This document discusses dental indices used to assess oral health conditions. It describes several limitations of index systems and classifications of indices. Indices can be classified based on whether the disease is reversible or irreversible, the causative factors, or the assessment method. Common indices for dental caries include the Prevalence Index, DMF Index, def Index, and DMF-S Index. The DMF Index is the most commonly used index to measure dental caries experience by counting the number of decayed, missing, and filled teeth. The def Index is similar but used for the primary dentition. Indices provide data for epidemiological studies, research, and oral health planning.

2. College of Dentistry
Community Dentistry
Epidemiology
Dr. Hazem El Ajrami

3. • Limitations of an index system:
1) An index properly used records objective
calibration of a particular factor of a
disease process but does not give the
operator a comprehensive picture of the
disease condition.
2) An index cannot be used for a pin-point
diagnosis or therapy for the patients.

4. 3) An error of judgment in calibration can
occur.
4) An index gives indication on the spot static
data but does not give a biological picture or
indication of dynamic process.

5. • Classification of indices:
Indices can be classified in different ways:
I. Classification according to nature of disease as:
A. Reversible: Reversible index is an index in
which scores attributed to the condition can be
reversed back to normal, as there is no
permanent damage. E.g. indices used to assess
gingival inflammation.
B. Irreversible: Irreversible index is an index in
which the condition cannot reverse back to
normal as the damage is a permanent damage.
E.g. index used to assess dental caries.

6. Gingival Inflammation

7. Dental Caries

8. II. Classification according to the cause or
causative factors responsible for the disease
e.g. calculus index, plaque index. In such
indices, the scores are given according to the
amount or extent of these factors present on
teeth.
III. Classification according to the condition for
which they are used, e.g. index used to assess
gingival inflammation, or index used to
assess periodontal condition.

10. Gingival Inflammation
Periodontal Condition

11. IV. Classification according to the method or
material used for assessment:
A. Simple: Simple index is one which can be
easily applied to the field studies and which
does not require any costly equipment,
material or complicated method.
B. Complex: Complex index is one which
requires costly equipment or complicated
method.

15. • Uses of Dental Indices:
1. To study the oral health status of population.
2. To study incidence and prevalence of oral
diseases.
3. To study etiological factors responsible for
oral diseases.
4. For collection of data in epidemiological
studies.
5. For research work.
6. For national and local planning for oral
health.

16. • Indices Used For The Assessment of Dental
Caries:
1. Prevalence Index.
2. DMF Index.
3. The def Index.
4. DMF-S Index.
5. Slack Index.
6. Caries Index of Treatment Needs (CCITN).

17. 1. Prevalence Index:
It is the simplest index used for dental
caries. It describes whether the disease is
present or absent. This is useful mostly when
observing and comparing populations with
wide difference in caries experience. Here, a
simple count of persons (units of
measurement) with and without signs of
caries, may be adequate to establish the
relative prevalence.

18. Number of all cases affected
with caries
The prevalence rate = -----------------------------------
Total population

19. 2. DMF Index:
Decayed plus missing plus filled teeth. It is
the commonest, of the current dental caries
measurements. Each permanent tooth is
considered individually and if it is decayed
(D), missing due to caries (M) or filled (F) it
scores one. The total number of the affected
teeth in an individual gives an individual
dental caries experience (individual DMF).

20. The average number of DMF teeth for a
group is found by dividing the total number of
the affected teeth of the individuals by the
number of individuals in the group.
• N.B.: Here the unit of measurement is the
tooth.

21. • In scoring this index, the examiner notes the
condition of each tooth, and no tooth is counted
more than once. For example, a tooth that
exhibits recurrent caries around an existing
restoration is scored as decayed. Often, it is
possible to elicit from the person why a tooth is
absent. This is important, as teeth that are
unerupted, congenitally missing, or extracted for
orthodontic purposes are not usually counted as
missing. The maximum DMF count is 28.

22. Number of D+M+F teeth
DMF Index =
Total number of examined individual

23. 3. The def Index:
This is an index for the primary dentition
where (d) denotes decayed deciduous teeth
indicated for filling, (e) indicates decayed
deciduous tooth indicated for extraction, and (f)
indicates filled deciduous teeth. Teeth missing,
for any reason were not recorded, and because
of this it may be regarded as a measurement of
observable dental caries prevalence.

25. A disadvantage of this index is that when a
population of children has received widespread
extraction because of dental caries may actually
show a lower def average than children in
another population with fewer carious lesions in
primary teeth. Often, however, the index has
been used in the same way as the DMF index
for the permanent dentition (i.e. dmf) thus
making it a measurement of the past and present
dental caries experience.

26. • Index used for children older than age six or
seven.
Number of d + e + f teeth
def Index =
Total number of primary teeth

27. • Since teeth indicated for extraction because of
advanced caries are, in fact, decayed, the index is
sometimes scored as if it were simply df.

28. Thank You