[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Dentistry](https://durgical.com/en/dentistry/) › [Dental anatomy and histology](https://durgical.com/en/dentistry/areas/anatomy-histology/) › Primary and permanent dentition and FDI tooth numbering # Primary and permanent dentition and FDI tooth numbering - Anatomy and histology Children have 20 primary teeth and adults 32 permanent teeth. The FDI two-digit system names each tooth by quadrant and position. Updated Nov 12, 2026 **See it in 3D:** [Upper right central incisor](https://durgical.com/en/anatomy/upper-right-central-incisor/) · [Lower left first molar](https://durgical.com/en/anatomy/lower-left-first-molar/) ## Key points - 20 primary teeth, 32 permanent teeth. - FDI: first digit is the quadrant (1–4 permanent, 5–8 primary), second the position from the midline. - 11 = upper right central incisor; 36 = lower left first molar. ## What it is Humans have two sets of teeth. The primary (deciduous) dentition has 20 teeth: in each quadrant two incisors, one canine and two molars. The permanent dentition has 32: in each quadrant two incisors, one canine, two premolars and three molars, the last being the third molar (wisdom tooth). Premolars replace the primary molars; the permanent molars erupt behind them with no predecessor. The FDI (World Dental Federation) system, used in Colombia and most of the world, gives each tooth two digits: the quadrant, then the position from the midline. ## Clinical anatomy - Permanent quadrants: 1 upper right, 2 upper left, 3 lower left, 4 lower right (as seen facing the patient, the patient's right is on the viewer's left). - Primary quadrants: 5 upper right, 6 upper left, 7 lower left, 8 lower right. - Second digit: 1–2 incisors, 3 canine, 4–5 premolars (or primary molars), 6–8 molars. - Examples: 11 is the upper right central incisor; 36 is the lower left first permanent molar; 85 is the lower right second primary molar. - The universal system used in the United States numbers permanent teeth 1 to 32 instead; check which system a record uses. ## Clinical correlation - Writing the wrong tooth number is a classic cause of wrong-tooth extraction: confirm the number, the side and the radiograph. - Missing teeth (hypodontia, most often third molars, upper lateral incisors and lower second premolars) and extra teeth (a mesiodens between the upper central incisors) change the count. - Dental charts and radiographs are used in forensic identification because the pattern of teeth and restorations is individual. ## Next step / Initial management - Record findings with the FDI number and the surface involved, so the dentist can act on them. - A primary tooth that does not fall out, or a permanent tooth that does not appear long after the expected age: request a radiograph through the dentist to look for a missing or impacted tooth. - Refer to the dentist or orthodontist when a tooth is missing, extra or clearly out of place. ## Test yourself Think of the answer, then tap the question to see it. ## How many primary and how many permanent teeth are there? 20 primary (deciduous) teeth and 32 permanent teeth. ## In the FDI system, which tooth is 36? The lower left first permanent molar (quadrant 3, position 6). ## Which primary teeth do the permanent premolars replace? The primary molars; the permanent molars erupt behind them with no predecessor. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/dentistry/primary-and-permanent-dentition-and-fdi-tooth-numbering/) ## Elsewhere in DurgiPedia - [Dental identification (forensic odontology)](https://durgical.com/en/forensic-medicine/dental-identification/) ## Connections ## See it in 3D 2 The structures of Durgical's 3D anatomy where it is found. - [Upper right central incisor](https://durgical.com/en/anatomy/upper-right-central-incisor/) - [Lower left first molar](https://durgical.com/en/anatomy/lower-left-first-molar/) ## Related 3 - [Tooth eruption: when the teeth come in](https://durgical.com/en/dentistry/tooth-eruption-when-the-teeth-come-in/) - [Dental charting and the DMFT index](https://durgical.com/en/dentistry/dental-charting-and-the-dmft-index/) - [The tooth: crown, root, enamel, dentine and pulp](https://durgical.com/en/dentistry/the-tooth-crown-root-enamel-dentine-and-pulp/) [← All of dentistry](https://durgical.com/en/dentistry/) Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once. Sources: [Anatomy, Permanent Dentition](https://www.ncbi.nlm.nih.gov/books/NBK570590/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Anatomy, Head and Neck, Teeth](https://www.ncbi.nlm.nih.gov/books/NBK557543/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Developmental Disturbances of the Teeth, Anomalies of Number](https://www.ncbi.nlm.nih.gov/books/NBK573071/) (StatPearls Publishing (NCBI Bookshelf), 2025). ## **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/dentistry/primary-and-permanent-dentition-and-fdi-tooth-numbering/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/dentistry/primary-and-permanent-dentition-and-fdi-tooth-numbering/