Dental charting is how a dental office records the condition of every tooth: what is healthy, what is missing, what has already been restored and what still needs treatment. In the United States, most offices identify teeth with the Universal Numbering System (teeth 1 to 32 for adults, A to T for baby teeth), name each tooth surface with a letter such as M, D or O, and use symbols and colors to show existing work and planned treatment.
For a new dental assistant, charting is one of the first skills that makes you useful chairside. The dentist calls out findings during the exam, and you record them quickly and accurately. We’ve trained dental assistants in the Houston area for 20+ years, and this guide covers what you need to chart with confidence: tooth numbers, surfaces, common symbols, periodontal readings and a simple step-by-step routine.
Dental Charting at a Glance
Here are the building blocks every chart uses. Each office has its own software and legend, so always learn your office’s version, but the core ideas are the same almost everywhere.
| Charting element | What it tells the team | Example |
|---|---|---|
| Tooth number | Which tooth the finding is on | #3 = upper right first molar (Universal system) |
| Tooth surface | Which side or face of the tooth is involved | MO = mesial and occlusal surfaces |
| Condition or restoration | What was found or what is already there | Caries, composite, crown, root canal, missing tooth |
| Status (often by color) | Existing work versus treatment still needed | Blue or black = existing; red = needs treatment (common convention) |
| Periodontal readings | Gum health around each tooth | Pocket depths in millimeters, bleeding points, mobility |
| Provider and date | Who recorded the entry and when | Initials or login stamp on the entry |
Tooth Numbering Systems Dental Assistants Should Know
The tooth numbering system is the foundation of every chart. If the number is wrong, every note attached to it is wrong too. There are three systems you may run into.
Universal Numbering System (used in the U.S.)
The Universal Numbering System is the standard in American dental offices and the one you will use in Texas. Picture yourself facing the patient:
- Tooth #1 is the upper right third molar (wisdom tooth).
- Numbers continue across the upper arch to #16, the upper left third molar.
- #17 is the lower left third molar, and numbers continue across the lower arch to #32, the lower right third molar.
- Primary (baby) teeth use letters A to T in the same pattern: A to J across the upper arch from the patient’s right to left, then K to T across the lower arch from left to right.
A missing wisdom tooth does not change the numbering. If #1 was never there, the upper right second molar is still #2.
FDI (ISO 3950) Two-Digit System
Most countries outside the U.S. use the FDI World Dental Federation system, also published as the ISO 3950 standard. The first digit is the quadrant (1 upper right, 2 upper left, 3 lower left, 4 lower right for adult teeth; 5 to 8 for baby teeth). The second digit counts from the midline outward, 1 for the central incisor through 8 for the third molar. You may see it on records from patients who had dental work abroad, so it helps to recognize it.
Palmer Notation
Palmer notation numbers each quadrant from 1 (central incisor) to 8 (third molar) and uses a corner-shaped bracket to show the quadrant. Baby teeth use letters A to E. It is still common in the United Kingdom and with some orthodontists.
| Tooth | Universal (U.S.) | FDI / ISO 3950 | Palmer |
|---|---|---|---|
| Upper right third molar | 1 | 18 | 8 with upper-right bracket |
| Upper right first molar | 3 | 16 | 6 with upper-right bracket |
| Upper right central incisor | 8 | 11 | 1 with upper-right bracket |
| Lower left first molar | 19 | 36 | 6 with lower-left bracket |
| Lower right third molar | 32 | 48 | 8 with lower-right bracket |
The Five Tooth Surfaces and Their Abbreviations
Every tooth has five surfaces, and charting uses one-letter abbreviations for each. Combining them describes exactly where decay or a filling sits.
| Abbreviation | Surface | Where it is |
|---|---|---|
| M | Mesial | Side facing toward the midline of the arch |
| D | Distal | Side facing away from the midline |
| O | Occlusal | Chewing surface of premolars and molars |
| I | Incisal | Biting edge of incisors and canines |
| B / F | Buccal / Facial | Surface facing the cheek (back teeth) or lips (front teeth); some offices use F for both |
| L | Lingual | Surface facing the tongue (some offices write P for palatal on upper teeth) |
Surfaces are combined in a set order, starting with mesial or distal. A filling that covers the mesial and occlusal surfaces is an MO; one that wraps mesial, occlusal and distal is an MOD. So “#30 MOD composite” means a tooth-colored filling on the mesial, occlusal and distal surfaces of the lower right first molar.
Common Dental Charting Symbols and Colors
Charting symbols are not fully standardized. Paper charts, textbooks and software such as Dentrix, Eaglesoft or Open Dental each have their own legend. Still, most offices follow a similar logic:
- Color shows status. A widely used convention is red for conditions or treatment still needed and blue or black for existing restorations and work already completed. Some software uses different colors for completed, existing and planned work, so check your office’s legend.
- Missing tooth: usually a large X through the tooth.
- Tooth to be extracted: often two parallel lines or a red X, depending on the office.
- Decay (caries): the affected surface outlined or shaded in red.
- Filling: the restored surface outlined or filled in, often solid for amalgam and outlined for composite.
- Crown: the crown of the tooth outlined or cross-hatched.
- Root canal: a line drawn through the root or roots.
- Sealant: often an S on the occlusal surface.
- Bridge: crowns on the anchor teeth connected to an X or pontic on the missing tooth.
- Impacted tooth: commonly circled.
Classifying Decay with G.V. Black’s Classes
Dentists often describe cavities by class, so you’ll hear these called out during exams:
- Class I: pits and fissures, such as the occlusal surface of molars and premolars.
- Class II: mesial or distal surfaces of premolars and molars.
- Class III: mesial or distal surfaces of incisors and canines, not including the incisal edge.
