Dental charting symbols, explained

A dental chart is a compressed clinical record. Everything a clinician needs to know about a mouth — what is there, what has been done to it, what is failing and what is planned — is written in a shorthand that takes about an hour to learn and then never changes.

This guide covers the whole notation: the three numbering systems, surface abbreviations, condition symbols, periodontal scores and the colour conventions, plus how the notation differs once you are working inside software rather than on paper.

The three tooth numbering systems

Before any symbol makes sense, you need to know which tooth is being discussed. There are three systems in active use, and which one you meet depends mostly on where you are.

Universal Numbering System (United States)

The standard in US practices, and therefore the default in US dental software. Permanent teeth are numbered 1 through 32 in one continuous sweep:

• 1–16 run across the upper arch, starting at the patient’s upper right third molar (#1) and finishing at the upper left third molar (#16).
• 17–32 continue along the lower arch, starting at the lower left third molar (#17) and finishing at the lower right third molar (#32).

The sweep is continuous, so #16 and #17 are adjacent vertically, not horizontally. Primary (baby) teeth use letters A through T, following the same path.

A useful anchor: #8 and #9 are the upper central incisors, #24 and #25 are the lower central incisors, and #1, #16, #17 and #32 are the wisdom teeth.

FDI World Dental Federation notation (international)

Used almost everywhere outside the US, and worth knowing because imported records and much of the research literature use it. Each tooth gets two digits:

• The first digit is the quadrant, numbered clockwise from the patient’s upper right as you face them: 1 = upper right, 2 = upper left, 3 = lower left, 4 = lower right. Primary teeth use 5 to 8 for the same quadrants.
• The second digit is the tooth’s position counting from the midline: 1 = central incisor, up to 8 = third molar.

So FDI 16 is read “one-six”, not “sixteen” — upper right first molar. That is Universal #3.

Palmer notation (still common in orthodontics and in the UK)

Each quadrant gets a bracket symbol showing which corner of the mouth it is, and teeth are numbered 1 to 8 from the midline. Written by hand it is fast and unambiguous; typed, it is awkward, which is why it has lost ground to FDI. Primary teeth use letters A to E instead of numbers.

Quick conversion

Tooth	Universal	FDI	Palmer
Upper right third molar	1	18	⌐8
Upper right first molar	3	16	⌐6
Upper right central incisor	8	11	⌐1
Upper left central incisor	9	21	1¬
Lower left first molar	19	36	6˩
Lower right central incisor	25	41	˩1

Surface abbreviations

Restorations and caries are recorded by which surfaces of the tooth they involve. Five surfaces, and every chart in the world uses the same initials:

Letter	Surface	Where it is
M	Mesial	The side facing the midline of the mouth
D	Distal	The side facing away from the midline
O	Occlusal	The biting surface — posterior teeth only
I	Incisal	The biting edge — anterior teeth only
B or F	Buccal / Facial	The side facing the cheek (back teeth) or lip (front teeth)
L	Lingual	The side facing the tongue
P	Palatal	The tongue-side of upper teeth — interchangeable with Lingual

They combine, in a conventional order, to describe the extent of a lesion or restoration:

• O — a simple filling in the biting surface only
• MO or DO — a two-surface filling involving one contact point
• MOD — a three-surface filling running right across the tooth
• MODBL — a restoration involving five surfaces, which usually means the tooth is a candidate for a crown instead

You will also see cervical (at the gum line) written out or abbreviated to C, though this varies more between practices than the five core surfaces do.

Condition and restoration symbols

This is the part that varies most between paper charts, and the part that software has largely standardised by drawing the condition directly onto a tooth diagram instead of writing a letter.

The abbreviations you will still meet in notes, treatment plans and older records:

Notation	Meaning
CA or a shaded outline	Caries — decay present
AM	Amalgam restoration
CO or COMP	Composite (tooth-coloured) restoration
CR or a full-crown outline	Crown
PFM	Porcelain-fused-to-metal crown
RCT or a line down the root	Root canal treatment
EXT	Extraction — planned or completed
MISS or a struck-through tooth	Missing tooth
IMP	Implant
IMPACT	Impacted, has not erupted into position
SEAL	Fissure sealant
VEN	Veneer
BRIDGE — abutment / pontic	A fixed bridge: abutments are the supporting teeth, the pontic is the false tooth spanning the gap
PD / FD	Partial denture / full denture
UNERUPT	Unerupted
FRAC	Fractured
RF	Root fragment retained in the bone

On a drawn chart, the shape carries the meaning. A tooth diagram divided into five segments is filled in to show which surfaces are involved; a full outline around the crown means a crown; a line through the tooth means it is missing; a shape spanning a gap between two shaded abutments is a bridge.

The colour convention

Nearly every dental chart, paper or digital, uses two colours:

• Red — work that needs doing, and pathology that is present. Caries, planned extractions, treatment-planned restorations.
• Blue or black — work already completed. Existing amalgams, existing crowns, restorations from previous visits.

