How this tool works

The Gingival Index (Löe and Silness, 1963) grades gum inflammation, not plaque. Each tooth has four scored areas: buccal, lingual, mesial and distal. Each area gets a score from 0 to 3.

Tooth GI = sum of its four scores ÷ 4.
Patient GI = sum of the tooth GIs ÷ number of teeth scored.

Because every tooth has four areas, the patient GI is also the mean of all areas scored. The original papers divide by six, the number of index teeth. They didn't replace missing teeth, so the calculator divides by the teeth you actually scored. Tick Missing for a tooth that isn't there.

The papers also allow grouping by tooth type, so the calculator reports incisors, premolars and molars separately (and canines in whole-mouth mode).

Worked example (the pre-filled one): the six teeth sum to 6, 3, 3, 7, 5 and 3, for a total of 27 over 24 areas. GI = 27 ÷ 24 = 1.13. Rounded to one decimal that's 1.1, which falls in the moderate band.

Scoring criteria (paraphrased)

Score	What you see
0	No inflammation
1	Mild inflammation: slight color change, little change in texture
2	Moderate inflammation: redness, swelling, glazing; bleeds on pressure
3	Severe inflammation: marked redness and swelling, tendency to bleed on its own, ulceration

Later versions of the criteria (Löe, 1967) are often taught with "no bleeding on probing" for score 1 and "bleeding on probing" for score 2. Either way, any area scored 2 or 3 bleeds, so the calculator also counts those areas.

The six index teeth (Ramfjord teeth)

Löe and Silness examined six teeth, one from each segment of the mouth:

FDI	Universal	Tooth
16	#3	Upper right first molar
12	#7	Upper right lateral incisor
24	#12	Upper left first premolar
36	#19	Lower left first molar
32	#23	Lower left lateral incisor
44	#28	Lower right first premolar

The 1963 paper notes this relies on the six teeth representing the whole mouth. Many modern studies score every tooth. Choose Whole mouth to do that; third molars start as not scored, and you can include them.

Interpreting the score

To describe their patients, Löe and Silness (1963) grouped average GI scores into three levels: 0.1–1.0 mild, 1.1–2.0 moderate and 2.1–3.0 severe inflammation. The same ranges are now widely taught as the GI interpretation:

Patient GI	Interpretation
0.0	No inflammation
0.1–1.0	Mild gingivitis
1.1–2.0	Moderate gingivitis
2.1–3.0	Severe gingivitis

The paper used these groups to describe a study population, not as diagnostic cut-offs. The bands are printed to one decimal, so the calculator rounds the GI to one decimal before choosing a band. Report the number itself in research and keep the band as a description.

Limits

The GI records inflammation at the gum margin. It doesn't measure attachment loss, so it can't tell gingivitis from periodontitis. For that, use the Periodontitis Staging & Grading Calculator.
Scores depend on the examiner. Calibrate before a study.
Score plaque separately with the Plaque Index, which uses the same teeth and areas.

Frequently asked questions

How is the Gingival Index calculated?

Score the buccal, lingual, mesial and distal areas of each tooth from 0 to 3. The tooth score is the sum ÷ 4. The patient's GI is the sum of the tooth scores ÷ the number of teeth scored, which is the same as the mean of all the areas.

Which teeth are used for the Gingival Index?

Löe and Silness examined six teeth, one per segment of the mouth: 16, 12, 24, 36, 32 and 44 (FDI). These are often called the Ramfjord teeth. Many studies now score every tooth instead; switch to whole mouth for that.

What GI score means gingivitis?

The usual interpretation calls 0.1–1.0 mild, 1.1–2.0 moderate and 2.1–3.0 severe gingivitis. These are the groups Löe and Silness (1963) used to describe the average scores of their patients, not diagnostic cut-offs. A score of 2 at a single area already means bleeding on pressure.

What if one of the six teeth is missing?

The original papers didn't substitute missing teeth. Tick Missing and the calculator averages the teeth you did score.

Sources

Löe H, Silness J. Acta Odontologica Scandinavica 21:533-551. Periodontal disease in pregnancy. I. Prevalence and severity. 1963. Criteria and calculation in the Methods; grouping of average GI scores (mild, moderate, severe) on p.545. Accessed October 26, 2026.
Silness J, Löe H. Acta Odontologica Scandinavica 22:121-135. Periodontal disease in pregnancy. II. Correlation between oral hygiene and periodontal condition. 1964. Confirms the six teeth and that missing teeth were not substituted. Accessed October 26, 2026.
Löe H. Journal of Periodontology 38(6 Suppl):610-616. The Gingival Index, the Plaque Index and the Retention Index Systems. 1967. Accessed October 26, 2026.
Mandal SK (SlideShare teaching slides, secondary source). Periodontal indices final. Teaching material showing the same GI ranges. Accessed October 26, 2026.

Last reviewed October 26, 2026 by the Dental Health Time editorial team, against the sources above. How we review.