The most expensive misunderstanding in dental charting is not a wrong tooth number. It is a new team member looking at a chart full of coloured marks and telling a patient, with complete sincerity, that they have eleven cavities. What the chart actually showed was six existing fillings, three proposed restorations, and two areas flagged to keep an eye on.
That conversation is awkward at best and a real problem at worst, and it comes entirely from not knowing that a dental chart layers several different kinds of information on top of the same picture. Some of it is history. Some of it is proposal. Some of it is observation. They look similar and they mean completely different things.
This lesson is about telling them apart, and about reading the second chart that lives alongside the first: the periodontal chart, which is nothing but numbers and is the part new staff find most intimidating.
What you will learn
- The three states every charted item is in: existing, treatment planned, or completed.
- How colour conventions usually work, and why you must never rely on them blindly.
- Status terms: watch, missing, impacted, unerupted, and what each records.
- What a six point periodontal reading is and how to read the grid.
- Recession, bleeding points, mobility, and furcation entries as measurements rather than conclusions.
Three states, one picture
Every entry on an odontogram, the tooth by tooth diagram at the centre of the chart, sits in one of three states.
Existing. Work that is already in the mouth. A filling placed in 2009 at another office, a crown from last year, an implant. This is a factual record of what is physically present. It gets entered when it is discovered, usually at a new patient exam, and it may carry a date or the note "existing other" meaning placed elsewhere.
Treatment planned. Work that a dentist has proposed but not done. This is a recommendation sitting in the chart waiting for a decision. It is not history, it is not a promise, and it is not necessarily what will end up happening. Treatment plans get revised, phased, declined, and superseded, all of which is normal.
Completed. Work this practice has actually performed, with a date. The moment a procedure is marked complete, it typically becomes part of the tooth's history, feeds into the ledger, and generally becomes eligible for a claim.
The flow is usually existing and planned at the exam, then planned moving to completed as work gets done. Understanding this sequence explains most of what you see. It also explains a category of front desk confusion: a patient looking at a printed treatment plan sees proposals, a patient looking at a ledger sees completed work, and the two documents will not match, because they are not supposed to.
A treatment plan is a clinical recommendation made by a dentist, and explaining, modifying, or justifying it clinically is the dentist's job. Non clinical staff can absolutely explain the sequence, the cost, the insurance estimate, and the scheduling. What they cannot do is interpret the findings or tell a patient what is wrong with them. Where that line sits, and who may present or discuss what, varies by role and by state, so check our state by state guide and your practice's own written protocols before you improvise.
How colour usually works, and why usually is the operative word
Most practice management software colours the odontogram to show state at a glance, and the broad convention across the industry is something like this: one colour for existing work, a second for treatment planned, a third for completed, and a distinct treatment for conditions such as missing teeth or areas being monitored.
In a very large number of offices that resolves to blue for existing, red for planned, and a change to a completed colour once work is done. But here is the part that matters more than the convention: colours are configurable. They differ between software packages, they differ between versions, and they are routinely changed by whoever set the system up in a given office. Some offices reverse them. Some add custom categories with their own colours for implants, watch items, or referred work.
So the rule is simple and non negotiable: learn the colour key for the software in front of you, in this office, and verify it rather than assuming. Most systems display a legend, and if yours does not, ask the office manager to write one down and post it. Reading a colour wrong is exactly how the eleven cavities conversation happens.
Our Open Dental charting and treatment plans module walks through one system's version of this in detail, and the structure it describes maps reasonably well onto the other major packages even when the specific colours do not.
Status terms you will see constantly
- Watch. An area a clinician wants to observe over time rather than treat now. It is a monitoring flag, not a diagnosis and not a plan. Watch items are one of the most useful things in a chart and one of the most commonly misread by new staff, who tend to interpret them as pending work.
- Missing. The tooth is not present. The chart may or may not record why. Missing is a factual status about the current mouth.
- Extracted. Specifically removed, as opposed to never present. Software often distinguishes these, because the history matters for claims and for planning.
- Unerupted. The tooth exists but has not come through into the mouth. Common and expected in children, and also seen in adults with third molars.
- Impacted. The tooth is blocked from erupting normally, typically by bone or by an adjacent tooth. Most often noted on third molars. Impacted is a descriptive status recorded by a clinician, usually from a radiograph.
- Partially erupted. Part way through. Sits between unerupted and fully erupted, and it is charted because the status affects what can be seen and cleaned.
- Retained root. Root structure remaining after the crown of a tooth is gone.
- Primary. A flag marking a tooth as a baby tooth, which changes the numbering from a number to a letter as Lesson 1 covered.
Every one of these is a statement about what is, recorded by someone qualified to record it. None of them are instructions, and none of them are yours to add, remove, or reinterpret without knowing your own scope.
The periodontal chart
Alongside the odontogram sits a second, very different looking document: a grid of numbers, usually six per tooth, sometimes with symbols and highlights scattered through it. This is the periodontal chart, and it is a record of the supporting structures you met in Lesson 3.
What a six point reading is
A periodontal probe is a slim instrument marked in millimetres. During a periodontal examination, it is placed gently into the sulcus, the small groove between gum and tooth, and the depth is read off the markings. That measurement is taken at six positions around each tooth: three on the facial side and three on the lingual side, at the mesial corner, the middle, and the distal corner of each.