This is a convention rather than a standard, and it is worth being deliberate about. Every major package lets you reconfigure the palette, and practices do. Some add a third colour for treatment that has been presented and declined, or for conditions being monitored rather than treated. Before you read a chart you did not create, confirm the scheme. Misreading blue as red is the difference between “this tooth has a crown” and “this tooth needs one”.

Periodontal charting notation

Perio charting is a separate exercise with its own numbers, and it is where charting takes the most chair time. A full perio chart records six probing depths per tooth — three buccal, three lingual — which for a full dentition is 192 measurements before you record anything else.

Probing depth (PD)

The distance in millimetres from the gingival margin to the base of the sulcus or pocket. Recorded per site.

• 1–3 mm — within normal limits
• 4–5 mm — early to moderate pocketing
• 6 mm and above — advanced pocketing

Recession (REC) and clinical attachment level (CAL)

Recession is how far the gingival margin has migrated apically from the cementoenamel junction. Clinical attachment level is the measurement that actually matters for diagnosis, because it is independent of where the gum happens to sit:

CAL = probing depth + recession

A 3 mm pocket with 4 mm of recession is 7 mm of attachment loss, and is a considerably more serious finding than a 5 mm pocket with no recession. Software calculates CAL automatically once you enter both values — one of the clearer arguments for digital perio charting over paper.

Bleeding on probing (BOP) and suppuration (SUP)

Recorded per site, usually as a dot or a highlighted cell. BOP indicates active inflammation. Suppuration — pus expressed on probing — indicates active infection and is a more serious finding.

Absence of bleeding on probing is clinically valuable in its own right: it is a strong negative predictor, meaning a site that does not bleed is very likely to be stable.

Furcation involvement

Where the roots of a multi-rooted tooth divide, bone loss can extend into the division. Graded on the Glickman classification:

• Grade I — incipient. The probe enters the flute of the furcation but cannot penetrate horizontally.
• Grade II — partial. The probe enters horizontally but does not pass through; a cul-de-sac.
• Grade III — through-and-through, but still covered by soft tissue.
• Grade IV — through-and-through and clinically visible, with the gingiva receded.

Usually marked with a triangle symbol, filled in progressively as the grade increases.

Mobility

Graded on the Miller classification:

• Class I — slightly more than normal; less than 1 mm of horizontal movement.
• Class II — moderately more than normal; more than 1 mm of horizontal movement.
• Class III — severe; horizontal and vertical movement, the tooth is depressible in its socket.

Plaque and calculus indices

Recorded per surface or per quadrant depending on the index in use. These drive the hygiene recall interval more than any other single number on the chart.

MGJ and keratinised tissue

MGJ marks the mucogingival junction, recorded where the width of attached keratinised tissue is a concern — typically before recession-related surgery or where a restoration margin will sit near the gingiva.

How the software changes the notation

Three things happen to charting notation once it moves into a practice management system, and all three are worth knowing before you compare products.

The tooth diagram becomes the primary interface. You click surfaces rather than write letters. The abbreviations persist in the treatment plan, the claim narrative and the printed record, but day to day you are drawing, not writing.

The numbering system becomes a setting. Every major US package defaults to Universal numbering and can be switched to FDI. If you have imported records or work with international referrals, check that the setting is right before the first chart is entered — retrospective conversion is possible but tedious.

Perio charting gets faster or it does not. This is the sharpest practical difference between packages. Manual entry of 192 measurements is slow. Voice-driven perio charting, where the hygienist calls out numbers and the software records them, is the single biggest time-saver in the category — and it is not universal. Dentrix Ascend and Denticon both offer voice perio; several others do not. If your hygiene department is your bottleneck, that one feature is worth more than most of the marketing on any vendor’s homepage.

Perio charting is also priced differently to how people expect. It is native in essentially every full practice management system we track — see the charting comparison for which systems include what — so it is rarely a reason to choose one product over another. Voice input is.

Notation that varies between practices

Most of the notation above is genuinely standard. A few things are not, and assuming they are is how charts get misread.

The colour scheme. Red-needs-doing, blue-is-done is the widespread convention, not a rule. Configurable everywhere, and practices change it — sometimes adding a third colour for treatment presented and declined, or for findings under observation.

“Watch” and monitoring codes. Some practices have a defined code for a lesion being monitored rather than treated, with a review interval attached. Many do not, and use “watch” informally, which produces records nobody can act on. Find out which kind of practice you are in.

Abbreviation sets for materials. AM for amalgam and CO or COMP for composite are near-universal. Beyond that — glass ionomer, resin-modified glass ionomer, gold, zirconia, e.max — practices diverge, and older records diverge more.

Charting the same finding twice. Whether an existing restoration with recurrent caries is charted as one entry or two varies. It matters for treatment planning and for what gets billed.

