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Epidemiological indices in periodontology

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Epidemiological indices are used to obtain valid information about the extent and distribution of disease.
As examples of a variety of common epidemiological indices, the gingival index, the periodontitis index and the periodontal screening index are presented here.
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Gingival index (GI)

The gingival index was proposed by Löe and Silness in 1963 and was used for epidemiological recording of pregnancy gingivitis. The gingival index has been used in a large number of epidemiological studies.

Criteria for the gingival index:

Grade Description
0 No inflammation
1 Mild inflammation
  • Slight change in color
  • Slight change in texture
2 Moderate inflammation
  • Slightly glassy appearance
  • Erythema
  • Edema
  • Hypertrophy
3 Severe inflammation
  • Marked erythema and hypertrophy
  • Tendency to spontaneous bleeding
  • Ulceration

The gingival index is measured on six teeth that represent the six segments of the jaw.
In the maxilla, these are the right first molar, right lateral incisor and left first premolar.
In the mandible, the following teeth are measured: left first molar, left lateral incisor and right first premolar.
For each of these teeth, scores are given for each side of the tooth (buccal, lingual, mesial and distal). These scores for each side are added and divided by four to obtain the GI for each individual tooth. The scores of the individual teeth are used to calculate an average GI for the individual tooth groups (incisors, premolars and molars). The sum of the tooth group GIs divided by six gives the GI for the patient. The patient's GI is therefore an average of the obtained subgrades (Löe and Silness 1963).

Example of use:

Measurement of individual scores:

Tooth b-l/p-m-d Tooth grade Group
16 1-2-3-2 2 Molar
12 1-2-2-1 1.5 Incisor
24 2-0-0-0 0.5 Premolar
36 2-3-2-3 2.5 Molar
32 2-3-2-2 2.25 Incisor
44 2-3-2-2 2.25 Premolar

Obtaining group scores:

Group Grade
Molar 2.25
Incisor 1.88
Premolar 1.38

Total GI: 1.8

Periodontitis index (PI)

Because no sufficiently valid indices were available in the mid-twentieth century for measuring the prevalence and epidemiological characteristics of periodontal diseases, Russell published the periodontitis index (PI) in 1956, with which it is possible to measure the effects of periodontal disease with minimal equipment to enable quantitative comparisons between individual populations (Russell 1956).

The following table shows the periodontitis index grading:

Grade Description of the criteria Additional radiological criteria
0 Negative. No inflammation Radiologically normal
1 Mild gingivitis. Free gingiva inflamed around part but not all of the tooth.  
2 Gingivitis. Inflammation around the entire tooth. No attachment loss.  
4   Early wedge-like resorption of the alveolar ridge
6 Gingivitis with pocket formation. The epithelial attachment is interrupted. A pocket forms because of the gingival swelling. No impairment of function, the tooth sits firmly in the socket and is not tilted. Horizontal loss of alveolar bone of up to 50 %
8 Advanced destruction with loss of masticatory function. The tooth can be loose or mobile. Dull percussion note, can be pushed into the socket. Advanced bone loss over 50 %. Intraosseous pocket, widened periodontal sulcus. Possibly root resorption or rarefication.
If in doubt, the better grade is chosen (Russell 1956).

Periodontal Screening and Recording PSR (= Periodontal Screening Index (PSI))

The PSR or PSI is a time-saving examination used in practice to establish whether a patient has gingivitis or periodontitis and whether there is a treatment need. The teeth are divided into sextants and assessed with a code of 0-4. Codes 3 and 4 indicate periodontitis. Codes 1 and 2 indicate gingivitis.

Sextant Teeth
1 17-14
2 13-23
3 24-27
4 37-34
5 33-43
6 44-47

The measurement is taken with a WHO probe, which has a black band from 3.5–5.5 mm.

Code Probing depth Other features Diagnosis and treatment
0 < 3.5 mm No bleeding, no calculus, no projecting restoration margins Healthy

Recall (regular follow-up)
1 < 3.5 mm Bleeding, no calculus, no projecting restoration margins Gingivitis

Oral hygiene instruction
2 < 3.5 mm Bleeding may be present, calculus, projecting restoration margins Gingivitis

Professional tooth cleaning (PTC)
Contouring of filling margins if necessary
Oral hygiene instruction
3 > 3.5 mm to < 5.5 mm

(black band partly visible)

If code 3 in 2 or more sextants, diagnosis and treatment of the entire dentition
4 > 5.5 mm

(black band not visible)

Periodontal status and periodontitis therapy
(Weber 2010, p. 124; Wolf et al. 2012, p. 73)

Other indices

The following indices are commonly used:
  • O’Leary plaque index
  • Silness & Löe plaque index
  • PMA index
  • Sulcus bleeding index
  • Papilla bleeding index
  • Gingiva bleeding index
  • Modified bleeding index
  • Oral hygiene index
  • OHI-S
  • Quigley-Hein index
  • Turesky modification of the QHI
  • Visible plaque index
  • Community periodontal index
  • Extent & severity index
(Müller 2012, p. 82–84)


  • Löe, Harald; Silness, John (1963): Periodontal Disease in Pregnancy I. Prevalence and Severity. In: Acta odontologica Scandinavica 21, S. 533–551
  • Müller, Hans-Peter (2012): Checklisten der Zahnmedizin Parodontologie. 3., Auflage. Stuttgart: Georg Thieme Verlag (Checklisten der Zahnmedizin)
  • Russell, A. L (1956): A system of classification and scoring for prevalence surveys of periodontal disease. In: Journal of dental research 35 (3), 350–359
  • Weber, Thomas (2010): Memorix Zahnmedizin. 116 Tabellen. 3., vollst. überarb. und erw. Aufl. Stuttgart [u.a.]: Thieme
  • Wolf, Herbert F.; Rateitschak, Edith M.; Rateitschak, Klaus H. (2012): Parodontologie. 3., vollst. überarb. und erw. Aufl. Stuttgart: Georg Thieme Verlag (Farbatlanten der Zahnmedizin, 1)