- Class IV: mesial or distal surfaces of incisors and canines that include the incisal edge.
- Class V: the gumline third of the facial or lingual surface of any tooth.
- Class VI (added later): incisal edges of front teeth or cusp tips of back teeth.
Periodontal Charting Basics
Periodontal charting records gum health. The dentist or hygienist measures each tooth with a periodontal probe, usually at six sites (three on the cheek side and three on the tongue side), and calls out the numbers in millimeters. The assistant often records them. A periodontal chart may also note:
- Pocket depths at each site. Readings of about 1 to 3 mm are generally considered healthy; deeper readings get the dentist’s attention.
- Bleeding on probing, usually marked with a dot or red mark at that site.
- Recession, where the gum has pulled back from the tooth.
- Mobility, or how loose a tooth is, often graded on a simple scale.
- Furcation involvement, bone loss between the roots of multi-rooted teeth.
Readings come fast, so practice the order your office uses (for example, facial side of the upper arch first, then lingual) until you can keep up without asking for repeats.
How to Chart a Dental Exam Step by Step
Here is a simple routine for dental charting for dental assistants during a new-patient or periodic exam:
- Confirm the patient and open the right chart. Check the name and date of birth before you enter anything.
- Review existing records. Look at prior charting and radiographs so you know what restorations should already be there.
- Set up your screen or form in the order the dentist examines, usually starting at tooth #1 and moving through #32.
- Record existing conditions first: missing teeth, crowns, fillings, root canals, implants and bridges.
- Record new findings the dentist calls out, with tooth number, surface and condition (for example, “#14 DO caries”).
- Read it back. Repeat findings to the dentist to catch errors, especially left versus right and look-alike numbers like #13 and #30.
- Add periodontal readings if a perio exam is done.
- Check the entry is signed and dated under the right provider before you close the chart.
Accurate charting supports the treatment plan, insurance claims and the patient’s legal record. The U.S. Bureau of Labor Statistics lists keeping records of dental treatments among a dental assistant’s typical duties.
Texas Dental Record Rules That Affect Charting
In Texas, the dentist is responsible for the patient record, but the assistant’s entries become part of it. Under Texas Administrative Code Rule 108.8 (Records of the Dentist):
- Dental records include dental and periodontal charting, along with radiographs, diagnoses, treatment plans and progress notes.
- When services are provided, the record must include the findings and charting of the clinical and radiographic oral examination.
- The record must identify the provider dentist and the person making record entries if that is someone else, which is why your login or initials matter.
- Records must be kept for at least five years from the last date of treatment. If the patient was under 18 at the last visit, they must be kept until the patient turns 21 or for five years, whichever is longer.
Radiographs feed directly into charting, too. Texas doesn’t require a license to work as a dental assistant, but only Registered Dental Assistants (RDAs) can take dental X-rays, so RDA registration widens what you can do in the operatory.
Tips for Learning Dental Charting Faster
- Memorize the landmarks, not all 32 numbers. Know that #1, #16, #17 and #32 are the third molars, #8 and #9 are the upper central incisors, and #24 and #25 are the lower central incisors. You can count from there.
- Say it as you chart it. “Thirty, M-O-D, composite” builds the habit of tooth, surface, condition.
- Practice on a typodont or a printed chart. Have a classmate call out findings while you record them.
- Learn your office’s software early. Most systems let you click a tooth and surface, then pick a condition, which is much faster once the layout is familiar.
- Pair charting with dental instrument names. Knowing the mirror, explorer and probe makes it easier to follow the exam as it happens.
Charting, tooth numbering and terminology also show up on exams. Our RDA exam study guide covers what else to review, and our guide to four-handed dentistry explains how the assistant works alongside the dentist during exams and procedures.
Learn Dental Charting Hands-On at Houston Dental Assistant School
Houston Dental Assistant School (HDAS) in Houston, Texas offers a 10-week hybrid RDA program for $3,550 all in, including your textbook, materials, BLS certification and the TSBDE-approved RDA course and exam. Dental anatomy and terminology are taught in weeks 1 to 3, and patient examination is part of the chairside block in weeks 4 to 6. Lectures are online and on demand, and every Saturday you practice in a four-hour lab inside a working dental office, in a group of four or five. Instruction is available in English and Spanish, and payment plans start at $975 down.
We have campuses in Katy and The Woodlands/Spring, and our Pearland campus opens January 16, 2027. Learn more about our 10-week dental assistant program in Houston, see the full tuition breakdown, or schedule a Saturday tour to see a lab in person.
FAQ
What is dental charting?
Dental charting is the record of a patient’s oral condition, tooth by tooth. It shows missing teeth, existing restorations, decay and other findings, periodontal readings and planned treatment, using tooth numbers, surface abbreviations, symbols and colors.
What tooth numbering system is used in the United States?
U.S. dental offices use the Universal Numbering System. Adult teeth are numbered 1 to 32, starting with the upper right third molar and ending with the lower right third molar. Baby teeth are lettered A to T.
What do red and blue mean on a dental chart?
On many charts, red marks conditions or treatment still needed, such as decay or a tooth to extract, and blue or black marks existing restorations or completed work. Colors vary by office and software, so always check your office’s legend.
Do dental assistants do charting in Texas?
Dental assistants commonly record findings the dentist calls out, along with periodontal readings from the dentist or hygienist. The dentist remains responsible for the record, and Texas rules require the record to identify the person who made each entry.
How do I learn tooth numbers fast?
Anchor on landmarks: #1, #16, #17 and #32 are the third molars, #8 and #9 are the upper front teeth, and #24 and #25 are the lower front teeth. Then practice charting out loud on a printed chart or typodont for a few minutes each day.