Sextant versus quadrant for perio recording, and the direction of travel within each. Agree it with your charting partner rather than discovering the mismatch halfway through.

None of these are worth arguing about. All of them are worth confirming before you read or write a chart you did not create.

Where the notation causes claim rejections

Charting notation is not only clinical — the surfaces you record become the surfaces on the insurance claim, and payers are unforgiving about mismatches.

The recurring causes of avoidable rejections:

Surface count mismatches. A restoration charted as MO but billed as MOD, or vice versa. The procedure code carries a surface count, and if it does not match the chart, the claim is queried.

Occlusal on an anterior tooth. Anterior teeth have an incisal edge, not an occlusal surface. Charting O on tooth #8 is a notation error that produces an invalid claim.

Charting work on a tooth previously recorded as missing. Software usually catches this; paper does not, and imported records frequently contain it.

Numbering-system drift. A practice that switched systems, or imported records from an FDI-notation source, can end up with charts where #16 means two different teeth depending on when it was written. This is genuinely dangerous, not merely untidy.

Existing recorded as planned. The patient is presented with treatment they have already had. Embarrassing, and it damages case acceptance for everything else you present that day.

If your practice sees claim rejections clustering around surfaces, the fix is at the chairside — in the charting habit — not in the billing office.

Reading an inherited chart

New associates and new practice owners inherit charts they did not write, and the notation needs interpreting rather than trusting.

Work through it in this order:

1. Establish the numbering system. If anything looks anatomically implausible, suspect FDI-versus-Universal drift before suspecting the clinician.
2. Establish the colour convention, from the software settings if you can rather than by inference.
3. Check the date of every entry. A chart is a stack of observations from different years, not a snapshot. A restoration charted in 2019 may have failed since.
4. Treat “watch” entries as unresolved, not as decisions.
5. Verify anything that changes your treatment plan by looking in the mouth. The chart tells you what to expect; it does not tell you what is there today.

That last point is the whole discipline in one line. A chart is a record of what somebody observed on a particular day. It is evidence, not fact.

A printable cheat sheet

The minimum you need at the chairside:

Numbering (Universal) — 1 to 16 upper, right to left. 17 to 32 lower, left to right. #8/#9 are upper centrals. #1, #16, #17, #32 are wisdom teeth.

Surfaces — M mesial, D distal, O occlusal (back), I incisal (front), B/F buccal/facial, L/P lingual/palatal.

Colour — red needs doing, blue is done. Confirm before trusting.

Perio — 6 sites per tooth. PD 1–3 normal, 4–5 moderate, 6+ advanced. CAL = PD + recession. BOP means inflammation. Furcation Glickman I–IV. Mobility Miller I–III.

Restorations — AM amalgam, CO composite, CR crown, RCT root canal, IMP implant, SEAL sealant, EXT extraction, MISS missing.

Where to go next

If you are learning to chart rather than looking up a symbol, start with dental charting for beginners, which covers the sequence and the common errors rather than the notation.

If you are choosing software and charting speed is the deciding factor, the charting category comparison shows which systems include clinical and periodontal charting natively, and the full software comparison covers what each one costs.

Frequently asked

What do the letters M, O, D, B and L mean on a dental chart?

They are tooth surfaces: Mesial (toward the midline), Occlusal (biting surface of a back tooth), Distal (away from the midline), Buccal or Facial (toward the cheek or lip) and Lingual (toward the tongue). On upper teeth, Lingual is often written Palatal. Front teeth have an Incisal edge instead of an Occlusal surface. They combine, so MOD means a restoration covering mesial, occlusal and distal surfaces.

What does red and blue mean on a dental chart?

In the most widespread convention, red marks work that needs doing or pathology present, and blue or black marks work already completed. It is a convention, not a standard — every major software package lets you reconfigure it, so confirm the scheme in use before reading someone else's chart.

What is the difference between the Universal and FDI numbering systems?

The Universal system, used in the United States, numbers permanent teeth 1 to 32 in a single continuous sweep starting at the upper right third molar. The FDI system, used almost everywhere else, uses two digits: the first is the quadrant (1 to 4 for permanent teeth) and the second is the tooth's position from the midline (1 to 8). So Universal #3 is FDI 16.

What does BOP mean in perio charting?

Bleeding on probing — bleeding provoked when the probe is placed to the base of the sulcus. It is recorded per site, usually as a dot or a highlighted cell, and it is the main clinical indicator of active inflammation. Absence of bleeding on probing is a strong predictor of periodontal stability.

How many measurements are taken per tooth in a perio chart?

Six probing depths per tooth — three from the buccal aspect and three from the lingual — giving 192 measurements for a full dentition of 32 teeth. Recession, bleeding, suppuration, furcation and mobility are recorded alongside them.

Software prices referenced in this guide were read from vendor sites on 2026-08-01 and are linked to their sources. Always confirm current pricing with the vendor.