What is tooth number 3 in FDI?

Universal 3 is the upper right first molar, which is 16 in FDI notation, read one six. In Palmer notation it is the upper right 6.

Which tooth numbering system is used in the United States?

The Universal system, 1 to 32 for permanent teeth and A to T for primary teeth. The FDI two digit system is used in most other countries and in international publications.

How do I convert Universal to FDI?

Find the quadrant, then count from the midline. Universal 1 to 8 is the upper right, FDI 18 to 11; 9 to 16 is the upper left, 21 to 28; 17 to 24 is the lower left, 38 to 31; and 25 to 32 is the lower right, 41 to 48.

Why is FDI 16 not read as sixteen?

Because the two digits are separate facts, the quadrant and the tooth. Reading it as one six keeps a listener from confusing it with Universal 16, a different tooth.

Universal vs FDI vs Palmer tooth numbering, ChartCall

How each system counts

Universal (ADA)

Universal gives every permanent tooth its own number. Counting starts at the patient's upper right third molar, number 1, runs along the upper arch to the upper left third molar, 16, drops to the lower left third molar, 17, and runs back along the lower arch to the lower right third molar, 32. Primary teeth follow the same path with the letters A to T; see primary teeth letters A to T. The advantage is that one number is one tooth. The drawback is that the number says nothing about the tooth type: you have to know that 3, 14, 19 and 30 are the four first molars.

FDI two digit

FDI splits the mouth into four quadrants numbered clockwise as you face the patient, starting at the upper right: 1, 2, 3, 4. Primary teeth use 5, 6, 7 and 8 in the same order. The second digit counts from the midline, 1 for the central incisor to 8 for the third molar. So every first molar ends in 6 and every canine in 3, which makes the tooth type readable from the number. Each digit is said on its own: 16 is one six, and 48 is four eight.

Palmer

Palmer also counts 1 to 8 from the midline, but shows the quadrant with a right angle drawn round the number, as if the mouth were divided by a cross and you were facing the patient. The upper right first molar is written 6 with the bracket on its right and below, 6┘. Because the brackets are awkward to type, software and notes often write UR6, UL6, LL6 and LR6. Primary teeth take the letters A to E from the midline.

Conversion chart for the permanent teeth

Right and left are the patient's. Read across a row to convert between systems.

Universal, FDI and Palmer, all 32 permanent teeth
Universal	FDI	Palmer	Palmer bracket	Tooth
1	18	UR8	8┘	upper right third molar
2	17	UR7	7┘	upper right second molar
3	16	UR6	6┘	upper right first molar
4	15	UR5	5┘	upper right second premolar
5	14	UR4	4┘	upper right first premolar
6	13	UR3	3┘	upper right canine
7	12	UR2	2┘	upper right lateral incisor
8	11	UR1	1┘	upper right central incisor
9	21	UL1	└1	upper left central incisor
10	22	UL2	└2	upper left lateral incisor
11	23	UL3	└3	upper left canine
12	24	UL4	└4	upper left first premolar
13	25	UL5	└5	upper left second premolar
14	26	UL6	└6	upper left first molar
15	27	UL7	└7	upper left second molar
16	28	UL8	└8	upper left third molar
17	38	LL8	┌8	lower left third molar
18	37	LL7	┌7	lower left second molar
19	36	LL6	┌6	lower left first molar
20	35	LL5	┌5	lower left second premolar
21	34	LL4	┌4	lower left first premolar
22	33	LL3	┌3	lower left canine
23	32	LL2	┌2	lower left lateral incisor
24	31	LL1	┌1	lower left central incisor
25	41	LR1	1┐	lower right central incisor
26	42	LR2	2┐	lower right lateral incisor
27	43	LR3	3┐	lower right canine
28	44	LR4	4┐	lower right first premolar
29	45	LR5	5┐	lower right second premolar
30	46	LR6	6┐	lower right first molar
31	47	LR7	7┐	lower right second molar
32	48	LR8	8┐	lower right third molar

Worked example: one callout in three systems

An operator in a US clinic says "number 30, MOD amalgam". Number 30 is the lower right first molar. A colleague trained on FDI charts the same tooth as 46, quadrant 4 for lower right and 6 for the first molar, and would say "four six, MOD amalgam". An orthodontic referral letter in Palmer would write LR6. To convert by hand, first name the quadrant, then count from the midline: central incisor 1, lateral 2, canine 3, premolars 4 and 5, molars 6, 7 and 8.

Common mistakes

Reading FDI 16 as sixteen. Universal 16 is the upper left third molar; FDI 16 is the upper right first molar.
Swapping left and right. The patient's right is on your left as you face them and on a standard chart.
Counting FDI quadrants the wrong way round. 3 is lower left and 4 is lower right.
Numbering from the back in FDI or Palmer. Both count from the midline, so 1 is always a central incisor.
Switching systems partway through a chart. Pick the one your program uses and stay in it.

ChartCall can label the odontogram and speak every callout in Universal or FDI, so you can drill the system your program uses. Switch it with the numbering toggle on the daily charting drill.

Sources

Checked against these sources on 26 September 2026. Conventions differ between schools, offices and clinics; where yours differ, follow your program.

ISO 3950, Dentistry: designation system for teeth and areas of the oral cavity. The international standard for the FDI two digit notation, first adopted by the FDI World Dental Federation in 1970.
American Dental Association, Universal Numbering System. Adopted by the ADA in 1975 and used on US dental records, claim forms and procedure coding.
Zsigmondy-Palmer notation. The quadrant grid first described in 1861 and later adapted into the Palmer notation, still taught in the UK and used in orthodontics.

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Universal vs FDI vs Palmer tooth numbering, with a conversion chart