Tooth Numbering Chart

Convierte entre los sistemas de numeración Universal (US), FDI/ISO (internacional) y notación Palmer para dientes permanentes y primarios. Haz clic en cualquier diente del arco para ver su número en los tres sistemas.

Full Reference Tables

Understanding Dental Notation Systems

Sistema de Numeración Universal (Estándar de EE.UU.)

El Sistema de Numeración Universal, respaldado por la Asociación Dental Americana (ADA), es el estándar en Estados Unidos. Los dientes permanentes se numeran del 1 al 32. La numeración comienza en el tercer molar superior derecho (muela del juicio, #1), cruza al tercer molar superior izquierdo (#16), luego baja al tercer molar inferior izquierdo (#17) y termina en el tercer molar inferior derecho (#32). Los dientes primarios (deciduos) utilizan letras de la A a la T siguiendo la misma ruta. La simplicidad de un único número secuencial permite dictarlos rápidamente en entornos clínicos.

FDI Two-Digit System (International Standard)

The FDI World Dental Federation system — published as ISO 3950 — is the global standard used in Europe, Latin America, Asia, and most countries outside North America. Each tooth is represented by two digits. The first digit denotes the quadrant: 1 = maxillary right, 2 = maxillary left, 3 = mandibular left, 4 = mandibular right for permanent dentition; quadrants 5–8 cover the same positions for primary dentition. The second digit identifies the tooth within the quadrant, counting from the midline outward: 1 = central incisor, 2 = lateral incisor, 3 = canine, 4 = first premolar (or first primary molar), 5 = second premolar (or second primary molar), 6 = first molar, 7 = second molar, 8 = third molar. So tooth #46 is the lower right first molar, and #21 is the upper left central incisor. The structured logic makes FDI notation self-explanatory once the quadrant key is memorized.

Palmer Notation (UK & Commonwealth)

Palmer notation, developed by Corydon Palmer in 1891 and still widely used in the United Kingdom, Ireland, Australia, and parts of Canada, uses a bracket symbol (a right-angle cross) positioned around a number or letter to indicate the quadrant. The vertical bar of the bracket represents the midline; the horizontal bar represents the occlusal plane. Numbers 1–8 indicate tooth position from the midline outward for permanent teeth; letters A–E are used for primary teeth. In electronic and plain-text contexts the quadrant is typically written as a two-letter prefix: UR (upper right), UL (upper left), LR (lower right), LL (lower left). Palmer notation is visually intuitive for clinicians who think in terms of quadrant and position.

Reading Dental Quadrants

All three systems share the concept of four dental quadrants. The mouth is divided by two axes: the midline (a vertical line separating right from left) and the occlusal plane (a horizontal line separating upper from lower). Quadrant 1 (or "upper right") contains the maxillary right teeth — the patient's own right side, which appears on the left side of a frontal dental diagram (as if looking at the patient). This frequent left-right reversal in diagrams is a common source of confusion. Always clarify whether a chart is from the patient's perspective or the clinician's view.

Dentición Primaria vs. Dentición Permanente

Humans have two sets of teeth. The primary (deciduous or "baby") dentition consists of 20 teeth — 5 per quadrant: 2 incisors, 1 canine, and 2 molars. Primary teeth begin erupting around 6 months and are fully present by about age 3. Shedding begins around age 6 as the permanent successors develop beneath them. The permanent (adult) dentition has 32 teeth — 8 per quadrant: 2 incisors, 1 canine, 2 premolars, and 3 molars (including the third molar / wisdom tooth). Most people complete the permanent dentition by age 12–13, with wisdom teeth erupting in the late teens or early twenties, if at all. Dental notation charts must clearly specify which dentition is being referenced, particularly in pediatric and mixed-dentition cases where primary and permanent teeth coexist.

Common Pitfalls When Converting

The most frequent conversion error is confusing patient-right with chart-left. Dental charts are traditionally drawn as if facing the patient, so the patient's upper-right quadrant appears on the left side of the diagram. A second pitfall involves assuming FDI quadrant digits match Universal numbering ranges — they do not; FDI 11 is the upper right central incisor while Universal 8 fills the same position. Third, Palmer notation in legacy paper records sometimes omits the text prefix (UR/UL/etc.) and relies on a hand-drawn bracket symbol, which can be ambiguous when digitized. When in doubt, cross-check against the tooth name (e.g., "upper right central incisor") which is unambiguous across all systems.

Frequently Asked Questions

• What is the Universal tooth numbering system?

  The Universal Numbering System (ADA system) assigns numbers 1–32 to permanent adult teeth starting from the upper right third molar (#1) and ending at the lower right third molar (#32). Primary teeth use letters A–T. It is the standard system used in the United States.

• What is the FDI (ISO) tooth numbering system?

  The FDI Two-Digit System, published by the Fédération Dentaire Internationale and adopted by ISO, encodes each tooth as a two-digit number. The first digit indicates the quadrant (1=upper right, 2=upper left, 3=lower left, 4=lower right for permanent; 5–8 for primary). The second digit indicates the tooth within that quadrant (1=central incisor through 8=third molar). It is the international standard used outside the US.

• What is Palmer notation?

  Palmer notation uses a bracket symbol alongside a number (1–8) or letter (A–E) to indicate the quadrant. The bracket "opens" toward the midline of the mouth. In text form it is written as UR1–UR8 (upper right), UL1–UL8 (upper left), LR1–LR8 (lower right), LL1–LL8 (lower left). It is common in the UK, Ireland, Australia, and many Commonwealth countries.

• How do I convert between Universal, FDI, and Palmer notation?

  Use the converter widget above: select the system you already know, pick the tooth value, and the tool instantly shows the equivalents in all three systems plus the anatomical name. For manual conversions, match the quadrant prefix (U/L + R/L) and the tooth position number to find the corresponding FDI two-digit code.

• What is the difference between primary and permanent teeth charts?

  Permanent (adult) teeth number 32 in total. Primary (baby/deciduous) teeth number 20. In the Universal system, permanent teeth use numbers 1–32 and primary teeth use letters A–T. In FDI, primary teeth use quadrant digits 5–8 instead of 1–4. A child typically begins losing primary teeth around age 6 and completes the transition to permanent dentition by age 12–13, except for the third molars (wisdom teeth) which erupt later.

• Which notation does DodoDentist use for clinical charting?

  DodoDentist supports all three notation systems — Universal, FDI/ISO, and Palmer — so clinicians can document in whichever system their practice prefers. The notation preference is set per-practice in the clinic settings.

• What are the four dental quadrants?

  The mouth is divided into four quadrants by vertical (midline) and horizontal (occlusal plane) axes: upper right (maxillary right), upper left (maxillary left), lower left (mandibular left), and lower right (mandibular right). In FDI notation, quadrant 1 is upper right, 2 is upper left, 3 is lower left, and 4 is lower right for permanent teeth.

• Why do wisdom teeth have three different numbers in the systems?

  The upper right wisdom tooth (third molar) is #1 in Universal, #18 in FDI, and UR8 in Palmer. The differences arise because each system uses a different starting position and counting direction. Universal starts at the upper right and counts around the arch; FDI uses quadrant + position coding; Palmer brackets the midline and numbers outward.