.
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Representative model, for educational purposes only.
