[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 second premolar [Digestive system](https://durgical.com/en/anatomy/system/digestive-system/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Lower left second premolar The lower left second premolar (tooth 35) is the tooth between the first premolar and the first molar; it helps crush and grind food. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=teeth_35&side=r) Opens in the Durgical app, no sign-up needed. ## 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 - After the third molars it is one of the teeth most often missing from birth; the primary second molar then may stay into adult life - The mental foramen is most often found below or just in front of its root tip; on a radiograph the foramen can mimic a lesion at the apex ## Key facts **Joints with** Alveolar socket of the [mandible](https://durgical.com/en/anatomy/mandible/) (gomphosis held by the periodontal ligament); bites against the opposing teeth **Landmarks** FDI 35, lower left second premolar: 1 root; two or three cusps; lies near the mental foramen; erupts at about 11–12 years; nerve: [inferior alveolar nerve](https://durgical.com/en/anatomy/inferior-alveolar-nerve/) (V3) ## Relations **In front** The [lower left first premolar](https://durgical.com/en/anatomy/lower-left-first-premolar/) **Behind** The [lower left first molar](https://durgical.com/en/anatomy/lower-left-first-molar/) **Above** The [upper left first premolar](https://durgical.com/en/anatomy/upper-left-first-premolar/) and the [upper left second premolar](https://durgical.com/en/anatomy/upper-left-second-premolar/) **Below** [Mental foramen](https://durgical.com/en/anatomy/mental-foramen/), usually just below the root tip, with the inferior alveolar canal running below toward it ## How to find it Fifth tooth from the midline on the lower left, directly in front of the first molar; most have one buccal and two small lingual cusps. ## On imaging In a child, a panoramic film shows its germ between the roots of the primary second molar, or its absence. In adults a periapical with a change of beam angle tells the mental foramen from an apical lesion. ## Clinical notes - Inferior alveolar nerve (V3); the mental nerve, leaving the foramen beside its root, supplies the lip and chin and is at risk with implants, flaps or a difficult extraction - Early loss of the primary second molar lets the first permanent molar tip forward and close the space, so this premolar may be left without room to erupt ## Anatomical variants - The lingual side has one cusp (two-cusp type) or two (three-cusp type with a Y-shaped groove, the more common form) ## Development Replaces the primary [lower left second molar](https://durgical.com/en/anatomy/lower-left-second-molar/) (FDI 75), a large primary tooth shaped like a small first 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. ## What can mimic a lesion at the apex of the lower left second premolar on a radiograph? The mental foramen, most often found below or just in front of its root tip. ## What happens when the lower left second premolar is missing from birth? The primary lower left second molar (FDI 75) may stay into adult life; this premolar is one of the teeth most often missing after the third molars. ## Which nerve is at risk with implants, flaps or a difficult extraction of the lower left second premolar? The mental nerve, leaving the mental foramen beside its root; it supplies the lip and chin. ## Which radiograph shows whether the lower left second premolar is missing from birth in a child? A panoramic film, which shows each premolar germ between the roots of the primary molar above it. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/lower-left-second-premolar/) 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-second-premolar/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/lower-left-second-premolar/