How this tool works
One patient. Each tooth on the chart holds one status: sound, D (decayed), M (missing because of caries), M other (missing for another reason), F (filled, no decay) or excluded. The calculator then applies the WHO 2013 counting rules and adds D + M + F. Switch "Record by" to Surface to score DMFS: select a tooth, then tap each surface to cycle sound, D and F.
Group or survey. Enter each person's age and D, M and F counts, or paste them as CSV. You get the mean, sample SD, median, % caries-free, the SiC index, the share of D, M and F in the total, and the WHO severity band when the group fits one. Download everything as CSV.
Nothing you enter leaves your browser. Share links carry tooth codes, ages and counts only, never names.
WHO counting rules
| What you see | WHO crown code (permanent / primary) | Counts as |
|---|---|---|
| Sound tooth, sealant, or crown/veneer/abutment not placed for decay | 0, 6, 7 / A, F, G | Not counted |
| Decay, including a filled tooth with new decay | 1 or 2 / B or C | D |
| Filled, no decay | 3 / D | F |
| Missing because of caries | 4 / E | M |
| Missing for any other reason | 5 / – | M only from age 30 |
| Unerupted or not recorded | 8, 9 / – | Excluded |
Three rules cause most scoring errors:
- The age-30 rule. Under 30, only teeth missing because of caries count as M. From 30 on, WHO counts teeth missing for any reason. Set the age and the calculator does this for you; the record table marks teeth "not counted".
- One tooth, one letter. A tooth with both a filling and decay is D, not D and F.
- Third molars count. The DMFT base is 32 teeth, so the index runs from 0 to 32.
Surfaces (DMFS and dmfs)
WHO provides surface forms but doesn't state a surface count. This tool uses the usual convention: 5 surfaces on premolars and molars (mesial, occlusal, distal, buccal, lingual) and 4 on incisors and canines (the incisal edge isn't scored). A missing tooth counts as all its surfaces.
| Index | Teeth | Maximum (derived from the convention) |
|---|---|---|
| DMFS | 32 permanent | 148 |
| DMFS | 28 permanent (no third molars) | 128 |
| dmfs | 20 primary | 88 |
These maximums are simple arithmetic, not WHO figures. If your protocol scores surfaces differently, adjust before comparing.
Primary and mixed dentition: dmft and deft
Lower-case letters score primary teeth the same way. In dmft, m means a tooth lost to caries at an age when normal shedding can't explain the gap. deft uses e for teeth extracted because of caries, and because shed teeth are hard to tell from extracted ones, many surveys leave missing primary teeth out. With the same findings, both give the same total here.
In mixed dentition, record a permanent tooth and its primary predecessor only once: WHO keeps the permanent tooth. The calculator warns you if both are marked present. "Typical teeth for this age" pre-excludes teeth that usually haven't erupted or have usually shed at that age, using the ADA eruption charts.
Group results: SiC index and WHO bands
The SiC index (Bratthall, 2000) is the mean DMFT of the third of the group with the highest scores. Bratthall proposed a global goal of SiC below 3 in 12-year-olds. The paper doesn't say how to handle a group that doesn't split evenly into thirds. We round n ÷ 3 to the nearest whole person and show the count used.
The WHO severity criteria apply to population means, never to one person:
| Level | 12-year-olds | Adults 35–44 |
|---|---|---|
| Very low | under 1.2 | under 5.0 |
| Low | 1.2–2.6 | 5.0–8.9 |
| Moderate | 2.7–4.4 | 9.0–13.9 |
| High | 4.5–6.5 | over 13.9 |
| Very high | over 6.5 | – |
A mean between two printed bands (for example 2.65) is placed in the lower band. WHO doesn't give numeric bands for other ages or for dmft.
Limits
DMFT records caries experience, not current treatment need, and it treats a small filling and a lost tooth alike. For gum health, pair it with the Gingival Index or the OHI-S.
Frequently asked questions
How do you calculate DMFT?
Do missing wisdom teeth count in DMFT?
What is the difference between dmft and deft?
What is the SiC index?
Can I use the WHO severity bands for one patient?
Sources
- World Health Organization (Petersen PE, Baez RJ). Oral health surveys: basic methods, 5th edition. 2013. Dentition status codes pp.43-47; DMFT rules p.47; severity criteria p.74. Accessed October 26, 2026.
- Bratthall D. International Dental Journal 50(6):378-384. Introducing the Significant Caries Index together with a proposal for a new global oral health goal for 12-year-olds. 2000. Accessed October 26, 2026.
- Nishi M, Stjernswärd J, Carlsson P, Bratthall D. Community Dentistry and Oral Epidemiology 30(4):296-301. Caries experience of some countries and areas expressed by the Significant Caries Index. 2002. Accessed October 26, 2026.
- Association of Public Health Epidemiologists in Ontario (APHEO). 6C deft/DMFT Index. Accessed October 26, 2026.
- American Dental Association (MouthHealthy). Permanent Tooth Development (eruption chart). 2012. Used only for the "typical teeth for this age" button. Accessed October 26, 2026.
- American Dental Association (MouthHealthy). Primary Tooth Development (eruption chart). 2012. Accessed October 26, 2026.
Last reviewed by the Dental Health Time editorial team, against the sources above. How we review.