What do the numbers some dentists call out actually mean? Find out all about
- tooth numbering systems and
- periodontal (gum) charting!
(we’ve got a separate page on Dental Terminology here)
Letters and numbers system
This system is very popular in the UK and Ireland. The 4 quadrants of the mouth are:
- UR – upper right
- UL – upper left
- LR – lower right
- LL – lower left
Within each quadrant, the teeth are numbered from 1 to 8 going from the front tooth to the wisdom tooth:
For example, UR1 is the upper right central incisor, and LL8 is the lower left wisdom tooth.
U.S. Tooth Numbering Chart (“Universal” system)
The American system of numbering teeth from 1 to 32 can hardly be described as elegant… but this handy tooth chart explains it all:
ISO System by the World Health Organisation (based on FDI Two-Digit Notation system)
The first digit denotes the quadrant and the second digit, like the Palmer method, denotes the type of tooth:
Palmer Notation Method
The mouth is divided into 4 quadrants (upper left, upper right, lower left, lower right), and as in the Letters and Numbers system, teeth are numbered 1-8 going from the front tooth to the wisdom tooth in each quadrant. Right angles symbols are used to denote which quadrant is being referred to:
Gum Charting (Periodontal Exam)
UK, Ireland and New Zealand
In the UK, Ireland and New Zealand, the most common screening tool used is the BPE (Basic Periodontal Examination). The mouth is divided into six sections as follows:
Each section is given a score, based on the least good finding in that section. To do this, a perio probe (a special gum millimetre ruler) is “walked around” below the gumline. The force used while doing this is so light that you may not even notice it and thus wonder how your dentist or hygienist comes up with the numbers.
The scoring is as follows:
- 0 = gingival (gum) pockets less than 3 mm and no bleeding on probing
- 1 = pockets less than 3.5 mm with some bleeding on probing
- 2 = pockets less than 3.5 mm with calculus (tartar) present and/or plaque-retaining factors such as overhanging restorations
- 3 = shallow periodontal pockets between 3.5 and 5.5 mm
- 4 = periodontal pockets deeper than 5.5 mm
- * (star added to the score, e.g. 4*) = bone loss that affects the area where the roots of tooth branch
- 0 = perfect
- 1 = your gums are a little inflamed – to get rid of the inflammation, try cleaning in between teeth once a day
- 2 = there is scale/tartar which should be cleaned off by your dentist or hygienist and/or there are restorations present which could retain plaque
- 3 = the probe goes a little further under the gum than it should. This is a sign of early gum disease. Don’t panic as this can readily be treated!
- 4 or 4* = not so good – pockets that are 6-7 mm indicate moderate problems and 8 mm+ indicates severe problems. Regular care will be very important to help stabilise things – talk to your dentist and hygienist, and consider consulting a periodontist
US and Canada
In the US and Canada, the numbers refer to the periodontal pocket depth readings. Normal, healthy pocket depths are usually 3 mm or less. Numbers may be read out in groups of three, which indicate readings taken from different areas of the teeth. To get an idea of what the different pocket depths mean, see above.