Six readings per tooth, across a full dentition, is why a complete periodontal chart contains roughly 168 numbers. Written down, they form a grid where each tooth has a column of six values, typically displayed as facial on top and lingual below.
The numbers are millimetres. That is the entire scale. A row of small numbers and a row of larger numbers describe different sulcus depths, and the pattern across the mouth, plus how it compares to the previous exam, is what gives the record its value. A single number in isolation says very little.
Recession
Alongside probing depths, charts record gingival recession: how far the gum margin sits from the cementoenamel junction, that crown to root boundary from Lesson 3. If the margin has moved apically, toward the root, the exposed distance is recorded in millimetres.
Depth and recession together give clinical attachment level, which is the measurement clinicians care about most because it accounts for where the gum margin actually is rather than just how deep the probe went. Many systems calculate it automatically from the two entries, which is worth knowing so you do not wonder where a third number came from.
Bleeding points
Charts mark whether a site bled on probing, usually as a dot, a highlight, or a checkbox at the specific site. This is recorded per site, not per tooth, which is why a tooth can show bleeding at one position and not the others. It is an observation made at the moment of measurement, and its value is largely in the pattern and the trend.
Mobility
Recorded per tooth rather than per site, usually on a small graded scale. Because a healthy tooth is suspended in a ligament, some movement is normal, and mobility notation records observed movement beyond that. You will see it entered as a single digit next to the tooth.
Furcation involvement
Only on multi rooted teeth, for the reason Lesson 3 explained: single rooted teeth have no furcation to involve. It is recorded with a symbol or a grade indicating how far the probe reached into the division between roots. On a full chart it appears only on molars and on the occasional two rooted premolar, and its absence elsewhere is correct rather than a gap.
A periodontal chart is a measurement record: a set of physical observations taken with an instrument on a given date by a clinician. It is not a diagnosis. Diagnosis combines those measurements with radiographs, history, risk factors, and clinical judgement, and it belongs to the treating dentist or, within scope, the hygienist. A number in a grid does not name a condition, and nobody should tell a patient what their numbers mean except the clinician responsible for the diagnosis.
Why the periodontal chart matters to the front office
It is tempting to file periodontal charting under "clinical, not my problem." That is a mistake if you touch scheduling, verification, or claims.
Periodontal procedures are among the most scrutinised categories in dental benefits. Payers commonly ask for documentation, including current periodontal charting and radiographs, before they will consider a periodontal claim, and they compare what was submitted against what the record shows. A chart with missing sites, stale dates, or entries that do not match the narrative slows everything down.
The front office consequence is concrete. If you verify benefits, you should know what the plan's documentation requirements are before treatment is scheduled, not after a claim comes back. Our verification lesson covers how to ask, and the same theme runs through the whole billing course.
There is also a records angle that outlasts the claim. The chart is the legal record of what was observed and when. Retention requirements, amendment rules, and what counts as an acceptable correction are governed by state law and by HIPAA, and they vary. Our piece on dental records retention covers what generally has to be kept and for how long, with the reminder that specifics depend on your state and that a records question with legal weight belongs with an attorney rather than a website.
Reading a chart in order
When you open an unfamiliar chart, a consistent sequence prevents most misreadings.
- Check the date on everything. A treatment plan from three years ago is history, not a plan. Periodontal readings have dates too, and a current chart and a four year old chart tell very different stories.
- Find the colour or symbol key for this software, in this office. Confirm it rather than assuming.
- Separate existing from planned before you interpret anything. Count them separately in your head.
- Note the status flags: missing, impacted, watch. These change what the rest of the picture means.
- Read the periodontal grid as a pattern, not as individual numbers, and check when it was last updated.
- Read the clinical notes. The narrative usually explains anything in the graphics that looks contradictory, and if it does not, that is a question for the clinician rather than a puzzle to solve alone.
More chart misreadings come from stale information than from misread symbols. Before you draw any conclusion from a chart, find out when it was last updated and by whom. If you build one habit out of this lesson, make it that one. The glossary handles the vocabulary; nothing handles a two year old treatment plan being read as current.
Try this in your own office
- Open your software's charting module and find the colour and symbol legend. Write it on a card and keep it at your station for a month.
- Take one chart and list, separately, the existing restorations, the treatment planned items, and the completed items. Compare your counts with someone experienced.
- Find a watch item in a real chart and confirm with the clinician what the note was intended to record.
- Look at a full periodontal chart and count the readings on a single molar. Confirm you find six, and identify which three are facial.
- Find a furcation entry and confirm it is on a multi rooted tooth. Then check that no single rooted tooth has one.
- Pick one patient's periodontal chart with two dated exams and compare them side by side to see what a trend looks like in practice.
THE CHAIRSIDE TAKE
Read the dates before you read anything else, then separate existing from planned before you form an opinion about a single tooth. Learn your own software's colour key by verifying it rather than assuming the industry convention holds, because it frequently does not. And treat every periodontal number as exactly what it is: a millimetre measurement taken on a date by a clinician, valuable as a record and a trend, and never yours to translate into a diagnosis for a patient.
Lesson 4 of 6 in Dental Terminology and Charting
This guide is educational content and does not constitute legal, financial, tax, or clinical advice. Laws and regulations vary by state and change over time. Consult your own dental-specific attorney, CPA, and state dental board before acting.